Fiber Laser Irradiation in Chemical Solution for Micro Fabrication: Mechanisms and Applications

The laser and electrochemical hybrid machining (LECM) could realize high-efficient and quality processing of difficult-to-cut materials and has become a research topic in microfabrication. However, it was difficult to ensure the stability and efficiency of laser transmission in chemical solutions, and an external voltage and auxiliary cathode should be added. In the present study, a novel fiber laser irradiation in chemical solution (LICS) has been proposed to process microstructures. The surface microstructures and chemical composition of the surfaces processed by LICS, laser irradiation in the ultrapure water, and electrochemical machining were compared. In LICS the materials were removed by laser processing and the following high-temperature gradient induced electrochemical dissolution. The high temperature gradient induced electrochemical dissolution could enhance the MRR and improve the surface quality. LICS can be regarded as a novel LECM process. The machining efficiency of LICS had been improved by 46.2% compared with that laser irradiation in the ultrapure water, and the proportion of laser-induced electrochemical dissolution was 31.6 % in the LICS process. Further, the effects of laser power, chemical solution concentration, and optical fiber end movement control on the processing of micro grooves were explored, considering the dimension, MRR, and surface roughness. A front gap of smaller than 0.8 mm between the optical fiber end and workpiece was recommended during LICS. The repeated feeding of optical fiber was proposed to improve the depth-to-width ratio of the micro grooves fabricated by LICS. Finally, LICS was used to process microstructures with the controlled profiles on the nickel-based superalloy and titanium alloy workpieces without a recast layer, which holds great potential in surface microfabrication and texturing.