X-RAY STUDIES OF PHASE TRANSITIONS IN SOME COMPLEX OXIDES CAUSED BY CONDITIONS OF THERMAL SHOCK AND THERMAL FATIGUE

摘要

The presented works are connected with the problem of high temperature resistant protective coatings deposited, among others, by plasma spraying technology. The main components of these coatings are ceTamic materials based on Al 2O3 and ZrO2. The studied coatings are used in numerous technical applications. One of the most important types of these coatings are the so-called thermal barrier coatings used among others in gas turbines and Diesel engines [1,2,3]. The investigated phase transitions are caused by two groups of factors. The first are connected with applied materials. Both A12O3 and ZrO2 show complex polymorphism. The second, more important group of factors, is connected with the high temperature processes involved, Both the plasma spraying and thermal cycling processes are characterised by short time processes temperature action and high cooling rate. In order to avoid phase transitions unfavourable for coatings performance some stabilising additions are used.