High velocity materials improvement: here's how better rust protection can be applied to body panels and electrical machines can be created on planar surfaces—both with the same process

Automotive Design & Production, March, 2004 by Gary S. Vasilash

Another benefit of the process is that there is greater accuracy in application of the material, with the achievable dimensions based on the size of the nozzle: "The best we've seen is 0.5 mm," McCune says. In other words, the coating material can be applied to the substrate in a fairly precise manner without the need for masking. (While some might argue that it is possible to do this with a laser cladding process, McCune notes that the cold spray process is done more simply: the powder is applied through the nozzle; with the laser approach there is the laser beam and the mechanism to introduce the powder into the heated zone. "We're actually looking at it as an alternative to laser cladding," he says. The application in question is on valve seats.)

FLAT MACHINES & TAILORED GALVANIZING. One of the things that this comparatively precision application potentially permits is to build electrical machines onto the surface of a material: drawing conductor lines and magnets, creating little generators or motors. These could be created on the surface of brake rotors or on flywheels. McCune admits that this is "purely speculative," but it is something they're thinking about. Or, more simply it could be the application of a magnet onto the surface of a shaft rather than having to mechanically attach a magnet: a much simpler approach to creating a sensor.

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McCune says that an area of interest is performing precise galvanizing. Presently, sheet materials are typically uniformly electrogalvanized. Consider a closure panel, such as a hood. Although the possibility of rust is more likely at the edges of the hood than at its center, the amount of electrogalvanizing is the same right across the surface. "My vision is for something like tailor-welded blanks," McCune says. Just as the tailor welded blanks provide properties where needed (e.g., thicker, stronger steel, where a door panel is attached to the body pillar, and thinner where strength isn't an issue), there would be localized electrogalvanizing.

Hem flanges are of considerable interest with regard to adding an additional amount of zinc through cold spray. McCune also notes that there is increasing interest in the use of the process to increase corrosion protection for steel fuel tanks.

He admits, "It's one of the emerging technologies. There's a lot of excitement about it because it can do things conventional thermal spray can't. Not all of the problems are solved yet." But chances are, many of them will be.

While there has been considerable development work performed on cold spray (e.g., there have been two multi-party consortia-based programs at Sandia; Ktech--which has participated in that work at Sandia--has a research lab dedicated to the process), according to Blose, so far, no automotive company or supplier has purchased a cold spray system from Ktech. Two systems have been sold--one to the Army and one to a defense contractor (and he has an RFQ in hand from another defense contractor). Blose also says that they regularly receive inquiries from companies in Korea, China, Belgium, Germany, Australia, and elsewhere. This seems like a case where U.S. automotive firms ought to act fast. (You can learn more about Ktech at its website: www.ktech.com)