Effect of Oxidation Behavior on the Mechanical and Thermal Properties of Plasma Sprayed Tungsten Coatings

Tungsten (W) coatings have been prepared via air (APS) and vacuum plasma spraying (VPS) technologies, respectively. The microstructures and chemical compositions of the coatings were comparatively studied; meanwhile, the mechanical and thermal properties were evaluated. The results obtained showed that oxide content in the VPS-W coating was apparently lower than that of the APS-W coating because of the different surrounding atmosphere, which influenced the mechanical and thermal properties of the coatings directly. Similar microstructures were observed for the VPS-W and the APS-W coating, but the VPS-W coating was much denser. The bonding strength of the VPS-W coating was much higher than that of the APS-W coating. Thermal conductivity of the VPS-W coating was 59.3 W/m · K at room temperature while the APS-W coating was 32.2 W/m  K. Thermal loading experiments of electron beam showed that the VPS-W coating could withstand the heat load of 10.75 MW/m2, while the APS-W coating formed serious cracks on its surface at the load of 7.5 MW/m2.