Engineered Coatings for Ni Alloys in High Temperature Reactors

Clark, Elizabeth A.; Yang, James Y.; Kumar, Deepak; Was, Gary S.; Levi, Carlos G.

doi:10.1007/s11661-012-1411-2

Cited by 10 publications

(2 citation statements)

References 33 publications

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“…Alumina has been shown to serve as an effective diffusion barrier against corrosive media. − While perhaps more frequently employed in a crystalline form, − even in its amorphous form, alumina coatings have been shown to reduce corrosion in an NaCl environment by up to 4 orders of magnitude . Likewise, a native amorphous alumina has been shown to have a low asphaltene affinity .…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Chemistry and Roughness on the High-Temperature Deposition of a Model Asphaltene

et al. 2019

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Fouling of processing units because of asphaltene deposition is a common phenomenon that interrupts the operation of oil refineries. In this study, the deposition behavior of a model archipelago asphaltene was investigated in the temperature range of 150 o C to 350 o C. For a fixed surface chemistry, the differences in deposit chemistry with fouling temperature is a function of the thermochemical properties of the model asphaltene. Under static high pressure and high temperature fouling conditions, both surface roughness and chemistry play an important role in asphaltene deposition. Rough surfaces are shown to develop larger deposits because of less restrictive physical barriers to inhibit deposit growth. Passivating the surface with an alumina chemistry significantly reduces the impact of surface roughness, as well as the total amount of deposition. This beneficial effect of using a protective alumina chemistry is attributed to its high thermal stability and low diffusivity that inhibit the uncontrolled formation of thiolate and sulfide deposits that are found on unpassivated steels. Instead, alumina modifies the surface reaction to a self-limiting chemisorption and oxidation process that produces thin sulfate deposits at the surface. With further consideration to the reactive species present in solution, the findings of this study may be extended to determine suitable surface conditions that mitigate asphaltene fouling.

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Section: Introductionmentioning

confidence: 99%

Effect of Surface Chemistry and Roughness on the High-Temperature Deposition of a Model Asphaltene

et al. 2019

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“…The exceptionally low tolerance for defects in the corundum structure (common to both alumina and chromia) means that bulk diffusion through the oxide is limited. 17,18 It also means that oxide nucleation and growth is slow; therefore, high temperatures are required to develop quality a-alumina and suppress the formation of faster growing metastable polymorphs. 19,20 Increasing the aluminum or chromium concentration in an alloy 14,21,22 or reducing the oxygen partial pressure (P O 2 ) 23,24 has also been proven effective in promoting the formation of protective oxides.…”

Section: Introductionmentioning

confidence: 99%