Effect of graphene on thermal conductivity of laser cladded copper

Abstract

A thick copper coating on the triangular plates of vacuum vessels has been proposed for plasma passivation and vertical stability in tokamak. Laser cladding technique is utilized to develop such coatings. However, the process leads to a drastic decrease in the thermal conductivity of the copper coating. Regaining the thermal conductivity of laser cladded copper is a challenging task. In this work, we have verifed that graphene deposition can improve the thermal conductivity of laser cladded copper. Graphene layers have been grown on a 3-mm-thick laser cladded copper at 900 °C under methane, argon, and hydrogen atmosphere inside a thermal chemical vapor deposition system. The thermal conductivity of the laser cladded copper was found to be improved from 140 W/mK for as-deposited cladding to 309 W/mK after graphene growth. Further, structural morphology and thermal conductivity of graphene-coated laser cladded copper remained intact after irradiation tests with high-energy prompt gamma-rays and heavy nuclei exposure, which depicted its sustainability in actual environmental conditions.