What are the forms of powder feeding by plasma spray gun? What are the characteristics of each?

       The powder feeding method of plasma spray gun is generally divided into two forms: powder feeding inside the gun and powder feeding outside the gun. The powder feeding hole in the gun is located in the nozzle compression hole. Generally, the number of powder feeding holes is 2mm~6mm away from the nozzle outlet end face. The number of powder feeding holes is 1 hole, 2 holes or 3 holes. There is a certain angle in or out. Its advantages are good powder heating effect, high deposition efficiency of sprayed powder, and high bonding strength of coating.



     The powder feeding tube for powder feeding outside the gun is located outside the end face of the nozzle, and there are two kinds of symmetrical placement of single hole and double hole commonly used. The advantage is that it can adapt to continuous work for a long time, and the nozzle structure is simplified; the disadvantage is that the powder deposition efficiency is low and the uniformity of powder heating is poor.