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Chen L.,Central South University | Chen L.,China Zhuzhou Cemented Carbide Cutting Tools Co. | Wang S.Q.,Central South University | Wang S.Q.,China Zhuzhou Cemented Carbide Cutting Tools Co. | And 7 more authors.
Surface and Coatings Technology | Year: 2010

Ti-Al-Si-N quaternary coating has recently been developed for industrial applications due to its excellent machining performance. Here, we present a comparative research on Ti-Al-N single layer, Ti-Al-Si-N single layer, TiAlN-TiAlSiN bilayer and TiAlN/TiAlSiN multilayer coatings deposited onto cemented carbide substrates by cathodic arc evaporation. The incorporation of Si into the Ti-Al-N coating results in an increase in hardness and thermal stability due to the formation of nanocomposite nc-TiAlN/a-Si3N4, and thereby causes an improved performance during continuous cutting. However, the lower toughness and adhesive strength with a substrate reduce its cutting-life during milling. Further optimization of Ti-Al-Si-N coated inserts during milling can be obtained by a structure adjustment from the nanocomposite into TiAlN-TiAlSiN bilayer and TiAlN/TiAlSiN multilayer coatings, which causes an increase to 156% and 172% for the life-time of Ti-Al-Si-N coated inserts, respectively. Our results indicate that the machining performance of coatings containing Si in both continuous cutting and milling can be optimized by the structure design of the TiAlN/TiAlSiN multilayer, where the coating sustains a high hardness of the Ti-Al-Si-N coating combined with a good cohesive strength with the substrate similar to the Ti-Al-N coating. © 2010.

Sha C.,Central South University | Bu M.,Central South University | Xu H.,Central South University | Du Y.,Central South University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2011

The experimental phase diagram data of the C-Cr-Ta ternary system available in the literature were critically reviewed. A thermodynamic modeling of the ternary system was then conducted by taking into account the literature data including the isothermal sections and invariant reactions. A set of self-consistent thermodynamic parameters for the Gibbs energies of individual phases in the C-Cr-Ta system was obtained by using the CALPHAD approach. Comprehensive comparisons between the calculated and measured phase diagrams show that all the reliable experimental information is satisfactorily accounted for by the present thermodynamic description. © 2011 Elsevier B.V. All rights reserved.

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