Journal articles: 'Monolithic Refractory'

1

Zamyatin, V. A., and I. V. Egorov. "Heating furnace monolithic refractory lining." Refractories and Industrial Ceramics 49, no. 2 (March 2008): 75–78. http://dx.doi.org/10.1007/s11148-008-9030-6.

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Cutard, Thierry, Nicolas Donval, Aurélien Mazzoni, Claire Michel, and Fabien Nazaret. "Thermomechanical Characterization of Monolithic Refractory Castables." Advances in Science and Technology 70 (October 2010): 37–46. http://dx.doi.org/10.4028/www.scientific.net/ast.70.37.

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This paper deals with the characterization of the thermomechanical behavior of monolithic refractory castables in a wide temperature range, up to 1200°C. Different test types are considered: tensile tests, compression tests, bending tests and tests on more complex shapes and geometries. A particular attention is paid to the detailed characterization and interpretation of the non-linear behaviors of these materials. Monotonic, cyclic and creep tests are considered. In some cases, digital image correlation (DIC) methods can be coupled to mechanical tests to obtain strain fields. Such results are particularly interesting to observe and to understand damage processes. As damage is a major characteristic of the monolithic castable behaviors, links are established between the thermomechanical behavior and damage mechanisms. Two main scales are taken into account for damage characterization: the macroscopic and the microscopic ones. Main mechanisms that are considered deal with microcracking, macrocracking, debonding and cavitation. Two types of materials are considered: non-reinforced and fiber reinforced refractory castables.

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Goski, Dana, and Matthew Lambert. "Engineering resilience with precast monolithic refractory articles." International Journal of Ceramic Engineering & Science 1, no. 4 (September 23, 2019): 169–77. http://dx.doi.org/10.1002/ces2.10024.

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Schmitt, N., Y. Berthaud, J. F. Hernandez, P. Meunier, and J. Poirier. "Damage of monolithic refractory linings in steel ladles during drying." British Ceramic Transactions 103, no. 3 (June 2004): 121–33. http://dx.doi.org/10.1179/096797804225012873.

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Goberis, S., and V. Antonovich. "The Monolithic Refractory Lining for Furnaces Fired by Wood Fuel." Refractories and Industrial Ceramics 44, no. 5 (September 2003): 295–97. http://dx.doi.org/10.1023/b:refr.0000009033.81186.53.

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Wynn, Andy, John Coppack, Tom Steele, and Gary Latter. "Improved Monolithic Materials for Lining Aluminium Holding and Melting Furnaces – Roof, Upper Walls and Flue." Materials Science Forum 693 (July 2011): 80–89. http://dx.doi.org/10.4028/www.scientific.net/msf.693.80.

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Monolithic refractories are now well established as linings for a range of holding and melting applications for the processing of aluminium. The refractory lining in an aluminium furnace has to withstand a wide variety of physical and chemical environments. Each of the different furnace zones presents a different set of operating conditions, in terms of peak temperature, temperature fluctuation, metal contact, flux contact, impact from ingot loading, etc. Therefore, in order for a monolithic material to successfully perform in a particular area of the furnace, it needs to be able to cope with the specific environmental conditions in that region of the furnace. Aluminium producers continue to increase productivity through their Melt-Hold furnaces to maintain competitiveness. The use of more powerful burners to increase heat input to the furnace is therefore becoming increasingly common practice. But faster melting leads to increased metal losses from surface oxidation and to segregation from large heat gradients. These effects are countered by increased use of fluxes and increased stirring. Given the increasingly challenging environment within which the refractory lining has to work, traditional lining solutions can no longer be relied upon to provide the service lives that were previously achieved. Therefore, a new generation of furnace lining materials is required to cope with today’s aluminium furnace. This paper describes one such newly developed monolithic material, designed specifically to improve performance in the superstructure zone of Aluminium furnaces. The non-metal contact, superstructure regions of aluminium furnaces present their own unique set of challenges for the refractory lining. Refractories in these regions – roof, upper walls and flue – have to cope with excessively high levels of alkali vapour and thermal shock. This paper reviews the operating conditions found in the superstructure areas of a typical melting and holding furnace and the implications these have on monolithic lining material design and performance. The improved behaviour of the newly developed monolithic material against the critical performance criteria in these furnace regions is demonstrated in the laboratory, compared to existing industry leading materials, using industry standard test methods.

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Angelescu, Nicolae, Dan Nicolae Ungureanu, and Florin Toma. "Special Refractories Resistant to the Melt Metals and Slags Attack." Scientific Bulletin of Valahia University - Materials and Mechanics 17, no. 16 (May 1, 2019): 28–31. http://dx.doi.org/10.2478/bsmm-2019-0004.

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Abstract The paper is an attempt to present and evaluate of the some monolithic refractory materials, originating from our research activity, with potential to be used as the thermoprotective linings for the nonferrous metals and ferrous alloys manufacturing installations in foundries and steelworks.

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Sugawara, Mitsuo, Seiya Hagihara, and Michihiko Nakagaki. "Nonlinear Finite Element Analysis of Alumina-Magnesia Monolithic Refractory Lining Material." Key Engineering Materials 247 (August 2003): 245–50. http://dx.doi.org/10.4028/www.scientific.net/kem.247.245.

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Osoba, Lawrence Opeyemi, and Ayo Samuel Afolabi. "Suitability of Nigerian Rocks as Refractory Materials for Monolithic Furnace Lining." Particulate Science and Technology 30, no. 3 (May 2012): 209–19. http://dx.doi.org/10.1080/02726351.2011.555936.

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Khajornboon, Jiraprabha, Kouichiro Washijima, and Takeshi Shiono. "Fracture Energy and Fracture Toughness of In Situ Calcium Hexaluminate (CA6)-Alumina Monolithic Refractory." Key Engineering Materials 766 (April 2018): 77–82. http://dx.doi.org/10.4028/www.scientific.net/kem.766.77.

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One of main raw materials for monolithic refractory is calcium aluminate cement which provides CA6 hexagonal plate-like microstructure with self-toughening properties and fracture resistance. In the present study, in-situ CA6 was formed by using sintered alumina mixing with alumina cement in stoichiometric composition to achieve 100 mass% and 50 mass% of CA6 in alumina monolithic refractory with 2 mass% of silica addition. Samples were fired from 1400-1500°C for 5 h and characterized for physical and mechanical properties. The results showed that both samples could not obtain CA6 content as expected and apparent porosity did not exhibit in the same tendency. However, only proper amount of CA6 content could gain proper amount of apparent porosity which is the main effect of mechanical properties. Especially the formation of CA6 lower than 50 mass% with the presence of low melting phase caused low apparent porosity and led to high fracture toughness and effective fracture energy.

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Angelescu, Nicolae, Cristina Stancu, Sofiane Amziane, Vasile Bratu, and Elena Valentina Stoian. "Study on Hydration and Strengthening of High Alumina Cements." Scientific Bulletin of Valahia University - Materials and Mechanics 15, no. 12 (April 25, 2017): 22–27. http://dx.doi.org/10.1515/bsmm-2017-0004.

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Abstract Refractory concretes based on aluminous cements are used with great success in areas where high temperatures are required. The mineralogical composition of the high alumina cement is the main factor which gives the physical and mechanical properties at high temperatures of refractory monolithic materials.It is therefore desirable to use high alumina cements based on mineralogical compounds with high refractoriness, because in the end those beneficial properties can be found in the final product - refractory concrete.The aim of this paper is to design, realize and characterize different compositions of high alumina cements based on mineralogical compounds with the highest refractory from the CaO-Al2O3 binary system (i.e. CA, CA2, and CA6), and to find ways of hydraulic activation of calcium hexa aluminate, also.

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Decker, Jens. "Phosphate Bonded Monolithic Refractory Materials with Improved Hot Strengths as a Potential Replacement for Phosphate Bonded Bricks." Materials Science Forum 693 (July 2011): 90–103. http://dx.doi.org/10.4028/www.scientific.net/msf.693.90.

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The phosphate bond generally provides a lower modulus of elasticity compared to more brittle conventional cement and ceramic bonded materials. The flexible bonding mechanism results in higher impact resistance. Moreover, phosphate bonded materials show excellent resistance to aluminium metal penetration and corundum growth. In addition, phosphate bonded bricks with low alkali content possess high hot strengths at elevated temperatures which can significantly increase their performance against mechanical abuse. Based on this information a project was started to develop phosphate bonded monolithic materials with similar or better physical and chemical properties than phosphate bonded bricks but with the advantage of installation characteristics of conventional cement bonded materials. Additional goals were to use a water based system and minimize restrictions on installations techniques. Flow and working time should be similar to conventional monolithic materials, making this material as versatile as possible. In order to achieve these goals extensive tests were carried out in collaboration with independent research laboratories and as a secondary step, some of the new formulations were installed in severe environment applications with high mechanical abuse and chemical attack. The development process and the physical and chemical properties of a new phosphate bonded monolithic material will be shown in context with available literature and in comparison with test data of phosphate bonded bricks and conventional cement bonded materials. The results of field tests and potential new applications will also be presented.

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Holčapek, Ondřej, Pavel Reiterman, and Petr Konvalinka. "Binder for Refractory Cement Composites – Hydration, Changing due to High Temperatures and Fracture Energy." Materials Science Forum 824 (July 2015): 185–90. http://dx.doi.org/10.4028/www.scientific.net/msf.824.185.

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This contribution brings summary of refractory hydraulic binder issue. The refractory cement composites (or refractory concrete) represent very specific area of modern material engineering. We can find its use in special monolithic structures in industry, for fire-resistance brick, protection cladding, etc. The composition brings opportunity for using aluminous cement with different amount of Al2O3, according to temperature level. Hydration process and products together with the decomposition due high temperatures is described in this paper. Also the risk of conversion metastable hydration to stable one is described. The issue of possible bonds between filler and binder is shown (hydraulic, ceramic and chemical). Paper also describes values of fracture energy of aluminous cement pastes with various water to cement ratio after temperature loading.

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Rangaraj, Lingappa, Canchi Divakar, and Vikram Jayaram. "Processing of Refractory Metal Borides, Carbides and Nitrides." Key Engineering Materials 395 (October 2008): 69–88. http://dx.doi.org/10.4028/www.scientific.net/kem.395.69.

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Transition metal borides, carbides and nitrides are candidates for very high temperature applications. A review of various processing techniques to fabricate dense monolithic and composite materials is presented. In particular, we focus on reactive hot pressing (RHP) which allows synthesis and densification to be achieved simultaneously. We report the RHP of composites in the Ti-B-N, Zr-B-C and Zr-B-Si-C systems using the reactions of Ti/BN, Zr/B4C (Si, SiC particulate) powder mixtures at moderate pressures and temperatures. Substantial reductions in processing temperature may be realized from those in excess of 1800°C down to as low as 1200°C by exploiting a combination of transient liquid phases, plasticity in a non-stoichiometric ZrC and enhanced transport in a sub-micron microstructure.

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León-Carriedo, M., C. A. Gutiérrez Chavarría, J. L. Rodríguez Galicia, Jorge López-Cuevas, and M. I. Pech Canul. "Rheological, Structural and Mechanical Characterization of Monolithic Zircon-Alumina Bodies." Materials Science Forum 793 (May 2014): 151–58. http://dx.doi.org/10.4028/www.scientific.net/msf.793.151.

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In the present work, the characterization of monolithic materials formulated at different weight concentrations was conducted; employing two of the ceramic materials most used in the refractory industry, zircon and alumina. These monolithic materials were fabricated using colloidal techniques, specifically plaster casting mold, in order to obtain pieces with a higher particle consolidation and density, reducing porosity to lower values than the obtained using traditional shaping process of these materials. The monoliths were obtained employing two ceramic powders with different average particle size and morphology to achieve better packing in the green body. This characterization was carried out, firstly, determining the particle size of the raw materials by laser diffraction and the evaluation of particle morphology by scanning electron microscopy. Aqueous suspensions were formulated by containing both ceramic materials, which were dispersed with Tamol 963, and analyzed by rheometric techniques. Subsequently, bars were manufactured having the following dimensions; 4 mm wide, 3 mm thick and 45 mm in length, according to ASTM C1161-02cc, to be characterized microstructural and mechanically, also was observed the fracture habit after the mechanical test. As a final result, the materials formulated at higher alumina content showed higher density values, reaching 94.95% of the theoretical density, also showed a higher thermal expansion coefficient and high rupture modulus, reaching up to 600 MPa and Young modulus of 230 GPa. From the microstructure characterization it was observed that alumina matrix shows a transgranular fracture across the grains and zircon particles exhibited intergranular fracture among the grain boundaries.

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16

Horvat, Barbara, and Vilma Ducman. "Influence of Particle Size on Compressive Strength of Alkali Activated Refractory Materials." Materials 13, no. 10 (May 12, 2020): 2227. http://dx.doi.org/10.3390/ma13102227.

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Influence of particle size on the mechanical strength of alkali activated material from waste refractory monolithic was investigated in this study. Precursor was chemically and mineralogically analysed, separated on 4 fractions and alkali activated with Na-water glass. Alkali activated materials were thoroughly investigated under SEM and XRD to evaluate the not predicted differences in mechanical strength. Influence of curing temperature and time dependence at curing temperatures on mechanical strength were investigated in the sample prepared from a fraction that caused the highest compressive strength.

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Mukhopadhyay, S., G. Das, and I. Biswas. "Nanostructured cementitious sol gel coating on graphite for application in monolithic refractory composites." Ceramics International 38, no. 2 (March 2012): 1717–24. http://dx.doi.org/10.1016/j.ceramint.2011.09.006.

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Mukhopadhyay, S., K. Dana, S. Moitra, S. BasuMallick, and T. K. Mukhopadhyay. "Thermal and thermomechanical characteristics of monolithic refractory composite matrix containing surface-modified graphite." Ceramics International 42, no. 5 (April 2016): 6015–24. http://dx.doi.org/10.1016/j.ceramint.2015.12.155.

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Nagorniy, A. O. "High alumina refractory concretes bonded with calcium aluminate phosphate binder." Scientific research on refractories and technical ceramics 120 (December 30, 2020): 91–97. http://dx.doi.org/10.35857/2663-3566.120.08.

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For many industries, further progress is possible provided that more efficient refractories of new types are created. The refractory concretes bonded by calcium aluminate phosphate binders in comparison with conventional refractories continue to gain in popularity because of the following advantages: quick installation and low construction costs; reduced and simplified furnace maintenance; good thermal-shock resistance; monolithic (no joints); linings of the units done need not be cured to develop initial strength. The longevity of refractory is essentially increasing provided structure is forming under conditions of the service site. That is why developing of new refractory materials must be carried out by means of its structure design. These principles have been realizing in the refractory concretes technology under the limited conditions of refractory lining installation and industrial unit final heat up. The present paper identifies the phosphate phases responsible for developing mechanical-strength properties of high alumina concretes bonded with calcium aluminate phosphate binders. It sets out the colloid and crystalline phases resulted from interphase interaction that provides the basis for calcium aluminate phosphate binders (suspensions) useful to the refractory industry. The concretes obtained retain their volume integrity after 30 cycles of heating and cooling; can be used for refractory applications > 1700 °С; exhibit sufficient strength of lining 40 MPa.

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Nevřivová, Lenka. "Pore Structure Regulation in Refractory Grog with Alumina Content over 45 %." Key Engineering Materials 834 (March 2020): 75–81. http://dx.doi.org/10.4028/www.scientific.net/kem.834.75.

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Increased alumina content in refractory grog is a product of the grog’s firing and, at the same time, it is a raw material used for the production of dense or insulating, shaped or monolithic refractories. Grog characteristics determine the properties of the final product. The specific characteristics of the grog are therefore optimized to suit the refractory product as close as possible. The basic characteristics determining the nature of the grog include its mineralogical composition, chemical composition, and apparent porosity. The present study focuses on ways of reducing the porosity of a high-alumina grog and thus obtaining a raw material suitable for the production of dense refractory materials. The experiments have shown that it is possible to regulate porosity by using clay with better sinterability and phosphoric acid in the production of grog from claystone with alumina content over 40 %, a minimal Fe2O3 content, a minimal content of CaO and alkali oxides.

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Mukhopadhyay, S. "Nanoscale calcium aluminate coated graphite for improved performance of alumina based monolithic refractory composite." Materials Research Bulletin 48, no. 7 (July 2013): 2583–88. http://dx.doi.org/10.1016/j.materresbull.2013.03.006.

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HAGHARA, Seiya, Hidetoshi KAMIO, Yutaka HAYAMA, Shinya TAKETOMI, and Yuichi TADANO. "2A1 Finite element analysis of water vapor pressure for monolithic refractory during drying process." Proceedings of Conference of Kyushu Branch 2013 (2013): 9–10. http://dx.doi.org/10.1299/jsmekyushu.2013.9.

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Pinto, D. G., Abílio P. Silva, A. M. Segadaes, and T. C. Devezas. "Influence of Surface Area on the Flowability Behaviour of Self-Flow Refractory Castables." Materials Science Forum 636-637 (January 2010): 124–29. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.124.

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Alumina, with high melting point (2050°C), high hardness and mechanical strength, and excellent abrasion resistance, is one of the most common raw materials used in self-flow refractory castables (SFRC) for monolithic linings and is commercially available in various fine to coarse size classes. However, the performance of the refractory lining depends not only on the properties of its ingredients but also on its easy installation (good flowability). The aim of this work was to evaluate the relationship between the flowability index (FI) of fresh castable and the specific surface area (SSA) of its particles, which is mostly determined by the finer particles content. The results obtained showed that, by controlling the proportion between matrix and aggregate, it is possible to control the SSA of the refractory castable and find a mathematical relationship between the specific surface area and the minimum flowability index required to obtain a self-flow refractory castable. It is, thus, possible to optimize the refractory castable size composition and obtain an estimate for FI as a function of SSA. Using a minimum 45 wt.% matrix content in the castable mixture, a SSA value above 2.215 m2/g is obtained, which leads to FI ≥ 80%, the recommended value for self-flow.

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Yoon, Jin Kook, Dong Wha Kum, and Kyung Tae Hong. "Manufacturing and Oxidation Behavior of Silicide-Based Nanocomposite Coatings on Refractory Metals by Displacement Reaction." Materials Science Forum 539-543 (March 2007): 135–40. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.135.

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The microstructure and oxidation resistance of MSi2-SiC or MSi2-Si3N4 nanocomposite coatings (M = Mo, W, Nb, Ta) on M substrates formed by displacement reactions between M-carbides or M–nitrides and silicon, respectively, was investigated. Present study demonstrated that the crack density formed in the MSi2-base nanocomposite coatings due to mismatch in the coefficient of thermal expansion between nanocomposite coatings and M substrates could be controlled by adjusting the volume fraction of the SiC or Si3N4 reinforcing particles with the low CTE values. The high- and low-temperature oxidation resistance of nanocomposite coatings was superior to that of monolithic MSi2 coatings.

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Zhao, Zhao, Anne Denquin, Stefan Drawin, and Jonathan Barreau. "Microstructure and Mechanical Behaviour of NbTiAl Based Alloys Doped with Low Additions of Silicon." Materials Science Forum 783-786 (May 2014): 1207–12. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.1207.

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Nb-base refractory intermetallic materials have potential interest for high temperature applications thanks to their low density and high temperature strength. While advanced intermetallics in monolithic form have limited prospects for providing the required balance of properties for use at high temperatures, two-phase or multicomponent intermetallic systems composed of a ductile, Nb-base refractory phase in equilibrium with one or more silicide intermetallics show promise for further development as structural materials. In the present paper, Nb-base refractory alloys based on Nb-35Ti-15Al (at.%) were doped with small amount of Si (1 and 2 at% of silicon) addition to improve its high temperature strength by keeping an acceptable ductility at room temperature. The samples were prepared by arc-melting starting from pure elements (99.99%). The silicon addition effects on the microstructural features were investigated by using X Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) techniques. Its effects on the mechanical properties were assessed by compression tests at ambient and high temperatures. Compression tests show the beneficial effect of the Si addition on strength.

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Mukhopadhyay, S., S. Das, and S. Moitra. "Thermomechanical and thermophysical characteristics of alumina-carbon monolithic refractory containing surface-modified graphites in matrix." Ceramics International 44, no. 9 (June 2018): 10061–68. http://dx.doi.org/10.1016/j.ceramint.2018.02.207.

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Rogers, D. L. "Monolithic integration of a 3-GHz detector/preamplifier using a refractory-gate, ion-implanted MESFET process." IEEE Electron Device Letters 7, no. 11 (November 1986): 600–602. http://dx.doi.org/10.1109/edl.1986.26487.

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Mukhopadhyay, S., A. Saha, S. Chatterjee, and S. Ghosh. "Thermomechanical Characteristics of Low Carbon Magnesia-Based Monolithic Refractory Containing Nanostructured Surface-Modified Graphites in Matrix." Transactions of the Indian Ceramic Society 76, no. 2 (April 3, 2017): 118–27. http://dx.doi.org/10.1080/0371750x.2017.1281765.

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Mukhopadhyay, Sunanda. "Effect of surface-treated graphites on the properties of carbon-containing monolithic refractory materials-A comprehensive comparison." International Journal of Applied Ceramic Technology 14, no. 4 (May 6, 2017): 719–30. http://dx.doi.org/10.1111/ijac.12691.

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Das, P., S. Sinhamahapatra, K. Dana, and S. Mukhopadhyay. "Improvement of thermal conductivity of carbonaceous matrix in monolithic Al2O3–C refractory composite by surface-modified graphites." Ceramics International 46, no. 18 (December 2020): 29173–81. http://dx.doi.org/10.1016/j.ceramint.2020.08.090.

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Akselrod, L. M., and V. Garten. "An alternative lining of steel ladles: technical and economic aspects." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information, no. 12 (December 19, 2018): 72–80. http://dx.doi.org/10.32339/0135-5910-2018-12-72-80.

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Quality of steel ladles lining to a big extent determine the economic efficiency of steel-making operation. Direct costs on the refractory lining of them can reach 30–50 % of the costs of lining of a steel-making complex. Experience of utilization of refractory materials of different composition considered with the purpose of efficiency increase of refractory materials application in the steel ladles lining under conditions of steel ladle treatment. Considerable abilities shown to make the lining of steel ladle walls and bottom by both carbon-containing and carbon-free refractory materials taking into account the economic aspect. Lining base of steel-making facilities — BOFs, EAFs and steel ladles — is composed by periclase-carbon (MgO–C) refractories. However those refractories have a high heat conductivity, that effects on the heat operation of steel ladles. When using MgO–С materials, vertical fractures can appear in the ladle walls lining as its residual thickness becomes small. Under definite conditions a working lining chipping takes place, problems appear with lining destruction in the pieces angles with cavities formation at the pieces joining. To level the MgO–С drawbacks, periclase-alumo-carbon (MgO–Al2O3–С) and alumo-periclase-carbon (Al2O3–MgO–С) refractory products are used. Al2O3–MgO–C refractories are widely used in most erosion-intensive lining zone — in the combatting place of steel ladle bottom lining. In Russia monolithic lining of steel ladle bottom is successfully displacing the lining by piece products, including alumo-periclase-carbon ones. Such a replace enables to decrease specific refractory consumption and specific costs of them. At present the technology of concrete application to bottom is implemented for ladles of BOF- and steel-making shops. A technology of concrete ladle walls and bottom is intensively implemented for 120–180-ton ladles. The concrete lining of steel ladles has the following advantages: high withstandability against impregnation by metal-slag melt; absence of metal carbonization by the carbon from ladle lining; increase of running duration of safety lining layer by 2–2.5 times; absence of necessity to use nest blocks in both steel outlet unit and for bottom blow-off lance; absence of cracks in lining, wash-outs in seams, angles and edges of pieces; decrease of gaseous hydrocarbon emissions(phenol, formaldehyde, benzapilene) during lining drying, heating-up and operation (only slag belt remains, where pieces have organic binders); saving of materials, working time and manpower while making and maintain the lining; decrease of specific consumption and specific costs for lining per 1t of steel. For lining of steel ladles of big volumes (more 250 t) alumo-periclase (alumo-spinel) products are widely used in China, Europe and Japan. For such a lining the thermo-mechanical tension, arising in monolithic ladle lining, has a less importance, including at its replacing with metal by using crane. It is easier for the products to compensate the ladle geometry change, resulted in metal shall geometry change in time. A positive influence of carbon-free lining, as well as a lining with low content of magnesium oxide, on metal quality noted, first of all for low- and ultralow carbon grades, and pipe low-alloyed steels.

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Silva, Abílio P., Ana M. Segadães, and Tessaleno C. Devezas. "MPT Influence on the Rheological Behaviour of Self-Flow Refractory Castables." Materials Science Forum 587-588 (June 2008): 133–37. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.133.

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The success of a refractory castable is largely due to the quality of its properties and ease of application. Self-flow refractory castables (SFRC), with high flowability index (>130%), can be easily accommodated in a mould without the application of external energy, being ideal for the manufacture of monolithic linings. SFRC castables without cement require a matrix of very fine particles, which guarantees improved rheological behaviour and performs the role of the binder in the absence of the refractory cement. The presence of the aggregate (coarse particles) hinders the flowability index, but improves the castable mechanical strength and reduces firing shrinkage, and also contributes to the reduction of the castable costs. The control of the maximum paste thickness (MPT) allows the reduction of the coarse particles interference, minimizing the number of contact points among the grains and avoiding the formation of an aggregate skeleton that impairs the flowability of the mixture. In the present work, 100% alumina SFRCs without cement were produced with a fixed matrix of fine particles, whose particle size distribution was optimized using statistical techniques (mixtures design and triangular response surfaces). Different aggregate particle size distributions were used, with several MPT values, with the objective of evaluating which was the mean distance that maximized the flowability index, simultaneously ensuring good mechanical strength for the refractory castable. Ensuring a minimum surface area of 2.22m2/g, the mixtures reach the self-flow turning point with a minimum water content and the maximum flowability is obtained for an aggregate particle size distribution modulus of q=0.22, and consequently an optimized MPT value. SFRC with high mechanical strength (>60MPa) were obtained.

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Ищенко, А. Н., С. А. Афанасьева, Н. Н. Белов, В. В. Буркин, В. З. Касимов, Л. С. Марцунова, К. С. Рогаев, А. Ю. Саммель, А. Б. Скосырский, and Н. Т. Югов. "Влияние начальной температуры на процесс проникания ударников из пористого сплава на основе вольфрама с упрочняющим наполнителем в стальную преграду." Журнал технической физики 90, no. 5 (2020): 811. http://dx.doi.org/10.21883/jtf.2020.05.49183.102-19.

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A researches series aimed at studying the features and revealing the general laws of penetration of impactors made of composite material based on a porous tungsten + nickel + iron + cobalt alloy with the addition of highly hard refractory particles of tungsten carbide under various initial conditions was continued. In particular, the effect of the initial impactor temperature in the range from −50 to 50 °C on the process of penetration into the steel shield by the experimental and computational methods was studied. The absence of appreciable effect initial impactor temperature in this range for the penetration depth into the shield at impact velocities of 2500 m/s was revealed. The penetration is exceeded by 20% compared with the monolithic mass-size analog of the WNiFe-90 alloy.

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Sciti, Diletta, Mylène Brach, and Alida Bellosi. "Oxidation behavior of a pressureless sintered ZrB2–MoSi2 ceramic composite." Journal of Materials Research 20, no. 4 (April 1, 2005): 922–30. http://dx.doi.org/10.1557/jmr.2005.0111.

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Ultra-refractory ceramic composites of composition ZrB2 + (5 to 20) vol% MoSi2were produced by pressureless sintering at 1830 °C under argon atmosphere.Sintering cycles and microstructural analysis point out that at least 20 vol% molybdenum disilicide is necessary for obtaining a dense material. Thereafter, the composite 80 vol% ZrB2 + 20 vol% MoSi2 was used to test the thermal stabilityunder oxidizing environment. Oxidation tests were carried out in flowing syntheticair in a thermogravimetric analyzer from 700 to 1400 °C with exposure time of30 h. In the low-temperature range (700–1000 °C), the oxidation of the composite resembles that of monolithic ZrB2 ceramics, for temperatures >1200 °C the silica resulting from oxidation of molybdenum disilicide seals the sample surface, preventing zirconium diboride from fast degradation.

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Jain, Manoj Kumar, J. Subrahmanyam, and Subrata Ray. "Development of Mo and Ta Foil Reinforced (MoSi₂ + 20 Vol% SiC_p) Matrix Laminated Composites." Advanced Materials Research 585 (November 2012): 306–10. http://dx.doi.org/10.4028/www.scientific.net/amr.585.306.

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MoSi2 based composites have been recognized as a potential candidate materials for high temperature structural applications. Although, MoSi2 has been reinforced by a variety of ceramic particles, ductile phase toughening of MoSi2 has received only limited attention. In the present investigation, ductile refractory metal (Mo and Ta) foils were used as reinforcements in MoSi2 matrix to prepare the laminated composites. 20 vol% SiC particles (SiCp) were also added in MoSi2 matrix to reduce the thermal expansion mismatch between MoSi2 and the ductile metal foils. The improved bonding between MoSi2-SiCp matrix layer and Mo / Ta foils due to reduced residual thermal stresses resulted in significant improvement in the room temperature fracture toughness of both the composite systems over the monolithic MoSi2.

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Martinovic, S., J. Majstorovic, V. Vidojkovic, and T. Volkov-Husovic. "Influence of the damage level during quenching on thermal shock behavior of low cement castable." Science of Sintering 42, no. 2 (2010): 211–19. http://dx.doi.org/10.2298/sos100518001m.

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In the recent decades, the use of unshaped monolithic refractories has been increasing greatly because of their significant advantages over other shaped refractory bricks of the same class. A low cement high alumina castable was synthetised and sintered at 1300?C in order to investigate thermal and mechanical properties, as well as thermal shock behavior. The water quench test was applied as an experimental method for thermal stability testing. Modification of the water quench test was performed by additional monitoring of the samples behavior during the water quench test such as implementation of image analysis and ultrasonic measurements. The image analysis program was applied on samples in order to measure the level of surface damage before and during the water quench test. Ultrasonic measurements were performed with the aim to measure the Young modulus of elasticity during the testing. Strength deterioration of the samples was calculated by the model based on ultrasonic velocity changes during the water quench test. The influence of monitoring the damage level before and during the quench experiment and its influence on thermal shock behavior will be discussed.

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Lücke, Jörg, and Christoph von der Malsburg. "Rapid Processing and Unsupervised Learning in a Model of the Cortical Macrocolumn." Neural Computation 16, no. 3 (March 1, 2004): 501–33. http://dx.doi.org/10.1162/089976604772744893.

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We study a model of the cortical macrocolumn consisting of a collection of inhibitorily coupled minicolumns. The proposed system overcomes several severe deficits of systems based on single neurons as cerebral functional units, notably limited robustness to damage and unrealistically large computation time. Motivated by neuroanatomical and neurophysiological findings, the utilized dynamics is based on a simple model of a spiking neuron with refractory period, fixed random excitatory interconnection within minicolumns, and instantaneous inhibition within one macrocolumn. A stability analysis of the system's dynamical equations shows that minicolumns can act as monolithic functional units for purposes of critical, fast decisions and learning. Oscillating inhibition (in the gamma frequency range) leads to a phase-coupled population rate code and high sensitivity to small imbalances in minicolumn inputs. Minicolumns are shown to be able to organize their collective inputs without supervision by Hebbian plasticity into selective receptive field shapes, thereby becoming classifiers for input patterns. Using the bars test, we critically compare our system's performance with that of others and demonstrate its ability for distributed neural coding.

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Zeng, Qingyi, Lai Lyu, Yaowen Gao, Sheng Chang, and Chun Hu. "A self-sustaining monolithic photoelectrocatalytic/photovoltaic system based on a WO3/BiVO4 photoanode and Si PVC for efficiently producing clean energy from refractory organics degradation." Applied Catalysis B: Environmental 238 (December 2018): 309–17. http://dx.doi.org/10.1016/j.apcatb.2018.07.005.

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Chou, T. C., T. G. Nieh, S. D. McAdams, G. M. Pharr, and W. C. Oliver. "Mechanical properties and microstructures of metal/ceramic microlaminates: Part II. A Mo/Al2O3 system." Journal of Materials Research 7, no. 10 (October 1992): 2774–84. http://dx.doi.org/10.1557/jmr.1992.2774.

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Synthetic multilayers consisting of periodic layers of the refractory metal Mo and the oxide ceramic Al2O3 have been produced by alternating d.c. and r.f. reactive sputter deposition. Microlaminates with four different modulation wavelength—5, 20, 30, and 100 nm—were investigated in this study. The compositions, periodicities, and microstructures of the microlaminates were characterized by Auger electron spectroscopy, low-angle x-ray diffraction, and transmission electron microscopy, including high resolution lattice imaging and microdiffraction. Transmission electron microscopy from the microlaminates indicated that the as-deposited Mo layers are polycrystalline, while the as-deposited Al2O3 layers are primarily amorphous. The Mo and Al2O3 layers are thermally compatible at 800 °C for 6 h, showing no evidence of atomic interdiffusion between the layers. The mechanical properties of the microlaminates, as well as those of monolithic films of Mo and Al2O3 (i.e., the baseline materials), were investigated using nanoindentation methods. A higher than expected modulus and hardness were observed for the microlaminate with the longest wavelength (100 nm); otherwise the mechanical properties are explainable by a rule-of-mixtures. The enhanced mechanical properties of the 100 nm microlaminate may be attributed to crystallization of the amorphous Al2O3 layers and the evolution of a structural texture within this phase.

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Tomšů, F., and S. Palčo. "Refractory Monolithics versus Shaped Refractory Products." Interceram - International Ceramic Review 66, no. 1-2 (March 2017): 20–23. http://dx.doi.org/10.1007/bf03401197.

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Shestakov, A. M., N. I. Shvets, and V. A. Rosenenkova. "Study of preceramic compositions based on modified polycarbosilane and polyorganosilazanes." Industrial laboratory. Diagnostics of materials 87, no. 9 (September 24, 2021): 30–37. http://dx.doi.org/10.26896/1028-6861-2021-87-9-30-37.

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Ceramic matrix composites (CMC) exhibit increased crack resistance and resistance to mechanical and thermal shock impacts retaining at the same time the valuable properties of monolithic ceramics. Therefore, they are widely used as parts of heat-loaded elements of aviation and rocket technology, in nuclear power industry, etc. LPI-method (liquid polymer infiltration) of CMC production is based on the impregnation of a skeleton of ceramic fibers with an organosilicon polymer, formation of a preceramic matrix by polymer technology, and subsequent high-temperature pyrolysis resulting in formation of a reinforced ceramic matrix. Ceramics obtained from polymer precursors have a predominantly amorphous structure which determines its high thermal stability. Moreover, introduction of the nanosized particles of carbides, borides and nitrides of refractory metals (Zr, Ti, Hf) into the matrix of a ceramic composite stabilizes its amorphous structure up to temperatures of 1500 - 1600°C. We present the results of studying the preceramic compositions based on polycarbosilane and polyorganosilazanes modified with Hf and Ta atoms. It is shown that introduction of the modifying additives Hf and Ta into the polyorganosilazane composition shifts the curing interval of the compositions towards lower temperatures. The yield of the gel fraction is 73.3 and 82.7 wt.%, respectively. The weight loss of pyrolysate samples heated to 1400°C in air does not exceed 0.5%. The physical and mechanical properties, as well as the thermal oxidative stability of novel ceramic composite materials obtained on the base of the studied compositions and carbon reinforcing filler are analyzed. It is shown that the density of CMC samples increases by 1.5 times with an increase in the number of impregnation cycles and reaches the maximum value of 1950 kg/m3 with five impregnation cycles of the filler with a composition based on polyorganosilazane modified with Ta. The results obtained can be used in the development of new CMCs.

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Masumoto, Ryouji, Yosinori Takesono, and Takaaki Taketuru. "Steelmaking. The Monolith Technology of Ladle Refractory." DENKI-SEIKO[ELECTRIC FURNACE STEEL] 70, no. 2 (1999): 179–85. http://dx.doi.org/10.4262/denkiseiko.70.179.

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Ryndenkov, D. V., A. S. Perevozov, A. Yu Nikitina, and E. N. Rybantsova. "Nonrecrystallized Granules in a Compacted Monolith from Refractory Nickel Alloys." Metal Science and Heat Treatment 56, no. 7-8 (November 2014): 409–12. http://dx.doi.org/10.1007/s11041-014-9771-4.

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Demidova, Zh N., P. I. Matsak, G. A. Ivanova, Z. A. Matsak, A. V. Chepovskii, L. B. Krushenok, N. A. Druzhinina, et al. "Refractory compounds of basic composition for the monolithin lining of steel-teeming ladles." Refractories 30, no. 7-8 (July 1989): 461–64. http://dx.doi.org/10.1007/bf01280678.

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Li, Zhong Qiu, Li Jie Ci, Tie Cheng Feng, and Shao Yan Zhang. "The Thermal Shock Resistance of Mg-PSZ/LaPO₄Ceramics." Advanced Materials Research 785-786 (September 2013): 187–90. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.187.

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The mechanical properties and thermal shock behavior of Mg-PSZ/LaPO4 ceramics was investigated. The thermal shock resistance of the materials was evaluated by water quenching and a subsequent three-point bending test to determine the flexural strength degradation. Mg-PSZ/15LaPO4 composite showed a higher thermal shock resistance and behaved as a typical refractory. The calculation of thermal shock resistance parameters for the composites and the monolith had indicated possible explanations for the differences in thermal shock behavior.

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Jobert, Gabriel, Pierre Barritault, Maryse Fournier, Cyrielle Monpeurt, Salim Boutami, Cécile Jamois, Pietro Bernasconi, Andrea Lovera, Daniele Braga, and Christian Seassal. "Miniature Optical Particle Counter and Analyzer Involving a Fluidic-Optronic CMOS Chip Coupled with a Millimeter-Sized Glass Optical System." Sensors 21, no. 9 (May 3, 2021): 3181. http://dx.doi.org/10.3390/s21093181.

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Our latest advances in the field of miniaturized optical PM sensors are presented. This sensor combines a hybrid fluidic-optronic CMOS (holed retina) that is able to record a specific irradiance pattern scattered by an illuminated particle (scattering signature), while enabling the circulation of particles toward the sensing area. The holed retina is optically coupled with a monolithic, millimeter-sized, refracto-reflective optical system. The latter notably performs an optical pre-processing of signatures, with a very wide field of view of scattering angles. This improves the sensitivity of the sensors, and simplifies image processing. We report the precise design methodology for such a sensor, as well as its fabrication and characterization using calibrated polystyrene beads. Finally, we discuss its ability to characterize particles and its potential for further miniaturization and integration.

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Alizadeh, S., A. Shalbafi, A. Monshi, and S. Yazdkhasti. "Influence of phosphate binders on the physical and mechanical properties of magnesia carbon monolithics composed of recycled refractory aggregates." Ironmaking & Steelmaking 43, no. 5 (March 18, 2016): 325–30. http://dx.doi.org/10.1179/1743281215y.0000000035.

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Wöhrmeyer, Christoph, Jianying Gao, Christopher Parr, Magali Szepizdyn, Rose-Marie Mineau, and Junhui Zhu. "Corrosion Mechanism of A Density-Reduced Steel Ladle Lining Containing Porous Spinel-Calcium Aluminate Aggregates." Ceramics 3, no. 1 (March 23, 2020): 155–70. http://dx.doi.org/10.3390/ceramics3010015.

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Refractory monolithics for steel ladle linings are typically products with low porosities and high bulk densities. They achieve high temperature, penetration, and corrosion resistance. Despite the high density of these products, which is due to the low porosity of the aggregates, their matrices still exhibit a high amount of pores. Since calcium magnesium aluminate (CMA) has already proven its resistance to penetration and corrosion as a binder in the matrix, this paper investigated if alumina spinel refractories containing microporous calcium magnesium aluminate aggregates can withstand conditions that occur in a steel ladle wall. The objective was to reduce the castable density with the advantage of a lower material requirement for a ladle lining and reduced heat and energy losses. This was achieved by replacing dense alumina aggregates by up to 38% of porous CMA aggregates (grains with 30 vol% porosity), which resulted in a bulk density reduction from 3.1 g/cm3 for the dense alumina castable to 2.8 g/cm3 for the 38% CMA aggregates containing castable. However, the despite the higher porosity, penetration, and corrosion resistance and thermomechanical properties were not impacted negatively for a model alumina spinel castable. A postmortem investigation was conducted on a newly developed dry-gunning mix that was installed in a steel ladle wall on top of a slag penetrated castable and that achieved a service life of 31 heats versus only 18 heats for the reference mix that contained dense alumina and spinel aggregates. This new repair mix contained the newly designed porous CMA aggregates, which in this case partly replaced the dense alumina and spinel aggregates. These porous aggregates consisted of magnesium aluminate and calcium aluminate micro-crystals. The postmortem study revealed two important phenomena that can explain the improved performance: at the hot face in contact with steel and slag, a thin densified zone was observed that blocked the slag penetration into the porous matrix and the porous aggregates. Iron oxides were almost completely blocked from penetration, and only some manganese oxide was observed in the penetrated zone together with some silica and lime from the slag. Clusters of calcium aluminate (CA6) and magnesium aluminate (MA) spinel build the refractory back-bone on the hot side of the material and gussets filled with mostly glassy calcium aluminum silicates close to the hot face and gehlenite further inside the penetrated zone. Alumina grains had a reaction rim consisting of CA2 or CA6 and a very intimate connection to the surrounding matrix unlike the CMA-free mix that showed micro cracks around the alumina grains. At the colder side, the gunning mix with CMA aggregates showed a very good connection to the substrate, supported by a hercynite formation in the gunning mix resulting from a cross-reaction with remains of iron oxide on the CMA containing repair mix. Furthermore, macroscopic observations of a CMA aggregate containing alumina magnesia castable in the metal zone of a steel ladle revealed that macro cracks developed only very slowly, which resulted in a superior service life.

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Lu, X. D., H. Gan, A. C. Buechele, and I. L. Pegg. "Corrosion of K-3 Glass-contact refractory in sodium-rich aluminosilicate melts." MRS Proceedings 556 (1999). http://dx.doi.org/10.1557/proc-556-279.

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AbstractThe corrosion of the glass-contact refractory Monofrax K-3 in two sodium-rich aluminosilicate melts has been studied at 1208 and 1283°C using a modified ASTM procedure with constant agitation of the melt by air bubbling. The results for the monolithic refractory indicate a fast initial stage involving phase dissolution and transformation and a later “passivated” stage in which the surface of the refractory has been substantially modified. The composition of the stable spinel phase in the altered layer on monolithic coupons of K-3 is almost identical to the equilibrium composition bracketed by the dissolution of powdered K-3 into under-saturated melts on the one hand, and by crystallization of spinels from supersaturated melts on the other. The temperature and melt shear viscosity were found to have significant effects on the rates of K-3 dissolution and transformation.

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Herman, David M., Bernard P. Bewlay, Laurent Cretegny, Richard DiDomizio, and John Lewandowski. "Fracture and Fatigue of Niobium Silicide Alloys." MRS Proceedings 1128 (2008). http://dx.doi.org/10.1557/proc-1128-u07-01.

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AbstractThe fracture and fatigue behavior of refractory metal silicide alloys/composites is significantly affected by the mechanical behavior of the refractory metal phase. This paper reviews some of the balance of properties obtained in the alloys/composites based on the Nb-Si system. Since some of the alloy/composite properties are dominated by the behavior of the refractory metal phase, the paper begins with a review of data on monolithic Nb and its alloys. This is followed by presentation of results obtained on Nb-Si alloys/composites and a comparison to behavior of some other high temperature systems.

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Journal articles on the topic 'Monolithic Refractory'

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