Reactive laser plasma coating formation

Reactive laser plasma surface treatments have proven to have a large potential for technical applications. Here, we present a new promising fast, flexible and clean technique for a direct laser synthesis of carbide and nitride coatings by short pulsed laser irradiation in reactive atmospheres (e.g. methane, nitrogen). The corresponding material is treated by short but intense laser pulses involving a plasma formation just above the irradiated surface. Gas–Plasma–Surface reactions lead to a fast incorporation of the gas species into the material and subsequently to the desired coating formation if the treatment parameters are chosen properly. This reactive laser synthesis can also be used for the improvement of steel surfaces, achieving drastically improved hardness, corrosion and wear resistance. We report here on the irradiation of pure iron in methane atmosphere. At low number of laser pulses, this results mostly in the formation of hexagonal ɛ-FexC, which is more and more transformed into cementite (θ-Fe3C) when increasing the number of pulses.