Thermal Barrier Coatings (TBCs) are widely used to reduce the metal substrate temperature and, as a consequence, extend part life. The coatings usually consist of an intermediate metal layer and a top ceramic layer. The metal layer is selected to provide enhanced corrosion and minimize thermal mismatch between the parent and the ceramic. The ceramic top coat's principal function is to provide thermal insulation. In most cases, the ceramic layer is an oxide, usually aluminium oxide or zirconium oxide. While most previous work concentrated on improving the spallation (or delamination) resistance of the ceramic due to thermal cycling in air, many recent studies have investigated the effect of corrosive constituents, such as chlorides, sulphur, vanadium, water and carbonates. The results show that the modes of coating failure can be significantly different, necessitating the need for new or modified coatings. The behaviour of TBCs under thermal cycling in corrosive environments will be the subject of this paper.
