Cold spraying has been found to be a useful approach for the selective protection of localized areas that are the likely locations for corrosive attack, as shown in the diagram. For example, folded or welded seams in galvanized sheet metal used for applications such as automotive door panels or stamped gas tanks often are susceptible to corrosion because the protective galvanizing layer is damaged or removed in the assembly process. Such areas can be easily protected by local application to the affected areas of an anticorrosion coating such as zinc.
The diagram is a schematic of a steel hem structure in which an inner piece is secured to an outer panel by a metal fold or hem. The potential placement of supplemental zinc protection in the vicinity of the hem is illustrated. Because the duration of galvanic protection by a sacrificial metal such as zinc on steel is linearly proportional to the amount of sacrificial metal available, it then becomes possible to “program” the amount of sacrificial protection according to the severity of the specific geometry and expected service environment.
In this manner, the galvanic protection can be strategically placed instead of relying on large expanses of precoated material to achieve protection goals in localized features. This would be similar in concept to the fabrication of tailored panels of steel with differing strengths and thicknesses for metal forming. Potentially, both weight and cost savings could be realized through such an approach.
https://dl.asminternational.org/books/book/12/chapter/133714/Cold-Spray-Process
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