Plasma flame-spraying process employing supersonic gaseous streams

Abstract

Abstract An improvement in a process for high velocity plasma flame-spraying of a powder onto a workpiece wherein an unlit plasma gas is passed through the nozzle of a plasma flame-spraying gun at a high velocity of at least 90 meters per second and an electric arc is struck between an electrode within said gun and a portion of said nozzle and powder is fed into the resultant flame exteriorly of said nozzle and said gun, which improvement comprises increasing the deposit efficiency of the coating of the powder onto the workpiece by carrying out said process such that the power through said electric arc is at least 15 kilowatts, disposing the arc created at the exit rim of said nozzle by regulating the gas velocity, length of nozzle and diameter of nozzle bore such that said arc is established at said exit rim of said nozzle, especially a process wherein a gas back pressure is maintained within said nozzle which is greater than 1 atmosphere gauge, the ignited plasma gas has an enthalpy of at least 7000 joules/standard liter of gas such that there are created zones of compression and rarefaction coterminously in the resultant flame and the powder is introduced into the zones of rarefaction; an apparatus for carrying out such a process.

Inventors

• 👤 Arthur J. Fabel
• 👤 Herbert S. Ingham, Jr.

Bibliographic Details