Method and apparatus for flame spraying thermoplastic powders

A method for flame spraying thermoplastic powders, the method comprising the steps of

• heating an article to be coated at a suitable working temperature through a flame generated by a spray gun;
• mixing thermoplastic powders to be sprayed with a transport inert gas;
• feeding said thermoplastic powders, transported by said transport inert gas, through a first discharge chamber shaped inside a mixing device of said spray gun;
• feeding a flow of one or more of compressed air and nitrogen through a second discharge chamber shaped inside said mixing device;
• activating said spray gun for directing said thermoplastic powders, transported by said transport inert gas, in a resulting flow, on a heated surface of said article to be coated, in a way as to determine melting of the thermoplastic powders in contact with said heated surface;
• spraying toward said resulting flow of directed thermoplastic powders, flowing out of said mixing device, at least a couple of flows of said one or more of compressed air and nitrogen, converging towards said resulting flow, so as to modify a shape of the resulting flow of said directed thermoplastic powders giving to said resulting flow a substantially flattened fan shape.