Corrosion Behavior of WC–10 wt % Ni3Al Composite in Acidic Media

Abstract

The room temperature corrosion behavior of WC–10 wt % Ni₃Al composite and WC–8 wt % Co hardmetal in various acidic solutions (1 M H₂SO₄, 1 M HCl and 1 M HNO₃) were compared and investigated utilizing immersion test, electrochemical measurement and surface analytical techniques. The results show that in H₂SO₄ solution WC–10Ni₃Al composite has a nobler free corrosion potential, lower corrosion current density (I_corr) values and intrinsically better corrosion resistance than WC–8Co. Notably, pseudopassivity was observed in the polarization curves of WC–10Ni₃Al in both HCl and H₂SO₄ solutions. In addition, although WC–10Ni₃Al is corroded much faster in HNO₃ solution than in the other two mediums, it exhibits a superior corrosion resistance compared to WC–8Co. The corrosion mechanism of WC–10Ni₃Al composites is dominated by Ni dissolution.