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Comparison of Structural and Electrochemical Properties among TiCN, BCN, and CrAlN Coatings under Aggressive Environments

Abstract:

The structural and electrochemical properties of the AISI 1045 steel coated with the following coatings, deposited using physical vapor deposition (PVD), were determined: titanium carbo-nitride (TiCN), chromium aluminum nitride (CrAlN) and boron carbo-nitride (BCN). A comparison of the x-ray diffraction results with the XPS results revealed that Ti-C-N, B-C-N and Cr-Al-N were the dominant constituents. The selected deposition conditions such as the nitrogen and carbon contents and activation energy were sufficient to form the coatings. The EIS results showed that CrAlN had the lowest porosity content, followed by TiCN and BCN. These data are linked to the polarization resistance of TiCN, CrAlN and BCN: Rp = 126.42x1010 ± 8.939x1011 KΩ cm2, Rp = 40.49x1010 ± 2.863x1011 KΩ cm2 and Rp = 23.10x1010 ± 1.633x1011 KΩ cm2, respectively; as well as the corrosion rate: 0.0049 ± 0.019 mm for CrAlN, 0.0123 ± 0.014 mm for TiCN and 0.0174 ± 0.010 mm for BCN. The AISI 1045 steel with the CrAlN coating had a higher corrosion resistance compared to the other coatings because Cr increased the electronegativity of CrAlN. These results indicate that the structural and electrochemical properties of the materials, the latter carried out in lubricated environments with simulated real service conditions, depend largely on the nature of the coating. Furthermore, these analyzed coatings can be used on components subjected to stresses with high wear in lubricated environments, specifically in the automotive and metalworking industries.