The use of low-pressure cold spray-formed Cu–Al2O3 MMC coatings to improve the surface properties of the electrical connectors

A major problem for electrical utilities companies is electrical power loss due to quality of the connections at each end of the line conductors. The currently used Al-based connectors are poorly compatible with cooper wires, resulting in electrochemical corrosion. In the case of Cu-plated Al-based connectors, the hazardous copper cyanide solution is used for plating and such connectors get worn out by fretting. In the present study the application of LPCS to deposit copper coatings on the electrical connector surfaces interfacing with line conductors has been explored. As the feedstock powder, Cu-Al₂O₃ (0.5 and 1.5 Wt. % of Al) metal matrix composites (MMCs) have been used, since they combine the high electrical and thermal conductivity of the copper phase and high strength and chemical stability of the Al₂O₃ phase. The powder Cu-Al₂O₃ MMCs were produced by a combination of oxidation and mechanical alloying and annealed before spraying to improve deposition efficiency. The influence of annealing temperature and Al₂O₃ concentration in the feedstock powders on the coating formation was evaluated in terms of microstructural analysis, adhesion strength and conductivity. To imitate fretting, the Cu-Al₂O₃ MMCs coatings were also subjected to dry sliding wear experiments from which the wear resistance was assessed.