INTRODUCING COMPRESSIVE SURFACE STRESSES INTO BRITTLE MATERIALS.

Sodium beta -Al//2O//3 changes its molar volume upon ion exchange. This effect can be utilized to introduce surface compression into brittle matrices. This process can be achieved by dispersing tetragonal ZrO//2 particles throughout a ceramic matrix and inducing their phase change to monoclinic in the composite surface. The compressive stresses arise from the volume increase accompanying the tetragonal-to-monoclinic phase transformation of the dispersed ZrO//2.