Dynamic creep tests were performed for the specimen with projections of sintered silicon nitride ceramics at test temperature, T = 1300℃, where triangular stress wave was imposed at stress ratesσ= 0.1, 0.5 and 20 MPa/s. Then dynamic creepdisplacement was measured between the two projections by means of the laser beam type displacement measuring system. Cyclic strain range decreased monotonously with increase in the number of stress cycles in dynamic creep test and this attenuation wasmuch more enhanced at the higher cyclic stress, suggesting that cyclic deformation resistance increases during dynamic creep at 1300℃. The equivalent stressesσ{sub}(eq.1) and σ{sub}(eq.2) were assessed to examine the relationships between the dynamicand static creep strain rates, and the dynamic and static creep life times to failure. Then minimum creep strain rateε{sub}(cmin) and creep life time to failure t{sub}f were plotted against the equivalent stresses in the dynamic creep. It was shown thatthe relationships between ε{sub}(cmin) and σ{sub}(eq.1), and t{sub}f and σ{sub}(eq.2) were in quite good agreement with those in the static creep.
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