No abstract

The thermal conductivities of α-Al2O3 and κ-Al2O3 wear-resistant coatings are measured using the 3ω method in the temperature range 80<T<600 K. The coatings are 13 μm thick and deposited by chemical vapor deposition on substrates of Co-cemented WC. The α-Al2O3 coating has a thermal conductivity comparable to sapphire at T>300 K. The relatively small thermal conductivity of κ-Al2O3, a factor of ∼3 smaller than α-Al2O3, suggests that this metastable phase of alumina can be applied as an effective thermal barrier for cutting tools.

No abstract

We have performed ab initio studies of the effect of substitutions on the phase stabilities of Ti1−xAlxN, x=0−1. The nonmetal substitutions studied include B, C, O, and Si. Metal substitutions studied include Sc, Zr, V, Cr, and Mn. The main objective has been to suggest substitutions that increase the thermal stability of the NaCl structure of Ti1−xAlxN at high Al contents. From these extensive and consistent calculations, some possible avenues for such stabilization present themselves, among which substitution with nonmetal C and Si, and metal V, Cr, and Mn are found to be the most promising.

No abstract