Microstructure and Properties of the Cr-Si-N Coatings Deposited by Combining High-Power Impulse Magnetron Sputtering (HiPIMS) and Pulsed DC Magnetron Sputtering

The Cr-Si-N coatings were prepared by combining system of high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The Si content in the coating was adjusted by changing the sputtering power of the Si target. By virtue of electron-probe microanalysis, X-ray diffraction analysis and scanning electron microscopy, the influence of the Si content on the coating composition, phase constituents, deposition rate, surface morphology and microstructure was investigated systematically. In addition, the change rules of micro-hardness, internal stress, adhesion, friction coefficient and wear rate with increasing Si content were also obtained. In this work, the precipitation of silicon in the coating was found. With increasing Si content, the coating microstructure gradually evolved from continuous columnar to discontinuous columnar and quasi-equiaxed crystals; accordingly, the coating inner stress first declined sharply and then kept almost constant. Both the coating hardness and the friction coefficient have the same change tendency with the increase of the Si content, namely increasing at first and then decreasing. The Cr-Si-N coating presented the highest hardness and average friction coefficient for an Si content of about 9.7 at.%, but the wear resistance decreased slightly due to the high brittleness. The above phenomenon was attributed to a microstructural evolution of the Cr-Si-N coatings induced by the silicon addition.