Erosion behaviour of cobalt-based coatings with different carbide contents under high-speed propellant airflow

Abstract

Three different cobalt-based alloy coatings were prepared on the surface of PCrNi3MoVA steel by plasma transferred arc method by adjusting the contents of Cr, W, and C. An accelerated erosion test was performed on the coatings under high-pressure hot airflow environment generated by propellant combustion in gun bore. Scanning electron microscopy and X-ray diffractometry were used to analyse the microstructure of the three coatings before and after erosion. The thermal behaviour of the three coatings was analysed by differential scanning calorimetry. Results show that erosion mainly occurs between the dendrites on the surface of the coating, manifested by eutectic melting erosion and carbide cracking. As the contents of Cr, W, and C decrease, the amount of carbides formed in the coating decreases, the erosion behaviour of the coating is significantly weakened, and the erosion resistance is highly improved.