Improved processing and oxidation-resistance of ZrB2 ultra-high temperature ceramics containing SiC nanodispersoids

Hwang, Sung Sic; Vasiliev, Alexander L.; Padture, Nitin P.

doi:10.1016/j.msea.2007.03.002

Cited by 189 publications

(112 citation statements)

References 11 publications

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“…For a certain fixed volume fraction, smaller pores and better connectivity inside ZrO 2 (c) could enhance the collection and retention of the silica-rich liquid. Thus, nanoscale SiC particles might improve the oxidation resistance of ZrB 2 1SiC, 20 by refining the microstructure of the in situ formed ZrO 2 (c) skeleton.…”

Section: Thermochemical and Mechanical Stability Analysis Of The mentioning

confidence: 99%

“…SiO 2 ðlÞ þ COðgÞ (2) respectively. Intense research is ongoing to characterize and enhance this scale as a barrier against oxygen [11][12][13][14][15][16][17][18][19][20][21][22][23] (the scale microstructure can be seen in, for example, Fig. 4 of Opila et al 15 ), which apparently is superior to that of either monolithic diboride or SiC at the intended high temperatures (see Fig.…”

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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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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%

mentioning

confidence: 99%

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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“…Hot Pressing Hot pressing is the conventional method for fabricating UHTCs and has been used extensively, [8][9][10]12,16,17,20,22,27,33,35,39,47,48,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] with typical temperatures of~2173 K (1900°C) and applied pressures between 30 and 50 MPa. It allows full densification without the use of sintering aids, although most research employs modest amounts of sintering aids such as silicides, borides, metals (e.g., Ni), or C to reduce processing times and temperatures, thus reducing the costs associated with the production technique.…”

Section: Densification Methodsmentioning

confidence: 99%

“…Ultrafine SiC also allows material to be produced by hot pressing at 2173 K (1900°C) without the presence of a sintering aid [24] and improves the oxidation resistance of the material. [24][25][26][27] The flexural strength of ZrB 2 -SiC composites produced with ultrafine SiC can increase after oxidation, whereas the flexural strength of composites produced with larger SiC powder (average particle size %6.4 lm) decreases after oxidation. [26] As the temperature is increased, a passive to active transition of SiC oxidation occurs between 1873 K and 1973 K (1600°C and 1700°C) in air under atmospheric pressure, [25,28] so that above these temperatures, any protection afforded by a glassy oxide layer is largely lost.…”

Section: A Oxidationmentioning

confidence: 99%

Toward Oxidation-Resistant ZrB2-SiC Ultra High Temperature Ceramics

Eakins

Jayaseelan

Lee

2010

Metall Mater Trans A

145

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“…According to the data of the absorption spectra, the optical bandgap (Eg) of NiO can be estimated by using the following Tauc equation [46]:…”

Section: Uv-visible Spectroscopymentioning

confidence: 99%

Synthesis of Pyramid-Shaped NiO Nanostructures using Low-Temperature Composite- Hydroxide- Mediated Approach

Shahid¹,

Khan²,

Zakria³

et al. 2016

J Material Sci Eng

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Composite-hydroxide-mediated (CHM) approach was used to synthesize NiO nanocrystals. The proposed method makes use of molten composite hydroxides; providing reaction media and lower the process temperature. Processing temperature and reaction time are the two potential parameters to control the growth of a nanomaterial. The method was used at temperatures in the range of 180-250°C and formation of the nanomaterial was monitored using XRD, SEM, EDX, FTIR, and UV-visible spectroscopy. The produced nanomaterial was purely polycrystalline with an average crystallite size in the range of 23.71-36.92 nm. Method suggested formation of pyramid shaped NiO nanocrystals in the temperature range 220-250°C. Evidence on the elemental composition, purity, and chemical bonding were obtained from EDX and FTIR analysis respectively. Estimation on direct bandgap was made from the optical analysis and found to be in the range 4.0-4.8 eV. The method is attractive and seems a cost effective route for the growth of transition metal oxides for research purpose. For further efficacy, the approach can be examined for other technologically significant nanostructures.

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Improved processing and oxidation-resistance of ZrB2 ultra-high temperature ceramics containing SiC nanodispersoids

Cited by 189 publications

References 11 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

Toward Oxidation-Resistant ZrB2-SiC Ultra High Temperature Ceramics

Synthesis of Pyramid-Shaped NiO Nanostructures using Low-Temperature Composite- Hydroxide- Mediated Approach

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Improved processing and oxidation-resistance of ZrB2 ultra-high temperature ceramics containing SiC nanodispersoids

Cited by 189 publications

References 11 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

Toward Oxidation-Resistant ZrB2-SiC Ultra High Temperature Ceramics

Synthesis of Pyramid-Shaped NiO Nanostructures using Low-Temperature Composite- Hydroxide- Mediated Approach

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Product

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About

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