Thermal conductivity of κ-Al2O3 and α-Al2O3 wear-resistant coatings

The thermal conductivities of alpha-Al2O3 and kappa-Al2O3 wear-resistant coatings are measured using the 3 omega method in the temperature range 80<T< 600 K. The coatings are 13 mu m thick and deposited by chemical vapor deposition on substrates of Go-cemented WC. The alpha-Al2O3 coating has a thermal conductivity comparable to sapphire at T> 300 K. The relatively small thermal conductivity of kappa-Al2O3, a factor of similar to 3 smaller than alpha-Al2O3, suggests that this metastable phase of alumina can be applied as an effective thermal barrier for cutting tools. (C) 1998 American Institute of Physics. [S0021-8979(98)08810-0].