Development of thermal barrier coating system with an intermediate layer containing MoSi<inf>2</inf> with superior thermal cyclic properties

Abstract

The authors have developed a successful method for improving the thermal cyclic resistance of the thermal barrier coating system that is deposited on gas turbine components. Conventional thermal barrier coating consists of duplex systems, top coating and bond coating. The developed system introduces a protective intermediate layer of MoSi 2 for preventing oxidation of the bond coating. Conventional duplex plasma sprayed coating was delaminated after 20 thermal cycles. On the other hand the developed triple layered coating system was not delaminated up to 60 cycles. The reason for the enhanced resistance to thermal cycle of the developed triple layered coating system is that the MoSi 2 layer existing between the top coating and the bond coating has the selfrepairing property. Here, MoSi 2 oxidizes to form SiO 2 which seals the cracks and pores formed between the top coating and the bond coating. Thus, the formation of TGO which leads to coating delamination is prevented and the thermal cyclic resistance is improved.