Electrochemical characterization and microstructure of cold sprayed AA5083/Al₂O₃ composite coatings

This work focused on the role of Al₂O₃ particles in the corrosion behavior of cold sprayed AA5083 aluminum alloy matrix composite (Al-MMC) coatings. The electrochemical characterization of the coatings was investigated in a 3.5 wt.% NaCl solution as a function of time. The results show that fragmentation of Al₂O₃ particles is not clearly observed in the case of AA5083/20 vol.% Al₂O₃ coating, while the broken Al₂O₃ particles can be seen clearly in AA5083/40 vol.% Al₂O₃ and AA5083/60 vol.% Al₂O₃ coatings. The addition of 20 vol.% Al₂O₃ particles yield the coating with the lowest porosity, and different volume fractions of Al₂O₃ in the feedstock have important effects on the electrochemical behavior of composite coatings. The Al-MMC coating reinforced with 20 vol.% Al₂O₃ particles exhibits the highest E_corr and the lowest i_corr compared with the other conditions. The order of current density is as follows: AA5083/20 vol.% Al₂O₃ < AA5083 < AA5083/40 vol.% Al₂O₃ < AA5083/60 vol.% Al₂O₃.