Development of diffusion barrier coats forCFC components by means of thermal sprayingtechnology

Within the framework of this research work, diffusion barrier coats on the basis of Y2O3, mullite and ZrO2 - 7 % Y2O3 were developed for CFC components. The coat systems were investigated in relation to the coat formation, structure and adhesion and to the thermal shock resistance and barrier function. The Y2O3 coat is the best single-coat system with regard to the coat formation, the coat adhesion and the thermal stability. Because of insufficient coat adhesion, mullite and ZrO2 - 7 % Y2O3 are not suitable as single-coat systems. The bond of the ceramic coats can be improved substantially by utilising an bond coat consisting of W or SiC. The cyclic furnace tests and the wetting tests showed that the developed coat systems exhibit a good thermal shock resistance and a good barrier function and are suitable as diffusion barrier coats.