REACTIVE TIN DEPOSITION ON ALLOYS USING LASER-RADIATION

The heterogeneous formation of TiN layers on titanium-based alloys has been demonstrated by surface alloying in nitrogen using laser radiation taking advantage of the melt dynamics. The homogeneous generation of TiN layers on stainless steel has also been observed by vaporization of titanium targets, simultaneous reaction of the metal atoms with nitrogen and subsequent deposition on the substrate. Continuous wave and pulsed CO2 laser radiation sources were used. The variation in laser power, power density distribution, beam diameter and traverse speed results in different power densities, interaction times and heating times, leading to different vaporization conditions during laser-assisted physical vapour deposition and different melt pool geometries (different depths and surface finish) covering substantial surface areas in gaseous alloying. The flow characteristics and composition of the processing gas were varied to obtain different film dimensions and resultant metallurgical and mechanical properties during laser-assisted physical vapour deposition and different dimensions and solute contents of the alloyed zone and resultant metallurgical and mechanical properties in gaseous alloying. The structural properties of the deposited films were investigated by scanning electron microscopy and X-ray diffraction and the mechanical properties by hardness measurements.