ABSTRACT
Dynamical thermomechanical analysis of 5 illite-based clays from deposits in Slovakia, Estonia, Latvia, and Hungary is presented. The clays consist of illite (37-80 mass%), quartz (12-48 mass%), K-feldspar (4-13 mass%), kaolinite (0-18 mass%), and calcite (0-3 mass%). Young's modulus is measured during the heating and cooling stages of firing (25 °C â 1100 °C â 25 °C). The liberation of the physically bound water increases Young's modulus by â¼70% for all studied clays. By increasing the temperature, dehydroxylation and the α â ß transition of quartz take place without a significant effect on Young's modulus. Sintering, which starts at 800 °C, leads to an intensive increase in Young's modulus up to the highest temperature (1100 °C). The increase remains also in the early stage of cooling (1100 °C â 800 °C). This increase of Young's modulus is also the result of solidification of the glassy phase, which is finished at â¼750 °C. A sharp minimum of Young's modulus is observed at around the ß â α transition of quartz. Then, Young's modulus still decreases its value down to the room temperature. The physical processes observed during heating and cooling do not differ in nature for the studied clays. Values of Young's modulus vary at around 8 GPa, up to 800 °C. During sintering, Young's modulus reaches values from 30 GPa to 70 GPa for the studied clays. The microstructure and composition given by the origin of the clay play a cardinal role for the Young's modulus of the final ceramic body.
ABSTRACT
We enhanced the performance of superconducting tapes during quenching by coating the tapes with various composites, with regards to the application of such coated systems in superconducting fault current limiters. In composition of the coating, we varied the type of epoxy matrix, the content of ceramic filler particles and the use of reinforcement in order to optimize the thermal and the mechanical stability of the coated tapes. By this way modified superconducting tapes were able to reduce the maximum temperature 170 °C of not modified superconducting tape to 55 °C during the quench with electric field up to 130 V m-1.