Adhesive-deformation relationships and mechanical properties of nc-AlCrN/ a-SiN_x hard coatings deposited at different bias voltages

摘要

A series of Al-Cr-Si-N hard coatings were deposited on WC-Co substrates with a negative substrate bias voltage ranging from -50 to -200 V using cathodic arc evaporation system. A Rockwell-C adhesion test demonstrated that excellent adhesion was observed at lower bias voltages of -50 V and -80 V, while further increases in bias voltage up to -200 V led to severe delamination and worsening of the overall adhesion strength. X-ray diffraction and transmission electron microscopy analysis revealed a single phase cubic B1-structure identified as an AlCrN solid solution with a nanocomposite microstructure where cubic AlCrN nanocrystals were embedded in a thin continuous amorphous SiNx matrix. Coatings exhibited a 002-texture evolution that was more pronounced at higher bias voltages (=-120 V). Stress-induced cracks were observed inside the coatings at high bias voltages (=-150 V), which resulted in stress relaxation and a decline in the overall residual stresses.