Fake diamonds help jet engines take the heat

Mar 17, 2008
Fake diamonds help jet engines take the heat
Conventional ceramic coating destroyed by molten glass. The field of view is about half a millimeter. Image by Aysegul Aygun and Nitin Padture, courtesy of Ohio State University

Ohio State University engineers are developing a technology to coat jet engine turbine blades with zirconium dioxide -- commonly called zirconia, the stuff of synthetic diamonds -- to combat high-temperature corrosion.

The zirconia chemically converts sand and other corrosive particles that build up on the blade into a new, protective outer coating. In effect, the surface of the engine blade constantly renews itself.

Ultimately, the technology could enable manufacturers to use new kinds of heat-resistant materials in engine blades, so that engines will be able to run hotter and more efficiently.

Nitin Padture, professor of materials science and engineering at Ohio State, said that he had military aircraft in mind when he began the project. He was then a professor at the University of Connecticut.

“In the desert, sand is sucked into the engines during takeoffs and landings, and then you have dust storms,” he said. “But even commercial aircraft and power turbines encounter small bits of sand or other particles, and those particles damage turbine blades.”

Jet engines operate at thousands of degrees Fahrenheit, and blades in the most advanced engines are coated with a thin layer of temperature-resistant, thermally-insulating ceramic to protect the metal blades. The coating -- referred to as a thermal-barrier coating -- is designed like an accordion to expand and contract with the metal.

The problem: When sand hits the hot engine blade it melts -- and becomes glass.

“Molten glass is one of the nastiest substances around. It will dissolve anything,” Padture said.

The hot glass chews into the ceramic coating. But the real damage happens after the engine cools, and the glass solidifies into an inflexible glaze on top of the ceramic. When the engine heats up again and the metal blades expand, the ceramic coating can’t expand, because the glaze has locked it in place. The ceramic breaks off, shortening the life of the engine blades.

In a recent issue of the journal Acta Materialia, Padture and his colleagues described how the new coating forces the glass to absorb chemicals that will convert it into a harmless -- and even helpful -- ceramic.

The key, Padture said, is that the coating contains aluminum and titanium atoms hidden inside zirconia crystals. When the glass consumes the zirconia, it also consumes the aluminum and titanium. Once the glass accumulates enough of these elements, it changes from a molten material into a stable crystal, and it stops eating the ceramic.

“The glass literally becomes a new ceramic coating on top of the old one. Then, when new glass comes in, the same thing will happen again. It’s like it’s constantly renewing the coating on the surface of the turbine,” Padture said.

Padture’s former university has applied for a patent on the technique that he devised for embedding the aluminum and titanium into the zirconia. He’s partnering with Inframat Corp., a nanotechnology company in Connecticut, to further develop the technology.

Padture stressed that the technology is in its infancy. He has yet to apply the coatings to complex shapes, and cost is a barrier as well: the process is energy-consuming.

But if that cost eventually came down and the technology matured, the payoff could be hotter engines that burn fuel more efficiently and create less pollution. Manufacturers would be able to use more sophisticated ceramics that boost the heat-resistance of engines. Eventually, technology could go beyond aircraft and power-generator turbines and extend to automobiles as well, Padture said.

Source: Ohio State University

Explore further: Scaling up armor systems

add to favorites email to friend print save as pdf

Related Stories

Solar chip monitors windows

Jan 06, 2015

A new kind of radio chip is intended to warn when windows are left open. This way, you can avoid having the heat go out the window on cold days. The sensor also detects break-in attempts early on. The key: ...

Vehicle body made from cotton, hemp, and wood

Jan 06, 2015

Carbon and glass fibers reinforce synthetics so that they can be used for vehicle body construction. But in this regard, there is an abundance of potential found in natural fibers – obtained from hemp, ...

A renewable bioplastic made from squid proteins

Dec 18, 2014

In the central Northern Pacific is an area that may be the size of Texas called the Great Pacific Garbage Patch. Made up of tons of floating plastic debris, the patch is killing seabirds and poisoning marine ...

Recommended for you

Galaxy dust findings confound view of early Universe

23 hours ago

What was the Universe like at the beginning of time? How did the Universe come to be the way it is today?—big questions and huge attention paid when scientists attempt answers. So was the early-universe ...

Evidence mounts for quantum criticality theory

Jan 30, 2015

A new study by a team of physicists at Rice University, Zhejiang University, Los Alamos National Laboratory, Florida State University and the Max Planck Institute adds to the growing body of evidence supporting ...

Scaling up armor systems

Jan 30, 2015

Dermal modification is a significant part of evolution, says Ranajay Ghosh, an associate research scientist in the College of Engineering. Almost every organism has something on its skin that provides important ...

Seeking cracks in the Standard Model

Jan 30, 2015

In particle physics, it's our business to understand structure. I work on the Large Hadron Collider (LHC) and this machine lets us see and study the smallest structure of all; unimaginably tiny fundamental partic ...

The first optically synchronised free-electron laser

Jan 30, 2015

Scientists at DESY have developed and implemented an optical synchronisation system for the soft X-ray free-electron laser FLASH, achieving facility-wide synchronisation with femtosecond precision. The performance ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

dse471
5 / 5 (1) Mar 17, 2008
"Synthetic" diamond and "faux" diamond are two completely different concepts. Consider synthetic oil; it's not natural, but it is physically oil. Cubic zirconia is *NOT* an allotrope of carbon; it is false/faux. Zirconia not physically equivalent to diamond.
DGBEACH
not rated yet Mar 18, 2008
Doesn't adding mass onto separate turbine fins in this fashion increase wear on the inner-bearings due to increased vibrations?

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.