Lise Donzel

High temperature superconductors for power applications

Abstract High temperature superconductivity (HTS, discovered in 1986) remains an active area of research worldwide, because its higher T c and, thus, more economical cryogenic cooling have raised the prospects for electric power application. The discovery of MgB 2 has rekindled the search for new superconductors with higher T c . Recently, various acceleration programs have been launched in Europe, USA and Japan. The advance in HTS conductor has enabled the demonstration of various application prototypes, including, power cables, transformers, motors, and fault current limiters. However, full commercialisation of HTS application critically relies on the realisation of HTS conductors that are reliable, robust and low cost with low AC-losses. Worldwide activities are, therefore, focused on developing processing technologies to fabricate the so-called coated conductor based on YBCO to fulfil the stringent specifications. While a high critical current density of around 5 MA/cm 2 (77 K) has been achieved, the conductor cost is currently estimated to be 10–50 times higher than what would be accepted.

Microstructure and mechanical properties of cubic zirconia (8YSZ)/SiC nanocomposites

Abstract The mechanical properties of cubic zirconia (8YSZ)/SiC “nanocomposites” were studied. These properties were found to be strongly dependent on the microstructure and processing conditions. For nanocomposites with SiC particles mostly inside the zirconia grains the bending strength, toughness and hardness were similar to that of monolithic 8YSZ. For nanocomposites with SiC particles located mainly on the grain boundaries, an improvement of the strength and an increase of the toughness were observed. The increase in strength is strongest at room temperature and decreases with rising temperature; the strengths of all materials are identical at ∼750°C. The higher strength cannot be completely accounted for by the observed increase in toughness, implying a reduced critical flaw size in the stronger material.