Electrical explosion spray of Ag/C composite coating and its deposition behavior

Abstract

Ag–C composite coating exhibits excellent electrical and thermal conductivities, good arc mobility, and low contact resistance, making it has a good prospect in switch contact of high voltage isolators. At present, the electro-deposition method is mainly used to prepare Ag/C composite coatings. However, the production efficiency of the electro-deposition method is low and the obtained coatings are thin. The electrical explosion spraying, due to its simplicity and high efficiency, has attracted significant attention in coating preparation. In this study, a new method that confines Ag and graphite powders in a tube for electrical explosion spraying was proposed. Powder electrical explosion spraying was used for preparing an Ag/C composite coating by employing a self-designed device. The heating behavior of the powder during exploding, macroscopic morphology, micromorphology, deposition efficiency, and thickness of the coatings, as well as the deposition behavior of the sprayed particles, were investigated. After a single spraying, a dense and uniform Ag/C composite coating was obtained at the charging voltage of 13 kV and a spray distance of 18 mm. The results show that the coating area is approximately 39.25 mm2, the coating thickness was 50 μm, and the deposition efficiency was 35%. the coatings have good adhesion with the substrate. the interface between the coating and the substrate appeared as an inter-diffusion of elements, which was typical of a metallurgical bonding interface. Graphite is evenly distributed in the coating. Furthermore, the underlying deposition behavior of the coating was carefully characterized.