The Protection of Aluminides by Alloying with Molybdenum in High Chlorine Containing Atmospheres at 1,000 °C

Galetz, Mathias C.; Rammer, B.; Schütze, M.

doi:10.1007/s11085-013-9464-1

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…In the pack aluminizing process utilised to coat the tubes, the volatility of aluminium chloride was exploited to form the coating [36]. However, if the reverse reaction can occur during plant exposure, aluminium will be removed from the coating via the formation of volatile aluminium chloride as observed by Galetz et al [37]. The aluminium chloride would then be transformed into non-protective outer aluminium oxide similar to the active oxidation reactions often reported for Cr and Fe [4].…”

Section: Ni Coated Tubementioning

confidence: 94%

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Dahl

Christiansen

et al. 2019

Surface and Coatings Technology

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Section: Ni Coated Tubementioning

confidence: 94%

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Dahl

Christiansen

et al. 2019

Surface and Coatings Technology

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“…Lee et al argue based on their observations that, at higher temperatures, the NiO layer possesses much fewer defects and no “active corrosion” occurs . If the chlorine content of the atmosphere is high enough, though, as in air with 10% Cl 2 , the NiO scale is directly attacked and reacts with chlorine from the environment to form chlorides .…”

Section: Chlorination Behavior Of Nickel and Molybdenummentioning

confidence: 99%

Refractory metals and nickel in high temperature chlorine‐containing environments ‐ thermodynamic prediction of volatile corrosion products and surface reaction mechanisms: a review

Galetz

Rammer

Schütze

2015

Materials & Corrosion

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Thermodynamic calculations are an important tool for prediction of chemical reactions. In many cases the results help to understand and describe the experimental observations. In others, especially if reaction kinetics play a major role, their predictive value can be rather limited and the projected results have to be treated with care. One such case are high temperature chlorine corrosion conditions. For example, thermodynamically a similar corrosion behavior of nickel and molybdenum is predicted in chlorine‐containing atmospheres at low oxygen partial pressures. In contrast to their calculated similarity, experimental results showed much higher resistance of molybdenum against the chlorinating attack. Above 800 °C nickel is rapidly consumed, whereas molybdenum remains almost inert. This paper reviews the literature on the corrosion mechanisms and kinetics of nickel and molybdenum in chlorine‐containing environments as well as in mixed oxygen‐chlorine‐containing atmospheres. Based on the literature review, differences in their reaction kinetics are discussed, taking into account the deviation from an ideal thermodynamic correlation between the partial pressure and the reaction kinetics via the often used Hertz‐Langmuir equation. Finally it is shown that the findings concerning the special characteristics of molybdenum and nickel and the conclusions drawn from experimental observations on high temperature chlorine corrosion can also be transferred to other metals.

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“…13 For high-temperature oxidation in dry air, Mo may have favorable effects on the selective oxidation of chromium, 14 but the formation of volatile MoO 3 degrades the oxidation resistance. 15 In different environments, Mo has been found to enhance the hot corrosion resistance in a chloride-containing vapor, [16][17] as well as improve the passivation, pitting resistance, and crevice corrosion in aqueous chloride media. [18][19][20][21][22][23][24][25] However, the details of how and why Mo changes the oxidation are still unclear and the synergetic mechanism of Mo and Cr in aqueous corrosion resistance is under active debate.…”

Section: Introductionmentioning

confidence: 99%

In Situ Observations of Early Stage Oxidation of Ni-Cr and Ni-Cr-Mo Alloys

Güleç

Andolina

et al. 2018

Corrosion

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Results of in situ transmission electron microscopy experiments on the early stage oxidation of Ni-Cr and Ni-Cr-Mo alloys are reported. An epitaxial rock-salt oxide with compositions outside the conventional solubility limits initiated at the surface of both alloys, progressing by a layer-by-layer mode. Kirkendall voids were found in Ni-Cr alloys near the metal/oxide interface, but were not seen in the Ni-Cr-Mo. The voids initiated in the oxide then diffused to the metal/oxide interface, driven by the misfit stresses in the oxide. A sequential oxide initiation was observed in NiCr alloys: rock-salt → spinel → corundum; however, for NiCrMo alloys, the metastable Ni 2-x Cr x O 3 (corundum structure) phase formed shortly after the growth of the rock-salt phase. Chemical analysis shows that solute atoms were captured in the initial oxide before diffusing and transforming to more thermodynamically stable phases. The results indicate that Mo doping inhibits the formation of Kirkendall voids via an increase in the nucleation rate of corundum, which was verified by density functional theory calculations.

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The Protection of Aluminides by Alloying with Molybdenum in High Chlorine Containing Atmospheres at 1,000 °C

Cited by 6 publications

References 18 publications

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Corrosion behaviour of Ni and nickel aluminide coatings exposed in a biomass fired power plant for two years

Refractory metals and nickel in high temperature chlorine‐containing environments ‐ thermodynamic prediction of volatile corrosion products and surface reaction mechanisms: a review

In Situ Observations of Early Stage Oxidation of Ni-Cr and Ni-Cr-Mo Alloys

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