MgO質燒結体の曲げ強度に及ぼす粒子径と表面粗さの影響

概要

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MgO and MgO-ZrO_2 sintered bodies with different grain sizes were prepared by the pressureless sintering. Four sides of the specimens were machined paralel to the eventual tensile axis of bending tests with three types of tools; lapping machine. grinding machine and emery paper. Then the strength was measured by 3-point bending to examine the effects of grain size and surface roughness on the bending strength of MgO sintered body. We propose a model of single edge crack length, a_s, that is controlled by the grain size (D) and the maximum surface roughness (R_<max>). In this model, an inherent crack which is dependent on grain size is assumed to situated at the bottom of the surface roughness curve with depth of 0.8R_<max>. Therefore, a_s is expressed by the equation, a_s=a_<s0>+0.8R_<max>, where a_<s0> is defined as the crack length controlling the strength of smooth-faced specimen. In the case of MgO sintered bodies, a_<s0> increased with an increase in grain size according to the equation, a_<s0>=4.48+0.25D-1.38×10^-3D^2. Consequently, the bending strength, σ, was expressed by the equation, σ=K_<IC>/[Y(4.48+0.25D-1.38×10^-3D^2+0.8R_<max>)^1/2], where Y is a shape factor.
社団法人日本材料学会の論文
1993-06-15