| 摘要 |
A method and apparatus for reliable flame spraying utilizes a transferred arc from a plasma torch as created between the cathode electrode coaxial with the plasma torch nozzle and the end of at least one wire or rod fed into the transferred arc axially beyond the exit of said plasma torch nozzle. A high velocity annular gaseous sheath is formed concentrically about the extended arc column to form an arc column guide to restrict the arc column to within a region closely spaced radially from the axial extension of the nozzle. A thin walled tube close to but radially outside of the arc column is affixed to but may be electrically insulated from the plasma torch body forming the torch nozzle. Gas flow is effected along at least the outer surface of the tube in the direction of the extended arc column such that the arc column cannot penetrate the sheath high velocity gas to cause the arc to extinguish itself when the wire or rod is withdrawn from the arc column region. Inner and outer flows may be used, of differing gas types. A secondary arc may be set up between the ends of two wires or rods being fed into the arc region and operated in parallel with primary transferred arc. |
