Optimization of Coating Layers in the Design of Ceramic Fiber Reinforced Metal Matrix Composites

The potential of using coating layers to reduce thermal stresses in the matrix of composites with a mismatch in coefficients of thermal expansion (CTE) of fiber and matrix is investigated. Two thermoelastic solutions based on a 3-cylinder model are developed and a comprehensive sensitivity study is conducted. It is shown that the performance of the layer can be defined by the product of its CTE and thickness, and that a compensating layer with a sufficiently high CTE can reduce the thermal stresses in the matrix significantly. A practical procedure offering a window of coating layer candidates is proposed. Easy-to-use contours of matrix stress reduction factors are produced.