Influence of the particle morphology on the spray characteristics in low-pressure cold gas process

Abstract

This study investigates the influence of particle morphology on spray characteristics in low-pressure cold gas spraying (LPCGS) by analyzing three copper powders with distinct shapes and microstructures. A comprehensive morphology analysis was conducted using both 2D and 3D imaging techniques. Light microscopy combined with image processing quantified particle circularity in 2D projections, while X-ray micro-computed tomography (micro-CT) enabled precise 3D reconstructions to determine sphericity, surface area, and volume distributions. The results showed significant variations in the particle morphology of the investigated feedstock copper powders, with irregularly shaped particles exhibiting lower circularity and sphericity compared to more spherical feedstocks. These morphological differences had a direct impact on the particle velocity distributions and spatial dispersion within the spray jet, as measured by high-speed particle image velocimetry. Irregular particles experienced stronger acceleration and exhibited a more focused spray dispersion, whereas spherical particles reached lower maximum velocities and showed a wider dispersion in the jet. These findings highlight the critical role of particle morphology in optimization of cold spray processes for advanced coating and additive manufacturing applications.