Estimation of Residual Stress Distribution of Ground Ceramics by Glancing Incidence X-Ray Diffraction Technique

Abstract

A new method was proposed to estimate nondestructively the steep distribution of residual stress in the surface layer of ground ceramics with the use of the glancing incidence X-ray diffraction method. In the estimation, we assumed an exponential decrement of the residual stress near the surface, and derived a formula for the strain measured by X-rays as a function of sin²ψ. Experimentally, we obtained the strain for a very wide range of sin²ψ from heavily ground silicon nitride by the glancing incidence X-ray diffraction method. A strong nonlinearity was found in sin²ψ diagram at very high ψ-angles, that is at very shallow penetration depths of X-rays. From the analysis of the nonlinearity by our new method, the stress distribution in the surface layer was determined. The residual stress took the maximum compression of about 2000MPa at 0.4μm from the surface, and then diminished at about 10μm in depth.