Press Release

NIST researchers in the Materials Reliability Division, Boulder, Colo., have developed an apparatus to measure the thermal conductivity of thermal-barrier coatings (known as TBCs) as thin as 20 micrometers. TBCs--used in aerospace materials, gas turbine engines and diesel engines--are thermal coatings applied to metal substrates to protect these substrates from high temperatures and excessive wear or corrosion.

Accurate measurement of thermal conductivities is critical before new coating systems can be incorporated into advanced engineering designs and future applications. For example, engineers want to keep lowering thermal conductivities so that TBC thickness can decrease as well.

The NIST device uses an infrared microscope to measure temperature differences on millimeter-sized specimens. The small size of the specimens allows the measurements to be made in air--rather than in a vacuum--which simplifies the apparatus needed. Another advantage is the non-contact nature of the infrared temperature measurement. Any contact between a sensor and a small specimen would affect the specimen's temperature.

For a copy of paper 1-99 describing the thermal conductivity measuring device, contact Sarabeth Harris, MS104, NIST, Boulder, Colo. 80303-3337; (303) 497-3237.

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Published in NIST Update , February 16, 1999.
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