Thermal diffusivity of plasma-sprayed tungsten coatings

Abstract

Refractory metals such as tungsten and molybdenum are currently considered as potential materials for the plasma-exposed divertor surfaces in future tokamak reactors. Tungsten and tungsten alloys are of interest owing to their low sputtering yield and good resistance to chemical erosion by hydrogen compared with carbon-based materials. In the present paper, the influence of the spraying parameters on the thermal diffusivity of tungsten coatings plasma sprayed on copper coupons was investigated. Experiments were carried out using a Taguchi fractional approach, and the thermal diffusivity of plasma-sprayed coatings was determined using the flash method. The results show that the spraying atmosphere is the dominant factor affecting the coating thermal diffusivity; the gun transverse velocity and the powder feed rate have a smaller influence. The arc gas and power were found to have no significant effect on the thermal diffusivity of the sprayed coatings.