Influence of Nitrogen Flow-Rate on Tribological Behavior of Magnetron Sputtered Zr-B-O-N Coatings

Herein, we reported the surface modification of N, O dual doped ZrO₂ (Zr-B-O-N) coatings, synthesized by DC reactive magnetron sputtering on substrate of 304 stainless steel. The influence of the N₂/(N₂+ O₂+Ar) flow-rate on the tribological properties of the coatings was investigated with scanning electron microscopy and mechanical probes. The results show that the flow-rate had a major impact. For example, N, O dual doping significantly enhanced the surface hardness and wear-resistance. As the flow-rate-ratio increased, the number and size of "large" grains on the surface decreased, resulting in the increases of surface toughness, compactness and wear-resistance, possibly due to formation of nanocomposite structure. Synthesized at a flow-rate of 5%, the coating displayed the smallest friction coefficient and the lowest wear-rate of 1. 65 μm³/N·mm, though its hardness was only 15 GPa. The wear-resistance was found to depend both on surface hardness and on elastic modulus.