Indentation and Scratch Response of CoNiCrAlY BN Abradable Coating

MCrAlY abradable coating containing boron nitride and polyester is used for sealing turbo-machinery at intermediate temperature. This coating is deposited on Ni base substrate using plasma sprayed technique. Plasma sprayed coating was subsequently subjected to cold isostatic pressure under different load. The microstructural features, indentation, and scratch response of these coatings are evaluated. The results indicate that cold isostatic pressure at 2.75 kbar increases the elastic modulus and hardness of this coating. Further increase in pressure initiates cracks on the surface. The friction coefficient under indentation scratch is not altered by applied load and processing of the coatings. However, lateral hardness, scratch hardness, and scratch toughness increase with applied load.