Experimental And Numerical Study Of Gas-Powder Flux In Coaxial Laser Cladding Nozzles Of Precitec

Laser cladding technology is used for coating deposition, worn surfaces repairing, and direct fabrication. However, the technological complexity and high cost prevents its wide industrial applications. In the present work, the gas-powder flux parameters are studding to optimize cladding conditions and the choice of appropriate nozzle. Using commercial Precitec (Germany) nozzles, the relations between the nozzle geometry and the powder flux parameters are analysed. The numerical simulation of gas and powder flux is compared with high-speed optical monitoring accompanied by post image treatment. Numerical simulation and experimental results have the same tendencies regarding the powder flux geometry, waist parameters and convergence angles. The difference is related to particle-particle collisions, which are neglected in simulation. The modelling results strongly depend on the energy loses in particle/nozzle wall collisions. It was found that for industrial cladding "short" nozzles with high-gap are more suitable. For 3D direct fabrication, the "medium" nozzles with low-gap are preferable.