Microstructure and Corrosion Resistance of the AlTiN Coating Deposited by Arc Ion Plating

A new type of AlTiN coating containing about 29.13 at.% Al,16.02 at.% Ti and 54.85 at.% N was prepared by arc ion plating technology. The coating is composed of singular fcc-(Al, Ti)N phase and has no hcp-AlN phase to be formed. Due to the high content of beneficial element Al, the hardness and effective elastic modulus of the coating are up to 33.9 and 486.1 GPa, respectively. The adhesion strength between the coating and substrate is about 39.7 N. Electrochemical test shows that the corrosion current density of the AlTiN coating is nearly one-sixth of the substrate, and the charge transfer resistance R ct of the AlTiN coating is much larger than that of the substrate, which means that the coating could act as a protective barrier between the substrate and corrosive electrolyte, enhancing the corrosion resistance.