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Protective Nanocoating Does Double Duty

Wednesday, April 4, 2012

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German scientists have developed a low-friction metal coating that purportedly protects against corrosion and lubricates without grease.

The new nanocomposite is designed for coating metals and metal alloys such as steel, aluminum and magnesium, say materials researchers from INM - Leibniz Institute for New Materials in Saarbucken, where the coating was developed.

Special Structure, Composition

“What is really special about our low-friction coating is its composition and structure,” says Dr. Carsten Becker-Willinger, who heads the research into the coating known as Nanomere.

© Uwe Bellhäuser

The sprayed coating ensures a smooth glide without using grease and while protecting against rust.

To make the coating, the team “embedded platelet-like solid-state lubricants and platelet-like particles in a binder,” he adds. “When the composite is applied onto a surface, a well-arranged microstructure forms, in which the various particles arrange in an imbricate structure,” overlapping like roof tiles.

A so-called transfer film then forms between the coating and the counterpart, which allows “an almost frictionless sliding” of the surfaces on each other, researchers said.

The coating’s unique proportion of components gives it a very low friction coefficient, Becker-Willinger says.

Corrosion Protection

Meanwhile, he adds, the coating’s imbricate structure acts as a barrier to prevent the penetration of humidity or salts to the metal surface, so it protects against corrosion.

The composite shows a corrosion resistance of more than 1,000 hours in a neutral salt spray test on low-alloy steel, he said.

The coating eliminates the problems of grease- and oil-containing lubricants, which combine with dirt and dust and soon clump and stick, researchers say.  That means extra cleaning and greasing for cog wheels, threads, machine parts, engines, cranks and other metal.  Nanomere contains no grease, avoiding that problem, the team says.

The coating, which can be applied by spray or dipping, will be demonstrated later this month at Research & Technology / Hannover Messe 2012, the world’s biggest industrial fair, located in Hanover, Germany.