TY - JOUR

T1 - Evolution of the thermal conductivity of arc evaporated fcc-Ti1-x-yAlxTayN coatings with increasing Ta content

AU - Waldl, Helene

AU - Tkadletz, Michael

AU - Winkler, Markus

AU - Großmann, Birgit

AU - Czettl, Christoph

AU - Pohler, Markus

AU - Schalk, Nina

N1 - Publisher Copyright: © 2020 The Authors

PY - 2021/1/25

Y1 - 2021/1/25

N2 - 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, Ti 1-x-yAl xTa yN 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)-Ti 1-x-yAl xTa yN 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 μm ± 0.4 μm. 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-Ti 1-xAl xN 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.

AB - 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, Ti 1-x-yAl xTa yN 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)-Ti 1-x-yAl xTa yN 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 μm ± 0.4 μm. 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-Ti 1-xAl xN 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.

UR - http://www.scopus.com/inward/record.url?scp=85097049692&partnerID=8YFLogxK

U2 - 10.1016/j.surfcoat.2020.126658

DO - 10.1016/j.surfcoat.2020.126658

M3 - Article

VL - 2021

JO - Surface & coatings technology

JF - Surface & coatings technology

SN - 0257-8972

IS - 406

M1 - 126658

ER -