Evolution of the thermal conductivity of arc evaporated fcc-Ti1-x-yAlxTayN coatings with increasing Ta content

SURFACE & COATINGS TECHNOLOGY

卷:406

Article

Waldl, Helene¹  Tkadletz, Michael²  Winkler, Markus³  Grossmann, Birgit⁴  Czettl, Christoph⁵  Pohler, Markus⁵  Schalk, Nina¹ 

[1] Univ Leoben, Christian Doppler Lab Adv Coated Cutting Tools, Franz Josef Str 18, A-8700 Leoben, Austria

[2] Univ Leoben, Dept Mat Sci, Franz Josef Str 18, A-8700 Leoben, Austria

[3] Fraunhofer Inst Phys Measurement Tech IPM, Dept Thermal Energy Converters, Heidenhofstr 8, D-79110 Freiburg, Germany

[4] Voestalpine BOHLER Edelstahl GmbH & Co KG, Mariazeller Str 25, A-8605 Kapfenberg, Austria

[5] CERATIZIT Austria GmbH, Metallwerk Plansee Str 71, A-6600 Reutte, Austria

关键词: PVD;    Hard coatings;    TiAlTaN;    TDTR;    Thermal conductivity;   

DOI  :  10.1016/j.surfcoat.2020.126658

来源: Elsevier

【 摘 要 】

Hard coatings are commonly applied in severe cutting applications, where significant heat is generated. Thus, their thermal conductivity should be kept low to provide a heat barrier to the substrate and consequently to increase the service life time of the tools. Although, Ti1-x-yAlxTayN protective coatings have been applied successfully in the cutting industry, their thermal conductivity is barely investigated. The focus of this study is to determine the thermal conductivity of face-centered cubic (fcc)-Ti1-x-yAlxTayN coatings with a Ti/Al ratio of 1:1 and a Ta content increasing from 0 up to 23 at.%. The investigated coatings were deposited by cathodic arc evaporation to a coating thickness of 3.2 mu m +/- 0.4 mu m. The microstructure and chemical composition were studied using X-ray diffraction and energy dispersive X-ray spectroscopy, respectively. Time-domain thermoreflectance measurements revealed a low thermal conductivity for fcc-Ti1-x-yAlxTayN with 5.7 W/(mK) and a further decrease with increasing Ta content to 2.4 W/(mK) for 23 at.% Ta. This trend can be explained by the small grain size caused by the Al addition leading to increased boundary scattering and the incorporation of Al and larger Ta atoms in the fcc-TiN lattice resulting additionally in alloy scattering, as the thermal conductivity decreases with increasing phonon scattering processes.

【 授权许可】

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