Oxidation kinetics of ZrB2-and HfB2-powders and their SiC reinforced composites

Oxidation kinetics of overstoichiometric TiB2 thin films grown by DC magnetron sputtering

“…This is in contrast to the oxidation behavior of most bulk TMB 2 [34,37,77,[79][80][81] and coatings [46,78,82] The weight change after air-annealing at T a = 300 and 400 • C for t a = 12 h is negligible. However, the powders isothermally air-annealed at T a = 500, 600, and 700 • C gain weight with rates that are higher during the first 3-h air-annealing period than for t a > 3 h. After 12-h isothermal air-annealing, the α values for T a = 500, 600, and 700 • C are 30%, 9%, and 54%, respectively.…”

“…The crystallites formed at the oxidation front follow Ostwald ripening through the diffusive transfer of material that varies as a function of time [98] and results in the coarsening of the crystallites toward the scale surface. Moreover, the TMO 2 (s) skeletons are typically anion deficient (containing a high concentration of oxygen vacancies) and exhibit a significant oxygen diffusivity tendency [80]. Thus, this coarsening is accompanied by enlarging the porosity between the elongated grains due to a decrease in their surface to volume ratio.…”

Self-contained dual-scale composite architectures in spray dried zirconium diboride

“…No traces of oxygen were detected by this method of characterization, suggesting that ZrB2 was oxidation resistant at the spray drying temperatures used. The oxidation stability of ZrB2 is dependent on the temperature and oxygen partial pressure in the system [10], [11] and an oxidation onset temperature of ⁓690 °C have been reported [41]. The systematic shift in the ZrB2 peaks in both the as-received powder and spray dried granulates is attributed to HfB2 impurities which may exist in the ZrB2 lattice volume.…”

Microstructural and nanoindentation study of TaN incorporated ZrB2 and ZrB2–SiC ceramics

“…Among the UHTCs, ZrB 2 possesses a number of intriguing properties, including outstanding hardness, a high elastic modulus, and excellent thermal and chemical stability 5 – 8 . Its particular qualities make it a suitable material for crucibles, armors, thermal shields, leading edges, turbine blades, and other applications 9 – 12 . Additionally, ZrB 2 's strong electrical conductivity makes it an appropriate substance for the production of electrical discharge devices and electrodes 13 , 14 .…”