Scanning electron acoustic imaging of residual stress distributions in ceramic coatings and sintered ceramics

Scanning electron acoustic microscopy has been used to reveal the residual stress distributions in the subsurface in carbon steel coating with Ti 3N 4. The experimental results show that residual stress distributions formed around the cracks are 2-fold, symmetrically butterfly-shaped with similar pattern of interchanging plastic and elastic zones. At the same time, we have observed the same butterfly-shaped residual stress fields surrounding the pores formed by the sintering process in piezoelectric transducer (PZT) ceramics. Moreover, the residual stress fields of the pores have the same orientation.