Academic literature on the topic 'Conventional nanoindentation'
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Journal articles on the topic "Conventional nanoindentation"
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Mueller, Johannes, Karsten Durst, Dorothea Amberger, and Matthias Göken. "Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations." Materials Science Forum 503-504 (January 2006): 31–36. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.31.
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The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.
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Randall, Nicholas X., Matthieu Vandamme, and Franz-Josef Ulm. "Nanoindentation analysis as a two-dimensional tool for mapping the mechanical properties of complex surfaces." Journal of Materials Research 24, no. 3 (March 2009): 679–90. http://dx.doi.org/10.1557/jmr.2009.0149.
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Instrumented indentation (referred to as nanoindentation at low loads and low depths) has now become established for the single point characterization of hardness and elastic modulus of both bulk and coated materials. This makes it a good technique for measuring mechanical properties of homogeneous materials. However, many composite materials are composed of material phases that cannot be examined in bulk form ex situ (e.g., carbides in a ferrous matrix, calcium silicate hydrates in cements, etc.). The requirement for in situ analysis and characterization of chemically complex phases obviates conventional mechanical testing of large specimens representative of these material components. This paper will focus on new developments in the way that nanoindentation can be used as a two-dimensional mapping tool for examining the properties of constituent phases independently of each other. This approach relies on large arrays of nanoindentations (known as grid indentation) and statistical analysis of the resulting data.
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Costelle, Leila, Liina Lind, Pasi Jalkanen, Minna T. Räisänen, Roman Nowak, and Jyrki Räisänen. "Conventional Nanoindentation in Self-Assembled Monolayers Deposited on Gold and Silver Substrates." Journal of Nanomaterials 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/585123.
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Self-assembled monolayers (SAMs) are promising materials for micromechanical applications. However, characterization of mechanical properties of monolayers is challenging for standard nanoindentation, and new efficient analysis techniques are needed. Hereby, a conventional nanoindentation method has been combined in a unique way with efficient data analysis based on consumed energy calculation and load-displacement data. The procedure has been applied on SAMs of 4,4′-biphenyldithiol (BPDT) on Au, 1-tetradecanethiol (TDT), and 1-hexadecanethiol (HDT) on Au and Ag substrates being the first study where SAMs of the same thiols on different substrates are analyzed by nanoindentation providing a new insight into the substrate effects. Unlike TDT and HDT SAMs, which are found to strongly enhance the homogeneity and stiffness of the underlying substrate, the BPDT covered Au substrate appears softer in mechanical response. In the case of TDT and HDT SAMs on Ag the structures are softer showing also faster relaxation than the corresponding structures on Au substrate. The proposed procedure enables a fast and efficient way of assessing the complex behaviour of SAM modified substrates. As a consequence, the results are relevant to practical issues dependent on layer activity and toughness.
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KUMAR, AMIT, and KAIYANG ZENG. "ALTERNATIVE METHODS TO EXTRACT THE HARDNESS AND ELASTIC MODULUS OF THIN FILMS FROM NANOINDENTATION LOAD-DISPLACEMENT DATA." International Journal of Applied Mechanics 02, no. 01 (March 2010): 41–68. http://dx.doi.org/10.1142/s1758825110000445.
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This paper presents alternative analysis methodologies to extract the elastic modulus and hardness of the ultra-thin films from nanoindentation load-displacement data, especially when the film thickness is only few hundred nanometers or less. At such film thickness, the conventional analysis methods for nanoindentation usually do not give accurate film properties due to the substrate effect. The new methods are capable to show how to determine the film-only properties and how the substrates affect the nanoindentation measurement, especially for ultra thin films. These methods give accurate results for nanoindentation of various metallic, ceramic and polymeric films. It also reveals the differences between the use of high-resolution nanoindentation set-up and normal nanoindentation set-up on the same films. The relationships between the mechanical properties and film thickness are also discussed.
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Long, Xu, Xiaodi Zhang, Wenbin Tang, Shaobin Wang, Yihui Feng, and Chao Chang. "Calibration of a Constitutive Model from Tension and Nanoindentation for Lead-Free Solder." Micromachines 9, no. 11 (November 20, 2018): 608. http://dx.doi.org/10.3390/mi9110608.
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It is challenging to evaluate constitutive behaviour by using conventional uniaxial tests for materials with limited sizes, considering the miniaturization trend of integrated circuits in electronic devices. An instrumented nanoindentation approach is appealing to obtain local properties as the function of penetration depth. In this paper, both conventional tensile and nanoindentation experiments are performed on samples of a lead-free Sn–3.0Ag–0.5Cu (SAC305) solder alloy. In order to align the material behaviour, thermal treatments were performed at different temperatures and durations for all specimens, for both tensile experiments and nanoindentation experiments. Based on the self-similarity of the used Berkovich indenter, a power-law model is adopted to describe the stress–strain relationship by means of analytical dimensionless analysis on the applied load-penetration depth responses from nanoindentation experiments. In light of the significant difference of applied strain rates in the tensile and nanoindentation experiments, two “rate factors” are proposed by multiplying the representative stress and stress exponent in the adopted analytical model, and the corresponding values are determined for the best predictions of nanoindentation responses in the form of an applied load–indentation depth relationship. Eventually, good agreement is achieved when comparing the stress–strain responses measured from tensile experiments and estimated from the applied load–indentation depth responses of nanoindentation experiments. The rate factors ψ σ and ψ n are calibrated to be about 0.52 and 0.10, respectively, which facilitate the conversion of constitutive behaviour from nanoindentation experiments for material sample with a limited size.
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Ahn, Byung, R. Mitra, A. M. Hodge, Enrique J. Lavernia, and S. R. Nutt. "Strain Rate Sensitivity Studies of Cryomilled Al Alloy Performed by Nanoindentation." Materials Science Forum 584-586 (June 2008): 221–26. http://dx.doi.org/10.4028/www.scientific.net/msf.584-586.221.
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Al 5083 alloy powder was mechanically milled in liquid nitrogen to achieve a nanocrystalline (NC) structure having an average grain size of 50 nm with high thermal stability, and then consolidated by quasi-isostatic (QI) forging. The consolidation resulted in ultrafine grains (UFG) of about 250 nm, and the bulk material exhibited enhanced strength compared to conventionally processed Al 5083. The hardness of as-cryomilled powder and the UFG material was measured by nanoindentation using loading rates in the range of 50−50,000 /N/s, and results were compared with the conventional grain size alloy. Negative strain rate sensitivity was observed in the cryomilled NC powder and the forged UFG plate, while the conventional alloy was relatively strain rate insensitive.
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Tsui, T. Y., W. C. Oliver, and G. M. Pharr. "Influences of stress on the measurement of mechanical properties using nanoindentation: Part I. Experimental studies in an aluminum alloy." Journal of Materials Research 11, no. 3 (March 1996): 752–59. http://dx.doi.org/10.1557/jmr.1996.0091.
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The influence of applied stress on the measurement of hardness and elastic modulus using nanoindentation methods has been experimentally investigated using special specimens of aluminum alloy 8009 to which controlled stresses could be applied by bending. When analyzed according to standard methods, the nanoindentation data reveal changes in hardness with stress similar to those observed in conventional hardness tests. However, the same analysis shows that the elastic modulus changes with stress by as much as 10%, thus suggesting that the analysis procedure is somehow deficient. Comparison of the real indentation contact areas measured optically to those determined from the nanoindentation data shows that the apparent stress dependence of the modulus results from an underestimation of the contact area by the nanoindentation analysis procedures.
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Sousa, Bryer C., Kristin L. Sundberg, Matthew A. Gleason, and Danielle L. Cote. "Understanding the Antipathogenic Performance of Nanostructured and Conventional Copper Cold Spray Material Consolidations and Coated Surfaces." Crystals 10, no. 6 (June 12, 2020): 504. http://dx.doi.org/10.3390/cryst10060504.
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The role of high strain rate and severe plastic deformation, microstructure, electrochemical behavior, surface chemistry and surface roughness were characterized for two copper cold spray material consolidations, which were produced from conventionally gas-atomized copper powder as well as spray-dried copper feedstock, during the course of this work. The motivation underpinning this work centers upon the development of a more robust understanding of the microstructural features and properties of the conventional copper and nanostructured copper coatings as they relate to antipathogenic contact killing and inactivation applications. Prior work has demonstrated greater antipathogenic efficacy with respect to the nanostructured coating versus the conventional coating. Thus, microstructural analysis was performed in order to establish differences between the two coatings that their respective pathogen kill rates could be attributed to. Results from advanced laser-induced projectile impact testing, X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, scanning transmission microscopy, nanoindentation, energy-dispersive X-ray spectroscopy, nanoindentation, confocal microscopy, atomic force microscopy, linear polarization, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and copper ion release assaying were performed during the course of this research.
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Minor, A. M., E. T. Lilleodden, E. A. Stach, and J. W. Morris. "Direct observations of incipient plasticity during nanoindentation of Al." Journal of Materials Research 19, no. 1 (January 2004): 176–82. http://dx.doi.org/10.1557/jmr.2004.19.1.176.
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The mechanical testing technique for in situ nanoindentation in a transmission electron microscope is described and is shown to provide real-time observations of the mechanisms of plastic deformation that occur during nanoindentation. Here, the importance of this technique was demonstrated on an aluminum thin film deposited on a single-crystalline silicon substrate. Significant results include direct observation of dislocation nucleation, characterization of the dislocation distribution created by indentation, and the observation of indentation-induced grain boundary motion. The observations achieved by this technique provide unique insight into mechanical behavior studied with conventional instrumented nanoindentation techniques and also provide microstructural-level understanding of the mechanics of ultrasmall volumes.
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Fischer-Cripps, A. C. "Multiple-frequency dynamic nanoindentation testing." Journal of Materials Research 19, no. 10 (October 1, 2004): 2981–88. http://dx.doi.org/10.1557/jmr.2004.0368.
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A new method of dynamic nanoindentation testing is introduced in this paper. Conventional dynamic nanoindentation testing involves the superposition of a single frequency sinusoidal force or displacement onto the quasi-static load–displacement curve. However, the viscoelastic response of many materials depends upon the frequency of the deformation of the material. This paper describes a method whereby the storage and loss modulus of viscoelastic solids can be determined using a multi-frequency dynamic oscillatory motion mode of deformation. In this method, the applied load is modulated by a pseudo-random force signal comprising multiple frequencies. A Fourier analysis is then used to deconvolute the signal into frequency-dependent values of storage and loss modulus for the specimen material as a function of frequency. The instrument response is cancelled by the use of a reference transfer function using an equalization process. Established modeling equations can then be used to extract the modulus of elasticity and the viscosity of the specimen material.
Dissertations / Theses on the topic "Conventional nanoindentation"
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Trivedi, Rutul Rajendra. "Studium povrchů tenkovrstvých materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233343.
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Disertační práce se zabývá studiem povrchových vlastností jedno a vícevrstvých filmů deponovaných z vinyltriethoxysilanových a tetravinylsilanových monomerů. Zabývá se také charakterizací adheze jednovrstvých filmů z tetravinylsilanu. Plazmaticky polymerizované tenké vrstvy byly připraveny na leštěných křemíkových substrátech pomocí plazmové depozice z plynné fáze za ustálených podmínek. Povrchové vlastnosti vrstev byly charakterizovány pomocí různých metod rastrovací sondové mikroskopie a nanoindentačních technik jako je konvenční a cyklická nanoindentace. Vrypový test byl použit pro charakterizaci vlastností adheze vrstev. Jednovrstvé filmy připravené za různých depozičních podmínek byly charakterizovány s ohledem na povrchové morfologie a mechanické vlastností (modul pružnosti, tvrdost). Výsledky morfologie povrchu, analýzy zrn, nanoindentace, analýzy konečných prvků a modulů mapování pomohly rozlišit hybridní charakter filmů, které byly deponovány při vyšších výkonech RF-výboje. Nový přístup byl použit v povrchové charakterizaci vícevrstvého filmu pomocí rastrovací sondové mikroskopie a nanoindentace. Adhezívní chování plazmaticky polymerizovaných vrstev různých mechanických vlastností a tloušťek bylo analyzováno pomocí normálních a laterálních síl, koeficientu tření, a snímků vrypů získaných pomocí mikroskopie atomárních sil.
Book chapters on the topic "Conventional nanoindentation"
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Arenz, R. J. "Compliance Plot Analysis of Nonlinear Response of PMMA During Nanoindentation." In Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials, Volume 3, 225–30. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0213-8_32.
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Rouf, Saquib, Sobura Altaf, Shezan Malik, and Kaleem Ahmad Najar. "Comparative Analysis Carried Out on Modern Indentation Techniques for the Measurement of Mechanical Properties: A Review." In Indium [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94224.
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Nowadays many indentation techniques are being commonly employed for determining some mechanical properties (harness, elastic modulus, toughness, etc.) using simple method of measuring the indentation depth. On the basis of measurement of depth of penetration, indentation technique has be classified into major categories i.e. microindentation and nanoindentation. Nanoindentation technique uses indirect method of determining the contact area as the depth of penetration is measured in nanometers, while in conventional indentation the area in contact is measured by elementary measurement of the residual area after the indenter is removed from the specimen. Dynamic hardness is the best result of dynamic indentation which can be expressed as the ratio of energy consumed during a rapid indentation to the volume of indentation. The parameter which are taken into consideration are indentation depth, contact force, contact area, mean contact pressure.
Conference papers on the topic "Conventional nanoindentation"
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Khan, Zafrul, Hasan M. Faisal, and Rafiqul Tarefder. "Fracture Toughness Measurement of Asphalt Concrete by Nanoindentation." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71840.
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Fracture toughness and fracture energy release rate are two important parameters to understand the crack propagation within any material. Fracture toughness of asphalt concrete (AC) is vital to explain the fatigue cracking and low temperature cracking of asphalt pavement. These two types of distresses are still unsolved issues for asphalt researchers. Measuring fracture toughness of AC is not a new phenomenon. Recently, researchers have used several techniques to measure the fracture toughness of AC. Tests like semi-circular bending (SCB) and disk-shaped compact specimen (DCT) testing have been used to measure the fracture toughness of the AC. From the SCB or DCT tests, past researchers have shown that crack in AC propagates through mainly binder and mastic phase. All these conventional tests are carried out in macro scale. It is important to understand that before propagation of these macro scale cracks, the cracks initiates at the nano/micro scale level. With the increment of the loads these nanoscale cracks become macro scale cracks and propagates through the sample. Therefore, it is important to understand the cracks at nanoscale. In this study, nanoindentation test was introduced to measure the fracture toughness of the asphalt concrete. In a nanoindentation test, the sample surface is indented with a loaded indenter. For this test, Berkovich indenter with load control method was used. A field cored asphalt concrete sample was used for this study. The sample was collected by coring at interstate 40 (I-40) near Albuquerque, New Mexico. The sample was field aged for four years. The maximum load applied in this study was 5-mn and the unloading was done at a faster rate than the loading rate. From the load-displacement curves of the nanoindentation tests, fracture toughness of the samples was measured. The unloading curve of the nanoindentation test was further used to obtain reduced modulus of the asphalt concrete using Oliver-Pharr method. In this study, fracture energy is thought of as a portion of irreversible energy. This irreversible energy is comprised of plastic energy and energy required for propagation of crack. By analyzing the load displacement curve along with the maximum indentation depth, energy release rate and mode I fracture toughness of asphalt concrete was measured.
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Molina-Aldareguia, Jon M., Maria R. Elizalde, Ibon Ocan˜a, Javier Gil-Sevillano, Jose´ M. Marti´nez-Esnaola, Francesca Iacopi, Youssef Travaly, and Marleen Van Hove. "Use of Nanoindentation to Characterise the Plasma Damage Region in Low-k Dielectric Films." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15835.
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The thermo-mechanical robustness of interconnect structures is a key reliability concern for integrated circuits. The introduction of new low dielectric constant (low-k) materials with deteriorated mechanical strength (i.e., Young Modulus decreases exponentially with film porosity, which is needed to lower the k value of the dielectric materials) to meet the RC delay goals increase the risk of mechanical adhesive and/or cohesive failure of the device during packaging or even in service. Therefore, the mechanical properties of low-k dielectrics must be studied in detail. This is made very challenging by the fact that they have submicron thickness and that they often display a graded structure due to the damage introduced by exposure to different plasmas during processing. In this context, we demonstrate that nanoindentation is very well suited to study this type of materials. We will show how conventional depth sensing nanoindentation is of limited value to characterise the extent of the plasma induced damage because this extents just a few tens of nanometres and the graded structure can not be sampled with enough depth resolution. However, nanoindentation in modulus mapping mode can achieve enough depth resolution to characterise such nanoscale graded structures. In this technique, the electrostatic force acting on the indenter tip is sinusoidally modulated, while contact mode imaging at a very small force is performed. The dynamical response is then analyzed to extract the local indentation modulus of the sample at each pixel. By using this technique, we have depth profiled the mechanical properties of the plasma induced damage region of OSG films exposed to different plasmas, by acquiring modulus maps as a function of thickness removed in wear experiments. The results correlate well with the density depth profiles derived from X-Ray Reflectivity measurements.
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Gupta, Shikha, Fernando Carrillo, Lisa Pruitt, and Christian Puttlitz. "Nanoscale Indentation of Simulated Soft Tissues." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61986.
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The use of small animal models, such as murine and rabbit models, are currently being explored to help elucidate the mechanobiological mechanisms of clinically relevant orthopaedic conditions such as fracture healing and osteoarthritis progression, with the goal of developing a comprehensive view of the biomechanical structure-function relationships at the tissue and cellular level. In addition to the heterogeneous nature of these tissues, the miniature size of the test specimens from these small animal models precludes the use of conventional bulk mechanical testing procedures to obtain material properties. Nanoindentation is a technique that is used to assess mechanical properties on a cellular scale. Though traditionally used to study hard, elastic-plastic materials, it has been effectively utilized to measure the material properties of mineralized biological materials [1, 2]. More recently, there have been some preliminary studies on soft, hydrated tissues, such as demineralized dentin, cartilage, and vascular tissues [3, 4]. However, this technique has not been validated for measuring the properties of tissues with extremely small, time- dependent tissue matrices (elastic moduli below 5 MPa). A finite element model (FE) of the nanoscale indentation process has been developed to assess some of the experimental issues associated with using nanoindentation on physical tissue specimens. In addition, we have used this FE model to predict the distribution of stresses and strains within the indenting substrate (tissue sample), mechanical parameters that cannot be mapped using currently-available experimental methods.
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Lee, Hyungsuk, and Junghyun Cho. "Development of Conformal PDMS and Parylene Coatings for Microelectronics and MEMS Packaging." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82955.
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There is a growing demand in the development of small-scale devices in microelectronics and microelectromechanical systems (MEMS). Packaging and reliability of such devices are of great concern as they introduce a number of unique packaging issues that are distinct and different from typical electronic packaging applications. In addition, the packaging or encapsulation materials are often exposed to harsh environments, for which their performance is drastically degraded. Importantly, such devices become lighter and smaller, precluding the use of conventional packaging materials and schemes. Given that, surface protective coatings can provide an innovative solution for some of the aforementioned issues. Polymers have indeed shown such a potential for use either as a standalone coating, or an intermediate layer for the subsequent harder, stiffer coatings. In this study, we explore processes and properties of the three coating systems: i) PDMS, ii) Parylene (para-xylylene), iii) Parylene/PDMS. In particular, parylene coating on PDMS is a focus of this study. The parylene coating having much higher mechanical properties than PDMS provided a way to enhance the surface properties of this PDMS. Proper surface modification of PDMS via oxygen plasma seemed to be essential to generate desirable microstructures of parylene coating. Mechanical properties of such coatings are systematically examined via a nanoindenter. The dynamic nanoindentation is also employed to assess viscoelastic properties, as well as depth-dependent mechanical properties. While characterizing the films using the nanoindentation, the substrate effect influenced the indentation data. In addition, extensive surface characterizations are carried out using atomic force microscope (AFM), scanning electron microscope (SEM), and optical microscopy.
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Skoric, Branko, Damir Kakas, and Aleksandar Miletic. "Influence of Ion Implantation on Tribo and Mechanical Behaviour of Duplex Hard Coatings." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24410.
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In this paper, we present the results of a study of TiN films which are deposited by a Physical Vapor Deposition and Ion Beam Assisted Deposition. In the present investigation the subsequent ion implantation was provided with N2+ ions. The ion implantation was applied to enhance the mechanical properties of surface. In the nanoindentation technique, hardness and Young’s modulus can be determined by the Oliver and Pharr method. Indentation was performed with CSM Nanohardness Tester. The results are analyzed in terms of load-displacement curves, hardness, Young’s modulus, unloading stiffness and elastic recovery The analysis of the indents was performed by Atomic Force Microscope. The stress determination follows the conventional sin2 Ψ method, using a X-ray diffractometer. A variety of analytic techniques were used for characterization, such as scratch test, calo test, SEM, AFM, XRD and EDAX. Therefore, by properly selecting the processing parameters, well-adherent TiN films with high hardness can be obtained on engineering steel substrates, and show a potential for engineering applications. The experimental results indicated that the mechanical hardness is elevated by penetration of nitrogen, whereas the Young’s modulus is significantly elevated.
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Swminathan, V. P., Ronghua Wei, and David W. Gandy. "Erosion Resistant Nano Technology Coatings for Gas Turbine Components." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27027.
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Solid particle and liquid particle erosion in the compressor section of gas turbines and steam turbine vanes and blades lead to significant reduction in turbine efficiency over time. This results in increased downtime and operating cost of the power plants. Some of the conventional coatings and erosion protection shields used by the currently available commercial processes have limitations in their temperature and erosion protection capabilities. Under a project funded by the Electric Power Research Institute (EPRI), nano coatings with thickness within 40 microns (about 1.5 mils) have been produced on test samples using a state-of-the-art Plasma Enhanced Magnetron Sputtering (PEMS) technique. Five coatings were selected for the initial screening tests. Titanium silicon carbonitride nano-composite (TiSiCN), stellite and modified stellite, chromium carbide and Ti-TiN nano layered coatings are being studies in this project. The substrate selection is based on some of the alloys currently used in aeroderivative engine compressor blades, land based gas turbine compressor blades and steam turbine blades and vanes. They include titanium alloys and stainless steels. The PEMS coating technique differs significantly from the conventional techniques such as air plasma spray (APS), low-pressure plasma spray (LPPS), diffusion coatings, chemical or physical vapor deposition (CVD or PVD) used on blades and vanes. PEMS method involves a magnetron sputtering process using a vacuum chamber with an independently generated plasma source from which high current density can be obtained. This method used heavy ion bombardment prior to and during deposition to increase the coating adhesion and limit columnar growth in the coatings. Single-layered thick nitrides coatings up to about 80μm and thick carbonitride coatings of TiSiCN about 30μm have been obtained by this process. A novel method using trimethylsilane gas instead of solid targets was successful in producing this nanocomposite. Initial tests conducted on some of the coated titanium alloy samples produced thus far show significant improvement in the erosion resistance in laboratory sand erosion tests. It was observed that TiSiCN exhibited the best low-angle erosion resistance — nearly 25 times higher than the uncoated Ti-6Al-4V and about 5–10 times higher than all other nitrides. This paper covers a brief description of the deposition technology and the properties of the coatings. Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS), and X-Ray diffraction (XRD) analysis were used to study the microstructure and morphology of these coatings. Nanoindentation was conducted to determine the hardness and Young’s modulus, while sand erosion tests were conducted to rank the erosion resistance of the coatings produced using several processing variables.
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Zhang, Qingwei, Vadym Mochalin, Ioannis Neitzel, Yury Gogotsi, Peter I. Lelkes, and Jack Zhou. "The Study on PLLA-Nanodiamond Composites for Surgical Fixation Devices." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38287.
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Biopolymers have a great potential in biomedical engineering, having been used as scaffolds for hard and soft tissues, such as bone and blood vessels for many years. More recently biopolymers have also found applications in surgical fixation devices. Compared with conventional metal fixation devices, bone grafts and organ substitutes, biopolymer products have advantages of no long-term implant palpability or temperature sensitivity, predictable degradation to provide progressive bone loading and no stress shielding, all of which leads to a better bone healing, reduced patient trauma and cost, elimination of second surgery for implant removal, and fewer complications from infections. However lack of initial fixation strength and bioactivity are two major concerns which limited more widespread applications of biopolymers in orthopedic surgery. Nanodiamond is attractive for its use in reinforcement of composite materials due to their outstanding mechanical, chemical and biological properties. Nanotechnology shows us many innovations and it is generally accepted view that many could be further developed and applied in tissue engineering. In this work, we conduct poly(L-lactic acid) (PLLA) and octadecylamine functionalized nanodiamond (ND-ODA) composite research to optimize the polymer/ND interface, thus to reinforce the mechanical strength. Composites comprising PLLA matrix with embedded ND-ODA were prepared by mixing PLLA/chloroform solution with chloroform suspension of nanodiamonds at concentrations of 0–10 by weight percent. The dispersion of ND-ODA was observed by transmission electron microscopy (TEM). TEM micrographs show that ND-ODA can disperse uniformly in PLLA till 10% wt. Nanoindentation result shows the mechanical strength of ND-ODA/PLLA composites improving following increasing the concentration of ND-ODA in composites. The noncytotoxicity of ND-ODA was demonstrated on 7F2 Osteoblasts. To test the usefulness of ND-ODA/PLLA composites as scaffolds for supporting cell growth, 7F2 Osteoblasts were cultured on scaffolds for 6 days. The attachment and proliferation of 7F2 on all scaffolds were assessed by fluorescent nuclear staining with Hoechst 33258 and Alamar BlueTM assay. The results showed that the adding ND-ODA does small influence cell growth, which indicates the composites have good biocompatibility. The morphology of 7F2 cells growing on all ND-ODA/PLLA composite scaffolds was determined by SEM, which confirms the Osteoblasts spread on the scaffolds. All these results combined suggest that ND-ODA/PLLA might provide a novel composite suitable for surgical fixation devices.
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Chowdhury, Md Mahmudur R., Mohd Aminul Hoque, Jeffrey C. Suhling, Sa’d Hamasha, and Pradeep Lall. "Evolution of the Microstructure of Lead Free Solders Subjected to Both Aging and Cyclic Loading." In ASME 2019 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ipack2019-6560.
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Abstract Currently, lead-free solders are being widely used as an alternative to traditional Sn-Pb solders in micro-electronic packaging industry due to the environmental concern of lead. Fatigue failure of solder joints is one of the common failure modes in electronic packaging which might be attributed to the experiences of thermo-mechanical fatigue (e.g. Power switching) or mechanical fatigue (e.g. vibration) loading. To design these lead-free solders more strategically for specific applications, it is important to understand the failure mechanism of lead-free solders under fatigue loading. Moreover, the microstructure and constitutive properties of conventional lead free solder joints in electronic assemblies such as SAC305 changes when exposed to isothermal aging. These changes consequently reduce the reliability of lead free electronic assemblies significantly due to aging. In this study, we have examined the effects of prior aging on damage accumulation occurring in SAC305 and SAC_Q (SAC+Bi) solder materials subjected to mechanical cycling (fatigue testing). Uniaxial samples have been prepared and polished so that the microstructural changes could be tracked after the initial aging, and then subsequently with mechanical cycling. In particular, we have examined the microstructural changes that occurred in small fixed regions in the solder samples, rather than using several different regions. Regions of interest near the center of the sample were marked using small indents formed with a nanoindentation system. Samples were then subjected to aging at 125 °C for various durations to produce several different initial microstructures. Scanning electron microscopy (SEM) were used to investigate the aging induced microstructural changes in the regions of interest in the solder sample. After aging, the samples were then subjected to mechanical cycling. After various durations of cycling (e.g. 0, 10, 25, 50, 75, 100, 200, 300 cycles) that were below the fatigue life of the materials, the regions of interest were again examined using SEM. Using the recorded images, the microstructural evolutions in the fixed regions were observed, and the effects of the initial aging on the results were determined. In case of SAC305, It was found that the number of IMC particles decreased while the average diameter of the particles increases significantly due to the initial aging. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged with the application of the mechanical cyclic load. Relative to the non-aged samples, there were significant differences observed in the rate and intensity of the micro crack growth occurring in the heavily aged samples that began with much coarser microstructures. Later, the cycling induced microstructure evolutions observed in the SAC_Q lead free alloy has been compared with the observed changes in the microstructure of SAC305 that occurred during the cyclic loading. Due to the presence of bismuth, significant difference in the microstructural evolution of the SAC_Q alloy during cycling were observed. Thus, the doped alloys have shown a high potential for use in thermal cycling conditions because of their improved resistance to aging-induced evolution.