Effect of sodium tungstate concentration on surface morphology and hardness variation of 6063 aluminium alloy using by plasma electrolytic oxidation

Abstract

The coatings were prepared on the surface of 6063 aluminium alloy using by plasma electrolytic oxidation in a sodium tungstate (Na2WO4) electrolyte solution with concentration varying from 0.017 to 0.068 mol/L. The power of plasma electrolytic oxidation is about 600 W, electrolysis time is 20 and 30 minutes, respectively. In this study using sodium tungstate as the main component of the electrolyte without any additives. The effects of Na2WO4 concentrations on the surface morphology and hardness variation of the 6063 aluminium alloys are investigated. These oxide films on aluminium were characterized by laser scanning confocal microscope, scanning electron microscopy (SEM) and Vickers microhardness indenter (Hv), respectively. The results reveal Na2WO4 electrolyte solution with concentration varying from 0.017, 0.034, 0.051 to 0.068 mol/L. When the electrolyte concentration is 0.034 mol/L, the maximum hardness value is 104 Hv after plasma electrolytic oxidation for 20 minutes. When the electrolyte concentration is 0.051 mol/L, the minimum surface roughness value obtained by plasma electrolytic oxidation for 30 minutes is Sa 0.324 μm.