Scale-up of nanoparticle production during laser ablation of ceramics in liquid media

Abstract

The study presents results in scale-up of nanoparticle production by laser ablation of ceramics in liquid media and gives a better understanding of influences of laser and process parameters on the nanoparticle productivity. Results presented in this work clearly reveal that laser fluence or pulse energy, laser pulse overlap on the target surface and laser repetition rate are the key parameters determining material removal rate and nanoparticle generation efficiency. The investigations show significant increase of several factors in nanoparticle productivity. Beside laser fluence we observed that a specific laser pulse overlap is required for increase of nanoparticle productivity. Investigations show that interpulse distance of 75 µm associated with 4 kHz laser frequency result in significant increase of material removal rate by factor 3 compared to machining in pulse overlap mode. Furthermore, material removal rate could be increased by factor 7 only by adjusting repetition rate from 9 kHz to 4 kHz using equal laser fluence and pulse overlap. In both cases we concluded that laser shielding on previously ejected nanoparticles combined with optimized temperature gradient occurred in the target material may play the important role in the enhancement of nanoparticle productivity. Using optimized laser and process parameters, 21.5 mg/min of ceramic nanoparticle productivity was reached by 4.65 mJ focalized laser pulse energy in aqueous media.The study presents results in scale-up of nanoparticle production by laser ablation of ceramics in liquid media and gives a better understanding of influences of laser and process parameters on the nanoparticle productivity. Results presented in this work clearly reveal that laser fluence or pulse energy, laser pulse overlap on the target surface and laser repetition rate are the key parameters determining material removal rate and nanoparticle generation efficiency. The investigations show significant increase of several factors in nanoparticle productivity. Beside laser fluence we observed that a specific laser pulse overlap is required for increase of nanoparticle productivity. Investigations show that interpulse distance of 75 µm associated with 4 kHz laser frequency result in significant increase of material removal rate by factor 3 compared to machining in pulse overlap mode. Furthermore, material removal rate could be increased by factor 7 only by adjusting repetition rate from 9 kHz to 4 kHz using...