Investigation of the Structure and Properties of Molybdenum Coatings Produced by Laser-Directed Energy Deposition

The paper considers the possibility of replacing the process of conventional vacuum brazing of a molybdenum plate on carbon steel using copper brazing with the process of laser-directed energy deposition of domestically produced molybdenum powder. The research task is motivated by the demand for removing low-melting copper brazing from molybdenum coatings on carbon steel. The parameters for the process of manufacturing molybdenum coatings using the additive technology of laser-directed energy deposition (LDED), which provides the required operational properties without further processing, have been developed. A study of the microstructure of the coating was carried out, including an examination of the distribution of the main elements over the depth of the coating. We established the preferred parameters of laser-directed energy deposition, which provide a high-quality deposited layer of Mo on the 25L carbon steel. The wear resistance of the coatings was examined following the << ball-on-disc >> scheme according to the ASTM G99 standard. The results show that wear rate of the brazed Mo plate is higher than that of the deposited Mo layer on the 25L carbon steel substrate.