Micromachining features of TiC ceramic by femtosecond pulsed laser

Femtosecond pulsed laser was employed to drill blind holes (or circle surfaces) and through holes in titanium carbide (TiC) ceramic by the helical drilling technique. The effects of spiral number, processing time, laser fluence and repetition rate on the qualities of holes (or circle surfaces) were investigated. Morphology of holes (or circle surfaces) and composition of irradiated areas were analyzed by a scanning electron microscope (SEM), a three-dimensional super depth digital microscope and energy dispersive spectroscopy (EDS), etc. The results indicated that laser fluence and repetition rate had major effects on ablation efficiency and quality. Blind holes with taper bottom were observed when the laser fluence was above 6.37×10^-1 J/mm². With the increase of laser fluence, hole depth increased firstly and then decreased. The change in hole diameter decreased when the laser fluence was above 0.51 J/mm². The effects of repetition rate on hole depth were similar to that of laser fluence, while it showed a faint change in hole diameter at laser fluence of 1.02 J/mm² and laser repetition rate ranging from 2 to 140 kHz. Furthermore, through holes were attained at narrowed laser fluence ranging from 0.51 to 1.53 J/mm². The drilled holes had good circular geometry for entrance and exit.