Abstract:Modulated pulsed power magnetron sputtering (MPPMS) and pulse direct current magnetron sputtering (PDCMS) were employed to deposit CrNx coatings by controlling the nitrogen/argon flow ratio and sputtering power, respectively. The influence of nitrogen flow ratio as well as sputtering power of MPPMS and PDCMS were systematically studied to learn the roles of process parameters on CrNx coatings composition, phase, microstructure and mechanical properties. The composition, phase, microstructure, morphology, hardness as well as fracture toughness of coatings were characterized through electron probe micro analysis (EPMA), X-ray diffractometer (XRD), scanning electron microscope (SEM), nanoindentation device. As the PDCMS sputtering power increased from 700 W to 1000 W, the peak power of MPPMS showed an increase of 43.5%. The Cr elements in the coatings were ranging from 61.0 at.% to 65.4 at.%, while N contents decreased from 39.0 at.% to 34.6 at.%. The CrNx coatings were mainly composed of Cr2N phase without obvious changes. With the increase of the sputtering power, the hardness of the CrNx coatings was about 20 GPa, while the fracture toughness of the coatings was improved significantly. Changing the flow ratio from 15% to 50%, the peak current of MPPMS first decreased followed by an increase, the phase structure of the coatings gradually varied from Cr2N to CrN. When the nitrogen flow ratio was about 35%, the CrNx coatings were mainly composed of Cr2N and CrN. And the hardness, residual compressive stress and fracture toughness of the CrNx coating all attained their maximum values of 20.5 GPa, -901.8 MPa and 6.5 MPa·m1/2, respectively. The electron temperature should be the driving force for phase structure variation for CrNx coatings, and the dense and two-phase microstructure controlled the toughness of CrNx coatings.