Influences of Bias Voltage and Target Current on Structure, Microhardness and Friction Coefficient of Multilayered TiAlN/ CrN Coatings Synthesized by Cathodic Arc Plasma Deposition

Multilayered TiAlN/CrN coatings have been synthesized on stainless steel substrates by cathodic arc plasma deposition using TiAl and Cr targets. Influences of the bias voltage, cath- ode current ratio I_TiAl/I_Cr, and deposition pressure on the hardness and friction coe±cient of the coatings were investigated. The measurement revealed existence of two cubic phases, face-center- cubic (Cr, Al)N and (Ti, Al)N, in the coatings deposited under various bias voltages except for the coating deposited at -400 V, which is amorphous. The hardness of the coatings was strongly dependent on the I_TiAl/I_Cr ratio and deposition pressure, and reached a maximum of 33 GPa at an ITiAl/ICr ratio of 1.0 and a pressure of 1.0 Pa. The incorporation of the element chromium can reduce the density of pinholes in the coatings and assist the optimization of deposition conditions for high quality TiAlN/CrN coatings.