Influence of electric-magnetic compound field on the WC particles distribution in laser melt injection

An advanced particle distribution controlling approach is proposed for laser melt injection process, which applies an electric-magnetic compound field to assist the laser melt injection process. The electric-magnetic synergistic effect on the reinforcement particle distribution in laser melt injection is investigated using numerical and experimental methods. Spherical WC particles are used as the reinforcement and their distribution in the longitudinal sections of the laser melt injection layers is examined with SEM and studied with computer graphics processing. The distributions of fluid temperature, fluid velocity and reinforcement particles in the molten pool are simulated using a 2D multi-physics model coupled with the equations of heat transfer, fluid dynamics, drag force, Lorentz force and phase transition. The results show that, the directional Lorentz force due to an electric-magnetic compound field, as a sort of volume force, can change the equivalent buoyancy acting on the particles. When the Lorentz force and gravity force are in same direction, majority of particles are trapped in the upper region of laser melt injection layer, while when the Lorentz force and gravity force are in opposite direction, most particles are concentrated in the bottom region. As a result, the distribution gradient of WC particles can be controlled by the electric-magnetic compound field, instead of the time-consuming adjustment of process parameters.