Plasma-sprayed Al-based coating with WC-addition for excellent corrosion resistance and enhanced wear protection of Mg alloys

Abstract

Thermal spray processes struggle to create a fully dense coating for corrosion protection in the as-sprayed state due to the poor inter-splat bonding. To tackle this problem, Al−15vol.%WC was utilized as the coating material and applied by atmospheric plasma spraying (APS) to produce a dense coating with self-metallurgical inter-splat bonding. The results show that due to the in-flight particle deoxidizing effect by C element and self-metallurgical bonding of the overheated droplet (>1800 °C), dense coating without oxides inclusions is produced under optimized plasma spraying conditions. The fully dense Al−WC coating exhibits excellent corrosion resistance, with corrosion current density lower by four and two orders than that of Mg alloy substrate and bulk Al, respectively. Due to the inclusion of hard WC particles, the Al−WC coating presents one order improvement in wear resistance compared with the bulk Al.