Deposition and tribological behaviors of ternary BCN coatings at elevated temperatures

• BCN coatings with controlled composition were deposited by IBAD.
• Hardness and internal stress increased with the boron content.
• B0.05CNx and B0.2CNx show better thermal stability than CNx and B0.01CNx.
• B0.05CNx shows the lowest friction coefficient (~ 0.1) at 300 °C.

In this work we studied the mechanical properties, thermal stability and tribological properties of ternary boron carbon nitride (BCN) coatings with controlled boron content. BCN coatings with different boron contents (B = 0, 1, 5, 20 at.%) were deposited by ion beam assisted deposition (IBAD). The thermal stability and oxidation resistance were investigated by the weight loss method in ambient air. The structure and composition were evaluated by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The hardness was measured by a nano-indenter. The tribological properties at room temperature and 300 °C were investigated by a designed high temperature ball-on-disk tribo-meter. The results show that the hardness and residual stress increased with the boron content. At room temperature, the friction coefficient was in the range of 0.2–0.3 and did not change a lot with the boron content. At 300 °C, the B0.05CNx coating shows the lowest friction coefficient (~ 0.1) among the four coatings, because the graphitized carbon transfer layer forms on the Si3N4 ball.