Cold Spray Using a Phase-Change Propellant Fluid Approach: Proof of Concept and Potential Benefits

Abstract

Cold spray (CS) has captured the interest of many researchers, scientists and industries resulting in significant development of the technology in the last decade. The process is shifting from fundamental studies to industrial application developments for mass production, with great potential in fields such as energy, electronics, biomedical, aerospace and semiconductor. However, besides the recent developments, improvements and deployment of the technology, CS has been mostly limited to the use of nitrogen and/or air. One potential improvement for the technology is to operate with a phase-changing driving/propellant gas, such as steam. While it is known that steam inherently provides better gas dynamic properties than nitrogen, using it while inducing phase-change, relying on the occurrence of condensation to increase the gas and particle temperature through the release of large latent heat energy, could improve performance and efficiency of the CS technology.To demonstrate this benefit of phase-changing propellant gas and its potential to bring a substantial breakthrough in the field, the current study compares deposition characteristics, i.e., porosity, microhardness, oxygen content and adhesion, of coatings generated using steam and nitrogen across the same CS system and operating parameters. A validated non-equilibrium steam computational fluid dynamics model is developed to describe the fundamentals of condensing water droplets’ influence on flow and feedstock particle condition. A finite element model is included to conceptualize the effect of steam and nitrogen flow on copper particle interfacial deformation upon impact.