Stress Analysis of Powder Compacts with Graded Structures in Sintering Process

Abstract

During sintering of metal/ceramic functionally grade materials, cracks are often formed on the surface on the top ceramic layer due to the internal stress produced by mismatch shrinkage and warpage. The ways to reduce the internal stress are examined by using the finite element method as well as the plate theory for sintering. Uniaxial pressing, which gives the counter moment against the warping, can decrease the bending stress but only in the middle of the surface. Thinning the top layer is found to be effective in reducing the tensile stress on the surface when the sintering properties of some layers are modified appropriately. The suppression of the surface cracking in the improved graded powder compacts is confirmed by experiment.