MoSi₂/ZrO₂系複合焼結体の機械的性質

抄録

Two kinds of composites of MoSi₂ and ZrO₂ stabilized with 8mol% Y₂O₃ (8Y-ZrO₂) were fabricated by sintering at 1873K for 90min under a vacuum of 2-8×10^-3Pa and subsequent HIPing at 1873K for 60min in Ar. The mechanical properties for both bodies were determined at room temperature. No new compound was produced in the MoSi₂/ZrO₂ composites by firing up to 1873K for 90min under a reduced pressure. Young's modulus of MoSi₂/8Y-ZrO₂ composites decreased linearly with an increase in the amount of 8Y-ZrO₂. On the other hand, Vickers hardness of the composites increased with an increase in the amount of 8Y-ZrO₂ and the effect of HIPing for sintered bodies on these values was clearly noticed. The bending strength of composites increased and then decreased with an increase in the amount of 8Y-ZrO₂. The bending strength of HIPed bodies was higher than that of as-sintered bodies over the 8Y-ZrO₂ content range of 0-60vol%. The 8Y-ZrO₂ content dependence of fracture toughness for composites was almost the same as that of bending strength, although the amount of 8Y-ZrO₂ at which the bending strength and fracture toughness for composites take a maximum values, were different.