Simulation of nanosecond laser cleaning the paint based on the thermal stress

Abstract

Laser cleaning is a non-contact and straight forward method to remove the paint from the substrate, based on the mechanism of thermal stress. In order to understand the mechanism detailly, it is crucial to investigate the relationship between the laser fluence, interaction time and the temperature rise quantitatively. Herein, we exhibit thermal stress is the primarily mechanism in the paint removal process by nanosecond (ns) laser pulses. Based on this, a theoretical model of nanosecond laser peeling off the paint is developed successfully. It is worth mentioning that the formation of plasma, plasma shielding effect and temperature dependent absorptivity are critical factors, which is considered in this model. The model can predict the theoretical cleaning and damage thresholds based on the mechanism of thermal stress. According to the temperature distribution in this model, it could be found the optimized parameter is at the laser fluence of 1.56 J/cm2. Together, it is expected that this study could provide a theoretical reference regarding to nanosecond laser cleaning the paint layers and pave the way for reducing the substrate damage in various industrial applications.