Hard wear-resistant coatings with anisotropic thermal conductivity for high thermal load applications
2014 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 1, 013507- p.Article in journal (Refereed) Published
High thermal load applications such as high speed dry cutting lead to high temperatures in the coated tool substrate that can soften the tool and high temperature gradients that can put stress on the coating/tool interface. In this work, theoretical considerations are presented for multilayer and graded protective coatings that can induce a significant anisotropy in their thermal conductivity. Solution of the heat equation shows that anisotropy of thermal conductivity has the potential to reduce temperatures and temperature gradients arising due to brief, localized heat at the coating surface ("hot-spots"). Experimental realization of high anisotropy is demonstrated in TiN/AlCrN multilayer coatings with variable layer thickness. In the coating with 50 nm bilayer periodicity, the highest anisotropy was obtained with a value of kappa(parallel to)/kappa(perpendicular to) = 3.0 +/- 0.9. Time-domain thermoreflectance is used to measure in-plane and cross-plane thermal conductivity of fabricated coatings. The observed high values of anisotropy of thermal conductivity are compared with theoretical predictions and its realisation is discussed with regard to the coating microstructure.
Place, publisher, year, edition, pages
2014. Vol. 116, no 1, 013507- p.
cutting-tool coatings aluminum nitride contact temperatures films alloys dry Physics
Other Materials Engineering
IdentifiersURN: urn:nbn:se:uu:diva-232142DOI: 10.1063/1.4886182OAI: oai:DiVA.org:uu-232142DiVA: diva2:746703