Optimum Design of Sintered Silicon Nitride Ceramics Specimen with Projections for High-Temperature Creep Test

Abstract

A tensile creep specimen with projections was designed to measure creep displacement by means of the laser-beam displacement meter at temperatures elevated over 1000°C. Stress/strain concentrations, however, occur around the root of projections in this specimen. The high-temperature creep strain was determined from the measurement of tensile displacement between the two projections by correcting influence of the projections. The procedures used to determine the steady-state creep constitutive equation of Si₃N₄ ceramics was proposed by combining a high-temperature creep test using the specimen with projections and the finite-element method(FEM) calculations for the specimen. Furthermore, the method for designing the optimum creep specimen with projections was determined via the FEM calculations using the steady-state creep constitutive equation.