Microstructural design and oxidation resistance of CoNiCrAlY alloy coatings in thermal barrier coating system

This paper aims to improve the oxidation resistance of plasma-sprayed CoNiCrAlY coatings by optimizing microstructure. A series of coatings that contained 22.5 ± 2.3%, 35.4 ± 2.2%, and 57.8 ± 2.5% unmelted particles were fabricated by a high efficiency supersonic plasma spraying (SAPS) system. Experimental results showed that the β phase mainly existed in the unmelted particles, and its content increased with increasing the content of unmelted particles. The coating that contained 35.4 ± 2.2% unmelted particles showed the best oxidation resistance. An accurate numerical model obtained from molecular dynamics simulation was used to explain the experimental results. Our study confirmed that an appropriate amount of unmelted particles can improve the oxidation resistance of CoNiCrAlY coating.