Sedimentation suppression and precipitation regulation of WC-reinforced particles in plasma arc deposited Ni-based coatings via an alternating magnetic field

Abstract

The pursuit of high quality, high efficiency, and low investment in ceramic particles reinforced Ni-based composite coating has prompted continuous advancement in surface modification technology. Herein, the WC/Ni60 coatings were prepared by a coaxial alternating magnetic field (AMF) coupled plasma arc cladding technology. The effects of AMF on the distribution of reinforcing particles and the improvement of coating quality were investigated. The results demonstrated that the AMF significantly suppressed the sedimentation behavior of WC particles within the coating, and the WC particles were dispersed and uniformly distributed under the AMF intensity of 20 mT. With the increase of the AMF intensity (10 mT–30 mT), the semi-quantitative evaluation of the combustion loss rate indicated a rise in the dissolution degree of WC particles from 10.1% to 33.4%, leading to a gradual increase in the content of precipitated carbides (i.e., M6C, M7C3) with varied morphological characteristics. AMF-induced magnetic stirring facilitated nucleation, contributing to remarkable grain refinement and an elevation in the proportion of high-angle grain boundaries. Mechanical testing witnessed that the AMF-assisted samples are superior in microhardness and wear resistance performance compared with the counterpart without AMF. In particular, the coating with AMF intensity of 20 mT exhibited the most uniform distribution of microhardness.