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Research Examines New Metal Coating Process that Skips Pretreatment Stage

Prominent Spanish university is testing a new type of metal coating that touts improved anti-corrosion properties.

Researchers at a prominent Spanish university are testing a new type of metal coating that touts improved anti-corrosion properties, according to a recent post on Azom.com, a materials analysis resource. According to engineers on the project, the application process does not require a pretreatment stage.

Researchers at Spain’s Universitat Jaume I de Castellon are working on a new type of coating that it claims provides higher protection against metal corrosion due to its improved adherence to the metal surface and its anti-corrosion properties. The novelty resides in the elements used in the treatment of the paints through three chemically different pathways and the synergistic effect they produce. When the components interact, adherence of the paint to the metal surface increases and anti-corrosive properties improve. This way, the new coating is said to offer the same protection afforded as when pretreatment is used—but with a single layer.

Previously, project researchers said, the traditional means of protecting metals against corrosion entailed an initial pretreatment that involves cleaning of the metal, followed by an additional protective coating. The idea behind the project, according to researcher Jose Javier Gracenea, is to remove the pretreatment stage altogether, thereby saving time and money—20%, according to early estimates.

Metal Finishing reached out to several experts in cleaning, pretreatment and surface preparation, to get their opinions on the research. The reviews were mixed:

“I think it is another ‘skin-the-pretreatment-cat,’ ” said John Durkee, independent industry consultant and ‘Cleaning Times’ columnist for Metal Finishing magazine. “One basically avoids the pretreatment step and applies an anti-corrosion coating over top of whatever was already there. I am skeptical because one can't get a good bond to a surface unless the surface is accessible (clean).”

Durkee is particularly skeptical of this new coating , given the fact that the tests have been conducted on galvanized metal, which, he says, is already cleaned and pretreated. “But plainly this is a goal of many—to avoid surface preparation and save the resources it takes,” he noted. “This work in Spain may be another step toward meeting that goal.”

Peter Dority, vice president of sales and marketing, Coral Chemical Company, also advocates proper cleaning and pretreatment practices. Although he believes there is a lot that formulators can do with the coating itself to make it more resistant to corrosion (think a zinc-rich coating), there’s no substitute for thorough surface preparation.

“Pretreatment not only improves adhesion and corrosion resistance of the coating as a whole, but it also protects the surface from increased corrosion when the coating has been damaged and the substrate exposed (back to the old cathode/anode corrosion sites when this happens),” Dority explained. “I’m not sure how this coating would act in a scribe salt spray or cyclic corrosion testing as the coating is damaged and the substrate exposed. Even with good adhesion, however, corrosion will spread. The non-conductive properties of a pretreatment reduce the likelihood of corrosion spreading under the paint film.”

Jim Deardorff, president of Chillicotte, Mo.-based Superior Coatings (parent company of Classic Blast), is taking the “middle ground.” From an operator’s perspective, he believes anything that will save time and money for coating application will be attractive to industry—as long as current performance standards are maintained.

'Maintained," being the operative word. “I feel the future of the coating industry for high-value, durable goods lies with the support of strategically engineered maintenance programs to extend the service life of the coating past design limits,” Deardorff explained. “Current coating formulations aren't specifically designed for long-term maintenance support, usually as a result of strict new environmental regulations. In my opinion, a return to coating maintenance is inevitable due to rising costs. Currently, the performance life of an OEM coating rarely exceeds 10 years under normal conditions—in the future, coating life of 25 years or more may be needed.”

At the very minimum, he would like to see more specifics (“The article didn't mention what type of application equipment is needed or the type of coating…solvent base, water base, or powder,” Deardorff noted.)

According to Gracenea, one of the lead researchers on the project, the process has been tested on aluminum and steel substrates, but is applicable to all metals, He expects the coating will be commercially available in approximately two years.

View the original Azom.com post online.

--Reginald Tucker

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Cleaning, Pretreatment & Surface Preparation  •  Industrial and Protective Coatings  •  Industry Trends & Happenings  •  Paint & Powder Coating Applications  •  Testing & Control

 

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