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Researchers used a tensile machine to pull a metal specimen with a ceramic thermal barrier coating sprayed on its surface. With a polariscope, they could measure changes in refractive index resulting from this applied strain. Some of the components of the GHz polariscope are seen on either side of the tensile machine. (Peter J. Schemmel, Heriot-Watt University)

Researchers have demonstrated, for the first time, that an optical analysis method can reveal weak areas in ceramic thermal barrier coatings that protect jet engine turbines from high temperatures and wear. The technique could be used to predict how long coatings would last on an airplane. The lifetime of a thermal barrier coating used on airplane turbine blades can range from as little as 1,000 hours up to 10,000 hours at full turbine thrust, even when the coating is applied in the exact same way.

The new technique could also be used to predict the lifetimes of coatings developed to be more reliable or tolerate higher temperatures, allowing engines to run more efficiently.

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