In this literature review, the antipathogenic properties and contact-mediated antibacterial and antiviral performance of copper cold spray surfaces are assessed and compared with alternative antimicrobial materials that are able to kill and/or inactivate infectious agents via direct contact. Discussion is also provided concerning the suitability of copper cold spray material consolidations as biocidal and viricidal surfaces that retain long-term functionality as a preventative measure against fomite transmission of pathogenic agents and hospital-acquired infections from contaminated high-touch surfaces. Numerable alternative antimicrobial coatings and surfaces that do not rely upon the oligodynamic action of copper are detailed. Given the ongoing need for recognition of said alternative antimicrobial materials by authoritative agencies, such as the U.S. Environmental Protection Agency, the relevant literature on non-copper-based antipathogenic coatings and surfaces are then described. Furthermore, a wide-ranging take on antipathogenic copper cold spray coatings are provided and consideration is given to the distinctive grain-boundary mediated copper ion diffusion pathways found in optimizable, highly deformed, copper cold spray material consolidations that enable pathogen inactivation on surfaces from direct contact. To conclude this literature review, analysis of how copper cold spray coatings can be employed as a preventative measure against COVID-19 was also presented in light of on-going debates surrounding SARS-CoV-2’s non-primary, but non-negligible, secondary transmission pathway, and also presented in conjunction with the inevitability that future pathogens, which will be responsible for forthcoming global pandemics, may spread even more readily via fomite pathways too.

This work explores the impact of thermally preprocessing recycled austenitic stainless-steel powder for solid-state cold spray metal additive manufacturing with a focus on increasing deposition quality and coating density while maintaining mechanical integrity. The recycled stainless-steel scrap was gas-atomized using a novel mobile foundry manufactured by MolyWorks Materials Corporation. The powder was thermally treated based upon thermodynamic modeling using Thermo-Calc. The powder and sprayed specimens were characterized using particle size–shape analysis, microscopy, x-ray diffraction, and nanoindentation. Diffraction results highlighted the presence of both austenite and ferrite phases in the powder. Nanoindentation confirmed that thermally processing the feedstock powder at the austenitization temperature decreased the amount of ferrite present, which was consistent with the porosity observed in the deposits due to the lower yield strength of austenite relative to ferrite. The untreated powder deposits exhibited extensive porosity and microcracking, as opposed to the virtually fully dense deposit from the heat-treated powder.

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This work employs an example of a through process experiment systematic approach to study the relationship among powder properties, cold spray (CS) processing parameters, and consolidated specimen behavior through a combined effort of characterization methods and computational models. This process will allow for the systematic isolation of variables that can affect powder and CS deposit properties. In this study, Al 7075 powder was used as feedstock to produce a CS coating using industry-standard processing parameters. Techniques such as SEM, EDS, XRD, nanoindentation, and tensile testing were used to characterize the properties of both the feedstock powder and CS deposits. In addition, computational thermodynamic modeling was used to guide the interpretation of microstructural features of the powder and CS specimen. Finally, an additive yield strength model was employed to quantify the strengthening components introduced through the CS process.

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