Study on the microstructure and mechanical properties of Zr-B-(N) tool coatings prepared by hybrid coating system

Abstract

The Zr-B-(N) coatings with different N contents were prepared by combining system of high power impulse magnetron sputtering (HiPIMS) and pulsed DC magnetron sputtering (PDCMS). By means of X-ray diffraction analysis, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy, the influence of nitrogen flow ratio on the coating microstructure and characteristics were investigated systematically, including the deposition rate, chemical compositions, phase constituents, chemical bonding, as well as cross-sectional morphologies. Meanwhile, the hardness and adhesion of above coatings were also evaluated by micro-indentation method and a scratch tester. And the tribological behaviour also was tested by tribometer. The maximal hardness reached 25.35 GPa which was attributed to the formation of nano-composite structure. After doping N element, all the coatings possessed the compressive stresses, and critical load increased gradually with increasing N content in the coating. By comparison, the Zr-B-N coating presented the best wear resistance as the N2 flow ratio was 6 sccm.