High energy X-ray diffraction analysis of strain and residual stress in silicon nitride ceramic diffusion bonds

High resolution X-ray scanning diffractometry is used to study the residual stress in binary metal/ceramic (Ni/Si3N4) diffusion bonds fabricated by simultaneous high temperature heating and uniaxial pressing. In order to diminish the experimental error on the stress determination, the method consists of three steps: (i) to measure the axial and radial strains following some selected lines at the inner volume of the ceramic; (ii) to fit the strain data using finite element method (FEM) analysis and (iii) to determinate stresses by using the results obtained from the FEM method in the strain calculation.