MoSi 2を主体とする発熱体の焼結条件とその性質

概要

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Some preliminary experiments were made to prepare an electric heat element chiefly composed of MoSi 2 fine powder mixed with oxide powders (Al2O3, SiO2), and the mixture was sintered with hot pressing process. The Optimum sintering conditions were thus made clear. The specimens obtained were subjected to some physical and mechanical tests. Results were summerized as follows: (1) The sintering temperature of MoSi 2 with some admixture of oxides (Al2O3, SiO2) was 1600-1650°C and the sintering pressure was 250kg/cm2, the density of the specimen attaining 90-97% of the theoretical density. (2) The corrosion resistance increased with the increasing amount of the oxides added. (3) Vichers hardness value of MoSi 2 with oxide admixture was higher than that of pure MoSi 2. They were in the range of 971-1300. In general, Vichers hardness in hot temperature decreased as the atmaspheric tempe-rature increased. (4) The addition of oxides to MoSi 2 made the electrical resistance of the corresponding specimen higher. (5) The electrical resistance increased linearly with the rise of temperature, for example 0.1×10-2Ω-cm at 1500°C. (6) The modulus of rapture decreased with the increasing amount the oxides. (7) The thermal shock resistance increased with the additiou of Al2O3. (8) The oxidizing tests in the air at 1200°C proved successful, The increase in weight of the specimen was in the range of 0.0002-0.0005g/cm2/day.