Papers by Keyword: Scratch Test

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Authors: Yusuke Ushiro, Daisuke Okai, Atsushi Yamamoto
Abstract: The fracture behavior and adhesion strength of CrN/Cr and CrN films on SKD61 substrates were investigated by a three-point bending test. The SKD61 substrates were coated with a film with multilayer of CrN/Cr and a single film of CrN by a physical vapor deposition (PVD). The fracture behaviors of CrN/Cr and CrN films at three-point bending test were observed by scanning electron microscopy (SEM). Adhesions of the CrN/Cr/SKD61 and the CrN/SKD61 were also evaluated using a scratch tester. The scratch test resulted in no great difference in the adhesion strength between the CrN/Cr/SKD61 and the CrN/SKD61. On the other hand, the three-point bending test showed a high adhesion of the CrN/Cr with the intermediate layer of Cr film compared to the CrN on the SKD61.
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Authors: Soo Chang Kang, Moo Whan Shin
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Authors: Ipek Karacan, Joshua Chou, Besim Ben-Nissan, Innocent J. Macha, Arion Juritza, Andy H. Wang, Wolfgang H. Müller, David Grossin, Valerio Taraschi, Faik N. Oktar, Michael Swain
Abstract: Surface modifications have been progressively applied in order to improve the mechanical, biological and chemical properties of metallic dental and orthopedic implants. Therefore, the novel and multifunctional biocomposites coating matrices, which also consist of local and targeted drug delivery systems, are the most recent applications in the medical field. In this study, gentamicin antibiotic containing HAp bioceramics were utilized in a biodegradable poly-lactic acid thin film matrix which was applied to Ti6Al4V metallic implant surfaces. nanoindentation and scratch test methods were applied. It was observed that, bonding between coating and the substrate is strong enough to be used in implant applications. Additionally, it was observed that the hardness and young modulus values of uncoated Ti6Al4V disc which were 4.3 and 125.2 GPa, respectively. However, under the same testing conditions, it was also observed that the H values (0.6-0.8GPa) and the E (50-60 GPa) values of PLA-HAp biocomposite coated samples are slightly higher than the H values (0.4-0.6 GPa) and the E values (40-50GPa) of only PLA coated sample.
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Authors: Laino Sebastián, Jorge Antonio Sikora, Ricardo C. Dommarco
Abstract: Carbidic ADI (CADI) is a new type of Austempered Ductile Iron containing free carbides in the microstructure, providing a particular combination of wear resistance and impact toughness. In this work, four CADI variants were evaluated, in which carbides were promoted by alloying with chromium. Tests performed under the low stress abrasion condition imposed by the ASTM G65 standard show that CADI can increase the wear resistance up to 100 % when compared with conventional ADI austempered at the same temperature. The carbide content must be higher than 10 % to promote a considerable reinforcing effect. However, at this carbide content level, the impact toughness varies between 7 and 11 J/cm2 for unnotched samples. These values are much lower than those of conventional ADI, but higher than those of other abrasion resistant materials, like white irons. Some CADI variants were also evaluated in field tests, producing abrasion under either low stress or high stress conditions. For this purpose, two CADI prototype parts were studied: screw segments for animal food extruders (low stress abrasion) and wheel loader bucket edges (high stress abrasion). The results gathered showed that CADI behaves satisfactorily under low stress abrasion, but the performance is not so good under high stress conditions. To analyze the differences in the abrasion response, scratch tests were performed in order to evaluate the interaction between the abrasive tip and the microstructure.
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Authors: Stuart R.J. Saunders, Jim P. Banks, Stephen Osgerby, David Rickerby, Christopher J. Chunnilall
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Authors: G. Chollon, R. Moreau, S. Fouquet, Stéphane Jouannigot, Roger R. Naslain
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Authors: Anna da Forno, Massimiliano Bestetti, Nora Lecis, Stefano Paolo Trasatti, Monica Trueba
Abstract: Oxide films have been produced on AM60B magnesium alloy using micro-arc oxidation process in an environmentally friendly alkaline solution with and without addition of different oxides nanoparticles (TiO2, ZrO2 and Al2O3). In order to seal the oxides porosity generated in the sparking process, a silane-based top coat has been applied. The surface morphology of samples was analyzed by Scanning Electron Microscopy (SEM). Scratch tests were performed for evaluating the adhesion strength of the anodic oxides. The corrosion resistance of the oxide- silane- based topcoat composite coatings was evaluated in 3.5% NaCl solution using anodic polarization tests. The anodizing in oxides nanoparticles rich solutions (ZrO2 or Al2O3), followed by a silane top coat treatment performed using OSi as precursor, is an interesting way to synthesize adherent corrosion resistant coatings on magnesium alloy AM60B.
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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.
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Authors: Yang Qiu, De Yi Meng, Yu Feng Chen, Chen Kui Zu
Abstract: Tin doped indium oxide (ITO) thin films were prepared on IR glass substrates at different oxygen flow rate by ion-assisted electron beam evaporation method, high purity ITO particles (In2O3: SnO2 = 9:1 Wt%) were used as source material. Properties such as microstructure, morphology and mechanical properties were investigated by X-ray diffractometer, SEM and scratch tester, respectively. Meanwhile, lattice constant a, crystal grain size and residual stress situation of films as-deposited were calculated and discussed in detail. The results indicated that all of the films as-deposited were polycrystalline and represented [111] preferential orientation. With the increasing of the oxygen flow rate, grain size and surface roughness of films as-deposited decreased, and inner stress remained in film increased. There were two types of failure mode occurred in ITO films according to different stress situation. Relative high level of residual stress improved the mechanical properties of ITO films in a certain extent.
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