MICROMACHINING OF AL2O3-TIC CERAMICS BY EXCIMER-LASER

Micromachining of Al2O3-TiC ceramic using a KrF excimer laser was stud ied in the fluence range 2 to 8 J/cm(2). The ablation rate decreases a nd the roughness increases with the first pulses but after about 200 p ulses the process reaches a stationary stage where both roughness and ablation rate become constant. Observation of the processed areas by s canning electron microscopy showed that a globular topography is forme d during the first stage and that the surface topography remains uncha nged with further pulses. This globular topography is responsible for the variation of roughness and ablation rate observed during the first stage. EDS analysis showed that the globular features present an exte rnal region with higher titanium content and a core formed of unaffect ed material.