IMPROVED PLASMA TRANSFERRED WIRE ARC THERMAL SPRAY APPARATUSAND METHOD

摘要

A plasma transferred wire arc thermal spray apparatus is described for applying a coating to a surface. The apparatus comprises a cathode (51) having a first negative electrical potential, a nozzle (50) generally surrounding a free end of said cathode (51) in spaced relation having a restricted orifice (55) opposite said cathode free end, said nozzle (50) having a second positive electrical potential, a source of plasma gas directing plasma gas into said nozzle (50) surrounding said cathode (51) and exiting said restricted nozzle orifice (55), and a wire feed (58a, 58b) continuously directing a free end of wire feedstock (56) opposite said restricted nozzle orifice (55) and said wire feedstock (56) having the same second positive electrical potential as said nozzle (50), said apparatus thereby establishing a plasma transferred-arc between said wire feedstock free end and said cathode (51) melting said wire feedstock free end and said plasma gas exiting said restricted nozzle orifice (55) atomising melted feedstock and propelling atomised melted wire feedstock toward said surface, thereby coating said surface. A method of coating a surface with a metallic coating is also disclosed.