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Ti-8.4 vol% M-47.4 vol% TiC (M: Cr, Mo, W) alloys were prepared through P/M technology and their microstructures and mechanical properties were investigated. It was noted that TiC grain size of W alloy was much smaller than that of both Cr alloy and Mo alloy. Smaller diffusion coefficient of M in β-Ti phase and smaller absolute value of Helmholtz standard free energy of formation of MC were thought to suppress TiC grain growth. It was found that hardness and transverse-rupture strength of W alloy were much higher than those of both Cr alloy and Mo alloy. The occurrence of numerous shallow cracks on the rubbing surface of cemented carbide was studied by using an apparatus simulated mechanical seal. If the Vickers indentation tests were conducted on the rubbing surface where the crack spacing was large, indentation cracks with almost the same length as the neighboring pre-cracks could be formed by the tensile residual surface stress. Thermal and elastic-plastic analyses shows that thermo-cracking mechanism cannot explain why cracks run perpendicular to the direction of sliding and that the dynamical action of a high contact stress together with a high tangential force plays a very important role in the occurrence of cracks. [ABSTRACT FROM AUTHOR]

A unique shield system has been developed utilizing electrostatic force to remove dust breaking into bearings and mechanical seals of equipment used for space exploration. Because the performance of the former system was not satisfactory for mitigating dust intrusion, we added wire electrodes above the former system to improve the performance. As the result, approximately 95 % of dust was repelled from the gap. Moreover, we developed a numerical calculation algorithm using distinct element method for decreasing calculation load without decreasing calculation accuracy. It was predicted by the developed numerical method that the shield performance of the electrostatic dust shield system would be great on the Moon and Mars environment if dust would be charged strongly. This technology is expected to increase the reliability of equipment used in long-term manned and unmanned activities on the Lunar and Martian surface.