9M Nozzle And Anode

The plasma spray process uses DC electricity to generate a stream of high-temperature ionized plasma gas, which acts as the spraying heat source. The coating materials, in powder form, is carried in an inert gas stream into the plasma jet where it is heated and propelled toward the substrate.

Because of the high temperature (15000°C） and high thermal energy of the plasma jet, materials with high melting points can be sprayed.

The plasma spray gun comprises a copper anode and tungsten cathode, both waters cooled .plasma gas (argon, nitrogen, hydrogen, helium) flows around the cathode and through the anode which is shaped as a constricting nozzle.

The plasma is initialized by high voltage discharge which causes localized ionization and a conductive path for a DC arc to form between the cathode and anode. The resistance heating from the arc causes the gas to reach extreme temperatures dissociate and ionize to form plasma. The plasma exits the anode nozzle as a free or neutral plasma flame (plasma which does not carry electric current) .

Plasma spraying produces a high-quality coating by a combination of a high temperature, high energy heat source a relatively inert spaying medium, and quite high particle velocities, typically 200-300m/s.

Plasma spraying has the advantage that it can spray very high melting point materials such as refractory metals like tungsten and ceramics like zirconium. plasma spray coating probably accounts for the broadest range of thermal spray coatings and applications and makes this process the most versatile.