Determination of inhomogeneous residual stress states in surface layers of machined engineering ceramics by synchrotron X-rays

Abstract

Ceramic components for engineering applications must in most cases be ground after sintering in order to achieve a sufficient precision of the final dimensions as well as a sufficient surface quality. Since the surface layers influenced by grinding are very shallow, the determination of near-surface grinding residual stresses and their gradients within the penetration depth of the X-rays is difficult. In this paper, a procedure is applied which allows the investigation of residual stress states in ground ceramic surfaces by X-ray diffraction using synchrotron radiation and parallel beam optics. Three different ceramics were examined. In all cases, compressive residual stresses were found in the surface layers of the materials investigated. The magnitudes and gradients of the grinding residual stresses markedly depend on the grinding parameters and on the resulting mechanism of materials removal.