An Investigation on Powder Injection in the High-Pressure Cold Spray Process

Abstract

High-pressure cold spray process is a relatively new coating process that uses high-velocity powder particles to form coatings. One of the requirements for this process is to inject the particles to be sprayed into a prenozzle chamber where both the particles and the powder feed gas are entrained into the primary gas stream. In this study, we investigated the effects of powder injection on coating formation through both experimental studies and computational simulations. Several issues related to powder injection will be examined, including the size of powder injector, the differential pressure, powder gas flow, and injector clogging. It is shown that an improved powder injector design not only enables the use of reduced amount of powder carrier gas flow but also maintains steady, clogging-free spraying conditions. Combining with properly selected injection conditions, it can also lead to enhanced coating deposition by kinetic spray process.

An Investigation on Temperature Distribution Within the Substrate and Nozzle Wall in Cold Spraying by Numerical and Experimental Methods

“…The standard k-e turbulence model is utilized to capture the turbulent flow features because it can save the computational time considerably, and the calculation converges easily. The choice is made following the previous numerical studies on the supersonic jet flow in CS ( Ref 22,23). The non-equilibrium wall function is chosen for the near-wall flow treatment because of its great capability to deal with the large pressure gradient in the impinging jet.…”

An analysis of the particulate flow in cold spray nozzles

“…However, particularly the dispersion of the particles was not captured sufficiently. Additionally, Han et al (2009) showed that the deposition strongly depends on the particle injection process. These aspects represent another direct link between the geometry and the deposition efficiency.…”

The influence of alumina content in Cu-Al2O3 powder on the properties of cold spraying coatings

“…Cold spraying technology is divided into low pressure cold spraying [2][3][4][5][6][7] and high pressure cold spraying [8][9][10][11][12][13]. High pressure cold spraying technology use heated high pressure gas in low temperature to change its kinetic energy into heat energy when the solid particles impact substrate and surface of coating material, thus forming a layer of almost impermeable coating [14].But in the process of application, the cold high pressure spraying has a lot of shortcomings,because the requirements for pressure (minimum to 15 atmospheres) lead to the stopping of large equipment and reducing the security of use.…”