チタン基焼結硬質合金の開発と腐食特性に関する研究

概要

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Ti-Mo alloy have difficulties in manufacturing by melting-casting process because of its heavy gravitational segregation. Sintered Ti-Mo, Ti-Mo-TiC, Ti-Mo-W-C alloys were developed by the powder metallurgical process, and their microstructures, mechanical properties and corrosion behaviors were investigated. Ti-30mass%Mo alloy was consisted of β-Ti phase, its corrosion resistance in 35%HCl solution was far better than that of pure titanium; this was thought to be caused by the spontaneously passivated film, in which molybdenum was enriched by preferential dissolution of titanium, suppressing the anodic reaction. Ti-Mo-(33-80)mass% TiC alloy had two phases of TiCx and β-Ti phases, and increasing the TiC content increased the hardness, and maximum hardness of HRC 66 was obtained in Ti-Mo-45mass%TiC alloy, but slightly decreased the transverse-rupture-strength. Its potentiodynamic curve revealed also same as that of Ti-30mass%Mo alloy. In this alloy, the spontaneously passivated film adopting to each environment was formed, causing the alloy to show an excellent corrosion resistance in every test solutions. In consequence of these results, this alloy was thought to have both wear resistance and corrosion resistance.
2009-08-15