Isegoria

A new ceramic dream material is poised to help power Boeing jets:

The metal “super-alloys” that now line the hottest parts of jet engines are heavy, about 70 percent as dense as lead. And engineers can’t increase combustion temperatures because the alloys would melt. Already, today’s engines employ elaborate cooling mechanisms that divert air for cooling that otherwise would be used to power the plane.

Ceramic matrix composites can withstand temperatures 20 percent higher than these metals, and they are one-third the weight.

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As early as 1994 Luthra had zeroed in on what he thought would be the basic chemistry and structure of the matrix — thin filaments coated with a ceramic that is shaped into a lattice. But it took years to find the perfect materials and the best way of putting them together.

One leap forward was a new type of fiber developed in Japan made of silicon carbide. But coating these fibers with a ceramic, each just one eighth the width of a human hair, evenly, was extremely difficult.

“If you don’t do that right you get a ceramic that behaves like china, and if you do it right you get ceramic with metal properties, and that’s the big deal,” he says.

He figured how to apply the coatings to each individual fiber in something called a chemical vapor deposition reactor, but no one made these devices commercially so GE had to build three of its own.

The fibers are then bathed in a polymer that arranges them into a lattice-like structure. Then, like all ceramics, the material is baked. The polymer burns away and leaves behind a strong, light lattice that is later filled with liquid silicon to create a solid structure.

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