Establishment of X-Ray Stress Measurement Method of Ceramics and Ceramic Composites

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1. A collaborating work of X-ray measurement of elastic constants and residual stress of Al_2O_3 and Si_3N_4 indicated that Al_2O_3 2.1.10 diffraction by Fe-Kalpha radiation and Si_3N_4 411 diffraction by V-Kalpha radiation were best suited for stress measurement.2. A new method for measurement of a steep gradient of residual stress below the ground surface of ceramics was proposed by using the glancing X-ray diffraction method.3. An imaging plate is useful for recording X-ray diffraction patterns, especially for measurement of stress in a local area. The cosalpha method is recommended to improve the accuracy of stress measurement.4. The X-ray method for measuring the triaxial state of residual stresses in ceramic composites such as Al_2O_3/ZrO_2, Al_2O_3/SiC, SiC/Al-alloy and WC-Co alloy is established.5. The residual stress in TiC film coated on several substrate by the CVD method was a function of the difference in the coefficient of thermal expansion.6. The c-axis of AIN films deposited on glass by sputtering is perpendicular to the specimen surface. A new method was proposed for stress measurement of such films.7. Composite coating of SiC and TiC by the CVD method does not have a strong texture, and need the triaxial stress analysis.8. Grinding residual stresses of Si_3N_4, Al_2O_3 and ZrO_2 were compression on the surface and decreased rapidly beneath the surface.9. The bending strength of ground Al_2O_3 and Si_3N_4 was increased when bent in the direction parallel to the grinding direction, while decreased when bent in the perpendicular direction. For the case of ground ZrO_2, the bending strength was increased for both directions.10. The R-curve method was proposed to predict the strength for fracture from small defects in ceramics.