Syntheses and mechanical properties of quaternary Cr-Mo-Si-N coatings by a hybrid coating system

Quaternary Cr-Mo-Si-N coatings have been deposited on AISI D2 steel and Si wafers by a hybrid coating system of arc ion plating (AIP) and dc magnetron sputtering techniques. A Cr3Mo AIP target with the fixed arc current of 55 A and Si sputtering target with the varying current of 0–1.4 A were utilized in Ar/N2 mixed atmosphere during Cr-Mo-Si-N deposition. Microstructure characteristics and mechanical properties of the Cr-Mo-Si-N coatings by this kind of hybrid coating technique were investigated in this paper. The results showed that the microstructure of Cr-Mo-Si-N coatings is nanocomposite consisting of Cr-Mo-N crystallites and amorphous Si3N4. The hardness of the Cr-Mo-Si-N coatings increased from 33 GPa of Cr-Mo-N coating to the peak value of about 50 GPa with Si content of 12.1 at.%, and then decreased with further increasing Si content. The hardness variation of Cr-Mo-Si-N coatings was related to the microstructure evolution in the coatings with increasing the Si contents. The average friction coefficient of Cr-Mo-Si-N coatings gradually decreased with increasing the Si content in the coatings.