A correlational study of process parameters on properties of low-pressure cold sprayed copper coatings

Here, statistics descriptive and inferential were employed to understand the acquired data from the process output variables such as porosity percentage, thickness, and deposition efficiency of the obtained coatings as a function of process input variables such as nozzle type, standoff distance, and the particle in-flight velocity before impact on the substrate. Coatings were produced by the LPCS process with copper powder deposited onto aluminum 6061 substrates, using two different nozzle shapes (rectangular and round) and two standoff distances (SOD) of 12.5 and 22.5 mm. It was found that nozzle type is the process input parameter with the most substantial contribution to the final coating properties. Particle in-flight velocity decreased by 38% at the standoff distance of 22.5 mm with the rectangular nozzle shape. In contrast, at the same standoff distance for the round nozzle shape, the in-flight particle velocity only diminished by 15%. The rectangular nozzle exhibits the uppermost change of in-flight particle velocity, impacting the particles at a very high speed. This could cause a high percentage of rebounded particles, diminishing the thickness and increasing the porosity percent. It was concluded that the round nozzle type is recommended to achieve coatings with low porosity levels without deep dependence on the standoff distance. This conclusion applies to the experimental conditions of this study with the given geometrical nozzle features.