펄스 레이저를 이용한 금속 표면의 윤활유 제거 공정 해석

Abstract

In this work, the mechanism of liquid layer removal from a solid substrate is investigated by experimental and numerical analysis. The removal of liquid layer is important in various applications, such as steel fabrication, dewetting, environmental restoration, etc. Especially, removal of oil film coated on the steel surface is important to improve the quality of the coated layer after rolling process in steel manufacturing. The conventional process used the chemical method has a critical disadvantage such as environmental problem. Recently, laser based oil film removal process is considered as one of promising techniques because this process does not use a chemical solution. In this research, we investigate the oil removal process using a mineral oil coated copper, stainless steel, and carbon steel substrates. The mechanism of oil removal by a pulsed laser is also investigated using a visualization technique and numerical analysis. The results show that oil removal critically depends on the optical properties of the oil. The removal mechanism depends on the optical properties of the oil film. For the transparent film to incident laser beam, the oil film is removed by momentum transfer with instantaneous heat expansion of the substrate and explosive vaporization of oil film at the interface between the oil film and the substrate. However, for opaque oils, the oil film is removed by direct photothermal/photochemical ablation of the oil.