Physical–computational model to describe the interaction between a laser beam and a powder jet in laser surface processing

Frequently laser surface treatments use a powder jet in conjunction with the laser beam. In this study we present a physical–computational model to describe the interaction between a laser beam and a powder jet. The model can be used to calculate the spatial distribution of particle temperature and laser beam attenuation at any moment and all over the region where the laser and particle beams interact. In calculating particle temperature, the attenuation of the laser beam by the particles themselves is taken into account. In the model, the influence of the physical parameters of the particles, of the laser beam, and of the interaction between them are clearly identified and easy to manipulate so that they can be adjusted to optimize the laser surface treatment. With certain simplifying assumptions, the computational structure of the model enables to take into consideration the variation of the materials properties that govern the process with temperature. The model was applied to two cases studies, the first assuming that all parameters are constant with temperature, and the second one considering that the specific heat and reflectivity vary with temperature. A systematic study of the behavior of the average particle temperature, power attenuation, and mass of particles melted as a function of the powder feed rate, and diameter and velocity of the particles was carried out.