A comparison of the DPSS UV laser ablation characteristic of 1024 and H10F WC-Co

An investigation on ablation characteristics of 1024 and H10F cobalt cemented tungsten carbide (WC-Co) with a DPSS nanosecond TJV laser (50 ns pulse width, 355 nm wavelength, 90 W average power and 10 kHz repetition rate) is presented. The ablation characteristic parameters such as ablationthreshold, incubation effect and optical penetration depth were evaluated based on the spot ablation diameter and depth. It was observed that the ablation threshold is significantly influenced by the number of pulses (NOP) and it decreases with increase NOP which is attributed to the incubation effect. Only one ablatidn region is observed at low laser fluence and an additional molten ablation region is observed at high laser fluerice accompanied with cracks. The cracks formation is due to the thermal induced stress and changes in WC microstructure during laser beam irradiation. The crack depth is proportional to the thickness of the molten WC region. The ablation threshold of 1024 WC-Co and H1OF WC-Co were found to be F-th(1)=4.32 J/cm(2) and F-th(1)=4.26 J/cm(2) respectively. The difference in chemical composition has insignificant effect on the ablation threshold value of the material. The incubation factor and optical penetration depth values of 1024 WC-Co and H1OF WC-Co were found to be xi=0.73, alpha(-1)=411 nm and xi=0.75, alpha(-1)=397 nm respectively.