Interaction of a focused laser beam and a coaxial powder jet in laser surface processing

Laser cladding, laser alloying, and laser free-form manufacturing are promising techniques where a laser beam is frequently used in conjunction with a coaxial powder jet for surface treating or rapid manufacturing. In the present work, a computational model was developed and used to simulate several experimental setups in order to optimize the processing conditions. More specifically, the model was used to calculate the distribution of particles temperature and the transmitted laser beam power as a function of the position of the origin of the powder jet in relation to the converging lens that focuses the laser beam. Two cases were analyzed, the first assuming that the powder density varies with the inverse of the square of the distance, and the second one considering a Gaussian powder density distribution. The intensity distribution in the laser beam was assumed to be Gaussian. In the present work, it was shown that when the characteristic parameters of the laser beam and of the powder jet are kept constant, the distance between the lens and the powder origin determines the particles temperature distribution and the laser beam attenuation and it is an important aspect in the optimization of energy transfer in the process. (C) 2007 Laser Institute of America.