Papers by Author: Tetsuya Senda

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Authors: Tetsuya Senda, Yoh-Ichi Kawagoe, Noriyuki Kotani, Kenji Murakami, Koshi Adachi
Abstract: Sliding wear surfaces of alumina were observed by transmission and scanning electron microscopy. Wear loss was very low (<10-7 mm3/Nm) at room temperature whereas it was high (>10-5 mm3/Nm) at 500oC. In a mild wear regime at room temperature, a layer of very fine particles (10 nm or less) is observed on the wear surface. Beneath the layer, a deformed bulk surface with extensive dislocations is observed. The layer exhibits a diffraction pattern of a meta-stable phase which is dissimilar to the original α-alumina. The layer appears to act as lubrication film at the contact interface to reduce the wear loss. In a severe wear regime at 500oC, a similar structure consisting of a fine-particle layer and deformed bulk surface is observed. However, extensive microcracks are observed in the layer and the bulk underneath that cause further material removal resulting in a high wear rate.
Authors: Han Ning Xiao, Ji Xiang Yin, Tetsuya Senda
Abstract: Friction and wear tests of TiB2 sliding against SiC were conducted without lubricant from room temperature to 1200°C in air and in vacuum. The friction coefficient of the couple of TiB2/SiC is affected obviously by the oxidation of TiB2. It increases with the increase of temperature and reaches a maximum at some temperature in air, then decreases remarkably. The friction coefficient of TiB2/SiC in vacuum exhibites almost a constant and keeps smaller value than that in air. Transition of TiB2 onto the sliding surface of SiC was observed, which improved the wear resistance of SiC at high temperatures.
Authors: Han Ning Xiao, Ji Xiang Yin, Tetsuya Senda
Abstract: Friction and wear tests of Al2O3 and SiC were conducted from room temperature to 1200°C both in air and in vacuum. Results show that the wear mechanism of Al2O3 is dominated by micro fracture, debris abrasive and delamination at temperatures below 600 °C, while is controlled by plastic deformation and recrystallization among 600~1200 °C, resulting in an obvious decrease of wear loss. The wear rate and surface microstructure of SiC are closely depending on the testing temperature, atmosphere and contact pressure. Oxidation of SiC at elevated temperatures plays important role on the wear rate. Self lubrication of both Al2O3 and SiC at high temperatures was observed, which is mainly depending on the formation of a specific surface layer composed of nano-particles or very thin glassy film.
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