Pulsed Laser Processing of Metals and Semiconductors in Reactive Atmospheres: Laser Nitriding and Carburizing

Abstract

AbstractHard surface coatings and thin layers can be synthesized by irradiating pure substrates with short laser pulses in reactive atmospheres. Various lasers with different pulse durations τ and wavelengths λ can be used for this purpose: XeCl excimer laser, Nd-YAG laser, free electron laser and Ti:sapphire laser. The irradiation of materials such as aluminum, iron and silicon in controlled nitrogen and methane atmospheres leads to surface modifications (e.g. hardness improvement) and to the formation of homogeneous coatings. The evolution of the surface properties (phase formation, hardness) as well as the mass transport mechanisms during the laser irradiation have been studied in detail as a function of the experimental parameters (laser fluence, ambient gas pressure, number of laser shots) for the Excimer Laser treatments. The formation of homogeneous AlN layers after irradiation of aluminum substrates in N2 atmosphere, the synthesis of homogeneous cementite coatings after irradiation of iron substrates in CH4 atmosphere and the successful incorporation of carbon after irradiation of (100) and (111) silicon single crystals in methane gas will be reported.