Papers by Keyword: Nanoindentation

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Authors: Y.L. Chiu, W. George Ferguson
Abstract: Nanoindentation technique has been widely used for measuring mechanical properties from a very small volume of material. The hardness measured using the depth sensing nanoindentation technique often decreases with increasing indentation size, the so called indentation size effect (ISE)[1, 2]. It has been generally acknowledged that the ISE in crystalline materials originates from the density change of geometrically necessary dislocations (GND) needed to accommodate a permanent indentation imprint. Conventionally, to characterize an ISE often requires a series measurement of hardness values at different indentation size. Based on the celebrated Oliver-Pharr scheme[3]. We propose a method to derive the ISE from the loading curve of one single indentation test. The application and limitation of the proposed method will be discussed.
Authors: Jong Ho Kim, Young Gu Kim, Hyeon Keun Lee, Do Kyung Kim
Abstract: The mechanical properties of brittle coating structures were characterized by various indentation techniques. The adhesion properties of the coatings were evaluated by in situ scratch and sphere indentation method. Physical vapor deposited TiN coatings on transparent substrates, sapphire, were scratched by diamond cone indenter and in situ observed through the transparent substrate. In situ scratch results reveal that the failure of coating is originated from the damage of the substrate and the plastic deformation of substrate is a primary factor for determining the adhesion breakage. The unique characterization technique for the strength measurement of brittle thin coating has been developed. The strength of the thin coating was evaluated by the sphere indentation on the trilayer structure. The CVD SiC coatings on graphite were characterized by the technique. It is concluded that the microstructure of SiC coatings influences the strength. In this paper, the various indentation technique were applied to evaluate the mechanical properties of TiN and SiC coatings and the effect of microstructure on the reliability of the brittle coating system was discussed.
Authors: Lukáš Šimůrka, Selen Erkan, Tuncay Turutoglu
Abstract: The influence of process parameters on amorphous reactively sputtered silicon nitride thin films is reported in this study. The films were prepared with various argon and nitrogen flows, and sputter power in in-line horizontal coater by DC magnetron reactive sputtering from Si (10% Al) target. Refractive index and mechanical properties like residual stress, hardness and elastic modulus were studied. We show that process pressure has an important influence on mechanical properties of the sputtered film. On the other hand, the nitrogen content is the key factor for the optical properties of the films.
Authors: Am Kee Kim, Md Anwarul Hasan, Hak Joo Lee, Seong Seock Cho
Abstract: Nanoindentation test has been performed to characterize the mechanical properties of aluminium alloy foam cell wall. Two of the mechanical properties: hardness and Young’s modulus of cell wall material were evaluated using the stiffness of contact during both loading and unloading. Properties obtained from unloading stiffness were in better agreement with the conventional test result than those obtained from loading stiffness. The finite element analysis using nonlinear finite element code ABAQUS was performed to characterize the yield strength and the stress-strain curve of the cell wall material of the foam. Properties of foam cell wall material were found to be substantially different from the properties of the material before foaming. The methodology used in this paper can be effectively used to characterize the mechanical properties of cell wall of any cellular material.
Authors: J. Srinath, G. Sudarshan Rao, G. Nagamalleswara Rao, Joji J. Chaman, P. Ramesh Narayanan, S.C. Sharma, Koshy M. George
Abstract: Gyroscope is an orientation determining sensor whose performance is mainly dependant on one of the critical element called the gimbal flexure. Thinner the flexure, better is the performance. To have sufficient strength, M300 maraging steel is used to fabricate the thin flexures machined by Electrical Discharge Machining (EDM) process down to the required thickness of 0.05 mm in various stages. After the EDM processing, the recast layer formed can cause degradation in the microstructure and mechanical properties. Micro-abrasive machining was carried out to remove the recast layer. An attempt was made to understand the changes that occurred after EDM and after micro-abrasive machining with respect to the microstructure using optical and Scanning Electron Microscopy (SEM) and with respect to mechanical properties using nanoindentation. Nanoindentation technique was adopted as the recast layer was just few microns thick. Indentations were carried out on the base material, as EDM cut flexure, and the micro-abrasive machined EDM cut flexure to obtain elastic modulus and hardness values for each condition and the results were analyzed.
Authors: Zbyněk Sucharda, Tomas Suchy, Radek Sedláček, Karel Balik, Josef Šepitka, Miroslav Sochor
Abstract: The effect of sterilization on the structural integrity of the polydimethylsiloxane (PDMS) matrix composite reinforced with carbon fibers (CF) is investigated by nanoindentation test. We present the investigation of the influence of sterilization processes on fiber/matrix interphase properties. The effect of multiple widely-used steam sterilization processes on fibers/matrix interphase region properties was studied by modulus mapping test.
Authors: Vladimír Starý, Ladislav Cvrček, Stanislav Daniš, Jan Krčil, Jaroslav Malek, Zdeněk Tolde
Abstract: We present here a study of coatings prepared from β-Ti binary alloy Ti-39wt%Nb, a promising metallic material. TiNb is a highly corrosion-resistant and non-toxic material that is potentially applicable as a biomaterial. TiNb coatings can be prepared on substrates of widely-used materials, and promise not only improved properties but also a less high price of potential TiNb implants. A TiNb film can also be used as a barrier for limiting the potential diffusion of some allergens and toxic elements from the substrate to the surface, which can be influenced by layer properties. We deposited thin layers of TiNb by magnetron sputtering, which provides excellent layer properties in applications. These layers were prepared on substrates made from Ti, Ti alloys (Ti39Nb and Ti6Al4V) and stainless steel AISI316. The aim of our work was to characterize the structure and the mechanical properties of the layers, in dependence on the type of substrate, for application as coatings for medical implants.
Authors: Andreas V. Kadavanich, Sang Hoon Shim, Harry M. Meyer, Stephen E. Savas, Edgar Lara-Curzio
Abstract: Photoresist stripping after ion implantation at high dosages (>1E15 atoms/cm2) is the most challenging dry strip process for advanced logic devices. Such high-dose implant stripping (HDIS) frequently leaves residues on the wafers after dry strip, unless fluorine chemistries are employed in the stripping plasma. Silicon loss requirements at sub-45nm nodes generally preclude such aggressive stripping chemistries. Instead, a wet clean is used to remove residues. However, the nature of the residues is not well understood, and are believed to usually contain some of the cross-linked, carbonized organic polymer formed in the implant [1]. In this paper we present chemical and mechanical data on HDIS residues produced from oxidizing and reducing chemistry strip processes.
Authors: Zhen Lin Wang
Abstract: Chemical tempered glasses were prepared using glass slides as substrate and KNO3 as melting agent by ion-exchange during 2h, 4h, 6h at 430°C,450°C and 500°C respectively. The surface composition of the glasses was analyzed by energy dispersive spectrometer (EDS), the mechanical properties and wear resistance were characterized by nanoindentation/nanoscratch tests. The results indicate that the ion- exchange method can be a good way to increase the strength and improve wear resistance of Na-Ca-Si glass. The chemical tempering has an optimal treating temperature and time.
Authors: B. Narayanamoorthy, B. Dineshkumar, S. Balaji
Abstract: The amino functionalized magnesium phyllosilicate clay (AC) intercalated over PVA-Nafion hybrid nanocomposite membranes were prepared by sol-gel method. The free standing membranes were obtained by solution recasting. The composition of clay materials such as AC and montmorillonite (MMT) was varied between 2-10 wt.% with respect to PVA-Nafion content. The molecular interactions and surface morphology of nanocomposite membranes were investigated by FT-IR and SEM analyses respectively. The thermal and mechanical stabilities of nanocomposite membranes were studied using TGA and Nanoindentation techniques. For 6 wt. % AC/PVA-Nafion, TGA results showed no appreciable mass change up to 380 °C and hardness calculated from nanoindentation studies was nearly 30 % higher than the other compositions. An improved conductivity was obtained for 6 wt. % AC/PVA-Nafion (1.4×10-2 S/cm) compared to pure Nafion (1.2×10-2 S/cm) and PVA-Nafion and MMT/PVA-Nafion composite membranes. From these studies, we observed that 6 wt. % AC/PVA-Nafion membrane possessed a good conductivity with higher thermal and mechanical stabilities.
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