Abstract
The X-ray elastic constants of sintered silicon nitride were measured for the diffraction plane (323) by using Cu-Kα radiation and for (411) by using Cr-Kα radiation. The values of E/(1+ν) (E=Young's modulus, ν=Poisson's ratio) were nearly identical for both planes, and were larger than the mechanically measured value. The residual stress on the lapped and ground surfaces was measured both with (323) and (411) diffractions. The measured values were all compression. The compressive stress for (411) plane was three to four times larger than that for (323) plane, which indicated a steep decrease of compression in the subsurface layer. The compressive residual stress in the direction perpendicular to the grinding direction was about twice the value in the grinding direction.
