论文和技术资料

Laser direct deposition is a process, different from molding or machining, which allows the producing of fully densified and operational components. This technique involves injecting metal powder through a coaxial nozzle into a melt pool obtained by a moving laser beam. The final object is obtained by superimposing the layers created by the process. The roughness of the functional part is strongly conditioned by surface tension and its temperature dependence, which is called Marangoni effect. In order to study this process, we have first developed a simple model to predict the geometry after resolidification of the molten zone of a rod heated at its top with a laser source. The energy and momentum equations are solved in a two-dimensional axisymmetric reference. The deformation of free surface is calculated using a moving mesh by the way of the ALE method. The calculated temperatures are compared with thermocouples measurements. The calculated dynamic shape of the free surface during melting and resolidification is compared with data obtained from high speed videos.