Effect of Substrate Bias Voltage on the High-Temperature Corrosion Resistance and Cutting Performance of CrAlN Coatings

Based on multiarc ion coating technology, three different bias modes (pulsed bias voltage, gradient bias voltage (GBV), and constant bias voltage) were selected to deposit CrAlN coatings on a carbide specimen and a milling cutter. High-temperature oxidation experiments and milling tests were conducted on the three types of specimens and milling cutters. The effects of different bias modes on the surface morphology, microstructure, microhardness, resistance to high-temperature oxidation, and milling performance of the CrAlN-coated specimens were investigated. The results show that the CrAlN-coated specimens exhibit obvious (1 1 1), (2 0 0), and (2 2 2) diffraction peaks. Compared to the other modes, the coatings in the gradient bias mode exhibited a more robust (200) growth orientation, the most miniature macroscopic particles on the coating surface, no noticeable columnar crystals in the cross section, and the highest hardness (25.6 GPa). The CrAlN coatings under gradient bias have better high-temperature oxidation resistance, and the oxide layer formed on the GBV coating surface is denser, blocking the penetration of O into the coating interior. In addition, the GBV-coated tools showed excellent cutting performance with low machining roughness and no apparent coating removal. [GRAPHICS] .