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In plasma spraying, the spray material, in powder form, is melted by a plasma jet in or outside the spray gun and propelled onto the work piece surface. The plasma is produced by an arc which is constricted and burns in argon, helium, nitrogen, hydrogen or their mixtures.
In the plasma transferred arc (PTA) process, the surface of the work piece is surface melted. A high density plasma arc serves as the heat source and the metal powder as the surfacing material. The arc is formed between a non-consumable electrode and the work piece. The plasma is generated in the plasma gas, between the central tungsten electrode and the water-cooled anode. The entire process takes place in the atmosphere of a shroud gas. |
