Galvanic corrosion evaluation of magnesium alloys coupled with brass alloys studied by scanning Kelvin probe technology

The galvanic corrosion of AZ91D magnesium alloy coupled with H62 brass alloy using accelerated testing in salt fog spraying was investigated by using the scanning Kelvin probe technique (SKP). The results show that the galvanic corrosion effect of AZ91D magnesium alloy is influenced by the potential difference between anode and cathode materials. The potential difference between AZ91D magnesium alloy and H62 brass alloy is about -1.22 V during accelerated testing in the initial stage of salt fog spraying. The galvanic corrosion effect of AZ91D magnesium alloy is very significant. Galvanic corrosion occurs mainly at the interface near to AZ91D magnesium alloy, and H62 brass alloy is of no significant corrosion. As the corrosion products of AZ91D magnesium alloy have a protective effect, the potential difference between the corrosion products and matrix is significant, and then new corrosion products occurs in the matrix of AZ91D magnesium alloy. With prolonging the salt spray test time, the galvanic corrosion effect of AZ91 D magnesium alloy reduces and the corrosion of H62 brass alloy accelerates.