Refractory Materials for Energy Applications

Abstract

The most extensively used refractory metals are tungsten, tantalum, niobium, rhenium, unalloyed molybdenum and its principal alloy, TZM. All of them are characterised by their extremely high melting point above 2000 °C (2273 K) and high hardness at room temperature. They are used in demanding applications that require high‐temperature strength and corrosion resistance, for example, wire filaments, casting moulds and chemical reaction vessels in corrosive environments. This contribution is focused on tungsten and new tungsten materials. The intrinsic problems of these materials, that is, their brittleness (even at elevated temperatures), thermal load capacity, heat conductivity, recrystallization, irradiation damage and specific defect processes, such as helium bubbles, swelling, new kinds of surface reactions, crack formation, brittle‐to‐ductile transition and tritium retention, require the development and assessment of new tungsten materials, and also new fabrication routes and processes.

Comparison of K-doped and pure cold-rolled tungsten sheets: As-rolled condition and recrystallization behaviour after isochronal annealing at different temperatures

“…Introduction of WC particles into the matrix [19] Zirconium carbide (ZrC) RX temperature 100 K higher than pure tungsten [20] Titanium carbide (TiC) Material produced by powder injection moulding [21] Hafnium carbide (HfC)…”

“…The stabilisation of an ultrafine-grained, severely deformed microstructure could be realised for example by formation of a solid solution [16], by adding second phase particles such as oxides [17,18] or carbides [19][20][21], as well as by doping with potassium (K) [22][23][24][25] (Table 1). The latter is what was chosen in our work.…”

Effect of shielding gas composition and welding speed on autogenous welds of unalloyed tungsten plates

“…For many years, refractory metals and their alloys have attracted the attention of numerous researchers due to their unique properties and their potential utilisations [1][2][3]. In fact, this class of materials is principally characterised by high melting point, good strength over a large temperature range, high thermal conductivity and low thermal expansion [4]. For these reasons, the refractories are suitable to manufacture components for high-temperature applications, f.i.…”

Compositional Effects and Electron Lone‐pair Distortions in Doped Bournonites

“…Materials exhibiting low thermal conductivity are a main focus for the development of a variety of applications, including thermoelectricity, [1] thermal barrier coatings, [2] and refractories. [3] In the case of thermoelectric devices, thermal transport is a limiting factor for high efficiency performance, materials properties that are essentially controlled by the dimensionless figure of merit ZT ¼ S 2 sT=k, where S is the Seebeck coefficient, s is the conductivity, and k is the thermal conductivity. [4] Materials with inherently low thermal conductivity have been especially attractive for thermoelectricity, where alloying, doping, defect engineering, and nanostructuring have proven to be effective ways for further optimization of the materials properties.…”

“…3 . These results show that all S-Sb-S angles are < 99 , however the doping atom reduces the angle involving Sb1 while increasing the angle involving Sb2.…”