Laser-induced microjet-assisted ablation for high-quality microfabrication  

作　　者：Yang Guo Pei Qiu Shaolin Xu Gary J Cheng 

机构地区：[1]School of Mechatronics Engineering,Harbin Institute of Technology,Harbin 150001,People’s Republic of China [2]Department of Mechanical and Energy Engineering,Southern University of Science and Technology,Shenzhen 518055,People’s Republic of China [3]School of Industrial Engineering,Purdue University,West Lafayette,IN 47906,United States of America

出　　处：《International Journal of Extreme Manufacturing》2022年第3期122-130,共9页极端制造（英文）

基　　金：financially supported by the Guangdong Provincial University Science and Technology Program(Grant No.2020KTSCX119);the Shenzhen Science and Technology Programs(Grant Nos.20200925155508001,GJHZ20190820151801786,JCYJ20210324115608024 and KQTD20170810110250357)。

摘　　要：Liquid-assisted laser ablation has the advantage of relieving thermal effects of common laser ablation processes, whereas the light scattering and shielding effects by laser-induced cavitation bubbles, suspended debris, and turbulent liquid flow generally deteriorate laser beam transmission stability, leading to low energy efficiency and poor surface quality. Here, we report that a continuous and directional high-speed microjet will form in the laser ablation zone if laser-induced primary cavitation bubbles asymmetrically collapse sequentially near the air-liquid interface under a critical thin liquid layer. The laser-induced microjet can instantaneously and directionally remove secondary bubbles and ablation debris around the laser ablation region, and thus a very stable material removal process can be obtained. The shadowgraphs of high-speed camera reveal that the average speed of laser-induced continuous microjet can be as high as 1.1 m sin its initial 500 μm displacement. The coupling effect of laser ablation, mechanical impact along with the collapse of cavitation bubbles and flushing of high-speed microjet helps achieve a high material removal rate and significantly improved surface quality. We name this uncovered liquid-assisted laser ablation process as laser-induced microjet-assisted ablation(LIMJAA) based on its unique characteristics. High-quality microgrooves with a large depth-to-width ratio of 5.2 are obtained by LIMJAA with a single-pass laser scanning process in our experiments. LIMJAA is capable of machining various types of difficult-to-process materials with high-quality arrays of micro-channels, square and circle microscale through-holes. The results and disclosed mechanisms in our work provide a deep understanding of the role of laser-induced microjet in improving the processing quality of liquid-assisted laser micromachining.

关 键 词：liquid-assisted laser ablation laser-induced microjet cavitation bubbles laser microfabrication 

分 类 号：TN249[电子电信—物理电子学]