Add A Small Amount Of Sn, Al Copper Alloy Corrosion Performance

In this paper, the corrosion resistances of the pure copper and the copper alloys with little Al, Sn, Si, Fe, Ni have been studied by means of High-speed Rotate Corrosion, seawater immerse corrosion, OM of section, electro-chemistry characteristic, SEM, XPS and AES. Experimental results show:1. The copper alloys Cu-(0. 3-3%)Sn-(l-2. 5%)A1 have the excellent corrosion resistance. The corrosion resistance of copper alloys with minor Al and Sn are more remarkably improved than the copper alloys with minor Al and Si compared to pure copper.2. The Cu2. 5Sn2Al alloy has the best mechanics property and corrosion resistance after annealing at 360℃ for an hour in vacuum, the tensile strength is 542MPa, the yielding strength is 523MPa, the percentage elongation is 14.6 percent; The average corrosion rate is 0. 0154mm/a, the corrosion current density is 8. 65X lCT3A/cm2.3. In the Cu-(0. 3-3%) Sn-(l-2. 5%) Al copper alloys, with the increase of the content of Al element, the corrosion current density and the corrosion rate are both decreased, and the alternating impedance is increased, so the corrosion resistance is increased. However, the influence of Sn element to the corrosion resistance of copper alloys is not the same with the influence of Al. Adding 2. 5%Sn to the copper alloy with 2%A1, the corrosion resistance of copper alloys is improved to the limit.4. The passivation film formed on the surface of Cu-(0. 3-3%) Sn- (1-2. 5%)A1 alloys are Cu oxidation, Sn oxidation and Al oxidation compounds, which are distributed evenly, compact and have strong bondage to the metal. Their synergistic passivation layer results in that the decrease of the porosity of the oxidation layer and the form of local acidity which leads to localized corrosion is avioded, which can greatly enhance the passivating power of the film, by decreasing its permeability and hindering the diffusion of Cu+ ions.