Spatial Dynamic Characteristics of Powder Stream and Particles During Laser Cladding with Coaxial Powder Feeding

Abstract To better understand variations in spatial concentration, motion paths, and laser-powder interactions during powder descent in laser coaxial feeding, high-speed imaging was used to capture the macro- and micromorphology of the powder stream and particles. Through a combination of grayscale image processing and particle tracking, this study systematically analyzed how different process parameters affect the spatial dynamics of the Ni60 powder. Initially, powder concentration distribution, flight speed, and motion trajectories were analyzed without laser activation, followed by an in-depth examination of laser-powder interaction mechanisms. Findings suggest that grayscale values effectively represent spatial powder concentration, which follows a Gaussian profile. The focal point height increases with carrier gas flow but is independent of the feeding rate. Powder flight speed and trajectory are influenced by both carrier and protective gas flows. Increased laser power allows more powder particles to interact stably with the laser; increased carrier gas flow accelerates particle crossing speed, significantly shortening the interaction time.