Development of novel brasses to resist dezincification

The effect of alloying Sn, Pb, As, Sb and P on the dezincification of commercial brass 60Cu–39Zn–1Pb has been investigated in 1% CuCl2 solution by immersion studies and electrochemical measurements. Specimens with a smooth surface finish exhibited more resistance to dezincification. Appreciable inhibitive effect on dezincification was observed for the 55Cu–40Zn–3Pb–2Sn brass composition. The galvanic coupling of lead phase with the matrix accelerated corrosion. To improve the dezincification resistance of the Sn containing brass, As, Sb and P were added at two different levels (0.05% and 0.1%). Brass of composition 48.95Cu–45Zn–5Pb–1Sn–0.05As was more resistant indicating the synergistic effect of Sn and As. The effect of 0.05 and 0.1% of arsenic addition with various concentrations of zinc was also studied. The alloy of composition 57.90Cu–40Zn–2Pb–0.1As showed better corrosion resistance than the alloy containing 1% Sn and 0.05% As (48.95Cu–45Zn–5Pb–1Sn–0.05As). To understand the influence of Sn and As on the dezincification of commercial brass, linear polarization and cyclic voltammetry experiments were conducted for the alloys 60Cu–39Zn–1Pb, 55Cu–40Zn–3Pb–2Sn and 57.90Cu–40Zn–2Pb–0.1As. Linear polarization measurements indicated that the alloys 55Cu–40Zn–3Pb–2Sn and 57.90Cu–40Zn–2Pb–0.1As possessed higher resistance to corrosion than commercial brass. Inspection of cyclic voltammograms revealed that the peak current densities as well as the passive current density were lower for the alloys 55Cu–40Zn–3Pb–2Sn and 57.90Cu–40Zn–2Pb–0.1As than the alloy 60Cu–39Zn–1Pb. The surface layer on the alloys 60Cu–39Zn–1Pb, 55Cu–40Zn–3Pb–2Sn and 57.90Cu–40Zn–2Pb–0.1As after immersion of 72 h in 1% CuCl2 solution were analyzed by X-ray diffraction and scanning electron microscopy. Higher enrichment of Sn and As at the interface of surface layer and metal was indicated for the alloys 55Cu–40Zn–3Pb–2Sn and 57.90Cu–40Zn–2Pb–0.1As, respectively.