Interlayer of Al2O3–Cr functionally graded material for reduction of thermal stresses in alumina–heat resisting steel joints

The present paper analyses the influence of an interlayerʹs construction and thickness on thermal residual stresses generated in ceramic–metal joints. cal calculations (the finite elements method—FEM) of the state of thermal residual stresses, as well as the verifying technological tests, were made for the following pair of materials: the Al2O3 ceramics–heat resisting steel. The model reference system was the direct joint of these materials. The results presented in this paper concern the influence of the type of a gradient material (various thickness, various construction profile—understood as the number of layers, various Al2O3–Cr composition and mutual position) on the state of residual stress in the joint. The numerical calculations carried out on the state of residual stresses showed that for the assumed composition and thickness of the gradient material it is possible to further lower the level of stresses in the ceramic element of the analyzed joint by modifying the profile of a gradient materialʹs inner structure. found that the dangerous stresses concentration area was shifted from the bonding line ceramic/FGM layer (of relatively low strength) further into the FGMʹs layer, i.e. to the dividing line layer I (75Al2O3/25Cr)/layer II (50Al2O3/50Cr), of much higher strength.