Characterization of carbon-boron coatings prepared on molybdenum by a vacuum arc deposition method

Abstract

A carbon-boron coating on the first wall is a promising method to improve plasma heating performance in nuclear fusion devices, since the oxygen impurity in plasma is effectively reduced by this method. As a method for producing carbon-boron coatings, vacuum arc deposition is fast, clean and easy to apply for in situ coating in vacuum vessel. In this study, carbon-boron coatings on molybdenum substrates were prepared using a vacuum arc deposition method, and the characterization of the coatings was carried out by X-ray diffraction, X-ray microanalysis, scanning electron microscopy and Raman spectroscopy. The results show that the basic structure of the coating material is like graphite; however, the defect density is very high. The boron concentration in the film was less than one-half of that in the raw material. X-ray diffraction peaks corresponding to boron carbides were observed when the boron concentration is larger than 18 wt.%. The interfacial reaction formed Mo 2C and MoC and improved the adherence of the coatings.