Fabrication of Cr-Si-N coatings using a hybrid high-power impulse and radio-frequency magnetron co-sputtering: The role of Si incorporation and duty cycle

Abstract

Cr-Si-N thin films were successfully fabricated by a hybrid deposition system containing a high power impulse magnetron sputtering (HiPIMS) and a radio frequency (RF) magnetron in an Ar and N2 mixture. It can be found that the deposition rate of Cr-Si-N films increased with increasing power of RF and duty cycle of HiPIMS. Varying both HiPIMS duty cycle and RF power lead to a variation in Si content in the resulting Cr-Si-N films, indicating that the Si content in thin films is a crucial parameter. The Cr-Si-N film grown at a duty cycle of 2.5%, a repetition frequency of 1000 Hz, a HiPIMS average power of 500 W, and RF power of 450 W exhibits the highest Si content of 14.2 at.%, hardness of 31.5 GPa, elastic modulus of 292 GPa, the highest resistance to failure value of 0.1079, and the smallest grain size of 8 nm, average surface roughness of 0.7 nm and a wear rate of 0.50 × 10−6 mm3/N-m. The improved film properties can be attributed mainly to the incorporation of Si element. More importantly, the existence of Si atoms in CrN grains for forming solid solution (Cr,Si)N phase or extra Si atoms reacting with N atoms for forming amorphous Si3N4 (Si-N) phase segregated at the boundaries of the columnar CrN grains has strong influence on the microstructure and mechanical properties of thin films. The lower duty cycle of HiPIMS and higher Si content show synergistic effects on the grain refinement and enhanced mechanical properties of Cr-Si-N films in this work.