Effect of moisture on the oxidation behavior of ZrB₂

Abstract

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Oxidation kinetics of silicon carbide‐containing refractory diborides, I: Revised model

“…In this work, we have conducted preliminary/initial model calibration and validation against the experimental data on oxidation of ZrB 2 in ambient air (Naraparaju et al 5 ) and ZrB 2 -SiC in static ambient air (Levine et al 4 ) and low-velocity water vapor (Nguyen et al 3 ). To the best of our knowledge, the study of Nguyen et al is the only one where kinetics of oxidation of UHTCs in water vapor were studied somewhat systematically.…”

“…Figure 15 shows computed permeability of water vapor and oxygen as a function of B 2 O 3 activity in the borosilicate glass and temperature. The calculations were performed using the available data on oxygen and water vapor permeation rate in SiO 2 and B 2 O 3 (see the companion paper 17 for details), adjusted to fit the experimental data of Naraparaju et al, 5 Levine et al, 4 and Nguyen et al 3 as described above. For pure SiO 2 , the permeability of water vapor in SiO 2 is indeed about one to two orders of magnitude higher than that of oxygen, depending on temperature.…”

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

“…These two phases can quickly evaporate and/or spall off. Spallation typically takes place due to volume expansion associated with the conversion of the oxide phase to the hydrated form [85][86][87]. Since the formation of H m BO n follows exothermic reactions [83], the additional thermal energy released from these reactions can also to some extent increase temperature and contribute to a higher evaporation rate.…”

Wettability and interfacial phenomena in the liquid‐phase bonding of refractory diboride ceramics: Recent developments

“…The surface chemistry and morphology of virgin diboride ceramics is altered by the atmosphere which in turn affects the wetting and spreading of liquids. Fahrenholtz and coworkers 75 SiC surface due to SiC surface graphitization following sublimation of silicon from the surface at high temperatures. Additional side reactions could alter the initial test atmosphere; for example, CO(g) and H 2 (g) may form from the reaction of residual water vapor with the graphite susceptor (used to enhance induction coupling) or with the substrate.…”