The effect of substrate bias on the characteristics of CrN coatings deposited by DC-superimposed HiPIMS system

Chromium nitride coatings were prepared by reactive DC-superimposed high-power impulse magnetron sputtering (HiPIMS) system. The influence of substrate bias on the microstructure and mechanical properties of CrN coatings was investigated. XRD and cross-sectional SEM were utilized to characterize the film structures. Mechanical properties were characterized by nanoindentation and Vickers indentation test. The results revealed that the microstructure and mechanical properties of CrN coatings were affected by bias voltage. The CrN coatings exhibited dense and fine columnar grain structure with the hardness of about 18.7 GPa. The fracture toughness of CrN coatings was around 3.16 MPa . m(1/2). However, further increase of the bias voltage from -250 V to -300 V led to the degradation of coating properties.