Overtemperature in Metal Scaling

Caplan, D.

doi:10.1149/1.2427697

Cited by 16 publications

(5 citation statements)

References 1 publication

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“…in air or oxygen) to the target temperatures and then held at the target temperatures isothermally. The advantage of this is that there is no rapid reaction taking place when the isothermal holding starts and therefore, there is very little over-heating caused by the sudden release of heat of formation (called overtemperature in an early study [11]). The disadvantage of this is that the oxide scale structure formed during heating would be different from that developed during isothermal holding and would possibly affect the final scale structure developed.…”

Section: Experimental Methodsmentioning

confidence: 99%

Short-time Oxidation Behavior of Low-carbon, Low-silicon Steel in Air at 850–1,180 °C––I: Oxidation Kinetics

Chen¹,

Yuen²

2008

Oxid Met

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In this study, the oxidation kinetics of low-carbon, low-silicon steel in flowing air at 850-1,180°C within 30 or 60 s were examined. The parabolic kinetics were established from the very early stage at 850°and 1,000°C, whereas the oxidation kinetics at 1,100-1,180°C appeared to obey a linear law initially and a more-parabolic one at a later stage. When the oxidation kinetics followed the linear law, ''rough''-scale with an undulating, saw-teeth like microstructure developed, whereas when the parabolic law was followed, smooth scale developed. It appeared that a critical scale thickness existed, at which the scale-growth mechanism changed from linear to parabolic. This thickness was less than 7 lm at 850°C, about 10 lm at 1,000°C, about 50 lm at 1,100°C and in the range of 60-80 lm at 1,180°C under the conditions examined. Blister formation at 900°C prevented clear observation of the linear-to-parabolic transition.

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Section: Experimental Methodsmentioning

confidence: 99%

Short-time Oxidation Behavior of Low-carbon, Low-silicon Steel in Air at 850–1,180 °C––I: Oxidation Kinetics

Chen¹,

Yuen²

2008

Oxid Met

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“…Based on previous experiences, 21 when a new sample was oxidized at temperatures above 1000 • C, an over-temperature phenomenon 22 would occur in the initial oxidation stage. The sample surface temperature would rise rapidly in the first 20 s of reaction, to a temperature much higher than the target temperature.…”

Section: Experimentalsmentioning

confidence: 99%

Isothermal and Step Isothermal Oxidation of Copper-Containing Steels in Air at 980?1220�C

Chen¹,

Yuen²

2005

Oxid Met

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The oxidation and copper enrichment behaviors of several copper-containing mild steels under isothermal and step-isothermal conditions at 980-1220 • C in ambient air, and the effects of nickel additions, are examined. The oxidation kinetics for all steels does not obey the parabolic law because of the formation of blisters in the scale. At 980 • C, decreased parabolic oxidation kinetics is observed, whereas at 1120 and 1220 • C, the oxidation kinetics exhibits an undulating pattern. High nickel content and high oxidation temperature are two prerequisites for the occlusion mechanism to operate during steel oxidation. For the low nickel steel, a planar scale-steel interface develops at all temperatures, and a copper phase is always seen to form and spread along the scale-steel interface. For the high nickel steels, a planar scale-steel interface develops at 980 and 1120 • C, but at 1220 • C, the scalesteel interface becomes rugged and the copper-rich phase is occluded into the scale. Introduction of a 980 • C and/or 1220 • C oxidation step significantly affects the copper enrichment behaviors of all steels normally exhibited at 1120 • C.

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“…That this is the actual reason for the rate difference is not established; also involved might be moisture content, Cr/Fe ratio, impurities, recrystallization, or some other characteristic of the oxide film. A possibility that surface overheating could account for the difference in rate was rejected by experiments February 1961 in which the surface temperature was followed by thermocouples welded to the specimens (8).…”

Section: Surface Preparationmentioning

confidence: 99%

The Effect of Surface Preparation on Oxide Films on Cr and Fe-Cr Alloys

Caplan

Harvey

Cohen

1961

J. Electrochem. Soc.

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The high-temperature oxidation rate of Fe-26 Cr alloys proved highly sensitive to the method of surface preparation. An attempt to deduce the nature of the thin oxide films left by the various treatments was made using electrochemical measurements. Electron microscopy and diffraction and parallel experiments with Cr and Fe were carried out for purposes of clarification. Films formed under strongly oxidizing conditions including electropolishing yielded a cathodic reduction curve having an anomalous sharp minimum. It is proposed that such films are nonstoichiometric oxide containing considerable high valency chromium ion and having a high reduction potential and hydrogen discharge potential. The latter is lowered when at a high enough overpotential the chromium at the surface is reduced to a lower valence.

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Overtemperature in Metal Scaling

Abstract: not Available.

Cited by 16 publications

References 1 publication

Short-time Oxidation Behavior of Low-carbon, Low-silicon Steel in Air at 850–1,180 °C––I: Oxidation Kinetics

Short-time Oxidation Behavior of Low-carbon, Low-silicon Steel in Air at 850–1,180 °C––I: Oxidation Kinetics

Isothermal and Step Isothermal Oxidation of Copper-Containing Steels in Air at 980?1220�C

The Effect of Surface Preparation on Oxide Films on Cr and Fe-Cr Alloys

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