ZHANG Ergeng, NIU Shuai, CHEN Qiang, HUANG Biao

(Shanghai Engineering Research Center of Physical Vapor Deposition(PVD) Superhard Coating and Equipment,
Shanghai Institute of Technology, Shanghai 201418, China)

Abstract: To study the composition, structure and mechanical properties of magnetically filtered cathodic arc deposited hydrogen-free diamond-like carbon (Ta-C) and vapor deposited hydrogen-containing diamond-like carbon (Hydrogen DLC), and the influence of the two coatings on the tool’s high-speed cutting of aluminum alloy, a high-resolution microscope was used to observe the surface morphology of the films; Raman spectroscopy was used to analyze the angle chaos of the sp²/sp³ bond, sp² cluster information, and the ratio relationship of sp³-C/sp²-C; the nanoindentation instrument was used to measure the film’s hardness; high-speed milling experiments characterize the cutting performance of the coated tool and analyze the failure of the tool and the quality of the workpiece. The test results show the surface of Ta-C coating is dense and smooth, the surface particles are small, and there is no obvious pit. The I_D/I_G D-to-G-peak intensity ratios of Ta-C and hydrogen-containing DLC coating in the Raman spectrum are 0.5 and 1.1. The thicknesses of Ta-C and hydrogen-containing DLC coatings are 0.7 μm and 1 μm, respectively, and the friction coefficients are 0.11 and 0.18, respectively, and the bonding strengths meet the industrial grades HF1 and HF2, respectively. For high-speed dry-cutting of aluminum alloys, Ta-C-coated cutters have a 1.5-fold longer cutting life than hydrogen-containing DLC-coated cutters, and the overall surface roughness of coated workpieces for milling cutters is on the rise, but Ta-C Coated tools have lower surface roughness values for machined workpieces. Compared with the hydrogen containing DLC coating, the magnetic filter cathode arc deposited Ta-C coated tool can inhibit the adhesion of the aluminum alloy material better, its cutting life is longer, and the surface quality of the workpiece is better. Therefore, it is more suitable for machining aluminum alloys.
Key words: hydrogen-free diamond-like carbon coating; hydrogen-containing diamond-like carbon coating; aluminum alloy