X-ray Diffraction Analysis of Residual Stress in Laminated Ceramic

The strength of ceramic was improved by lamination by suppressing the propagation of cracks with compressive residual stress in the face layer of the laminate. Hot pressed SiAlON+SiC/SiC/SiAlON+SiC laminate discs were fabricated for tailored residual stress. The residual stress in this laminate was studied by X-ray diffraction (XRD). There was considerable compressive residual stress in the face layer. A Finite Element Analysis (FEA) was performed to support the measured XRD results and to determine the stress field in the laminate. The residual stress measured by XRD had satisfactory agreement with the analytically calculated and FEA values. The measured value by XRD was -385 +/- 20 MPa over most of the face layer. The calculated and FEA values were -386 MPa and -371 MPa, respectively. FEA also showed significantly modified stresses and the maximum tensile stress near the edge region which are possible crack generators in the presence of flaws or contact damage.