On the topographical/chemical analysis of polycrystalline diamond pulsed laser ablated surfaces

Pulse laser ablation (PLA) is a widely used material removal technique. This paper investigates the effects of various changes of laser parameters on surface integrity and binder composition when PLA (using a Nd: YAG laser) on polycrystalline diamond composites (grain size 2÷25 μm, binder Cobalt). Firstly, 2D/3D surface micro-geometry has been evaluated using contact autofocus profiling. Environmental scanning electron microscopy was carried out to establish surface damages after ablation on different grain size composites. Compositional chemical analyses were performed by Energy-dispersive X-ray spectroscopy, to evaluate the role of binder percentage in the surface integrity after ablation. This showed an increased percentage of Cobalt in particular in the areas of higher energy density/fluence. In particular, as a consequence of a single spot laser ablation, the coarse and fine grain composites proved to have similar reaction to laser ablation in term of remaining Co percentage, while in the ablation of a continuous groove the fine diamond grain specimen showed an higher Co percentage than the coarse specimen (35% versus 20%) proving that the percentage of the Cobalt in the ablated area is proportional to the material percentage before laser ablation.