Wear behaviour and coating performance of WC–Cu composite electrodes on ZE41A magnesium alloy using electrospark deposition

Abstract

ABSTRACT Magnesium alloys, being relatively softer than other structural metal, has lower hardness and is prone to wear under abrasive and frictional conditions. To enhance their wear and abrasion resistance, tungsten carbide-copper (WC-Cu) composite coating was developed on ZE41A magnesium alloy using electro-spark deposition (ESD). The composite electrodes, with combinations of 50:50 and 70:30 was prepared using powder metallurgy. ESD parameters, including spark current (SC), pulse-on time (Ton) and pulse-off time (Toff) were selected for coating. Wear behaviour was evaluated using pin-on-disc tribometer under varying sliding parameters; applied load (20N–40N), sliding speed (150 rpm–350 rpm), and sliding time (5 min–9 min). The WC70:Cu30 electrode coating exhibited the highest CR of 0.00298 gm/min and maximum layer thickness of 92.12 μm, attributed to thermal conductivity of tungsten. EDS analysis confirmed higher deposition of Cu (18.68%) and WC (3.58%) in the WC70:Cu30 coating compared to WC50:Cu50, which showed Cu (11.33%) and WC (3.06%). The lowest WR of 0.000185 mm3/min was achieved with the WC70:Cu30 coating due to higher WC deposition. SEM analysis revealed wear mechanisms such as scratch, delamination, grooves, and adhesive wear. The WC70:Cu30 composite electrode improved performance with higher CR and lower WR compared to WC50:Cu50.