Behaviour of Laser Treated with Water Droplet on Carbon Nanotubes Coated Silicon Surface
C. Wang, G. Zhang, L. Wang, Q.G. Wang, X.C. Lu and W. Yao
Laser processing is a promising method for the modification and micro/nano structuring of solid surfaces. The key factors which greatly affect the quality of laser processing are the size of heat-affected zones (HAZ) and surface debris. A water droplet assisted laser processing method on carbon nanotube (CNT) coated surfaces is proposed in this paper. The static contact angle (CA) and fragmentation induced by laser of the water droplet on the surface of the system are conducted by experiment. The results reveal that the surface of silicon can be changed from hydrophilic to hydrophobic by introducing CNT coatings and the CA of water dropletincreases with the coating layers of CNTs. The water droplets, which behaved as a focusing lens, could obviously enhance the laser intensity underneath the water droplet. It was found that the smaller water droplets show a much better focusing effect. The experimental results show the proposed method has great potential to reduce the size of HAZ and removes the spatter generation.
Keywords: Laser processing, carbon nanotubes, water droplet, contact angle, fragmentation