Evolution of structure during the oxidation of zirconium diboride–silicon carbide in air up to 1500°C

Rezaie, Alireza R.; Fahrenholtz, William G.; Hilmas, Greg

doi:10.1016/j.jeurceramsoc.2006.10.012

Cited by 349 publications

(204 citation statements)

References 19 publications

(37 reference statements)

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“…Reaction (3) could then happen on one end of the gas finger, BO, B 2 O 3 , SiO, CO, etc. would then diffuse along the gas finger with O 2 diffusing in the opposite direction, and finally when pO 2 gets high enough, SiO could get reoxidized to form SiO 2 (l) on the other end of the finger, 22 and B 2 O 3 , etc. would get solvated in the liquid and continue to diffuse up the scale.…”

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

“…2(b) bottom), is both thermochemically and mechanically sound if the ZrO 2 (c) skeleton is long enough, such that even after the retreat the liquid phase can still hold onto the solid by capillary forces, to have a ''solid pillars, liquid roof'' architecture as suggested by many experiments. 15,16,21,22 The actual oxidation of SiC particles at T4T B then no longer follows reaction (2), but directly SiCðcÞ þ O 2 ðgÞ ! SiOðgÞ þ COðgÞ (4) a gas-solid reaction without going through the liquid phase, 22 which will lead to a porous ''SiC-depleted'' substrate layer in the ZrB 2 1SiC.…”

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

“…15,16,21,22 The actual oxidation of SiC particles at T4T B then no longer follows reaction (2), but directly SiCðcÞ þ O 2 ðgÞ ! SiOðgÞ þ COðgÞ (4) a gas-solid reaction without going through the liquid phase, 22 which will lead to a porous ''SiC-depleted'' substrate layer in the ZrB 2 1SiC. 13 The ZrO 2 (c) ''solid pillars'' will also grow longer at the base by gas-solid reaction, with O 2 (g) reactant and B X O Y (g) product.…”

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

“…We think the experiments 15,16,21,22 suggest that with a porous ZrO 2 (c) skeleton, the high gas volatility problem can be avoided simply by the liquid phase retreating somewhat outwards, 21 while still maintaining mechanical integrity by holding onto the outer ZrO 2 (c) skeleton with capillary forces. The porous ZrO 2 (c) skeleton acts as a condensing substrate and mechanical support to the borosilicate liquid.…”

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Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Lenosky

Först

et al. 2008

Journal of the American Ceramic Society

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Refractory diboride with silicon carbide additive has a unique oxide scale microstructure with two condensed oxide phases (solid+liquid), and demonstrates oxidation resistance superior to either monolithic diboride or silicon carbide. We rationalize that this is because the silica‐rich liquid phase can retreat outward to remove the high SiO gas volatility region, while still holding onto the zirconia skeleton mechanically by capillary forces, to form a “solid pillars, liquid roof ” scale architecture and maintain barrier function. Basic assessment of the oxygen carriers in the borosilicate liquid in oxygen‐rich condition is performed using first‐principles calculations. It is estimated from entropy and mobility arguments that above a critical temperature TC∼1500°C, the dominant oxygen carriers should be network defects, such as peroxyl linkage or oxygen‐deficient centers, instead of molecular O2* as in the Deal–Grove model. These network defects will lead to sublinear dependence of the oxidation rate with external oxygen partial pressure. The present work suggests that there could be significant room in improving the high‐temperature oxidation resistance by refining the oxide scale microstructure as well as controlling the glass chemistry.

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Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

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Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Lenosky

Först

et al. 2008

Journal of the American Ceramic Society

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“…ZrB 2 -30 vol% SiC specimens were fabricated at Missouri University of Science and Technology using attrition milled powders which were then hot pressed 25,66 . WC contamination (~2 wt%) was observed due to the attrition milling, which used WC milling media in polyethylene jars.…”

Section: Chapter 3 Experimental Procedures Specimen Preparationmentioning

confidence: 99%

Oxidation Behavior of Zirconium Diboride Silicone Carbide Based Materials at Ultra-High Temperatures

Shugart

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ZrB 2 -SiC is of high interest for Thermal Protection Systems (TPS) for future hypersonic vehicles. Both ZrB 2 and its oxidation product, ZrO 2 , possess high melting temperatures (T m =3245°C and 2715°C respectively) needed for this application. SiC is added to improve the oxidation resistance. However, the oxidation resistance of ZrB 2 -SiC at ultra-high temperatures is poor and the oxidation mechanisms are not well understood. The aim of this work was to perform a quantitative study of the oxidation behavior in order to improve life prediction.The oxidation behavior of ZrB 2 -30 vol% SiC was studied using two oxidation procedures. A box furnace was used to oxidize specimens for times between 30 seconds and 100 hours at temperatures of 1300°-1550°C in stagnant air. For ultra-high temperature testing, a resistive heating system was designed and built, which allowed oxidation at temperatures of 1300°-1800°C for times between 5 and 70 minutes in controlled oxygen atmospheres. Oxidation was quantified by measuring mass change and oxidation product layer thicknesses. A combination of scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectrometry, and time of flight secondary ion mass spectrometry was used to characterize the oxidation products.Two oxidation regimes were identified; 1) low temperature oxidation below 1627°C and 2) high temperature oxidation at and above 1627°C. Low temperature oxidation exhibited a twolayer oxide, which consisted of a borosilicate glass layer above a ZrO 2 +C layer. Key findings indicate that oxygen transport in both zirconia and borosilicate glass must be considered in modeling the low temperature oxidation behavior of ZrB 2 -30 vol% SiC. In addition composition and thickness variations of the borosilicate glass layer must also be considered. ivThe transition between the low and high temperature oxidation regimes is attributed to a change in the thermodynamically favored oxidation products, considering a locally SiC-rich microstructure. High temperature oxidation, T≥ 1627°C, resulted in formation of three oxidation product layers. A borosilicate glass layer was found above a layer with ZrO 2 and borosilicate glass. Beneath these was a porous layer of ZrB 2 resulting from SiC depletion due to active oxidation to SiO(g). Key findings indicate that the oxidation rate is much more rapid in this oxidation regime, that the SiC depletion layer growth is best explained by parabolic gas phase diffusion in the porous layer, and again, oxygen transport in both zirconia and borosilicate glass must be considered in modeling the high temperature oxidation behavior of ZrB 2 -30 vol% SiC.This work provided a quantitative analysis of the oxidation kinetics of ZrB 2 -30 vol% SiC.The thermodynamic and kinetic analyses of the two distinct oxidation regimes of ZrB 2 -30 vol% SiC enable improved life prediction.v

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Oxidation of ZrB ₂ ‐SiC: Comparison of Furnace Heated Coupons and Self‐Heated Ribbon Specimens

Karlsdóttir

Halloran

Monteverde

et al. 2007

Mechanical Properties and Performance of Engineering Ceramics and Composites III

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Evolution of structure during the oxidation of zirconium diboride–silicon carbide in air up to 1500°C

Cited by 349 publications

References 19 publications

Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Oxidation Behavior of Zirconium Diboride Silicone Carbide Based Materials at Ultra-High Temperatures

Oxidation of ZrB ₂ ‐SiC: Comparison of Furnace Heated Coupons and Self‐Heated Ribbon Specimens

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Evolution of structure during the oxidation of zirconium diboride–silicon carbide in air up to 1500°C

Cited by 349 publications

References 19 publications

Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB2+SiC and Oxygen Transport Mechanisms

Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB2+SiC and Oxygen Transport Mechanisms

Oxidation Behavior of Zirconium Diboride Silicone Carbide Based Materials at Ultra-High Temperatures

Oxidation of ZrB 2 ‐SiC: Comparison of Furnace Heated Coupons and Self‐Heated Ribbon Specimens

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Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Thermochemical and Mechanical Stabilities of the Oxide Scale of ZrB₂+SiC and Oxygen Transport Mechanisms

Oxidation of ZrB ₂ ‐SiC: Comparison of Furnace Heated Coupons and Self‐Heated Ribbon Specimens