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Hydrogen-free tetrahedral amorphous diamond-like carbon coatings for forming and cutting tools

Hydrogen-free tetrahedral amorphous diamond-like carbon (ta-C) coatings have high wear resistance, low friction coefficients, good chemical inertness, and good thermal stability. Many applications of the ta-C coatings have been developed recently, including engineering components, pressing and forming tools, and cutting tools. However, low adhesion strength and high surface roughness of the ta-C coatings are challenging issues for forming and cutting applications of nonferrous materials. For instance, partial delamination and unevenness of the ta-C coatings cause early build-up of the work material on the cutting edges during processing of aluminum and copper. Moreover, adhesion of the ta-C coatings is generally enhanced by introducing metallic and/or ceramic under layers between the base metal and the coating. Likewise, surface roughness is improved by the plasma filtering technology or mechanical post treatments. The purpose of this study is to deposited smooth and well-adhered ta-C coatings and to study mechanical and surface properties of the ta-C coatings. In this study, ta-C coatings were deposited using a T-shaped filtered arc cathodic deposition system and their properties were investigated. Particularly, nanohardness, surface roughness, adhesion strength, wear resistance, and thermal stability of the ta-C coatings were evaluated. In addition, Raman spectra, hydrogen content, and SP 2 /SP 3 ratio of the deposited ta-C coatings were reported. Furthermore, high adhesion of the coatings was achieved by controlling the deposition parameters of the coatings. It was found that the T-shaped filtered arc deposition can provide very smooth and well adhered ta-C coatings.