Synthesis and mechanical properties of Cr–Si–N coatings deposited by a hybrid system of arc ion plating and sputtering techniques

Ternary Cr–Si–N coatings, in which Si was incorporated into CrN, were synthesized onto steel substrates (SKD 11) using a hybrid system of arc ion plating (AIP) and sputtering techniques. In the hybrid coating system for Cr–Si–N coatings, the CrN coating process was performed substantially by a cathodic AIP technique using Cr target, and Si could be added by sputtering Si target during CrN deposition. In this work, comparative studies on microstructure and mechanical properties between CrN and Cr–Si–N coatings were conducted. The hardness of the Cr–Si–N coatings increased from ∼22 GPa for CrN, and reached a maximum value of approximately ∼34 GPa at the Si content of 9.3 at.%, and then decreased again with further increase of Si content. The high hardness of Cr–Si–N coatings was related to the composite microstructure consisting of fine CrN crystallites and amorphous Si3N4. The average friction coefficient of Cr–Si–N coatings gradually decreased with increase of Si content in CrN coatings.