Effect of C₂H₂ Flow Rate on the Structure and Properties of WC-DLC Coatings

WC-DLC wear-resistant coatings were prepared by DC magnetron sputtering, and the influence of C₂H₂ gas flow rate on surface morphology, microstructure, mechanical and tribological properties of WC-DLC coatings prepared with a flow rate of C₂H₂ at 10−50 mL/min was investigated. Results show that, with the increasing flow rate of C₂H₂, the content of carbon in the coatings increases, the constituent of the coating gradually changes from columnar grain to fine grain, and the coating becomes denser. The nano-hardness of the coating is closely related to the content of hybridized sp³ carbon atoms. As the content of sp³-C in the coating increases, the hardness and wear rate of the coatings increase first and then decrease. When the carbon atom exceeds a certain content, a large amount of amorphous carbon will appear, the surface of the coating will become amorphous, and the friction coefficient gradually decreases and becomes more stable.