Abstract: The apparatus comprises an explosion chamber 1 in the form of a tube closed at one end and communicating through a discharge pipe with a powdered coating batcher while a safety pipe communicates it with a mixing chamber 9 which prepares the explosive mixture ignited in the explosion chamber 1 by a spark plug 21. Installed between the safety pipe and the explosion chamber 1 is a circular precombustion chamber 10 which surrounds said explosion chamber and communicates with its space through holes 11 in its walls 12. The end of the discharge pipe 5 mounts a jet nozzle 13 which is installed in the face of the closed end of the explosion chamber coaxially with the latter so that its outlet section 16 is arranged ahead of the holes 11 in the walls of the explosion chamber 11 relative to the open end 17 of the latter.

Abstract: Metallic patterns such as electrically conductive pathways are sprayed onto a metallic surface of a substrate by a high temperature flame spray process which process also is used to spray an intermediate layer of ceramic insulation onto the substrate. The patterns are formed in a template through which powdered electrically conductive material is sprayed by a spray gun and a low amperage alternating current of high voltage is applied between the substrate and the spray gun.

Abstract: A low temperature melting metal such as tin, is contained in a small pot, heated by the flame of a burner. The metal is drawn from the bottom of the pot through a spray nozzle by venturi action of an air jet which forcefully throws molten droplets of metal against the surface to be coated. Means associated with the pot are provided to preheat the air stream before it comes into contact with the molten metal. Advantageously, the pot is closed by a cover, and air under pressure is supplied to the top of the pot, so as to force the molten metal towards the spray nozzle.