A new zinking process without cyanide for Al-Si alloy cast

A new non-cyanide zinking process for high-Si aluminum cast has been studied in this paper. The variation of surface morphology of zinc coating with zinking time and temperature was observed using scanning electron microscopy (SEM). The quality and adhesion of the zinc coating were e-valuated. Relied on quadrature test, a better zinking process has been-developed. The optimal processing conditions were that the bath consisted with of which the optimum 90 g/L sodium hydroxide, 9 g/L zinc oxide, 35 g/L Nickel sulfate, 90 g/L non-cyanide chelating agents and 6 g/L mixed additive B, the bath temperature is 25°C, and finaly the zinking is a two step process with a first step for 60 s and a second step for 30 s.The zinc coating obtained with the above process was dense and uniform with fine crystallines and high adhesion.