Improving thermal conductivity of Inconel 718 through thermoelectric coupling to reduce cutting temperature

Abstract

Inconel 718 is hard to machine with higher cutting temperature generated during machining process due to its low thermal conductivity. The thermal conductivity of materials consists of phonon and electronic thermal conductivity. The increase of electrical conductivity of material will improve its electronic thermal conductivity based on the Wiedemann–Franz law. A novel surface conductive active medium (SCAM) coating method is proposed. The SCAM is coated on the surface of Inconel 718 to be machined to decrease tool cutting temperature. The composition of electronic and phonon thermal conductivity of Inconel 718 is inspected by four-probe experiments. Two SCAMs including copper conductive adhesive (1.7 × 106 S m) and silver conductive adhesive (3.3 × 106 S m) are sampled in this research. The effect of SCAMs on improving the thermal conductivity of Inconel 718 is analyzed based on the serial electrical conductivity theoretical model. The maximum temperature of cutting tool during orthogonal cutting experiment decreases with the increase of SCAM electrical conductivity, which is agreed with the cutting temperature distribution predicted by theoretical calculations. It is demonstrated that the cutting tool temperatures can be reduced by improving thermal conductivity of Inconel 718 through coating surface conductive active mediums with high electrical conductivity.