MICROSTRUCTURE, COMPOSITION AND PROPERTY RELATIONSHIPS OF PLASMA-SPRAYED THERMAL BARRIER COATINGS

The benefits deriving from the use of thermal barrier coatings are briefly reviewed. Properties important for a thermal barrier coating are discussed and reasons for the selection of ZrO2-based alloys highlighted. Candidate zirconia alloys are critically evaluated in terms of their thermal and mechanical properties. Since coatings currently applied consist of a tetragonal phase, the long-term stability of the phase structure and the avoidance of the monoclinic phase is addressed, as is the effect of long-term ageing on the thermal properties. The relationship between microstructure and properties of plasma coatings is reviewed. Future trends, such as extending areas of application in jet engines, use of alternative alloys, and methods of application and optimization of plasma sprayed coatings by modelling the plasma spray process, are also briefly discussed.