STUDIES ON CERAMIC COATINGS - DEDUCTION OF MECHANICAL AND THERMAL-PROPERTIES FROM THE MICROSTRUCTURE OF THE MATERIAL

This paper is concerned with the development of analytical as well as numerical models for the prediction of mechanical and thermal properties of plasma sprayed ceramic layers. Based on a computer-generated microstructure, the evolution of interacting microcracks and the associated elastic moduli are studied, taking into account initial stresses of thermal origin. Considering pores embodied in the layer, an analytical model is developed, which allows an estimation of the reduction of the thermal conductivity as a function of pore volume, orientation and geometrical shape. Additionally, a finite element calculation is utilized to assess the validity of the analytical approach. The appearance of anisotropy is predicted and studied for the elastic proper-ties as well as for the thermal conductivity of the coating.