June 23, 2010

National Institute of Standards and Technology funds research in greener steel coating

STEPHEN DAFOE

correspondent

A team of three American companies have been awarded $1.79 million from the National Institute of Standards and Technology to create a new way to coat steel faster, cheaper and greener.

Ohio-based MesoCoat Inc. has been chosen as lead on the project and is working with The Edison Materials Technology Center (EMTEC) and Seattle-based Polythermics LLC to create a new coating technology.

It will use a high-intensity infrared light source to bond nanocomposite metal-ceramic and polymer coatings onto steel surfaces for use in infrastructure projects.

The research team is hoping that the process will replace the electroplating, chromate primers, hot-dip galvanizing and fusion-bonded epoxy technologies that are commonplace today.

Dr. Greg Engleman, MesoCoat’s chief technical officer said the materials are called nanocomposites because they are taking metal matrix binders that are common in metals and combining those with nano-sized ceramic particles.

“Nano is kind of the smallest level where we can currently engineer materials,” Engelman said, noting that one nanometre is one billionth of a metre.

The smaller they go with the engineering process, the harder the material becomes in many metals and ceramics.

Additionally, the technology increases corrosion resistance because the bonded materials move well with the metals below them.

“That gives us the advantage of having these hard particles that have the wear and corrosion resistance in a metal matrix that is more ductile and tough,” Engleman said.

“So, we really have the ability to tailor these materials to a particular application.”

The application process puts the research on the cutting edge. The high-intensity infrared light technology came out of Oakridge National Laboratory, where Engleman worked for nine years.

“This technology takes high-energy density processing methods and allows us to very quickly fuse coatings to the substrate,” he said, noting that they’re able to go as high as 3,500 watts per square centimetre.

“It allows very rapid processing over large areas, which is one of the breakthrough technologies,” he said.

“If you compare it to currently used technologies, which are thermal spray technologies or laser cladding, we have the advantage that we can process a much larger area. Due to the size of the beam that we’re using, we don’t tend to get a whole lot of mixing of the substrate material, which means that we can use less coating material.”

That material is a powder coating developed by MesoCoat’s parent company, Powdermet Inc.

But, applying the new technology to large-scale infrastructure projects is something the team is still working on.

The project’s current phase is laboratory-based, where they are coating samples about 10 inches wide and a couple of feet long. However, Engleman said bigger testing samples are not far behind.

“Within the next month we’ll actually have a set up that will allow us to process 4 by 8 sheets and within the next six months, we’ll have the process set up and be able to run pipes 40 feet long,” he said.

Not only is the team hoping to expand its ability to coat bigger pieces of material, they are ultimately looking to reduce the number of coats required to do so.

Engleman said that current bridge and infrastructure coatings tend to be three-layer processes made up of a primer, an epoxy bond layer and a top layer that protects the steel from the elements.

He is hoping to reduce that to two or even one layer, eliminating the bond coat from many applications. The technology also seeks to reduce environmental impact.

Current coating protection systems rely on often hazardous primer materials made of heavy metals coated with organic polymer paint, used as a moisture barrier.

Since these coatings are subject to ultra violet degradation over time, they must be regularly repaired or replaced.

The rehabilitation process often involves stripping the coatings with volatile organic compounds (VOCs).

“We’ve got a more green process that involves less chemicals, so there’s less waste, less material in the air,” he said.

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