Residual Stress Assessment in the Al₂O₃\Mullite Based Laminated System

Abstract

To improve mechanical properties of mullite, a mullite-Al2O3\mullite laminate composite was prepared. Lamination generates residual stresses within the structure, measured by piezospectroscopy. A preliminary and complete piezo-spectroscopic characterization of the Al2O3\mullite system was carried out. A method to determine the concentration of Al2O3 in the composite by Raman spectrum was proposed and used to assess the composition of the laminated structure along the cross section. The experimental results evidenced a gradual change of composition and residual stress state between the two layer.

Lamination Process to Obtain Structure with Tailored Residual Stress Distribution

“…To stimulate residual stresses in a material several techniques can be used: bonding of layers with different CTE, inducing phase transformation in the constituent materials (i.e. tetragonal to monoclinic phase transformation in zirconia based materials) [47] or promoting phase reactions such as in mullite based materials [48]. According to the model outlined before, in this paper we limited our analysis to the effect produced by rigidly bonded layers of two different materials with different coefficients of thermal expansion and shrinkage.…”