High performance Co–Cr 3 C 2 composite coating by jet electrodeposition

Abstract

This paper studied the Co–Cr₃C₂ composite coatings on the nickel-based super alloy GH4169 deposited by pulse reverse jet electrodeposition in conjunction with ultrasonic vibration. The GH4169 substrates were first annealed at 500°C for 20 min to eliminate the internal stress, and then the surface was activated chemically. The surface activation procedure and ultrasonic pulse interval time in the jet electrodeposition were investigated. The results showed that the Cr₃C₂ particle contents, microhardness, wear resistance of the coatings were significantly improved, while the surface roughness and the coefficient of friction were reduced, when the ultrasonic vibration is applied in the jet electrodeposition of the Co–Cr₃C₂ composite coatings. It is found that the intermittent ultrasonic vibration at 8 s interval time has the greatest effect on the coatings. The Cr₃C₂ particle content at this condition is at its maximum of 23.85%, with evenly particle distribution and good adhesion with the cobalt matrix. The hardness of the composite coating is 652 HV(0.5), and frictional coefficient is 0.15. It has also high thermal stability, and the microhardness can hold up to 800°C without degradation, showing a great potential for high-temperature applications.