Vaporization, melting and heat conduction in the laser drilling process

Melting and vaporization phenomena during the laser drilling process are in vestigated in this paper. The locations of the solid-liquid and liquid-vapo r interfaces were obtained by solving energy conservation equations at the interfaces. The dependence of saturation temperature on the back pressure i s taken into account by using the Clausius/Clapeyron equation. The conducti on heat loss to the solid is also included in the model and is solved by us ing an integral approximate method. The results show that the fraction of t he heat lost through conduction to the solid is very small and its effect o n the vaporization process is not significant. On the other hand, the condu ction heat loss significantly reduces the thickness of the liquid layer, wh ich becomes the recast layer after drilling. (C) 1998 Elsevier Science Ltd. All rights reserved.