Mechanisms and driving forces of metal dusting

Szakálos, Peter

doi:10.1002/maco.200303737

Cited by 62 publications

(43 citation statements)

References 14 publications

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“…The granulometry distribution at 7508C was larger than the others and revealed an important proportion of exploded grains. This behavior should be linked to the high productivity X 1 at 7508C during the first hour of reaction, and/or to the fast kinetics of metal dusting 22 at this temperature, leading to a more marked explosion of the catalytic grains.…”

Section: Influence Of Temperaturementioning

confidence: 96%

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

et al. 2008

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in Wiley InterScience (www.interscience.wiley.com).Multi-walled carbon nanotubes (MWCNTs) have been produced with high selectivity by fluidized bed catalytic chemical vapor deposition from ethylene on Fe/Al 2 O 3 catalysts. The influence of operating parameters such as deposition duration, temperature, ethylene and hydrogen partial pressures, and iron loading on MWCNT productivity, process selectivity, characteristics of final powders, and chemical composition of the outlet gases has been analyzed. Using gas phase chromatography, methane and ethane have been detected, whatever are the conditions used. Between 650 and 7508C, no catalyst deactivation occurs because nucleation remains active all along the synthesis, thanks to the explosion of the catalyst grains. Above 6508C, ethane itself produces MWCNTs, whereas methane does not react in the temperature range, 550-7508C. The formation of MWCNTs induces marked bed expansions and sharp decreases of grain density. Apparent kinetic laws have been deduced from the collected data. The apparent partial orders of reaction for ethylene, hydrogen, and iron were found to be 0.75, 0, and 0.28, respectively.

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Section: Influence Of Temperaturementioning

confidence: 96%

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

et al. 2008

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“…15b). The formation of oxide or graphite in this way would be accompanied by volume changes which would lead to disintegration of the surface of the metal grain, the mechanism of attack proposed for high alloy metals [22,[25][26][27][28]. The formation of small metallic particles would in turn catalyze deposition of graphite and may therefore explain the formation of coke in the pores that eventually led to local eruptions on the coating surface.…”

Section: Discussionmentioning

confidence: 99%

Corrosion resistance of Ni‐50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

Saaedi

Arabi

Coyle

et al. 2011

Materials & Corrosion

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Metal dusting attack has been examined after three 168 h cycles on two Ni-50Cr coatings with different microstructures deposited on 310S alloy substrates by the high velocity oxy-fuel (HVOF) thermal-spray process. Metal dusting in uncoated 310S alloy specimens was found to be still in the initiation stage after 504 h of exposure in the 50H 2 :50CO gas environment at 620 8C. Dense Ni-50Cr coatings offered suitable resistance to metal dusting. Metal dusting was observed in the 310S substrates adjacent to pores at the interface between the substrate and a porous Ni-50Cr coating. The porosity present in the as-deposited coatings was shown to introduce a large variability into coating performance. Carbon formed by decomposition of the gaseous species accumulated in the surface pores and resulted in the dislodgement of surface splats due to stresses generated by the volume changes. When the corrosive gas atmosphere was able to penetrate through the interconnected pores and reach the coating-substrate interface, the 310S substrate was carburized, metal dusting attack occurred, and the resulting formation of coke in the pores led to local failure of the coating.

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“…The Cr-depleted substrate is then subject to attack according to the mechanism for low-alloyed steels with the carbides either being oxidized simultaneously [6] or after substrate disintegration [7].…”

Section: Introductionmentioning

confidence: 99%

Initial Stages in the Metal-dusting Process on Alloy 800

Röhnert

Phillipp²,

Reuther

et al. 2007

Oxid Met

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The initial stages of the metal-dusting process on Alloy 800 at 620°C were investigated by light optical microscopy, RAMAN spectroscopy, atomic-force microscopy, Auger electron spectroscopy, transmission-electron microscopy and electron back-scatter diffraction. As it turned out the incubation period for metaldusting is characterized by simultaneous formation of a heterogeneously growing oxide scale and deposition of carbon. The material surface shows different tarnish colors depending on the substrate-grain orientation with different susceptibility to the beginning of metal-dusting attack. ''Low-index'' grains were not attacked within the times investigated while the other grain orientations showed pitting. Carbon is evidently incorporated into the oxide scale from the very beginning of exposure with different intensities depending on the underlying substrate-grain orientation leading to differences in the tarnish colors. As a consequence carbides are formed even underneath ''dense'' oxide layers. Evidently metal-dusting attack starts at positions of the oxide scale where ''higher carbon concentrations'' are present.

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Mechanisms and driving forces of metal dusting

Cited by 62 publications

References 14 publications

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

Kinetic study of carbon nanotubes synthesis by fluidized bed chemical vapor deposition

Corrosion resistance of Ni‐50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

Initial Stages in the Metal-dusting Process on Alloy 800

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