Characterization of High Temperature Structural Ceramics and Composites

Since 1984 the Advanced Ceramics and Glasses group has worked closely with the Department of Energy’s Oak Ridge National Laboratory to characterize high-temperature ceramics being developed for use in land-based gas turbines. As a result of this effort we have constructed a world-class high-temperature testing laboratory to determine the mechanical and thermal properties of structural ceramics, coated ceramics, and composites. The data we make available enables designers to predict component lifetimes with a high degree of confidence. Other programs conducted with industry, the Air Force, and the Army have expanded the work done on these materials.

We have one of the most advanced creep test facilities in the country for characterizing creep behavior and stress rupture. The laboratory has 16 tensile creep frames capable of operating at 1500 C for extended periods of time. In addition there are six compression creep units. Extensive testing has been performed at both room and elevated temperatures using tensile tests, biaxial flexure tests, three and four point bend tests, and compression testing. The group has also developed a special high-temperature hoop stress test, which enables a much higher volume of material to be tested than in the standard tensile test. The equipment has also been used for static, dynamic and cyclic fatigue testing to 1600 C in support of lifetime prediction studies.

We can also determine Young’s modulus, Poisson’s ratio, thermal expansion, thermal diffusivity and fracture toughness over a wide temperature range. More recently we have been investigating methods of determining shear strength and mode-2 fracture toughness.