Stress Generation in Tantalum During Oxidation

Pawel, R.E.; Cathcart, J. V.; Campbell, J. J.

doi:10.1149/1.2425812

Cited by 57 publications

(25 citation statements)

References 3 publications

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“…The pentoxide appears to grow adherently on the metal surface, apparently under considerable compressive stress (21). These stresses eventually cause the oxide to break away from the metal (6), and oxidation starts immediately on the freshly exposed surface.…”

Section: Morphological Resultsmentioning

confidence: 99%

The Effect of Nitrogen on the Oxidation of Tantalum at High Temperatures

Stringer

1965

J. Electrochem. Soc.

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The effect of nitrogen on the oxidation of tantalum has been studied at 600 °, 820 °, and 925°C. In all cases, the oxygen partial pressure was close to 360 Torr; nitrogen partial pressures in the range 0 to 250 Torr were investigated. At all three temperatures, nitrogen reduces the rate of oxidation, the effect increasing with temperature. Although the oxidation in pure oxygen follows a linear rate law, with nitrogen present the reaction ceases to be linear. The interpretation of the results in terms of the existing kinetic models is discussed. It is suggested that the pressure drop associated with the flow of the gas through the porous outer scale cannot be neglected. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.210.126.199 Downloaded on 2015-06-11 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.210.126.199 Downloaded on 2015-06-11 to IP

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Section: Morphological Resultsmentioning

confidence: 99%

The Effect of Nitrogen on the Oxidation of Tantalum at High Temperatures

Stringer

1965

J. Electrochem. Soc.

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“…The action of the lateral or Poisson strain components during even one-dimensional flexure of thin specimens is sufficient to alter the stress Sg by a factor of 1/ (1-v2) (22), where v is Poisson's ratio. The Poisson's ratio of nickel is 0.336 (29).…”

Section: Introductionmentioning

confidence: 99%

Stresses in Bi-Layered NiO Scales

Ueno

1974

Trans. JIM

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flexure of the specimen (99.9 % pure) is achieved during oxidation; the former is on the convex side. When removed electrochemically from the substrate of nickel (99 or 99.9% pure), the black/green bi-layer was elongated causing bending to the opposite side. On the contrary, the black/black bi-layer formed on the 99.9 % pure nickel remained straight with a negligibly small elongation as compared with the black/green bi-layer. It is found that high compressive stresses occur in the green layer, and negligibly small stresses in the black/black bi-layer. Macroscopic elastic stresses in the green layer at room temperature are estimated to be the order of magnitude 109 dynes/cm2. Stress gradients across the scale are roughly estimated. Discussions are given of the formation of bi-layered structures.

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“…First, the localized surface Ta 2 O 5 scale can experience basic/acidic dissolution to form TaO 3 − or Ta 4 O 11 2− /Ta 5+ ions, and the reactions can generate a large number of volatile products, thus fracturing the corrosion scale and leading to the generation of defects in it, such as pores and cracks. Second, the transformation from Ta to oxides can cause a huge volume expansion; for example, based on the crystal parameters of Ta, Ta 2 O 5 , and Na–Ta–O, one Ta atom transforming to Ta 2 O 5 , NaTaO 3 , and Na 2 Ta 4 O 11 expands the volume by 2.59, 3.63, and 3.06 times, respectively, leading to a stress generated in the corrosion scale and at the Ta interface . As the scale thickness increases, the stress in the corrosion scale increases; thus, the corrosion scale breaks and detaches from the surface when the stress increases to a certain level (Figure e,f).…”

Section: Discussionmentioning

confidence: 99%

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

Zeng

et al. 2019

Materials & Corrosion

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The corrosion behavior of pure Ta and laser surface melting-treated Ta sheets was investigated in an equimolar NaCl-KCl melt at 850°C in air. The results show that the predominant factors involved in the consumption of materials were reactions that form sodium-containing oxides and Ta 2 O 5 . High corrosion stress led to slip of the untreated Ta surface grains, further resulting in preferential corrosion along slip bands. The slip of surface grains substantially deteriorated the bonding between the corrosion scale and matrix, thus leading to rapid degradation of the corrosion scale. The melt layer consisted of a thin Ta 2 O 5 film, and the inner dendrite layer demonstrated self-healing characteristics during corrosion and presented a better hot corrosion resistance than the untreated Ta owing to the excellent bonding at the scale and melt layer interface. K E Y W O R D S chloride, hot corrosion, LSM, oxidation, Ta

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Stress Generation in Tantalum During Oxidation

Cited by 57 publications

References 3 publications

The Effect of Nitrogen on the Oxidation of Tantalum at High Temperatures

The Effect of Nitrogen on the Oxidation of Tantalum at High Temperatures

Stresses in Bi-Layered NiO Scales

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

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