Introduction of paint application techniques and methods for thermal spraying

       The use of paint in thermal spraying industry began in the early 20th century. It was first invented by Dr. M.U.Schoop in Zurich, Switzerland in 1910. In 1912, he successfully developed a wire flame spray gun, and in 1916, he developed a practical arc spray gun.



Paint wire flame spraying is still in use today. It is a thermal spraying method in which oxygen-acetylene combustion is used as the heat source and the spraying material is wire. The spray gun introduces acetylene, oxygen and compressed air respectively through siphoning, and the acetylene and oxygen are mixed to generate a combustion flame at the nozzle outlet. The wire feed wheel drives the wire to continuously send the flame through the center of the nozzle, and it is heated and melted in the flame. The compressed air forms a conical high-speed airflow through the air cap, and the molten wire is atomized into fine particles. Molten particles are sprayed onto the pretreated substrate surface to form a coating.



The coating structure of linear flame spraying of paint is an obvious layered structure, and the coating has more pores and oxide slag. For zinc and aluminum coatings, the porosity is 10%~15% during the spraying process. , The flow and pressure of the compressed air must be kept constant, otherwise the wire feeding will be fast and slow, which will seriously affect the melting effect of the wire.