Substrate bias effects on mechanical and tribological properties of nanoscale multilayer CrTiAlN coatings prepared by closed field unbalanced magnetron sputtering ion plating method

摘要

Nanoscale multilayer CrTiAIN coatings were deposited on M42 tool steel by reactive close-field unbalanced magnetron sputtering ion plating process under Ar-N_2 gas mixture. The effects of substrate negative bias voltages (V_b) on the mechanical and tribological properties have been studied by applying bias voltages from -50V to -100V during deposition. The above properties were characterized by microhardness tester, scratch tester, Rockwell-C indenter, and ball-on-disk tribometer. The results showed that the coating hardness increased significantly from V_b= - 50V (7 GPa) to V_b= - 70V (34 GPa). Further increase of the bias voltages led to a decrease of hardness. The wear tests showed that the friction coefficient of the coatings was around 0.3 to 0.5, while excellent wear performance of the coatings only found at V_b between -60 and -80V (10~(-17)m~3/Nm). Adhesion tests also showed coating deposited at -60V to - 80V had excellet adhesive strength.