New coating protects steel and superalloys

March 23, 2006
New coating protects steel and superalloys
An electron micrograph of a coated 316 stainless steel coupon in cross-section shows the diffusion-reaction layers. Starting from the left hand side of the photo, which is the surface of the steel the following layers are visible: 1) Aluminum oxide outer layer (not visible at lower magnifications) 2) FeAl layer, 3) Fe3Al inner layer, and 4) 316SS.

Researchers at Pacific Northwest National Laboratory have developed a new ceramic-based coating for steel and superalloys that prevents corrosion, oxidation, carburization and sulfidation that commonly occur in gas, liquid, steam and other hostile environments.

The low-cost, easy-to-apply material is available for licensing and joint research opportunities through Battelle, which operates PNNL for the Department of Energy and facilitates the transfer of lab-created technologies to the marketplace.

The new coating bonds with the metal substrate and is “resilient, inexpensive and simple,” said PNNL scientist Chuck Henager. Because the coating is fabricated at significantly lower temperatures than typically required for conventional ceramic coatings, the new process also can save energy and reduce harmful emissions, he said.

Researchers created the coating by mixing a liquid preceramic polymer with aluminum metal-flake powders to form a slurry that can be applied to a metal object by dipping, painting or air-spraying. A low-temperature curing process follows, using a commercial Ruthenium-based catalyst that enables polymer cross-linking and dries the slurry to a green state.

The coated steel is then heated in air, nitrogen or argon at 700 to 900 degrees Celsius. The heat converts the green state layer into an aluminum diffusion/reaction layer that permeates surface of the steel and provides an aluminide surface coating on the steel.

According to PNNL Commercialization Manager Eric Lund, the diffusion reaction makes the coating so durable that it can’t be chipped or scratched off.

The reaction layer on the surface of the steel is much stronger than an external coating because it is an integral part of the steel, Henager said. This layer develops during use as the coating is heated at very high temperatures, such as those that occur with the heating of pipes in a process facility.

Unlike similar products, the liquid form of the coating can be applied with a spray gun. This feature makes the PNNL coating practical for protecting large areas, researchers said.

Source: PNNL

Explore further: Lengthening the life of high capacity silicon electrodes in rechargeable lithium batteries

Related Stories

'Wetting' a battery's appetite for renewable energy storage

August 1, 2014

Sun, wind and other renewable energy sources could make up a larger portion of the electricity America consumes if better batteries could be built to store the intermittent energy for cloudy, windless days. Now a new material ...

Recommended for you

From a very old skeleton, new insights on ancient migrations

October 9, 2015

Three years ago, a group of researchers found a cave in Ethiopia with a secret: it held the 4,500-year-old remains of a man, with his head resting on a rock pillow, his hands folded under his face, and stone flake tools surrounding ...

Gold nanomembranes resist bending in new experiment

October 9, 2015

The first direct measurement of resistance to bending in a nanoscale membrane has been made by scientists from the University of Chicago, Peking University, the Weizmann Institute of Science and the Department of Energy's ...

What are white holes?

October 9, 2015

Black holes are created when stars die catastrophically in a supernova. So what in the universe is a white hole?

Image: Sentinel-1A captures Azore islands

October 9, 2015

This Sentinel-1A radar image was processed to depict water in blue and land in earthen colours. It features some of the Azore islands about 1600 km west of Lisbon, including the turtle-shaped Faial, the dagger-like Sao Jorge ...

Image: Pluto's blue sky

October 9, 2015

Pluto's haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn's moon ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.