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1
Bhatt, Hemanshu D. "Effect of interfacial thermal conductance and fiber orientation on the thermal diffusivity/conductivity of unidirectional fiber-reinforced ceramic matrix composites." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07282008-135034/.
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Shayed, Mohammad Abu, Heike Hund, Rolf-Dieter Hund, and Chokri Cherif. "Thermal and oxidation resistant barrier on carbon fiber with Si and Si–Ti based pre-ceramic coatings for high temperature application." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35416.
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Carbon fiber (CF) must be protected from thermal oxidation for high temperature application because of its low thermo-oxidative stability above 450°C in air. CF is now increasingly being used as a reinforcing material in the construction industry. A thermal and oxidation resistant coating is necessary for CF-reinforced concrete (CFRC) composites in order to satisfy a high level of safety standard in the case of fire. New types of pre-ceramic coatings, such as Tyranno® polymer (Si–Ti based pre-ceramic) and SiO₂ sol–gel, have been deposited on CF filament yarn by means of a wet chemical continuous dip coating method. The results of surface analyses, e.g. scanning electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy, showed the changes in topographical properties of CF caused by the coatings. Thermogravimetric analysis proved that the high temperature (up to 800°C) oxidation stability of CF was considerably improved due to the coatings. Tensile test results indicated that the strength of CF yarn at 20°C was increased by up to 80% with the coatings. Thermo-mechanical properties were also enhanced up to 600°C. CF yarn retains its original strength and elasticity modulus, i.e. the stiffness at 700°C, with a Tyranno® polymer coating.
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Terril, Nathaniel D. "Field Simulation for the Microwave Heating of Thin Ceramic Fibers." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36863.
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Microwave processing of ceramics has seen a growth in research and development efforts throughout the past decade. One area of interest is the exploration of improved heating control through experiments and numerical modeling. Controlled heating may be used to counteract non-uniform heating and avoid destructive phenomena such as cracking and thermal runaway. Thermal runaway is a potential problem in materials with temperature dependent dielectric properties. As the material absorbs electromagnetic energy, the temperature increases as does its ability to absorb more energy. Controlled processing of the material may be achieved by manipulating the applied field. The purpose of this research is to model the interaction of the EM-field with a thin ceramic fiber to investigate possible mechanisms that may affect the heating process. The fiber undergoes microwave heating in a single-mode resonant applicator. Maxwell's equations for the fields within the cavity are solved using mode-matching techniques taking into account the field interaction of the fiber and an arbitrarily shaped coupling aperture. Effects of varying the aperture shape on the field distribution are explored. The coupled nature of the electromagnetic solution with the material's temperature-dependent properties, including an analysis of non-uniform heating, is also discussed.Master of Science
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Depalma, Carlos Mariano A. "The role of the thermal contact conductance in the interpretation of laser flash data in fiber-reinforced composites." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10062009-020306/.
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Zahedi, Maryam. "Meshfree Method for Prediction of Thermal Properties of Porous Ceramic Materials." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/954.
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In the presented thesis work, meshfree method with distance fields is applied to create a novel computational approach which enables inclusion of the realistic geometric models of the microstructure and liberates Finite Element Analysis(FEA) from thedependance on and limitations of meshing of fine microstructural feature such as splats and porosity.Manufacturing processes of ceramics produce materials with complex porosity microstructure.Geometry of pores, their size and location substantially affect macro scale physical properties of the material. Complex structure and geometry of the pores severely limit application of modern Finite Element Analysis methods because they require construction of spatial grids (meshes) that conform to the geometric shape of the structure. As a result, there are virtually no effective tools available for predicting overall mechanical and thermal properties of porous materials based on their microstructure. This thesis is a separate handling and controls of geometric and physical computational models that are seamlessly combined at solution run time. Using the proposedapproach we will determine the effective thermal conductivity tensor of real porous ceramic materials featuring both isotropic and anisotropic thermal properties. This work involved development and implementation of numerical algorithms, data structure, and software.
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Chawla, Prashant. "Exploratory investigation of solar photothermal effects on carbon fibers." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/8659.
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Simmons, Jed. "OPTICAL AND PHYSICAL PROPERTIES OF CERAMIC CRYSTAL LASER MATERIALS." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4123.
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Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near the reported values for single crystal Nd:YAG. With a similar experimental setup as that for the thermal expansion measurements, dn/dT for ceramic crystal Nd:YAG was measured and found to be slightly higher than the reported value for single crystal. Depolarization loss due to thermal gradient induced stresses can limit laser performance. As a result this phenomenon was modeled for ceramic crystal materials and compared to single crystals for slab and rod shaped gain media. This was accomplished using COMSOL Multiphysics, and MATLAB. Results indicate a dependence of the depolarization loss on the grain size where the loss decreases with decreased grain size even to the point where lower loss may be expected in ceramic crystals than in single crystal samples when the grain sizes in the ceramic crystal are sufficiently small. Deformation-induced thermal lensing was modeled for a single crystal slab and its relevance to ceramic crystal is discussed. Data indicates the most notable cause of deformation-induced thermal lensing is a consequence of the deformation of the top and bottom surfaces. Also, the strength of the lensing along the thickness is greater than the width and greater than that due to other causes of lensing along the thickness of the slab. Emission spectra, absorption spectra, and fluorescence lifetime were measured for Nd:YAG ceramic crystal and Yb:Lu2O3 ceramic crystal. No apparent inhomogeneous broadening appears to exist in the Nd:YAG ceramic at low concentrations. Concentration and temperature dependence effects on emission spectra were measured and are presented. Laser action in a thin disk of Yb:Y2O3 ceramic crystal was achieved. Pumping was accomplished with a fiber coupled diode laser stack at 938 nm. A slope efficiency of 34% was achieved with maximum output energy of 28.8 mJ/pulse.Ph.D.
Department of Physics
Sciences
Physics PhD
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Prasad, Ajit. "Influence of processing variables on the mechanical properties of SiC fibers prepared by chemical vapor deposition." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19651.
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Yang, Fan. "Electrical and thermal properties of yttria-stabilised zirconia (YSZ)- based ceramic materials." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/electrical-and-thermal-properties-of-yttriastabilised-zirconia-ysz-based-ceramic-materials(82568afe-ffcb-4a38-9166-e5de83337763).html.
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Electrical and thermal conductivities of the yttria-stabilised zirconia/alumina (YSZ/Al2O3) composites and the yttria-zirconia-ceria (YSZ-CeO2) solid solutions are studied in this thesis. The electrical conductivity of the YSZ/Al2O3 composites decreases with an increase in the volume fraction of Al2O3 and exhibits typical percolation behaviour. The electrical conductivity of the YSZ/Al2O3 interface is higher than that of the YSZ grain boundary, but lower than that of the YSZ grains. The thermal conductivity of the YSZ/Al2O3 composites increases with an increase in the Al2O3 volume fraction, and it can be fitted well to the Maxwell theoretical model, which indicates the absence of obvious interfacial thermal resistances in the composites. The low interfacial thermal resistance of the YSZ/Al2O3 interface is due to the 'clean' and coherent nature of the YSZ/Al2O3 interface, along with the small difference between the elastic properties of YSZ and Al2O3. The electrical conductivity of the [(ZrO2)1-x(CeO2)x]0.92(Y2O3)0.08 (0 ≤ x ≤ 1) solid solutions has a 'V-shape' variation as a function of the mole ratio of CeO2 (x). In the ZrO2-rich region (x < 0.5), CeO2 doping increases the concentration of defect associates which limits the mobility of the oxygen vacancies; in the CeO2-rich region (x > 0.5), the increase of x increases the lattice parameter, which enlarges the free channel for oxygen vacancy migration. A comparison of the YSZ-CeO2 solid solutions with the YSZ-HfO2 series indicates the ionic radius of the tetravalent dopant determines the composition dependence of the ionic conductivity of the solid solutions.The thermal conductivity of the [(ZrO2)1-x(CeO2)x]0.92(Y2O3)0.08 (0 ≤ x ≤ 1) solid solutions also has a 'V-shape' variation as a function of the mole ratio of CeO2 (x), which indicates an incorporation of Zr4+ and Ce4+ can effectively decrease the thermal conductivity of the end members YSZ and yttria-doped ceria (YDC). In the ZrO2-rich region (0 ≤ x ≤ 0.5), the thermal conductivity is almost temperature independent; in the CeO2-rich region (0.5 ≤ x ≤ 1), it decreases obviously with increasing temperature. By calculating the phonon scattering coefficients, it is concluded that the composition dependence of the thermal conductivity in the ternary solid solutions is dominated by the mass difference between Zr and Ce at the cation sites, whereas the temperature dependence is determined by the order/disorder of oxygen vacancies at the anion sites.
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Govindarajan, Raghavan. "Evolution of structure and properties during thermal annealing of poly(para-BENZOBISOXAZOLE) (PBO) fibers." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/8531.
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Bai, Yiqun. "Structure and properties of linear and star-like thermotropic liquid crystalline polymeric fibers." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/9976.
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Namjoshi, Shanatanu Ashok. "Reaction synthesis of dynamically-densified Ti-based intermetallic and ceramic forming powders." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19572.
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Aldridge, Matthew. "Aspects of the processing, mechanical properties and thermal shock behaviour of a ductile particle toughened alumina." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/605/.
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Johnson, Carter David. "Examination of lignocellulosic fibers for chemical, thermal, and separations properties addressing thermo-chemical stability issues /." [Ames, Iowa : Iowa State University], 2007.
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Furlong, Scott Davis. "Reduction of radiated thermal conductivity in thin-wall hollow ceramic spheres using scattering phases." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/9341.
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Hicks, David Cyprian. "Aligned Continuous Cylindrical Pores Derived from Electrospun Polymer Fibers in Titanium Diboride." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/99423.
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The use of electrospun polystyrene (PS) fibers to create continuous long range ordered multi-scale porous structures in titanium diboride (TiB2) is investigated in this work. The introduction of electrospun PS fibers as a sacrificial filler into a colloidal suspension of TiB2 allows for easy control over the pore size, porosity, and long range ordering of the porous structures of the sintered ceramic. Green bodies were formed by vacuum infiltrating an electrospun-fiber-filled mold with the colloidal TiB2 suspension. The size, volume, distribution, and dispersion of the pores were optimized by carefully selecting the sacrificial polymer, the fiber diameter, the solvent, and the solid content of TiB2. The green bodies were partially sintered at 2000 C in argon to form a multiscale porous structure via the removal of the PS fibers. Aligned continuous cylindrical pores were derived from the PS fibers in a range of ~5 - 20 μm and random porosity was revealed between the ceramic particles with the size of ~0.3 - 1 μm. TiB2 near-net-shaped parts with the multi-scale porosities (~50 to 70%) were successfully cast and sintered. The multi-scale porous structure produced from electrospun fibers was characterized both thermally and mechanically, at room temperature. The conductivity ranged from 12-31 W m^(-1) K^(-1) at room temperature and the compressive strength ranged from 2-30 MPa at room temperature. Analytical thermal and mechanical models were employed to understand and verify he processing-structure-properties relationship. Finally, a method was devised for estimating the effective thermal conductivity of candidate materials for UHTC applications at relevant temperatures using a finite difference model and a controlled sample environment. This low-cost processing technique facilitates the production of thermally and mechanically anisotropic structures into near-net shape parts, for extreme environment applications, such as ultra high temperature insulation and active cooling components.MS
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Stadelmann, Richard. "Mechanical Properties and Thermal Residual Stresses of ZrB2-SiC Ceramic Composites for Hypersonic Vehicle Applications." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6022.
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Ultra High Temperature Ceramic (UHTC) ZrB2- 10, 20, 30wt%SiC composites are of high interest for use in hypersonic air-breathing vehicles. In this work, ZrB2- 10, 20, 30wt%SiC UHTC composites were produced by the Spark Plasma Sintering (SPS) technique. After sintering, almost dense ceramics with ~ 5-8% porosity were produced. Their mechanical properties, such as Young's, shear, and bulk moduli, along with Poisson's ratio, 4-point bending strength, and single edge V-notched beam (SEVNB) fracture toughness were measured. In addition, in-situ bending experiments under a Raman microscope were performed to determine the piezo-spectroscopic coefficients of SiC Raman active peaks for calculation of thermal residual stresses. The results show that these materials are possible candidates for hypersonic air-breathing vehicles due to their high Young's modulus, ability to withstand high temperatures, and relatively low densities.M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Thermofluid Aerodynamic Systems
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Mishra, Ketaki. "From the determination of thermal properties of fibers to multiscale modeling of heat transfer in composites." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4047.
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La prédiction de la conductivité effective des composites nécessitent des informations aux petites échelles et le développement de modèles pertinents. Dans notre travail, la méthode 3ω est utilisée pour estimer la conductivité thermique axiale et radiale ainsi que la capacité thermique volumique de fibres de carbone. En utilisant des modèles analytique et numérique, une analyse de sensibilité est effectuée pour choisir une plage de fréquence de travail appropriée. Une source de courant constante sur la méthode 3ω utilisé pour mesurer la conductivité thermique de chromel et de fibres de carbone de type FT300B et FT800H. Les conductivités thermiques axiales estimées sont en accord avec les valeurs de la littérature. La conductivité thermique radiale estimée pour la fibre de carbone FT300B est 10 fois inférieure à la valeur axial et affiche une incertitude bien plus incertitude bien plus grande en raison de faibles coefficients de sensibilité La conductivité thermique effective a été calculée à l’aide d’une technique d’homogénéisation pour des microstructures avec des carrées uniformes (100 fibres) et bandes de composites (700 fibres). Un modèle thermique 3D est développé pour la simulation de la dépose de bandes chauffées par une source laser dans placement automatique de fibres (AFP). Des maillages adaptés aux microstructures des bandes Solvay et Suprem sont générés. La distribution de la source de chaleur dans le composite au cours de sa fabrication a été calculée. Son influence sur la distribution de la température montre une forte inhomogénéité de la température à l'intérieur de la bande. La température moyenne calculée est comparée aux résultats expérimentaux. Les résultats confirment le besoin de modèles continus spécifiquesThe prediction of effective thermal properties of composite requires information at small scale and also appropriate numerical 3D models able to account explicitly the local distribution of fibers. In our work, the 3ω method is used for estimating the axial and radial thermal conductivities and volumetric heat capacity of single carbon fiber. Using analytical and numerical models, a sensitivity analysis is performed for choosing a proper frequency range. A constant current source with differential and lock-in amplifiers are used to measure the thermal conductivity of chromel, and FT300B, FT800H carbon fibers. The measured axial thermal conductivities are in good comparison with the literature values. The estimated radial thermal conductivity of FT300B carbon fiber is 10 times lower than the axial one and shows much larger confidence band due to smaller. sensitivity coefficients. The computation of the effective thermal conductivity by homogenization technique is done for uniform square cell microstructures (100 fibers) along with composite tapes (700 fibers). The effective properties of tapes are interesting for advanced manufacturing techniques such as Automated Fiber Placement (AFP). A 3D thermal model is developed for the tapes heated by a laser source. Meshes in resemblance to the multiple microstructures of Solvay and Suprem tapes are generated. The heat source distribution within the composite during manufacturing is presented and the temperature distribution shows a strong inhomogeneity of the temperature inside the tape. The calculated average temperature is compared with the experimental results. Results confirm the need for specific continuous models
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Tsoi, Marvin S. "Modeling of thermal properties of fiber glass polyester resin composite under thermal degradation condition." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4711.
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Composites, though used in a variety of applications from chairs and office supplies to structures of U.S. Navy ships and aircrafts, are not all designed to hold up to extreme heat flux and high temperature. Fiber-reinforced polymeric composites (FRPC) have been proven to provide the much needed physical and mechanical properties under fire exposure. FRPC notable features are its combination of high specific tensile strength, low weight, along with good corrosion and fatigue resistance. However FRPC are susceptible to thermal degradation and decomposition, which yields flammable gas, and are thus highly combustible. This property restricts polymeric material usage. This study developed a numerical model that simulated the degradation rate and temperature profiles of a fiber-reinforced polyester resin composite exposed to a constant heat flux and hydrocarbon fire in a cone calorimeter. A numerical model is an essential tool because it gives the composite designer the ability to predict results in a time and cost efficient manner. The goal of this thesis is to develop a numerical model to simulate a zonal-layer polyester resin and fiber-glass mat composite and then validate the model with experimental results from a cone calorimeter. By inputting the thermal properties of the layered composite of alternating polymer and polymer-infused glass fiber mat layers, the numerical model is one step closer to representing the experimental data from the cone calorimeter test. The final results are achieved through adding a simulated heat flux from the pilot ignition of the degraded gas of the polyester resin. The results can be coupled into a mechanical model, which may be separately constructed for future study on the mechanical strength of composites under fire conditions.ID: 030646184; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 53-54).
M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Thermo-Fluids Track
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Jadhav, Amol D. "Processing, characterization, and properties of some novel thermal barrier coatings." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1183851697.
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Graham, Samuel Jr. "Effective thermal condutivity of damaged composites." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16935.
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Connor, Daniel Martin. "Design and synthesis of comonomers to enhance the optical, physical, and thermal properties of poly(ethylene terephthalate)." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/29882.
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Kelly, JoEllen. "A numerical and experimental investigation of the effects of thermal history on the structure/property relationship of PPS/carbon fiber composites." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39780.
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The purpose of this investigation was to examine the effects of thermal history during cooling from the melt on the degree of crystallinity, morphology, and mechanical properties of (polyphenylenesulfide) PPS/carbon fiber composites. Three thermal treatments were employed in this study: isothermal crystallization from the melt at 140,160,180,200, and 220°C, quenching from 315° C and then annealing at 160 and 200° C, and nonisothennal crystallization from the melt at rates varying from 0040 C/minute to 68° C/second. The effect of varying the thermal history of the sample on the degree of crystallinity developed in the matrix polymer was determined using differential scanning calorimetry. The effect of thermal history on and the resulting matrix morphology was examined by scanning electron microscopy. The subsequent effects of the degree of crystallinity and the morphology on the mechanical behavior of the samples were monitored by transverse tensile tests and flexural tests. In all cases, the transverse tensile and flexural moduli increased as the amount of crystallinity in the samples increased. However, samples with greater amounts of crystallinity did not always yield higher transverse tensile or flexural strengths. Upon examination of the composite samples by electron microscopy, it was observed that trends in the values of the transverse tensile and flexural strengths could be correlated with structural changes in the matrix.
This paper is concerned with the simulation of the development of crystallinity and morphology (both amount of crystallinity and the size of spherulites) which arise during the cooling of a slab of a semicrystalline polymer reinforced with long continuous carbon fibers. This situation is commonly found during the processing of semicrystalline thermoplastic composites. Whereas published attempts at simulating this process have treated the composite material as a continuum and thereby used mass averaged physical properties (such as thermal conductivity, density, and specific heat), we use a quasi-continuum approach in which locally we consider the properties of the matrix and fiber separately. Once a temperature distribution is calculated using the continuum approach, the fmite element method is applied locally at various points in the slab to calculate the amount of crystallinity and the size of the developing spherulites. This is done by using the Avrami equation and the Hoffman and Lauritzen radial growth equation. The amount of crystallinity and the spherulite size are predicted as a function of fiber spacing and packing geometry, and the predictions are found to be in good agreement with experimental results obtained on polyphenylenesulfide/carbon fiber composites. The advantages of our approach over the continuum approach is that a relatively accurate prediction of the spherulite size is possible due to constraints imposed by the fiber on the spherulitic growth.Ph. D.
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Russ, William M. "Structure, property, and processing relationships of CMZP - [(Ca0.6,Mg0.4)Zr₄(PO₄)₆]." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/40630.
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Appiah, Kwadwo Ampofo. "Microstructural and microanalytical characterization of laminated (C-SiC) matrix composites fabricated by forced-flow thermal-gradient chemical vapor infiltration (FCVI)." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/14910.
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Raheem-Kizchery, Ayesha Rubiath. "Ceramic coatings for silica and sapphire optical waveguides for high temperature embedding and sensing." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09052009-040217/.
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Almansour, Amjad Saleh Ali. "USE OF SINGLE TOW CERAMIC MATRIX MINICOMPOSITES TO DETERMINE FUNDAMENTAL ROOM AND ELEVATED TEMPERATURE PROPERTIES." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron148640184494135.
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Almadi, Alaa. "Investigating mechanical properties of ordinary portland cement : investigating improvements to the mechanical properties of Ordinary Portland Cement (OPC) bodies by utilizing the phase transformation properties of a ceramic (zirconia)." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/7315.
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The effects of metastable tetragonal zirconia on the properties of Ordinary Portland Cement were observed during which the effect of crystallite size pH on the preparation solution, precursor salt, and the presence of co-precipitates, Fe(OH)3, SnO2 and SiO2 on the crystallization temperature, enthalpy and crystal structure, immediately following the crystallization exothermic burst phenomenon in ZrO2 were measured. Thermal analysis and x-ray methods were used to determine crystallite sizes and structures immediately following the exothermic burst. Comparisons were made for zirconias prepared from oxychloride, chloride and nitrate solutions. The existence of tetrameric hydroxidecontaining ions in oxychloride precursor is used to rationalise low values of crystallization enthalpy. The position of the crystallization temperature, Tmax was not dependent on crystallite size alone but also on the pH at which the gel was made, the surface pH after washing, and the presence of diluent oxides. Enthalpy v r1/2 and Tmax v (diluent vol)1/3 relationships indicate that surface coverage effects dominate a surface nucleated phenomenon. The data established for ZrO2 systems was used to develop tetragonal-ZrO2-SnO2 powders capable of improving the mechanical properties of Ordinary Portland Cement discs. The ZrO2-OPC discs were prepared by powder mixing, water hydration and uniaxial pressing. Vicat needle tests showed that tetragonal-ZrO2 increases the initial setting rate. Microscopy indicated that porosity distribution changes near to ZrO2 particles. Zirconia has also been introduced into OPC discs by vacuum infiltration methods developed for solutions and colloidal suspensions. Comparisons between OPC discs and the OPCtetragonal ZrO2 composites have been made on the basis of diametral compression strength, Young’s modulus, hardness and toughness (K1c), as estimated by the cracked indentation method. Bell-shaped curves are found for the way the mechanical properties are changed as a function of Zirconia content.
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Apreutesei, Mihai. "Temperature impact on thermal evolution of advanced PVD ceramic and metallic glass thin films : Physico-chemical and microstructural analysis." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0009/document.
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Ces dernières années, les exigences de l'industrie dans le développement de nouveaux matériaux fonctionnels en mesure de résister aux conditions difficiles pendant l'opération d'usinage sont en constante augmentation. Les chercheurs doivent donc trouver de nouvelles solutions pour répondre aux besoins industriels de plus en plus sévères. L’utilisation de revêtement protecteur à la surface de l’outil de coupe est une solution très efficace. Des nouveaux matériaux architecturés sont étudiés pour leurs propriétés mécaniques, physiques et chimiques uniques assurant une résistance aux dégradations de surface dues à la corrosion, l'usure, le frottement; en particulier lorsque ces outils sont utilisés dans des environnements hostiles. Dans le cadre de cette thèse de doctorat, l'influence de la température sur la stabilité structurale de deux types de films minces déposés par PVD a été étudiée. Des films céramiques et de verre métallique ont été envisagés. Afin de préparer et optimiser ces films, le projet s’est axé sur l'étude de l'influence des conditions de dépôt sur les caractéristiques de croissance du film: composition chimique, structure, morphologie, puis sur les changements ultérieurs des principales propriétés des films minces, à savoir la résistance à l’oxydation et à la cristallisation lors de leur utilisation à hautes températures. Une démarche multi-échelle a été développée pour caractériser au mieux les couches. La première partie du travail est liée aux revêtements céramiques à base de CrN pour donner de nouvelles fonctionnalités et améliorer la surface des outils de coupe dans le but essentiel d'accroître leur durée de vie. La seconde partie du manuscrit est dédiée aux films minces de verres métalliques de Zr-Cu préparés par un procédé de co-pulvérisation magnétron PVD. Le but de cette partie consiste en l’étude de la relation entre la structure amorphe de ces films et leurs propriétés mécaniques. La conservation du caractère amorphe de ces films en température présente également un caractère essentiel. Les verres métalliques ont récemment attiré un fort intérêt car ils présentent des propriétés mécaniques intéressantes à température ambiante. Ils présentent, de ce fait, un grand potentiel pour des applications d'ingénierie en raison de leurs caractéristiques mécaniques et physico-chimiques uniques (haute limite élastique, résistance à la corrosion ...). Pour relier les propriétés mécaniques des couches à l’évolution de leurs microstructures, une partie importante de ce travail a porté sur l’observation de l’évolution de la couche au cours du chauffage au moyen de techniques de caractérisation in situ. Les films minces proposés au cours de ce travail peuvent être envisagées pour un large gamme d’application dans l’ingénierie de surface pour protéger les surfaces et améliorer la durée de vie des matériauxIn the recent years the industrial requirements to develop new functional materials able to overcome the severe conditions during machining operation are continuously increasing. Researchers then must find novel solutions to respond to their severe industrial requirements. To coat the tool surface with advanced coatings is the most efficient solution. New nanostructured materials may nowadays exhibit unique mechanical, physical and chemical properties ensuring notable degradation resistance where the surface protection of materials against corrosion, wear, friction or oxidation is a key issue, particularly when operating in hostile environments. Within the scope of this Ph.D. thesis the influence of the temperature on the structural stability of two different PVD ceramic and metallic glass thin films is proposed. The main goal consists in the development of two distinct classes of thin films, with a wide range of properties. In order to prepare these films, the project will be focused on the study on the influence of PVD deposition conditions in the particular film’s growth characteristics: chemical composition, structure, morphology and the subsequent changes in the main properties of the thin films, namely oxidation and crystallization resistance, especially. For that purpose we adopted the multiscale approach. The first part is related to the ceramic CrN-based coatings to give new functionalities and improve the tools’ surface with the primary aim to increase their lifetime. Secondly, new protective materials able to better protect the exposed surfaces against high temperature oxidation have been proposed, namely CrAlN and CrAlYN coatings as will be evidenced in this manuscript. The second part of the manuscript is dedicated to the innovative Zr-Cu thin films metallic glasses prepared by a PVD magnetron co-sputtering method with the objective to investigate the amorphization ability and their structural properties. Their excellent properties at room temperature have recently attracted attention as a new class of materials with great potential for engineering applications due to unique mechanical and physico-chemical characteristics (high elastic strain limit, corrosion resistance…). Finally, an important approach during the course of this thesis was the real time observation of the structure and surface modifications during heating by means of in situ methods. The thin films proposed during the course of the work could be straightforward used as surface engineering solutions to protect and extend the lifetime of the materials and components
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Novotný, David. "Vliv anorganických vláken na fyzikálně mechanické vlastnosti cihlářského střepu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265311.
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This diploma thesis will discuss possibilities of using inorganic fibers to improve the mechanical properties of the resulting physical body bricks. Assessment of the effect of fiber length, fiber thickness is in the order of micrometers. In this work we were used fibers which are commercially produced for the purpose of reinforcement, but also waste fibers, which mainly serves as an insulator.
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Ribeiro, Bruno. "Study of Effective Use of Sugarcane Residue as Eco-friendly Construction Materials for Disaster Prevention Structures." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263808.
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付記する学位プログラム名: 京都大学大学院思修館京都大学
新制・課程博士
博士(総合学術)
甲第23347号
総総博第20号
京都大学大学院総合生存学館総合生存学専攻
(主査)教授 山敷 庸亮, 教授 山本 貴士, 教授 寶 馨, 教授 齋藤 敬
学位規則第4条第1項該当
Doctor of Philosophy
Kyoto University
DFAM
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Oliveira, Paulo Willyam SimÃo de. "Study of dielectric properties in the microwave MgTiO3 Arrays (MTO) - CaCu3Ti4O12 (CCTO) and BiNbO4 - CuO and its thermal stability for use in communication systems." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15904.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoWith the recent advances in telecommunications industry in antenna area itâs increasingly required the development of ceramic materials which have high values of permittivity dielectric, low dielectric loss and a good thermal stability. Dielectric ceramics of CaCu3Ti4O12 are candidates as high values of permittivity dielectric materials and have been studied extensively. Nowadays ceramics offer materials several significant advantages in relation to others since present low production cost for electronic devices that operate of radio and microwave frequency, as well as being low weight materials, stable with temperature and extremely amenable to miniaturization. Sample preparation for structural analysis and dielectric, had the addition of CaCu3Ti4O12 to the phase MgTiO3 calcined in ratios of 4.0; 6.0; 8.0; 10.0 and 12.0 % by mass. The X-ray diffraction was important for the structural characterization of the obtained composite. The morphology of the samples was observed by Scanning Electron Microscopy (SEM). The dielectric characterization of radio frequency spectroscopy of impedance was performed which occurred two conductivity mechanisms for a sample. Models of dielectric relaxation approach the Cole-Cole and Havriliak-Negami type model. The experiments indicated that it is possible to obtain ceramic composites with good values of dielectric permittivity and low dielectric losses, resulting in scalebility and efficiency for devices designed to operate in those frequencies. Numerical simulation was performed with samples verifying good agreement with the experimental data. They studied the BiNbO4 phase doped with copper oxide and its possible applications in RF and Microwave. Addition of CaCu3Ti4O12 with MgTiO3 matrix contributed to the reduction of temperature coefficient of resonant frequency -39.25 ppm/ÂC to 9.62 ppm/ÂC, increased dielectric permittivity and dielectric loss. This thesis also presents a proposal for samples act as dielectric resonator antennas in the frequency range of 5.4 GHz to 6.1 GHz (C-band).The composites evaluated in this work has behaved properly as materials for use in microwave
Com os recentes avanÃos da indÃstria de telecomunicaÃÃes na Ãrea de antenas se faz cada vez mais necessÃrio o desenvolvimento de materiais cerÃmicos que apresentem altos valores de permissividade dielÃtrica, baixa perda dielÃtrica e uma boa estabilidade tÃrmica. CerÃmicas dielÃtricas CaCu3Ti4O12 sÃo candidatas como materiais de elevado valor de permissividade dielÃtrica e tÃm sido estudadas amplamente. Hoje as cerÃmicas oferecem vÃrias vantagens por apresentarem baixo custo de produÃÃo para dispositivos eletrÃnicos que operam em radiofrequÃncia e micro-ondas, alÃm de serem materiais de peso pequeno, estÃveis com a temperatura e extremamente passÃveis de miniaturizaÃÃo. A preparaÃÃo das amostras para anÃlise estrutural e dielÃtrica, teve a adiÃÃo de CaCu3Ti4O12 à fase MgTiO3 calcinada, em proporÃÃes de 4,0; 6,0; 8,0; 10,0 e 12,0 % em massa. A difraÃÃo de raios-X foi importante na caracterizaÃÃo estrutural dos compÃsitos obtidos. A morfologia das amostras foi estudada pela microscopia eletrÃnica de varredura (MEV). A caracterizaÃÃo dielÃtrica em rÃdio frequÃncia foi realizada por Espectroscopia de ImpedÃncia na qual se verificaram dois mecanismos de condutividade para uma das amostras analisadas. Os modelos de relaxaÃÃo dielÃtrica se aproximam do modelo do tipo Cole-Cole e Havriliak-Negami. Os experimentos realizados indicaram que à possÃvel obter compÃsitos cerÃmicos com bons valores de permissividade dielÃtrica e baixas perdas dielÃtricas, resultando em compactaÃÃo e eficiÃncia para dispositivos a serem projetados. SimulaÃÃo numÃrica foi realizada com as amostras verificando-se boa concordÃncia com os dados experimentais. Foram estudadas a fase BiNbO4 dopada com CuO e suas possÃveis aplicaÃÃes em radiofrequÃncia e micro-ondas. A AdiÃÃo de CaCu3Ti4O12 à matriz MgTiO3 contribuiu para a reduÃÃo do coeficiente de temperatura da frequÃncia de ressonÃncia de -39,25 ppm/ÂC para 9,62 ppm/ÂC, com o aumento da permissividade dielÃtrica e da perda dielÃtrica. Este trabalho de tese tambÃm apresenta uma proposta para as amostras funcionarem como antenas ressonadoras dielÃtricas na faixa de frequÃncias de 5,4 GHz a 6,1 GHz (banda C). Os compÃsitos avaliados nesse trabalho comportaram-se adequadamente como materiais para uso em micro-ondas.
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MARINUCCI, GERSON. "Desenvolvimento, fabricacao e analise de falha e fratura de cilindros de fibra de carbono colapsados por pressao interna." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10913.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Šafaříková, Hana. "Vliv obsahu kalcitu v cihlářských zeminách na vlastnosti vypáleného střepu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225878.
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This master´s thesis is focused on the use of primary raw materials (clays) in the brick manufacturing. These soils differ mainly CaO contect and it most often in the form of calcite. Diversity of soils is manifested primarily in the mineralogical composition after firing and the existence of anorthite in the calcium clays. In the practical part I am trying to define the optimal type of soil suitable for the production of masonry units.
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SILVA, NELSON M. da. "Obtenção e avaliação mecanodinâmica de compósitos, ortotrópicos e anisotrópicos, com matriz polimérica reforcada com fibras de carbono ou poliaramida." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11375.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Rosa, Bruno de Paula [UNESP]. "Caracterização mecânica e térmica de um polímero termorrígido modificado com fibra de buriti." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150094.
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Pensando na sustentabilidade, a introdução de fibras naturais em substituição às sintéticas no reforço de matrizes poliméricas, faz-se necessária entre outras coisas devido à preservação do meio ambiente, redução de custos, sem que comprometa a qualidade final do material. Esse projeto tem o objetivo de obter as características mecânicas e térmicas de materiais compósitos a base de resina epoxídica curada DGEBA/TETA com a adição de porcentagens específicas de fibras de buriti. A fibra escolhida foi o buriti, pela abundância no Mato Grosso do Sul, buscando um desenvolvimento sócio econômico para a região e a matriz escolhida foi a epóxi DGEBA/TETA por ser a resina mais utilizada no mundo. Foram utilizadas fibras com diâmetro de 0,17mm e comprimento de 30mm em porcentagens em massa de 1%,5%,10%,15% e 17,6% do total do compósito. A caracterização mecânica foi realizada através de ensaios de tração. Após a ruptura dos corpos de prova foi verificado com uso da Microscopia Eletrônica de Varredura (MEV),a formação de microvazios através dos ensaios de Termogravimetria (TGA) e Calorimetria Diferencial de Varredura (DSC) foram verificadas a degradação e temperatura de transição vítrea (Tg) dos compósitos. O compósito com a adição de 5% em massa de fibras apresentou um aumento de 11,98% (60,12 para 67,32 MPa) no limite de resistência a tração (LRT) e de 8,21% no módulo de elasticidade (E) (901,06 para 977,82 Mpa) em relação a resina pura, acima de 5% as propriedades permaneceram constantes. Já o Limite de Resistência à propagação de trincas (K1C) não apresentou alterações significativas ao se adicionar fibras a resina (permanecendo em torno de 1,19 MPa). Não houve alteração na transição vítrea, ficando em torno de 70ºC. Já o TGA verificou que a temperatura de degradação dos compósitos apresentou um valor intermediário entre a resina pura e a fibra pura.
Thinking about sustainability, the introduction of natural fibers instead of synthetic fibers in the reinforcement of polymer matrices, is necessary among other things due to the preservation of the environment, cost reduction without compromising the final quality of the material. This project aims to obtain the mechanical and thermal characteristics of composite materials based on cured DGEBA / TETA epoxy resin with the addition of specific percentages of buriti fibers. The fiber was buriti, due to the abundance in Mato Grosso do Sul, seeking a socioeconomic development for the region and the chosen matrix was the epoxy DGEBA / TETA as the most used resin in the world. Fibers with a diameter of 0.17mm and a length of 30mm were used in mass percentages of 1%, 5%, 10%, 15% and 17,6% of the total composite. The mechanical characterization was performed through tensile tests. After the rupture of the specimens was verified with the use of Scanning Electron Microscopy (SEM), the microgravity formation through the Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC) tests showed the degradation and glass transition temperature ( Tg) of the composites. The composite with the addition of 5% by mass of fibers presented an increase of 11.98% (60.12 to 67.32 MPa) at the tensile strength limit (LRT) and 8.21% in the modulus of elasticity ( E) (901.06 to 977.82 MPa) relative to pure resin, above 5% the properties remained constant. However, the Limit of Resistance to crack propagation (K1C) did not show significant changes when adding fibers to the resin (remaining around 1,19 MPa). There was no change in the glass transition, being around 70ºC. The TGA verified that the degradation temperature of the composites showed an intermediate value between the pure resin and the pure fiber.
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Borchani, Karama. "Développement d'un composite à base d'un polymère biodégradable et de fibres extraites de la plante d'Alfa." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES010/document.
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Cette étude constitue une contribution à la recherche de nouveau matériau composite originaire des ressources naturelles végétales. Elle vise alors à l’exploitation des fibres naturelles extraites de la plante d’Alfa avec une matrice biopolymère thermoplastique de type Mater-Bi® afin d’élaborer des biocomposites. Trois types de fibres courtes extraites de la plante d’Alfa sont préparés ; non traitées et traitées par un traitement alcalin à 1 et 5%. Les diverses techniques utilisées pour la caractérisation des fibres ont révélé une augmentation de la rugosité, du taux de cellulose, de l’indice de cristallinité ainsi de la stabilité thermique après le traitement alcalin. Les matériaux composites sont préparés par extrusion bivis suivi d’une opération d’injection en faisant varier le pourcentage des fibres de 0 à 25%. Les analyses thermiques des biocomposites ont montré un accroissement significatif de la vitesse de cristallisation suite à l'incorporation des fibres d’Alfa ainsi une amélioration de la stabilité thermique pour les matériaux à base de fibres traitées. La résistance à la traction et le module de Young des biocomposites ont augmenté alors que la ténacité et l’allongement à la rupture ont diminué avec l'augmentation du taux de fibres. Les micrographies MEB des surfaces fracturées indiquent une bonne adhésion entre la matrice et les fibres d’Alfa traitées ou non. L’étude de la cinétique de cristallisation des différents biocomposites a prouvé le fort effet nucléant des fibres d’Alfa traitées ou nonThis study is a contribution to the search for new composite material from vegetable natural resources. It aims at the exploitation of natural fibers extracted from the Alfa plant with a bioplastic of the Mater-Bi® type in order to develop biocomposites. Three kinds of short fibers extracted from Alfa plant were prepared; untreated, 1% and 5% alkali treated. The various techniques used for fibers characterization showed an increase in the roughness, cellulose level, crystallinity index and thermal stability after the alkali treatment. The composite materials were prepared by twin screw extrusion flowed by an injection operation by varying the fiber contents of 0 to 25%. Thermal analysis showed significant increase of the crystallization rate with the incorporation of Alfa fibers and enhancement of thermal stability by alkali treatment. Modulus and tensile strength of biocomposites also improved whereas toughness and elongation at break decreased upon increasing the fibers fraction. Scanning electron microscopy (SEM) on fractured surfaces indicated good adhesion between the matrix and the treated or untreated Alfa fibers. The study of crystallization kinetics of biocomposites showed strong nucleating effect of treated or untreated Alfa fibers
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Rosa, Bruno de Paula. "Caracterização mecânica e térmica de um polímero termorrígido modificado com fibra de buriti /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150094.
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Orientador: Newton Dias FilhoResumo: Pensando na sustentabilidade, a introdução de fibras naturais em substituição às sintéticas no reforço de matrizes poliméricas, faz-se necessária entre outras coisas devido à preservação do meio ambiente, redução de custos, sem que comprometa a qualidade final do material. Esse projeto tem o objetivo de obter as características mecânicas e térmicas de materiais compósitos a base de resina epoxídica curada DGEBA/TETA com a adição de porcentagens específicas de fibras de buriti. A fibra escolhida foi o buriti, pela abundância no Mato Grosso do Sul, buscando um desenvolvimento sócio econômico para a região e a matriz escolhida foi a epóxi DGEBA/TETA por ser a resina mais utilizada no mundo. Foram utilizadas fibras com diâmetro de 0,17mm e comprimento de 30mm em porcentagens em massa de 1%,5%,10%,15% e 17,6% do total do compósito. A caracterização mecânica foi realizada através de ensaios de tração. Após a ruptura dos corpos de prova foi verificado com uso da Microscopia Eletrônica de Varredura (MEV),a formação de microvazios através dos ensaios de Termogravimetria (TGA) e Calorimetria Diferencial de Varredura (DSC) foram verificadas a degradação e temperatura de transição vítrea (Tg) dos compósitos. O compósito com a adição de 5% em massa de fibras apresentou um aumento de 11,98% (60,12 para 67,32 MPa) no limite de resistência a tração (LRT) e de 8,21% no módulo de elasticidade (E) (901,06 para 977,82 Mpa) em relação a resina pura, acima de 5% as propriedades permaneceram consta... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Thinking about sustainability, the introduction of natural fibers instead of synthetic fibers in the reinforcement of polymer matrices, is necessary among other things due to the preservation of the environment, cost reduction without compromising the final quality of the material. This project aims to obtain the mechanical and thermal characteristics of composite materials based on cured DGEBA / TETA epoxy resin with the addition of specific percentages of buriti fibers. The fiber was buriti, due to the abundance in Mato Grosso do Sul, seeking a socioeconomic development for the region and the chosen matrix was the epoxy DGEBA / TETA as the most used resin in the world. Fibers with a diameter of 0.17mm and a length of 30mm were used in mass percentages of 1%, 5%, 10%, 15% and 17,6% of the total composite. The mechanical characterization was performed through tensile tests. After the rupture of the specimens was verified with the use of Scanning Electron Microscopy (SEM), the microgravity formation through the Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC) tests showed the degradation and glass transition temperature ( Tg) of the composites. The composite with the addition of 5% by mass of fibers presented an increase of 11.98% (60.12 to 67.32 MPa) at the tensile strength limit (LRT) and 8.21% in the modulus of elasticity ( E) (901.06 to 977.82 MPa) relative to pure resin, above 5% the properties remained constant. However, the Limit of Resistance to crack... (Complete abstract click electronic access below)
Mestre
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Benetti, Paula. "Compatibilidade térmica entre cerâmicas infiltradas por vidro e cerâmicas feldspáticas: avaliação do ângulo de contato e da resistência de união ao cisalhamento." Universidade Federal de Pelotas, 2008. http://repositorio.ufpel.edu.br/handle/ri/2284.
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Previous issue date: 2008-01-07The aim of this study is to estimate the thermal compatibility of ceramics, contributing to fill in for an important gap in the standard for all-ceramic systems. The objectives of this study are: 1) to determine the shear bond strength (σc) of core-veneer ceramic systems and to evaluate the mode of failure; 2) to estimate the wetting behavior of veneer on core ceramics, using the contact angle measurement (θ); 3) to correlate the values for σc, θ, and CTE of the ceramics. Glass-infiltrated alumina (IA - In-Ceram Alumina) and zirconia (IZ - In-Ceram Zirconia) core ceramics, and Vita VM7, VM9 and VM13 veneer ceramics were combined into 6 groups. The baseline surface roughness (Ra) of core ceramic disk specimens (12 mm X 1,2 mm) was measured A cylinder of veneer ceramic (2 mm X 2 mm) was applied at the center of the core ceramic specimens, sintered and tested for σc to failure in a universal testing machine with a crosshead speed of 0,5 mm/min. For the θ evaluation, a cylinder of veneer ceramic (1 mm height x 2 mm diameter) was applied on core ceramic.Specimens images were taken before and after the firing procedure and the θ was measured using the AutoCAD 2006 program. The mean values of σc (MPa) and θ (º) for the compatible ceramic groups (A7 and Z7) were: 19,4 A e 48,9 c; 23,5 A e 56,0 b; for the groups with poor compatibility (A9 and V9) were: 0,9 C e 54,9 bc; 9,5 B e 59,8 b; and for the incompatible ceramic groups (A13 and Z13) were 0 D e 70 a; 0 D e 67,1 a. Different letters means statistical differences between groups (p≤0,001). Correlation analyses showed that as the difference between the ceramics CTE increases, the θ increases and the σc decreases
Esse estudo tem a finalidade de estimar o grau de compatibilidade térmica das cerâmicas, contribuindo para supressão de uma lacuna importante nas normas de avaliação de sistemas cerâmicos. Os objetivos desse estudo são: 1) determinar a resistência de união ao cisalhamento (σc) entre combinações de cerâmicas de IE e de cobertura e avaliar o modo de fratura; 2) estimar o grau de molhamento superficial das cerâmicas de IE pelas de cobertura, utilizando a medida do ângulo de contato superficial (θ); 3) correlacionar os resultados do θ, da σc e os valores do CET das cerâmicas. Cerâmicas infiltradas por vidro a base de alumina (IA- In-Ceram Alumina) e reforçada por zircônia (IZ- In-Ceram Zircônia), e as cerâmicas feldspáticas de cobertura Vita VM7, VM9 e VM13 foram combinadas em 6 grupos. A rugosidade superficial (Ra) de discos (12 mm X 1,2 mm) das cerâmicas de IE foi aferida para certificação da padronização dos CP.Para o teste de σc um cilindro de cerâmica de cobertura (2 mm X 2 mm) foi aplicado no centro da superfície superior do disco de IE e posteriormente acoplado à máquina de ensaios universal e submetido ao teste com velocidade de carga de 0,5 mm/min. Para avaliação do θ, um cilindro de cerâmica de cobertura (1 mm de altura x 2 mm diâmetro) foi aplicado sobre a IE. Imagens de cada CP foram realizadas antes e depois da sinterização para a medida do θ no programa AutoCAD 2006. A média dos resultados da σc (MPa) e do θ (º) para os grupos compatíveis (A7 e Z7) foram: 19,4 A e 48,9 c; 23,5 A e 56,0 b; para os grupos pouco compatíveis (A9 e Z9) foram: 0,9 C e 54,9 bc; 9,5 B e 59,8 b; e para os grupos incompatíveis (A13 e Z13) foram 0 D e 70 a; 0 D e 67,1 a. Letras distintas significam diferenças estatísticas entre os grupos (p≤0,001). A análise de correlação mostrou que à medida que a diferença entre os CET das cerâmicas aumenta, o θ aumenta e a σc diminui
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Novák, Vítězslav. "Vývoj pokročilých zdicích prvků pro novodobé obvodové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226704.
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This thesis deals with improving thermal properties of contemporary ceramic fittings for external walls using built-in thermal insulation. In the practical part, PUR foam and PUR granulate waste mixes were designed. Based on insulation, mechanical and physical properties and estimated price, the best mix was chosen. Using the chosen mix as integrated isolation, the resulting ceramic block was simulated.
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Ben, Kaabar Aymen. "Durabilité des assemblages céramique-métal employés en électronique de puissance." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0064/document.
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Les composants d’électronique de puissance ont (et vont encore avoir !) eu une grande influence sur les secteurs de l'énergie et des transports. Ces pièces sont notamment constitués d’assemblages céramique –cuivre pour lesquels la tenue mécanique doit être maîtrisée afin de garantir dans le future une durabilité d’environ 30 ans sous l’action de cycles thermiques plus en plus grande. Une analyse des mécanismes de défaillance des assemblages DBC (Direct Bonding Copper) utilisés en électronique de puissance est étudiée (le délaminage le long de l’interface cuivre -céramique et/ou la rupture fragile de la céramique). Pour identifier le comportement élastoplastique du cuivre, nous avons montré qu’il est nécessaire d’utiliser une plaque de cuivre ayant subi l’ensemble des traitements thermiques liés au processus d’assemblage. Le comportement élastique fragile de la céramique est décrite dans le cadre d’une statistique de Weibull. Dès lors, une caractérisation du délaminage cuivre-céramique sous flexion quatre points a permis d’identifier un modèle cohésif pour l’interface. La calibration des paramètres cohésifs est menée en utilisant les données à deux échelles : i) macroscopique de force-déplacement ii) locale de suivi optique de la fissuration avec le déplacement imposé. L’intégrité mécanique des assemblages DBC pour différentes épaisseurs des couches de cuivre et de céramique a été étudié. Nous avons montré que les configurations avec un rapport proche de l’unité sont les plus dangereuses en engendrant un délaminage, qui se poursuit sous cyclage thermique. Ce dernier peut être notablement réduit en structurant le pourtour de la surface de cuivre avec des trous cylindriques répartis périodiquement. Ainsi, un modèle éléments finis permettant d’évaluer les assemblages les plus prometteurs en terme de durabilité a été établie. En l’absence de défauts géométrique, la couche de cuivre reste intègre, même dans le cas d’un délaminage dont le front induit une concentration de contrainteThe power electronics components (and still will have!) have a great influence on the energy and transport sectors. These parts are made of ceramic-copper assemblies for which the mechanical strength must be controlled to ensure durability about 30 years under the thermal cycles increasingly larger. A failure mechanisms analysis in DBC (Direct Copper Bonding) assemblies used in power electronics is studied (the delamination along the interface copper - ceramic and/or the brittle ceramic fracture). To identify the elastoplastic behavior of copper, we showed that it’s necessary to use a copper plate having undergone the heat hole treatments related to the assembly process. The ceramic gragile elastic behavior is descrobed within the Weibull statictics framework. Consequently, a copper-ceramic delamination characterization under four points bending made it possible to identify a cohesive model for the interface. The cohesive calibration parameters is carried out by using the data in two scales: i) strentgh-displacement macroscopic ii) local cracking optical follow-up with imposed displacement. The mechanical integrity of DBC assemblies of different thickness of copper and ceramic has been studied. We showed that the configurations with a ratio close to the unit are most dangerous by generating a delamination, which continues under thermal cycling. This risk of delamination can be notably reduced by structuring the copper circumference surface with cylindrical holes distributed periodically. Thus, a finite elements model allowing us to evaluate the most promising assemblies in term of durability, was estabilshed. In the absence of geometrical defects, the copper layer must remains, even in the delamination case whose face induces a concentration stress
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CAMPOS, REJANE D. de. "Influência da mercerização e irradiação por feixe de elétrons na aderência da fibra do ouriço da castanha do Brasil em matriz de polietileno de alta densidade." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/25303.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Morais, Dabney S?rgio Guedes de. "An?lise das propriedades termof?sicas, mec?nicas e geom?tricas de telhas cer?micas queimadas em forno caieira e forno ab?bada." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15637.
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Previous issue date: 2011-03-31In the industry of ceramic in Rio G. do Norte, tile stands out as the most manufactured product by this industry, being the intermittent kiln ab?bada and caieira the principal type of kiln used in burning. There was a need to make a study of the influence exerted by the type of kiln in which tiles are burnt in their thermo physical properties. The analysis started with 24 raw samples of tile, which was split in two groups of 12 samples and burnt in Ab?bada and Caieira kiln. Besides that, it was made study of the tax of heat transfer to the environment (for each kiln). After having been burnt the samples were taken for laboratory analysis. The properties verified were impermeability, determination of dry mass, absorption of water, the load of bending rupture and its geometric characteristics, the tests were conducted following the currents standards. The tests were carried out according to the ABNT - NBR 15310. The calculation of the rate of heat transfer showed that the ab?bada kiln is more efficient than the Caieira, however the results of tests on the samples revealed no superiority of one over another sample. So the furnace had no influence on the performance of the ceramic tiles
Na ind?stria de cer?mica vermelha a telha desponta como o produto mais fabricado pela ind?stria de cer?mica do Serid?/RN, sendo os fornos intermitentes do tipo ab?bada e caieira os mais utilizados para a queima destas telhas. Verificou-se a necessidade de se fazer um estudo da influ?ncia exercida pelo tipo de forno no qual as telhas s?o queimadas nas suas propriedades termof?sicas, mec?nicas e geom?tricas. Sendo selecionadas 24 amostras de um mesmo processo de fabrica??o, no entanto estas foram posteriormente separadas em dois lotes de 12 unidades e levadas a queima no forno caieira e ab?bada. ? importante ressaltar que os corpos de prova n?o fazem parte do processo produtivo das cer?micas de onde foram utilizados os fornos para queima, ou seja, as cer?micas gentilmente cederam seus fornos para a realiza??o do experimento. Foi realizado um estudo da taxa de transfer?ncia de calor ao meio ambiente para cada tipo de forno. Assim as amostras ap?s serem queimadas foram levadas para an?lise em laborat?rio. As propriedades verificadas foram ? impermeabilidade, determina??o da massa seca e da absor??o da ?gua, determina??o da carga de ruptura ? flex?o e de suas caracter?sticas geom?tricas. Os ensaios foram realizados segundo a norma ABNT - NBR 15310. O calculo da taxa de transfer?ncia de calor mostrou que o forno ab?bada ? mais eficiente que o caieira, no entanto os resultados dos ensaios nas amostras mostraram que n?o houve superioridade de uma amostra sobre outra, assim os fornos n?o tiveram influ?ncia no desempenho das telhas
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Granda, Garcia Luis Angel. "Evaluación de las propiedades de materiales compuestos fabricados a partir de fibras semiquímicas de Leucaena collinsii y polipropileno." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/398953.
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This thesis studies the effect produced by the reinforcement of polypropylene with a semichemical fibre of Leucaena collinsii in the mechanical, thermal and water uptake properties.
Samples with different reinforcement content are obtained and stabilized in a climatic chamber for 48 hours before being tested to tensile, flexural and the termal properties are studied by TGA, DSC, TMA, DMA and thermal conductivity test. Finally, the water uptake maximum capacity was determined.
The addition of increasing quantities of reinforcement increases the maximum resistance and stiffne of the material, but a diminution of the deformation capacity was observed. None of the thermal transitions were affected by the addition of reinforcement. However, the crystallinity increased when increasing the fiber contentLa presente tesis estudia el efecto que produce reforzar una fibra semiquímica de Leucaena collinsii en las propiedades mecánicas, térmicas y de sorción de agua de materiales compuestos de polipropileno. Se obtienen probetas de materiales compuestos con distinto contenido de refuerzo y se estabilizan en una cámara climática durante 48 horas antes de ser ensayadas a tracción, flexión e impacto, y se analiza la morfologia de la fractura mediante SEM. Posteriormente se estudian sus propiedades térmicas mediante TGA, DSC, TMA, DMA y el análisis de la conductividad térmica de los materialses. Finalmente, se determinará la capacidad para absorber agua de estos compuestos. La adición de cantidades crecientes de refuerzo provoca un aumento de la resistencia máxima y de la rigidez del material, pero una disminución de su capacidad de deformación. Las temperaturas de transición no se ven afectadas pero sí su cristalinidad, aumentando al añadir contenidos superiores de refuerzo
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Choi, Keum-Ran. "3D thermal mapping of cone calorimeter specimen and development of a heat flux mapping procedure utilizing an infrared camera." Link to electronic thesis, 2005. http://www.wpi.edu/Pubs/ETD/Available/etd-020205-215634/.
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Dissertation (Ph.D.)-- Worcester Polytechnic Institute.Keywords: temperature measurement; heat flux maps; Cone Calorimeter; three-dimensional heat conduction; fire growth models; retainer frame; ceramic fiberboard; edge effect; one-dimensional heat conduction; heat flux mapping procedure; infrared camera; specimen preparation; edge frame; one-dimensional heat conduction model; thermal properties. Includes bibliographical references (p.202-204).
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Vignon, Pierre. "Caractérisation et optimisation des propriétés d’isolants thermiques non tissés à base de fibres de bois." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0182.
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Les travaux présentés ici s’insèrent dans le contexte actuel du fort potentiel de développement commercial des isolants bio-sourcés. Ils sont menés dans le cadre d'une thèse CIFRE portée par l’entreprise FINSA France et effectuée au laboratoire I2M de Bordeaux, au sein d'un projet industriel, ECOMATFIB (ADEME BIP, 2014-2017) : ECOconception et Optimisation multi-objectif de MATériaux isolants à base de FIBres de bois. L’objectif de cette thèse est de concevoir, fabriquer, caractériser et optimiser les propriétés d’isolants thermiques à base de fibres de bois, réalisés à l’aide d’un procédé textile non-tissé. Après une analyse de la ressource bois présente en nouvelle Aquitaine, des isolants ont été fabriqués à partir de nappes de fibres de bois de pin maritime, de pin taeda, de peuplier et d’eucalyptus avec adjonction de fibres thermoplastiques puis consolidation par voie thermique dans un four à air chaud. Après identification préliminaire des paramètres de réglage de la chaîne de non-tissé disponible au laboratoire, de nombreux matériaux fibreux ont été réalisés, à partir d'une matière première diversifiée et de paramètres machines adaptés. Ceux-ci ont été caractérisés thermiquement principalement par la méthode du plan chaud puis de manière hydrique pour connaître leur faculté d’interaction avec l’humidité relative de l’air ambiant. Enfin, leur caractérisation en compression a permis d'étudier leur propension à conserver leurs propriétés après sollicitation mécanique. Les données recueillies ont permis d’identifier les paramètres de la matière première ainsi que du procédé de fabrication ayant un impact significatif sur les propriétés de ces isolants. Une première approche de modélisation des propriétés a conduit à identifier des pistes permettant l’amélioration des propriétés thermiques et de valider leur très bonne capacité de régulation hydriqueThe works presented here fit into current context of strong commercial development potential of bio-sourced insulators. They are carried out as part of a CIFRE PhD financed by the company FINSA France. They took place at I2M laboratory in Bordeaux, within an industrial project, ECOMATFIB (ADEME BIP, 2014-2017) : ECOconception et Optimisation multi-objectif de MATériaux isolants à base de FIBres de bois. The Objective of this PhD is to design, manufacture, characterize and optimize properties of thermal insulation based on wood fibers, produced using nonwoven textile process. After analysis of wood resource present in the New-Aquitaine region, insulating materials were designed out of sheets from maritime pine, pine taeda, poplar and eucalyptus wood fibers with addition of thermoplastic fibers then thermally consolidated in hot air oven. After preliminary identification of adjustment parameters of nonwoven chain available in I2M laboratory, many fibrous materials were made from diversified raw materials and suitable machine parameters. These bio-based materials were thermally characterized mainly by hot plane method and then in hydric manner to know their ability to interact with relative humidity of ambient air. Finally, their characterization in compression made it possible to study their propensity to preserve their properties after mechanical stress. Datas collected made it possible to identify parameters of raw materials as well as manufacturing process having significant impact on properties of these insulators. A first approach to modeling properties has led to identification of avenues to improve thermal properties and to validate their very good capacity for water regulation
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Rodier, Loïc. "Matériaux de construction en zone tropicale humide : Potentialités de sous-produits ou de matériaux naturels locaux en substitution ou addition à la matrice cimentaire." Thesis, Antilles-Guyane, 2014. http://www.theses.fr/2014AGUY0804/document.
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L’incorporation de sous-produits agricoles ou de matériaux naturels dans la matrice cimentaire confère des propriétés intéressantes aux composites élaborés. L’objectif de cette thèse est d’élaborer un matériau pouvant répondre aux exigences mécaniques, thermiques et de durabilité des matériaux de construction en zone tropicale humide. Dans un premier temps, l’activité pouzzolanique d’une pouzzolane naturelle, de cendres de tronc de bambou et de cendres de bagasse de canne à sucre ont été évaluées. L’influence de leur incorporation a été ensuite étudiée sur les propriétés mécaniques et la durabilité des mortiers exposés à des ions chlorures et sulfates. Dans un second temps, l’influence de l’ajout de fibres de bagasse sur les propriétés thermiques et mécaniques des composites a été étudiée en fonction de différents paramètres (teneur en fibres, environnement de vieillissement, type de matrice cimentaire).Les résultats obtenus ont permis de montrer que les matériaux étudiés possèdent une activité pouzzolanique et qu’il est possible de les incorporer au ciment afin de lutter contre la corrosion. De plus, les composites élaborés avec des fibres de bagasse sont plus isolants que ceux élaborés sans fibres. Cependant, du point de vue des propriétés mécaniques, l’incorporation de fibres de bagasse diminue les contraintes à la flexion des compositesThe incorporation of crop wastes or natural materials in the cement matrix confers interesting properties to composites prepared. The aim of this thesis is to develop a material that can reach the mechanical, thermal and durability requirements for building materials in the humid tropical zone. Firstly, pozzolanic activity of a natural pozzolan, bamboo stem and sugar cane bagasse ashes has been determined. Influence of their incorporation on mechanical properties and durability of mortars exposed to chloride and sulphate ions was studied. Secondly, influence of addition of bagasse fibers on thermal and mechanical properties of composites was studied as a function of various parameters (fibers content, curing, type of cement matrix).These results has shown that the materials studied have pozzolanic activity and it is possible to incorporate them into the cement to fight against corrosion. Moreover, composites elaborated with bagasse fibers are more insulating than those elaborated without fibers. However, from the viewpoint of mechanical properties, incorporation of bagasse fibers decreases flexural strength of composites in the present work and under the conditions producing procedures that were adopted
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Hort, Martin. "Polyfunkční dům." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-410007.
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Diploma thesis describes the design and processing of project documentation of the multifunctional building. The multifunctional building is located in the central part of the town Náměšť nad Oslavou. The building has 4 floors. It is partly cellared building with flat roof and walkable terraces. This building is consisted of 2 functional parts, the first part is designed for living and the second one is designed for contact with the customer. There are shops and offices. The first floor is wheelchair accessible. In the basement there is a technical background of the building and cellars for housing units. In this multifunctional building we can find 13 residential units and five offices. All of the floors are connected with staircase and lift. The Carpark and the private garden with playground are also part of this residential area. This building is based on concrete blocks. Load-bearing, peripheral walls and connecting walls are made of ceramic blocks. A monolitic ceiling construction is the combination of the iron and the concrete. Two types of insulation are used in peripheral walls. The first one is called ETICS, external thermal insulation composite system, made of polystyrene. The second type of insulation is facade cladding system where the main insulation layer is made of mineral wool. The insulation layer is replaced by XPS polystyrene where facade is in contact with the ground. Facade cladding panels are made of cement and wood fibers called Cembrit.
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Gulshan, Zubaida A. "Fabric composite radiation heat transfer study." Thesis, 1993. http://hdl.handle.net/1957/36175.
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A Fabric Composite Radiation Heat Transfer Study has been
conducted to determine the effective emissivities of specific
fabric composite materials. The weave of the fabric and the
high strength capability of the individual fiber in
combination with the thermal conductivity and chemical
stability of specific metallic liner, result in a very
efficient light weight heat rejection system. Primary
investigation included aluminum, copper, stainless steel and
titanium as liner materials, and three different ceramic
fabrics - Astroquartz II (a trademark of JPS Co., Slater, SC),
Nextel (a trademark of 3M Co., St. Paul, MN) and Nicalon (a
trademark of The Nippon Carbon Co., Japan). Experiments
showed that fabric composite materials have significantly
higher effective emissivities than the bare metallic liner
materials. Aluminum and Astroquartz II combination and
aluminum and Nextel combination appeared to be the most
promising among the tested samples. To simulate deep space
the experiment was performed in vacuum where coolant fluid was
cirulated at about -10°C. The effective emissivity
measurements were conducted at 376 K, 521 K and 573 K. Also
high temperature effective emissivity measurements need to be
performed.Graduation date: 1993
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Mayeaux, Brian Mitchell. "Synthesis, characterization, and thermal properties of ceramic-fullerene thin films." Thesis, 2000. http://hdl.handle.net/1911/19534.
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Thin films containing ZrO2 and dispersed fullerenes have been synthesized using codeposition processing, and the role that dispersed fullerenes play in the thermal behavior of co-deposited films has been characterized. The presence of C60 within the films has been confirmed using a new application of electron impact mass spectrometry, and the structure and stability of dispersed C60 in Zr and ZrO2 have been studied using Raman spectrometry, TEM, XRD, and WDS. Strong interactions between neighboring ZrO2 grains and dispersed C60 are manifested in the decreased desorption rate of C60 from the ZrO2 surface, and effects of dispersed C60 on the ZrO2 microstructure are observed using TEM. The potential for the use of fullerenes and fullerene-like structures in thermal barrier applications has been examined using both steady state and transient thermal conductivity measurement methods to measure the effective film conductivity. Significant reductions have been observed in the co-deposited film conductivity due to the contact resistance between dispersed fullerenes and neighboring ZrO2 grains, and contributions of fullerenes and the affected grain boundary region to thermal conductivity reductions have been identified. Dispersed C60 is proposed to affect phonon scattering in ZrO2 by imposing an interfacial resistance that is strongly dependent upon fullerene particle size, shape, and distribution.