Formation of tungsten coatings by gas tunnel type plasma spraying

Tungsten is a material that has the highest melting point of 3422 °C among metals. Therefore, when deposited as a coating, it can protect the substrate surface from high heat flux. In this study, tungsten (W) sprayed coatings were formed on stainless steel substrates by gas tunnel type plasma spraying at a short spraying distance. The Vickers micro-hardness of the W coating was measured as a guide to its mechanical properties. The tungsten coating has a hardness of Hv = 260–300 along its cross section, which is a little lower than the hardness usually quoted for pure tungsten. Regarding the microstructure, the coating contains some pores. The results of X-ray diffraction and energy dispersive X-ray spectroscopy show that the coating consists of pure tungsten.