Fraunhofer ISC, Center for High Temperature Materials and Design HTL, Bayreuth
The measurement of material properties at high temperatures requires precise control of the sample temperature. Measurement volumes must be sufficiently large to provide representative material properties, yet not larger than necessary to allow for short heating and cooling cycles. For many measurement tasks - especially for homogeneous materials - commercial solutions are already available, which are used at Fraunhofer Center HTL for high-temperature characterization. In addition, the HTL uses specially developed thermo-optical measuring systems (TOM) to obtain precise high-temperature data for heterogeneous materials or otherwise inaccessible material properties and temperature ranges.
The following thermal, mechanical, electrical, optical, and chemical material properties can be measured at high temperatures:
- Temperature/thermal conductivity
- Heat capacity
- Hemispherical and directional emissivity
- Thermal expansion coefficients
- Thermal shock behavior
- Thermal cycling resistance
- High-temperature strength
- Creep behavior
- Corrosion resistance
- Wetting behavior
- Impedance properties
For the measurement of thermal and thermomechanical material behavior at sample volumes between 10 and 100 ccm, the TOM_wave system was developed. The mechanical high-temperature behavior is investigated with the TOM_mech system as well as commercial testing equipment. The TOM_imp and TOM_ac systems are available for the analysis of impedance and wetting properties. Conventional thermal analyses are carried out using commercial equipment for differential thermal analysis, thermogravimetry (coupled with mass spectrometry), laser flash analysis, and pushrod dilatometry.