Laser plasma treatment of materials at nearly atmospheric pressures

Abstract

An analysis on the influence of a plasma formation during laser surface alloying (LSA) and laser cladding (LC) using direct powder injection are presented. It is shown that gas optical discharge plasma formation under atmospheric pressure becomes possible due to the presence of a large number of disperse particles, having a work function much lower than that of the ionization potential of the gas in the laser affected zone. It is also shown, that a plasma formation close the treated target surface results in much more effective treatment than direct irradiation without plasma formation. This phenomenon is a result of plasma re-radiation in the shorter wavelength range. The development of LSA and LC processes using an optical discharge plasma of both active and inert gases is discussed.