A comparative analysis of different surface tribological and electrochemical properties of TiAlN, TiAlSiN, and CrAlN thin film coatings in seawater

Abstract To reveal the wear mechanisms of TiAlN, TiAlSiN, and CrAlN coatings in a seawater environment, the changes in frictional surfaces and the electrochemical characteristics of these coatings were compared and analyzed in this paper. The coatings were deposited on 316L stainless steel surfaces. Tribological tests were investigated using a ball-on-disk tribometer with Si 3 N 4 ceramic balls as the counter material. Although the friction coefficient of 316L stainless steel was the lowest at 0.34, the order of wear rates was 316L stainless steel (7.38 × 10 −5 ) > TiAlN(5.31 × 10 −6 ) > TiAlSiN(4.23 × 10 −6 ) > CrAlN(1.10 × 10 −6 ) and the electrochemical protective efficiencies of TiAlSiN and CrAlN were both greater than 97%. Seawater penetrated through the grain boundaries of the TiAlN coating, which led to corrosion and delamination failure. Conversely, the grain refinement in TiAlSiN and CrAlN coatings can significantly slow down the penetration of seawater into the coating under frictional pressure, and the oxide lubricating layer formed during the friction process can become an effective barrier to isolate seawater. Therefore, mechanical wear was the main wear form of these two coatings. Additionally, among the oxides formed in the friction, Cr 2 O 3 showed the strongest corrosion resistance, making the CrAlN coating exhibit superior wear resistance and the lowest wear rate in seawater.