Corrosion protection and electrical conductivity of copper coatings deposited by low-pressure cold spraying

Aluminium/copper contacts occur in power networks made of aluminium alloy busbars. Bolted joints of aluminium and copper cause galvanic corrosion of aluminium in the presence of electrolyte. The paper focuses on the effect of different powder morphology and the addition of ceramics on coating porosity and consequently on corrosion resistance and electrical conductivity behaviour. In this work, corrosion protection of copper coatings deposited by low-pressure cold spraying (LPCS) onto AA 1350 aluminium alloy is examined. The coatings were sprayed using two copper powders of different morphology, namely spherical and dendritic ones. These powders were mixed with alumina before spraying in a 50:50 weight ratio and composite coatings were deposited. The coating microstructures were characterized by the scanning electron microscopy (SEM). The measurements of coating hardness in the middle of the coating thickness were carried out. The coating corrosion protection was analysed by polarization measurements. All coatings showed increased corrosion potential as compared to the substrate. The electrical conductivity of coatings was determined by eddy-current measurements and showed coating conductivity up to 63% IACS. Moreover, coatings heat treatment was conducted to further increase electrical conductivity.