Effect of feeding speed on micro-hole drilling in TiC ceramic by femtosecond laser

Abstract

By spiral drilling hole technology, micro-holes were drilled at different feeding speeds in TiC ceramic. The morphologic features of micro-holes were examined by scanning electron microscope, the elemental compositions for untreated specimens and laser-treated areas were identified by using an energy dispersive spectroscopy and the chemical bonds for untreated specimens and laser-treated debris were analyzed by an X-ray photoelectron spectroscopy. Then, the mechanism of interaction between femtosecond laser and TiC was further discussed. The results indicate that the drilled micro-holes show a good morphology without visible microcracks in ablated areas. The roundness of entrance is above 98%, better than that of the exit. The diameter at entrance is slightly smaller than that of the diameter at exit. The feeding speed has an obvious effect on micro morphology of entrance. When the feeding speed is lower, the regular ripples are observed in ablated areas. With increasing feeding speed, the surface is characterized by sporadic particles. High oxygen content is detected in a deposited layer at low and high feeding speeds, respectively, and the optimum feeding speed is 6.4 μm/s in this research. Moreover, the machining mechanism could be explained by the multiphoton absorption theory. When the C-Ti bond is broken during machining, the titanium ion will combine with oxygen and the TiO2, Ti2O3 in debris will be generated.