Interaction of Laser beam, Powder Stream and Molten Pool in Laser Deposition Processing with Coaxial Nozzle

Powder-based laser deposition technology has widely used for parts coating, repairing and additive manufacturing. The quality and efficiency of laser deposition largely depends on the powder stream controlling. For some special laser deposition processing, such as ultra-high-speed laser cladding, inside laser cladding, FGM(Functionally Graded Materials) and MMC(Metal Matrix Composite) coating or parts manufacturing, the power stream controlling become more complex, because the powder melting behaviour is changed and varying proportion mix powder is used. In order to achieve the best feeding properties and highest powder efficiency aiming to different application requirement, the optimization of the nozzle geometry and controlling of powder flow are quite necessary. For this purpose, a comprehensive numerical model is developed to study the powder flow of coaxial nozzles, which include powder stream spatial distribution, flow rate, and trajectory. The powder stream convergence characteristics for different laser deposition application, and the interaction between laser beam, powder stream and molten pool are studied by numerical and experimental methods. The nozzle geometries, powder properties, and shield gas setting are optimized based on the understanding of the powder concentration distribution.