Femtosecond laser processing of cemented carbide for selective removal of cobalt

Diamond coating of tungsten carbide-cobalt (WC-Co) cemented carbide tools using chemical vapour deposition (CVD) requires removal the cobalt (Co) binder phase from WC-Co surface in order to improve adhesion. Laser ablation is shown be a promising technique for selective Co, which based on difference melting and boiling temperatures between different phases. However, laser with conventional nanosecond (ns) pulses typically induces remelting, incomplete Co removal, metallurgical changes WC due large heat-affected zone (HAZ) involved. Ultrashort pulsed lasers have emerged as an alternative minimized HAZ thermal stresses, enabling cold ablation. This paper reports effect femtosecond (fs) polished surfaces. The influence several process variables including pulse energy, number pulses, scanning speed morphology fs-laser ablated surfaces was investigated. Two grades 6% 10% wt grain sizes were examined this study. A ytterbium fiber (250 fs, 1030 nm) used morphologies such spots, lines, square regions. Field emission electron microscopy (FESEM) energy-dispersive X-ray (EDX) analysis characterize microstructure composition processed experimental results indicated that fs processing at optimized parameters could achieve successful selectively morphological or effects grains.