Acid and Alkali Resistance of Hydrophobic Copper Surfaces Prepared by Laser Shock Imprinting (LSI)
Z-B. Shen, S. Hu, Z. Shi, C. Li and P. Li
A hydrophobic Cu foil surface with microgroove textures was prepared by laser shock imprinting (LSI). First, a micromould with groove features is prepared by laser marking, and then the microgroove textures on the micromould are copied to the workpiece surface by LSI. The hydrophobic Cu surface was subjected to fluorination modification treatment, and it was found that self-assembled monolayers (SAMs) were formed on the surface, which enhanced the surface roughness and reduced the surface free energy. Then, the effects of different ablative medium thickness, laser energy and workpiece thickness on the surface morphology and static contact angle of the workpiece surface were studied. When the thickness of the ablative medium is 40 μm, no breakdown occurs. When the laser energy increases from 565 to 1690 mJ and the workpiece thickness decreases from 150 μm to 80 μm, the degree of replication of microtextures on the workpiece surface gradually increases. Meanwhile, the static contact angle of the surface increases, and the hydrophobicity increases. The acid resistance and alkali resistance of the hydrophobic Cu surface prepared by the LSI process were systematically studied. By observing the microtexture morphology and measuring the element composition of the workpiece, It was found that the hydrophobic surface was still hydrophobic after being immersed in HCl solution of pH=2 and NaOH solution of pH=12 for 24 hours, which shows that the hydrophobic surface prepared by LSI has good acid resistance and alkali resistance.
Keywords: Fibre laser, Nd:YAG laser, copper, Cu, laser shock imprinting (LSI), microgroove, hydrophobicity, acid resistance, alkali resistance