Thermal properties of cutting tool coatings at high temperatures

Cutting tools with coated inserts are widely used in high-speed cutting and in the cutting of hard-to-machine materials. The thermal properties of the coatings (or thin films) have a major impact on the cutting process and tool life. As there is a lack of data for high temperatures, we are presenting an experimental study of thermal conductivity and volumetric specific heat of different coatings in the range from room temperature to 500 °C. The coatings under investigation were TiN, TiAlCN, TiAlN, AlTiN, TiAlSiN and CrAlSiN. The thermal properties were measured using the pulsed photothermal radiometry method. The thermal conductivity of the coatings under investigation varied from 2.8 to 25 W m−1 K−1 and increased with the rise in temperature. The lowest thermal conductivity was observed for the CrAlSiN coating.

► Thermal properties of coatings for cutting tools measured in range from 20 to 500 °C. ► Coatings were based on nitrides of Ti, Al, Cr and Si. ► Thermal conductivity varies from 2.8 to 25 W m−1 K−1 and grows with temperature. ► Lowest thermal conductivity was observed for CrAlSiN coating.