Oxidation of hafnium carbide and hafnium carbide with additions of tantalum and praseodymium

Courtright, E.L.; Prater, J. T.; Holcomb, Gordon R.; Pierre, G. R. St.; Rapp, Robert A.

doi:10.1007/bf01151590

Cited by 94 publications

(47 citation statements)

References 6 publications

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“…First, monolithic HfC ceramic is hard to be sintered due to its strong covalent bonds, 26,27 and a series of previous works reported that extremely high temperatures (2200-2690 • C) 26 are needed for densification even by hot pressing. This temperature is obviously higher than that of ZrB 2 based composites.…”

Section: Applications: Pressureless Densification Of Zrb 2 -Sic By DImentioning

confidence: 99%

ZrO2 removing reactions of Groups IV–VI transition metal carbides in ZrB2 based composites

Zou

Zhang

Sun

et al. 2011

Journal of the European Ceramic Society

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Section: Applications: Pressureless Densification Of Zrb 2 -Sic By DImentioning

confidence: 99%

ZrO2 removing reactions of Groups IV–VI transition metal carbides in ZrB2 based composites

Zou

Zhang

Sun

et al. 2011

Journal of the European Ceramic Society

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“…As discussed, these equations have been solved analytically by several authors (6)(7)(8)(9)(10)(11)(12). The first step is to derive an expression for x f /L .…”

Section: Oxidation Modelingmentioning

confidence: 99%

Oxidation of Carbon/Carbon through Coating Cracks

et al. 2009

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Reinforced carbon/carbon (RCC) is used to protect the wing leading edge and nose cap of the Space Shuttle Orbiter on re-entry. It is composed of a lay-up of carbon/carbon fabric protected by a SiC conversion coating. Due to the thermal expansion mismatch of the carbon/carbon and the SiC, the SiC cracks on cool-down from the processing temperature. The cracks act as pathways for oxidation of the carbon/carbon. A model for the diffusion controlled oxidation of carbon/carbon through machined slots and cracks is developed and compared to laboratory experiments. A symmetric cylindrical oxidation cavity develops under the slots, confirming diffusion control. Comparison of cross sectional dimensions as a function of oxidation time shows good agreement with the model. A second set of oxidation experiments was done with samples with only the natural craze cracks, using weight loss as an index of oxidation. The agreement of these rates with the model is quite reasonable.

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“…The counter-current gaseous diffusion model was first developed for the oxidation of HfC [1][2][3][4] and is presented here for the oxidation of graphite through porous alumina overcoats. Any system with gaseous oxidation products and a porous or cracked scale or coating is a candidate for the oxidation being controlled by counter-current gaseous diffusion.…”

Section: Application Of the Model To Other Oxidation Systemsmentioning

confidence: 99%

“…In some cases, oxidation kinetics may be described by counter-current diffusion of oxygen inward and the gaseous product outward through the porous layer. This has been proposed as the oxidation mechanism of HfC between 1200 and 1530°C [1][2][3][4] .…”

Section: Introductionmentioning

confidence: 99%