Date of Award
Master of Science in Material Science Engineering (MSMatSE)
Since its invention in 1981, the cold spray (CS) additive manufacturing (AM) process has been studied and optimized to produce well-adhered, dense material coatings. CS can operate at a wide range of temperatures if the feed material remains in a solid state. Copper and zinc were studied to characterize and understand the effects of heating element voltage, travel speed, and standoff distance on deposit porosity, grain size, microhardness, and coating thickness. Samples were sprayed on 3.2 mm x 25 mm x 150 mm 6061 aluminum substrates. Sections were taken from the middle of the samples to represent steady-state conditions. Sample sections were polished and imaged with optical microscopy before being etched and imaged again. Sample sections were repolished for Vickers microhardness testing. Results from the copper CS deposits show that porosity, grain size, and microhardness can be controlled in the variable range, (69%-100% voltage to a heating element, 33-251 mm/min travel speed, and 4.2-15.2 mm standoff distance) of the study however, copper porosity results exclude travel speed as a variable which goes against other research in the field, suggesting some physical phenomenon was not accounted for in the study. Results from the zinc CS deposits show that porosity can be controlled in the variable range of the study and that optimal processing parameters to produce minimal porosity (1.5%) are 94% heating element voltage, 69 mm/min nozzle travel speed, and 9.7 mm standoff distance. There was no correlation in zinc grain size data or microhardness data from any of the tested processing parameters. Thickness results from both tested materials indicate a strong correlation with the studied processing parameters and thickness can be controlled.
Hughes, Cameron, "Optimization of Porosity in Cold Spray Produced Copper and Zinc Coatings" (2023). Graduate Theses & Non-Theses. 300.