Scientist Makes Another Breakthrough on Corrosion-Resistant Zeolite Coating

Hexavalent chromium played the villain in the film “Erin Brockovich,” causing severe and permanent health problems for people living near a power plant.

UC Riverside Professor Yushan Yan and his colleagues were the first to demonstrate that zeolite coatings could replace traditional hexavalent chromium coatings widely used in aerospace and defense applications. Now they have discovered a new way to bring the technology closer to commercialization.

Yan’s most recent paper, with co-authors from UCR’s Department of Chemical & Environmental Engineering and the Center for Environmental Research and Technology, was published as the cover story in Angewandte Chemie International Edition, the journal of the German Chemical Society.

Zeolite films are well-known as molecular sieves for membrane applications, but they may also be useful as nontoxic, corrosion-resistant coatings to replace chromate-based materials.

Over the years, the Environmental Protection Agency, the Department of Defense and the UC Toxic Substances Research and Teaching Program have closely followed Yan’s work; several years ago the team received a $1.6 million grant for their research from the Department of Defense.

The researchers used the approach to coat a corrosion-susceptible aluminum alloy commonly used in aerospace and defense applications with the silicoaluminophosphate zeolite SAPO-11. When deposited, the zeolite showed good resistance to pitting corrosion, especially when topped with a silane sealant.

“For commercial aircraft, approximately 75 percent of the weight is aluminum alloy,” explains Yan. “These alloys are light and have wonderful mechanical properties, but they are very prone to corrosion. If we can use corrosion resistant zeolite coatings commercially, we can eliminate the use of chromium, creating a significant environmental benefit.”

Hydrothermal zeolite coating methods Yan and coworkers developed in the past require high process pressures, which Yan says is difficult for the surface-finishing industry to adopt commercially. To make the coatings at ambient pressure, Yan and coworkers adapted a technique normally used to prepare zeolite powders. Their method relies on an “environmentally benign” ionic liquid solvent rather than water or an organic solvent.

Zeolite, a crystal composed of silicon dioxide and aluminum oxide, is not new. It is used in granular form as a catalyst for producing gasoline and as a media for separating air into oxygen and nitrogen. In addition to nontoxic, corrosion-resistant zeolite coatings, Yan has developed thin films of zeolite for semiconductor applications not explored before, as well as created very small zeolite crystals for use in fuel cells.

Source: University of California, Riverside

Related stories:

Fiber 'Wrap' Preserves Tissue and Encourages Blood Vessels to Open
(PhysOrg.com) -- Scientists at The University of Texas at Dallas have filed a patent disclosure on a medical device that looks like a blue elastic bandage and acts like a wonder-cloth that helps preserve transplant organs, improve circulation and heal wounds.
Gas pump made of minerals has no moving parts
(PhysOrg.com) -- Scientists have discovered that a type of hard mineral called zeolite can provide a high rate of gas flow in a micro-scale gas pump. Because the pump is based simply on temperature differences and has no moving parts, it could provide reliable and precise control of gas flow for a variety of applications, such as gas-sensing breath analyzers and warfare agent detectors.
Super multi-use minerals unveiled
This material forms around a third of the average packet of washing powder and helps refine 99 per cent of the world's petrol. It is also used to clean up nuclear waste. This extremely useful material is a zeolite. In its natural form it originates from volcanoes but it is synthesised for commercial purposes.
Halting methane squanderlust
The pipes that rise from oil fields, topped with burning flames of natural gas, waste fossil fuels and dump carbon dioxide into the air. In new work, researchers have identified the structure of a catalytic material that can turn methane into a safe and easy-to-transport liquid. The insight lays the foundation for converting excess methane into a variety of useful fuels and chemicals.
New materials can selectively capture carbon dioxide
UCLA chemists report a major advance in reducing heat-trapping carbon dioxide emissions in the Feb. 15 issue of the journal Science.
Georgia Tech Takes Comprehensive Biofuels Approach
We feel it at the pump. Fuel prices are at record highs and so is the demand for alternative fuels. But major scientific and technological advances are still required before economically viable alternative fuels become a significant part of the U.S. energy supply.
New catalyst helps eliminate NOx from diesel exhaust
A catalyst developed by Argonne researchers could help diesel truck manufacturers eliminate harmful nitrogen-oxide emissions from diesel exhausts.
Laying microscale tiles
Craftsmen tile walls or floors by hand; but how can you get an ordered monolayer onto a substrate when the "tiles" are microscopically small instead of big and easy to handle? Previously, self-assembly processes have been the method of choice for this scale. Korean researchers have now come to the realization that even such tiny components can be arranged in a "do-it-yourself" method. As they describe in the journal Angewandte Chemie, their manually produced monolayers of microcrystals are qualitatively superior to the self-assembled variety.

News discussion:

General Science news