Thick Si-Doped DLC Coatings With High Load Bearing Capacity on Cold Working Tool Steels by PECVD

Abstract For improving the wear resistance, thick silicon doped hydrogenated amorphous carbon (a-SiC:H) coatings were deposited on cold working tool steels by plasma-enhanced chemical vapor deposition (PECVD) technology. The increase of the acetylene (C2H2) flow rate distinctly tuned the microstructure of a-SiC:H coatings, including an increase in the coating thickness (>15 µm), a decrease in the silicon content, a greater sp2/sp3 ratio, and higher degree of graphitization. The highest hardness of 19.61 GPa and the greatest critical load of 50.7 N were obtained. The coating showed low wear rate against different friction pairs and presented excellent abrasive wear resistance at high applied load and the wear rate decreased with increasing loads, which exhibited an outstanding application prospect in cold working tool steels.