Oxidation Behavior and Cutting Performance between Ti_(0.75)-Al_(0.25)-N and Ti_(0.69)-Al_(0.23)-Si_(0.08)-N Coated Tool through Measurement of Cutting Temperature

摘要

Ti-Al-Si-N and Ti-Al-N coatings were deposited on WC-Co substrates by a DC magnetron sputtering method. The oxidation behavior of two kinds of Ti_(0.75)Al_(0.25)N and Ti_(0.69)Al_(0.23)Si_(0.08)N coatings were comparatively investigated by XRD patterns and GDOES depth profiles. Si addition of 8 at.% into Ti-Al-N film modified its microstructure to a fine composite comprising, Ti-Al-N crystallites and amorphous Si_3N_4, and to a smoother surface morphology. While the solid solution Ti_(0.75)Al_(0.25)N film had superior oxidation resistance up to around 700°C, the composite Ti-Al-Si-N film showed further enhanced oxidation resistance. Both Al_2O_3 and SiO_2 layers played roles as a barrier against oxygen diffusion for the quaternary Ti-Al-Si-N film, whereas only the Al_2O_3 oxide layer formed at surface did a role for the Ti-Al-N film. The cutting performances of two coated carbide ball-end mills were evaluated by cutting of AISI D2 cold-worked die steel (60 HRC) under high-speed cutting condition. The tool wear and cutting temperature are discussed along with coating characteristics.