Thermal Properties Laboratory

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Thermal Expansion Testing

Horizontal dual alumina-pushrod dilatometer

A complementary thermal expansion testing capability also exists in the Thermal Properties Laboratory. Thermal expansion tests are performed in inert gas over a temperature range from room temperature to 1500 °C.

Thermal expansion is measured using a horizontal dual alumina-pushrod dilatometer (shown at right) that utilizes absolute displacement transducers for simplicity of operation and increased reliability. Standard thermal expansion tests can be conducted with any combination of heating and cooling rates. The furnace can also hold temperatures to within a few degrees for any length of time to allow equilibrium thermal expansion tests or in-situ sintering or annealing studies.

The system is completely automated and can accommodate testing of two samples simultaneously. Samples may be tested individually or they maybe tested in comparison to a standard for more precise thermal expansion measurements. The standard sample length is 38 mm, but lengths from 13 to 65 mm can be accommodated with custom fixturing. Samples can have round, rectangular, or other irregular cross-sections up to a maximum diameter of 10 mm. Irradiated or unirradiated samples may be tested in this system without risk of cross-contamination.

Previous testing experience includes thermal expansion measurements on monolithic ceramics, ceramic composites, metals, alloys, and metal-matrix composites. In addition, the system has been used for isochronal annealing tests on irradiated high purity silicon carbide specimens for the purpose of determining irradiation temperature. Used in conjunction with the thermal diffusivity systems, the isochronal annealing tests on irradiated materials offers complementary data that can help to determine irradiation damage mechanisms and irradiation-induced defect structures. The system also has been used to measure, in-situ, the shrinkage of pre-ceramic polymer joints in SiC during curing and pyrolysis.

Project Contact: D. Senor