Mechanical property evaluation of ZrSiN films deposited by a hybrid superimposed high power impulse- medium frequency sputtering and RF sputtering system

Abstract

The high power impulse magnetron sputtering (HiPIMS) technique has been studied intensively due to its high peak power density and high ionization rate. The drawback, low deposition rate, of the HiPIMS can be improved by superimposing the middle-frequency (MF) pulses during the off-time of HiPIMS pulsing. In this study, a hybrid coating system consisting of a radio frequency power supply and a superimposed HiPIMS-MF sputtering system was used to deposit the ZrN and ZrSiN coatings with different Si contents ranging from 0 to 11.5 at.%. The Zr target surface status was maintained at the transition mode by a plasma emission monitoring system for keeping high deposition rate. The microstructure of ZrSiN film changed from a fine columnar to a featureless structure when the Si content was higher than 4.7 at.%. The maximum hardness of 33.4 GPa was obtained for the film containing 4.7 at.% Si due to the solid solution hardening and grain refinement strengthening effects. The film hardness further decreased to 20.9 GPa as the Si concentration increased to 11.5 at.%, which can be attributed to the formation of large amount of soft amorphous SiNx phase. On the other hand, the corrosion resistance of ZrSiN film increased with increasing Si content due to the effective reduction of grain size, lower surface roughness, and further densification of microstructure by amorphous SiNx phase. The corrosion resistance of AISI304 stainless steel substrate can be effectively improved to 8 to 15 times better by the ZrSiN coating. The 4.7 at.% Si contained ZrSiN coating had the highest hardness, good adhesion and corrosion resistance in this work.