A new hybrid suspension and solution precursor thermal spray for wear-resistant silicon carbide composite coatings

Abstract

Silicon Carbide (SiC) coatings offer exceptional wear resistance and excellent tribological characteristics; however, it is a challenging material to be thermally sprayed due to a lack of melting point. In this study, a hybrid, single-step suspension and solution precursor feedstock design is proposed, consisting of a SiC suspension modified with Yttrium Aluminium Garnet (YAG) precursors, for thermal spraying of SiC/YAG coatings. The decomposition of SiC was restricted in all spray campaigns. The solid loading of SiC (from 10 wt% to 20 wt%) and YAG phase (from 20 wt% and up to 50 wt%) were varied in an attempt to improve wear performance, enhance coating cohesion, and minimise porosity of the studied coatings. Among all studied coatings, 60 wt% SiC/40 wt% YAG and 50 wt% SiC/50 wt% YAG coatings at a 10 wt% solid loading were the best-performing coatings, demonstrating a promising wear resistance up to a sliding distance up of 1000 m, a dense coating structure with porosity at 0.4 ± 0.2%. The feedstock design opens up a new method to process materials which are difficult, if not impossible, to process using a conventional thermal route.