Numerical and Experimental Investigation of Cold Spray Gas Dynamic Effects for Polymer Coating

摘要: Low melting temperature materials such as polymers are known to be difficult deposit using traditional cold spray techniques. Computational fluid dynamics (CFD) models were created for various nozzle geometries and flow conditions. A schlieren optical system was used visualize the density gradients characteristics in free jet impingement region. Based on CFD models, it determined that a diffuser placed into carrier gas near exit not only leads lower particle impact velocity required polymer deposition, but also provides appropriate application of compression heating particles produce conditions necessary at successful coating adhesion these materials. Experiments subsequently confirmed deposition polyethylene powder onto 7075-T6 aluminum substrate. Using air gas, 53-75 μm diameter 0.94 g/cm3 density, deposited substrate, with critical 191 m/s. No apparent observed. Refinements concepts currently under investigation patent disclosure idea is pending.