Temporally evolved recoil pressure driven melt infiltration during laser surface modifications of porous alumina ceramic

Laser surface modification of porous alumina ceramic with a high power laser is associated with a series of physical processes such as heating, melting, and evaporation of material. Above certain threshold laser intensity (similar to 10(10) W/m(2)), rapid evaporation at melt surface generates strong recoil pressures. These laser-induced evaporation recoil pressures tend to drive the flow of molten material into the porous substrate thus contributing to the overall observed depth of melting. This paper presents a three-dimensional thermal model to calculate the temporal evolution of temperature during laser surface modifications of alumina ceramic. This is followed by the determination of recoil pressures at the evaporating surface based on experimentally verified physical model of melt hydrodynamics and laser-induced evaporation proposed by Anisimov [Sov. Phys. JETP 27, 182 (1968)]. Finally, Carman-Kozeny equations were employed to analyze the effect of recoil pressure on the depth of infiltration which is subsequently integrated with the calculated depth of melting from thermal model. Such an integrative approach results in better agreement of the predicted values of depths of melting with the experimental values. (c) 2007 American Institute of Physics.