Reactive laser synthesis of carbides and nitrides

Carbides and nitrides play an important role for technological applications. Here, we present a new promising technique for a direct laser synthesis of carbides and nitrides by pulsed laser irradiation in reactive atmospheres, e.g. methane and nitrogen. A number of laser types have been used (excimer laser, Nd:YAG, Ti:sapphire, free electron laser) and a number of different nitrides and carbides have been produced (e.g. TiN, AlN, Fe3C, SiC). The mechanisms and examples will be presented and it will be shown that also the lateral and in depth structuring can be modified from nanoscale to mesoscale. The dependence of phase formation and resulting properties are given in relation to the laser treatment parameters, such as laser type, pulse duration, material and reactive gas pressure. This reactive laser synthesis can also be used for the improvement of steel surfaces. For example, the irradiation of pure iron in methane atmosphere at low pressures or low number of laser pulses results in the formation of an amorphous carbon surface layer and hexagonal ɛ-Fe1−xCx, which is more and more transformed into cementite when increasing the number of pulses or the gas pressure.