The behavior of powder particles in coaxial laser cladding

The metal powder flow is sprayed by a coaxial nozzle with carrying gas in laser cladding, and the powder particles are radiated to be melt metal by high power laser beam. The melting metal enters the melting pool on the substrate which is radiated by the same laser beam. The cladding layer forms, when the melting metal cool down. It is crucial to study the influences of different process parameters on the motional and thermal behavior of moving powder particles. In this paper, 2D model about a moving particle's motional and thermal behavior were established. Results show that the increasing mode of the velocities of a powder particle and the carrying gas depends on their initial velocity; the maximum value of the particle velocity appears in the middle of the nozzle exit; and the temperature of the particle rises rapidly and then falls due to the relationship between cold gas, the variation of laser intensity and its velocity and so on. The results are very helpful to design the nozzle and to select process parameters in coaxial laser cladding.