Corrosion and wear of zinc in various aqueous based environments

The corrosion and corrosive wear resistance of zinc sliding against 440C martensitic stainless steel counterface, were studied in aqueous based solutions having different NaCl and sodium molybdate dihydrate concentrations respectively. The main objective was to investigate the effect of aqueous based environments and corrosion inhibitors on the interface and tribological characteristics of this tribosystem, as in several cases the formation of a thin corrosion product layer can act as a lubricating film. The experimental results indicated that sodium molybdate dihydrate acted as a corrosion inhibitor, decreasing significantly the corrosion susceptibility of zinc. However, during the corrosive wear of zinc under free corrosion conditions, the addition of sodium molybdate dihydrate inhibitor did not improve the tribological properties of zinc, as higher friction coefficients of the tribosystem were recorded. This observation indicates that aqueous lubrication cannot be applied in this tribosystem, even though an inhibitor was used to minimize the effect of Cl− halide ions. In addition, the observed wear mechanisms of zinc were mainly plastic deformation and abrasion. These wear mechanisms coexisted with pitting and dissolution–precipitation corrosion phenomena on the surface of this material.