Influence of environment on delayed failure of alumina ceramics

Баринов, С. М.; Ivanov, N. V.; Орлов, С. В.; Shevchenko, V.Ja.

doi:10.1016/s0955-2219(98)00116-2

Cited by 22 publications

(6 citation statements)

References 16 publications

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“…46,47 High-purity polycrystalline alumina may not suffer attack by acid, 48 but this conjecture is disputed. 49 Even for silica glass, assessing the role of water is difficult. Classic studies show that water enhances subcritical crack growth.…”

Section: Discussionmentioning

confidence: 99%

Monazite Coatings on Fibers: II, Coating without Strength Degradation

Boakye

Hay

Mogilevsky

et al. 2001

Journal of the American Ceramic Society

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Washed and unwashed rhabdophane (LaPO 4 ⅐xH 2 O) sols were used to apply monazite coatings to 3M Nextel 720 and 610 fibers. This precursor was designed to minimize stress corrosion from gaseous decomposition products at high temperature. The coatings were heat-treated in-line at 900°-1300°C, in air, using a continuous vertical coater with immiscible liquid displacement. Coatings were characterized by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The sol was characterized with light-scattering and zeta-potential measurements. Precursor phase evolution was studied with differential thermal analysis/thermogravimetric analysis and X-ray diffractometry. The washed sol had a higher pH and lower weight loss than the unwashed sol. The as-coated fibers were tensile tested, along with coated fibers heattreated in air at 1200°C for 100 h. The precursor was slightly phosphate-rich, and this excess phosphate reacted with alumina in the fiber to occasionally make very small (<10 nm) pockets of AlPO 4 at the coating-fiber interface after 100 h at 1200°C. Both washed and unwashed sols made coated fibers with higher tensile strengths than those of coated fibers made from other precursors, and the washed sol may actually have slightly increased fiber strength when in-line heat treatments at <1200°C were used. A small amount of AlPO 4 may also have helped seal preexisting flaws. Degradation mechanisms during fiber coating are discussed in this paper.

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Section: Discussionmentioning

confidence: 99%

Monazite Coatings on Fibers: II, Coating without Strength Degradation

Boakye

Hay

Mogilevsky

et al. 2001

Journal of the American Ceramic Society

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“…This value is in reasonable agreement with the values of stress corrosion cracking exponent previously reported in literature, between 40 18 and 60. 39 We can follow a similar reasoning for the case of cyclic loading of alumina, and arrive to similar relationships as Eq. (13).…”

Section: Discussionmentioning

confidence: 64%

Hertzian contact fatigue on alumina/alumina-zirconia laminated composites

Jiménez‐Piqué

Ceseracciu

Chalvet

et al. 2005

Journal of the European Ceramic Society

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“…In Ref. [2] we point out that bulk alumina itself had been reported to be subject to moisture accelerated slow crack growth (static fatigue or stress corrosion) by Wiederhorn [22], later confirmed in numerous subsequent studies of moisture-assisted static and dynamic fatigue of alumina [23][24][25][26][27][28]. This phenomenon is based on moisture breaking strong Al-O bonds in Al 2 O 3 to form weak Al-(OH) bonds, presumably as some hydroxide species.…”

Section: Alternative Mids Mechanismsmentioning

confidence: 78%

Hydrogen and moisture-induced scale spallation: Cathodic descaling of a single crystal superalloy

Smialek

2011

Electrochimica Acta

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Moisture-induced delayed spallation (MIDS) of protective alumina scales at room temperature is a well known phenomenon. One mechanism proposes that water and Al alloy react, produce hydrogen at the scale-metal interface, and enable spallation. To test this mechanism, preoxidized samples of a single crystal superalloy, Rene'N5 + Y, were subjected to standard cathodic hydrogen charging treatments known to produce hydrogen embrittlement in bulk Ni and Ni 3 Al alloys. Cathodic hydrogen charging, at <1 mA and an estimated −0.45 V SCE, stripped the scales at the oxide-metal interface, resulting in an initial loss of ∼3 mg/cm 2 and little additional change with time. This was supported by macro-photos and SEM of the spalled surface. On the other hand, anodic polarization at <1 mA produced less, but steady, linear weight loss (0.3 mg/cm 2), primarily by anodic dissolution of the metal. Hydrogen charging was thus shown to be detrimental to the alumina scale-metal bond, supporting the hydrogen factor in MIDS. These and other MIDS results show remarkable similarities to embrittlement of Ni subject to hydrogen charging at similar potentials and varying amounts of interfacial (grain boundary) sulfur segregation. The MIDS phenomenon is also discussed in terms of comparative static corrosion fatigue characteristics. It is not necessarily related to other diverse moisture effects occurring at high temperature.

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Influence of environment on delayed failure of alumina ceramics

Cited by 22 publications

References 16 publications

Monazite Coatings on Fibers: II, Coating without Strength Degradation

Monazite Coatings on Fibers: II, Coating without Strength Degradation

Hertzian contact fatigue on alumina/alumina-zirconia laminated composites

Hydrogen and moisture-induced scale spallation: Cathodic descaling of a single crystal superalloy

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