A comprehensive ab initio analysis of the ultra high temperature ceramics ZrB2 and HfB2 is presented. Density functional theory (DFT) computations were performed for the electronic, mechanical, thermal, and point defect properties of these materials. Lattice constants and elastic constants were determined. Computations of the electronic density of states, band structure, electron localization f...

An approach to producing hierarchical multi-scale porous ultra-high temperature ceramics (zirconium diboride, ZrB2) using 3D printing has been developed. Porous ceramic filaments can be printed via Direct Ink Writing (DIW) (paste extrusion). Millimeter scale porosity is created by the scaffold filaments. We introduce 20-micron-scale into with addition of oil produce capillary suspension paste i...

A fracture strength model applied at room temperature for embedded elliptical crack in brittle solid was obtained. With further research on the effects of various physical mechanisms on material strength, a thermo-damage strength model for ultra-high-temperature ceramics was applied to each temperature phase. Fracture strength of TiC and the changing trends with elliptical crack shape variation...

Pressure-less consolidation of transparent alumina requires several hours dwelling at high temperature (1600 °C) under a strongly reducing atmosphere (hydrogen). Here, we report on the ultrafast translucent ceramics 1360 °C. Transparency was promoted by synergistic effects initial green density (62.7%) and rapid sintering using Ultra-fast High-temperature Sintering (UHS) technique. The proposed...

The excellent physical and chemical properties of ultra-high temperature ceramics make them suitable for many high-temperature structural components, while their poor toughness high sintering become key limitations to application. Laminated toughening has long been considered an effective method improve the mechanical ceramics. In this study, laminated ZrB2-Mo5SiB2 with Mo-Mo5SiB2 interlayer we...

with the perovskite structure and with the trivalent cation (M) substitution at the B-site to introduce oxygen vacancies. The high affinity for hydrogen ions (H) is advantageous for protonic transport, but it increases the reactivity toward water (H2O) and carbon dioxide (CO2), which can lead to premature membrane failure. In addition, there are considerable technological challenges related to ...