X-RAY RESIDUAL-STRESS ANALYSIS ON MACHINED AND TEMPERED HPSN-CERAMICS

The residual stress state induced by grinding and tempering of hot pre ssed silicon nitride (HPSN) samples is studied by X-ray diffraction. T he results reveal that the residual stress values at the surface of th e samples as well as their gradient within the penetration depth of th e X-rays depend on the sintering aid and thus, on the glassy phase con tent of the HPSN. Tempering of the ground HPSN reduces the residual st ress values due to microplastic deformation, whereas an oxidation of t he glassy phase leads to the formation of compressive residual stresse s. (C) 1997 Elsevier Science S.A.