Effect of Bias on Microstructure and Tribological Behavior in Artificial Seawater of CrN Coatings

Mono-layer and multi-layer chromium nitride coatings were deposited on M2 high speed steel substrates and silicon wafers by multi-arc ions plating technique. Microstructure, mechanical properties including hardness, modulus and critical load, polarization curves and tribological properties in artificial seawater were investigated. Results show that multi-layer CrN performed optimally both in mechanical and friction performance. Dense structure and sophisticated intergranular boundaries induced by laddered changing bias during coating process enhanced the wear and corrosion resistance (E_corr=-0.234 V, I_corr=3.052×10^-8 A) of this multi-layer CrN obviously compared to other mono-layer ones. The average fricition coefficient less than 0.15 when Hertzian contact stress was attained 3.47 GPa,corresponded to relatively low specific wear rate, 1.26×10^-15 m³/(Nm) in sliding process.