Effect of Al Content on the Corrosion Resistance of Cu-Ni Powder Metallurgy Alloy

Abstract

For improving the corrosion resistance of Cu-10Ni alloy, a series of Cu-Ni-Al alloys were prepared by powder metallurgy method with adding Al element in different proportions in the basis of traditional Cu-10Ni alloy. The effects of different contents of Al element and Cl- concentrations on the corrosion resistance of Cu-Ni-Al alloy were studied by scanning electron microscopy (SEM), static total immersion corrosion experiment and electrochemical test. Results showed that spark plasma sintering (SPS) could prepare Cu-Ni-Al alloy with excellent comprehensive properties, such as density, hardness, conductivity, etc. When Cu-Ni-Al alloy was soaked in NaCl corrosion medium for a long time, a corrosion protection film containing Cu2O was gradually formed on the surface of the alloy. Meanwhile, the outer layer of Cu2O protective film would further react with Cl- in the corrosion medium to form Cu2(OH)3Cl product film, and furthermore, the Cu2O and Cu2(OH)3Cl bilayer films were formed on the alloy surface. When content of Al element was the same, the increase of Cl- concentration in the corrosive liquid caused that the corrosion of the alloy became more serious, which indicated that within a certain test range, the increase of the concentration of the Cl- would promote the corrosion.

Keywords

• cu-ni alloy|spark plasma sintering (sps)|al element content|oxide film|corrosion resistance