Plasma Transferred Arc (PTA) is an overlay welding process with deposits that are homogenous and fused to the substrate, forming a metallurgical bond.
Plasma Transferred Arc makes use of a constricted arc and powdered alloy, which is carried from a feeder to the plasma torch in a stream of argon gas. The powder is then directed away from the torch into the effluent arc, where it is melted and fused to the base metal.
NOTE: A single pass, however, commonly results in a 5% to 20% dilution of the substrate in the deposit - a dilution that will generally weaken the hardness range of the coating by 5RC. Therefore, many design-engineers specify a two-pass minimum, with the added requirement that not less than half of the second pass be machined away.