Numerical Examination of Particle and Substrate Oxide Layer Failure and Porosity Formation in Coatings Deposited Using Liquid Cold Spray

Cold spray (CS) uses high-velocity gas to deposit solid particles without oxidation or phase change. To make the spraying process more economical, a wider-sized cut of feedstock particles needs to be deposited. The liquid cold spray (LCS) process, which uses water as a propellant, has been developed to achieve this goal. The use of water as a propellant may adversely affect particle deformation and adhesion. In this study, numerical methods are used to analyze particle and substrate oxide failure to determine the effects of wetting on particle adhesion to a substrate. The results indicate that water on the particle surface or on substrate would reduce the deformation of both. The area in which oxide layers fail and metallurgical bonding can occur would be reduced. A portion of the water may become entrapped between the particle and the substrate, adversely affecting the bonding area. Increasing particle velocity and decreasing water thickness can reduce the volume of trapped water and improve density by increasing particle deformation and decreasing pore size.