Abstract: According to the main reason of the cause of failure at the exit surface of the CWS ceramic nozzle, the gradient function material (FGM) theory was applied into the design and manufacture of CWS ceramic nozzle material, which aimed to induce a compressive residual stress and reduce the tensile stress at the entry area of the FGM ceramic nozzles.  The coefficients of thermal expansion of the constituent phases and neighboring layers, the physical models of FGM-Z and FGM-R were set up by the optimum component distribution.  Analyzing by FEM, the results show that available compressive stress fields are found to exist in the two FGM nozzles, especially in the inner-hole surface of FGM-R ceramic nozzle.  The design model of FGM-R was determined by comparison.

Key words: functionally gradient material, thermal residual stress , nozzle