Carbon Permeability of Nickel and Ni–Cu Alloys

Zhang, Jianqiang; Maryam, Safarzadeh; Young, David J.

doi:10.1007/s11085-008-9108-z

Cited by 15 publications

(13 citation statements)

References 11 publications

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“…Alloys of Ni20Cr, with and without copper additions, were found [26] to carburise at the same rate. It is therefore concluded that copper does not affect carbon permeability (N ðsÞ C D g C ), but does inhibit graphite nucleation.…”

Section: Effect Of Copper On Nickel and Stainless Steel Dustingmentioning

confidence: 87%

Recent advances in understanding metal dusting: A review

Young

Zhang

Geers

et al. 2011

Materials & Corrosion

127

101

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Recent experimental investigations have widened the understanding of metal dusting significantly. Microscopic observations have been used to dissect dusting mechanisms. Iron dusts by growing a cementite surface scale, which catalyses graphite nucleation and growth. The resulting volume expansion leads to cementite disintegration. Cementite formation on iron can be suppressed by alloying with germanium. Nonetheless, dusting occurs via the direct growth of graphite into the metal, producing nanoparticles of ferrite. This process is faster, because carbon diffusion is more rapid in a-Fe than in Fe 3 C. Austenitic materials cannot form cementite, and dust via formation of graphite at external surfaces and interior grain boundaries. The coke deposit consists of carbon nanotubes with austenite particles at their tips, or graphite particles encapsulating austenite. TEM studies demonstrate the inward growth of graphite within the metal interior. It is therefore concluded that the dusting mechanism of austenitic materials like high alloy Cr-Ni steels and Ni base materials is one of graphite nucleation and growth within the near surface metal. In all alloys examined, both ferritic and austenitic, the principal mass transfer process is inward diffusion of carbon. Alloying iron with nickel leads to a transformation from one mechanism with carbide formation to the other without. Copper alloying in nickel and high nickel content stainless steels strongly suppresses graphite nucleation, as does also an intermetallic Ni-Sn phase, thereby reducing greatly the overall dusting rate. A surface layer of intermetallic Ni-Sn Fe-base materials facilitates the formation of a Fe 3 SnC surface scale which also prevents coking and metal dusting. Current understanding of the roles of temperature, gas composition and surface oxides on dusting rates are summarised. Finally, protection against metal dusting by coatings is discussed in terms of their effects on catalysis of carbon deposition, and on protective oxide formation.

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Section: Effect Of Copper On Nickel and Stainless Steel Dustingmentioning

confidence: 87%

Recent advances in understanding metal dusting: A review

Young

Zhang

Geers

et al. 2011

Materials & Corrosion

127

101

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“…On the other hand, point defects such as vacancies could be easily introduced during nucleation, radiation and corrosion processes, and defects in alloy always serve as the trapping site for carbon. The metal solute as well as defects and their interactions can greatly affect the carbon solubility, [13][14][15][16] diffusion, 15,16 carbon segregation 14 and carbide precipitations properties 14,17 in nickel. However, it is extremely difficult to directly observe the behavior of carbon and the corresponding microcosmic mechanisms since all of the FIAs-FSAs interactions are atomic-scale problems.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the substitutional solute effect on the interstitial carbon in nickel-based alloy

et al. 2017

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“…However, for the 20 wt% Cu alloys, Cu rich phases developed causing internal carburization at the Cu-c phase interphases [44]. Recently, Zhang and Young [52] confirmed that Cu does not affect the C permeability in Ni as it was earlier proposed [53] but rather interferes with the nucleation of graphite.…”

Section: Cumentioning

confidence: 85%

Metal Dusting Protective Coatings. A Literature Review

et al. 2011

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Metal dusting is a catastrophic form of carburization attack that takes place in carbon-supersaturated gaseous atmospheres, and is most commonly encountered in steam reforming processes such as the production of hydrogen or syngas for ammonia, Fischer-Tropsch and methanol applications. The consequence of metal dusting can be a severe loss of metal from the process units, leading to high-cost maintenance and serious safety issues. The present literature review discusses the latest developments within metal dusting protection of alloys with special emphasis on protective coatings. In the first part of the paper, an overview of the main theories for metal dusting of alloys as well as fundamental studies is provided. In the second part, the paper focuses on the different methods to prevent metal dusting, including surface poisoning, alloying, chemical, mechanical and laser treatments as well as coatings. Particular focus is given to coatings and their composition, and fabrication methods, and a critical analysis of the different materials' behaviours and the suitability perspectives of deposition techniques are provided.

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Carbon Permeability of Nickel and Ni–Cu Alloys

Cited by 15 publications

References 11 publications

Recent advances in understanding metal dusting: A review

Recent advances in understanding metal dusting: A review

Theoretical study of the substitutional solute effect on the interstitial carbon in nickel-based alloy

Metal Dusting Protective Coatings. A Literature Review

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