Corrosion,oxidation and high-temperature tribological properties of Ti–B–N coatings

Abstract

Ti–B–N (nc-TiN/ a-BN) composite coatings with various boron contents were deposited by magnetron sputtering. nano-indentation, ball-on-disc dry sliding X-ray diffraction, and, Raman spectroscopy was used in evaluating the compositional, mechanical and tribological properties of these coatings. The corrosion behaviour of the Ti–B–N coatings was assessed by the electrochemical potentiodynamic polarisation method in a 3 mol-% of NaCl solution. The coefficient of friction (CoF) of the coatings initially increased to 1.0 when the test temperature was 200°C, but a further increase in temperature to 700°C resulted in a decrease in the CoF value to ∼0.18 which was due to the presence of Magneli-type Ti _n O_2n−1 oxides. In contrast to the CoF, there was a consistent increase in wear rate when the temperature was increased; the highest wear rate was obtained at 700°C. The B incorporated coatings exhibited improvement in both oxidation and corrosion resistance properties.