Formation and growth of protective alumina scales

Chevalier, Sébastien

doi:10.1533/9781845694258.2.290

Cited by 13 publications

(4 citation statements)

References 219 publications

(239 reference statements)

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“…Such a thermally grown oxide (TGO) scale can provide excellent oxidation resistance for high‐temperature structural alloys in oxidizing environments, and understanding the factors that impart oxidation resistance has been an active area of research for decades. Recent reviews on Al 2 O 3 scale formation include those by Stott, 1,2 Chevalier, 3 Jedlinski and Borchardt, 4 Prescott and Graham, 5 Pint and Alexander, 6 and Hou 7 …”

Section: Introductionmentioning

confidence: 99%

Alumina Scale Formation: A New Perspective

et al. 2011

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Oxidation of Al2O3 scale‐forming alloys is of immense technological significance and has been a subject of much scientific inquiry for decades. The oxidation reaction is remarkably complex, involving issues of alloy composition, kinetics, thermodynamics, microstructure, mechanics and mechanical properties, crystallography, etc. A brief overview of the formation of passivating, thermally grown oxide Al2O3 scales will be given in the light of recent findings on the defect structure and associated transport behavior of α‐Al2O3. It is inferred that the electronic structure of Al2O3 is of direct relevance to understand the Al2O3 scale growth. We also discuss the effect of the so‐called “reactive” elements (REs)—Y, Zr, and Hf—on reducing the rate of Al2O3 scale thickening by reducing the outward flux of aluminum. An important aspect of the “new perspective” is the suggestion that the REs change the electronic structure of Al2O3—the relevant near‐band‐edge defect (grain boundary) states that are crucial to vacancy creation both at the scale/gas and scale/metal interfaces.

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Section: Introductionmentioning

confidence: 99%

Alumina Scale Formation: A New Perspective

et al. 2011

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“…In the alloy, peaks corresponding to θ -Al 2 O 3 have been identified. θ -Al 2 O 3 is a metastable alumina phase [ 64 , 65 ]. θ -Al 2 O 3 structures are based on a cubic close packing of oxygen anions.…”

Section: Resultsmentioning

confidence: 99%

“…θ -Al 2 O 3 is a transition phase. It transforms into stable forms of alumina during long term annealing [ 65 ]. Metastable θ -Al 2 O 3 has been found in oxidized Al-Cu-Fe alloys studied previously [ 66 ].…”

Section: Resultsmentioning

confidence: 99%

Oxidation of Al-Co Alloys at High Temperatures

et al. 2020

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In this work, the high temperature oxidation behavior of Al71Co29 and Al76Co24 alloys (concentration in at.%) is presented. The alloys were prepared by controlled arc-melting of Co and Al granules in high purity argon. The as-solidified alloys were found to consist of several different phases, including structurally complex m-Al13Co4 and Z-Al3Co phases. The high temperature oxidation behavior of the alloys was studied by simultaneous thermal analysis in flowing synthetic air at 773–1173 K. A protective Al2O3 scale was formed on the sample surface. A parabolic rate law was observed. The rate constants of the alloys have been found between 1.63 × 10−14 and 8.83 × 10−12 g cm−4 s−1. The experimental activation energies of oxidation are 90 and 123 kJ mol−1 for the Al71Co29 and Al76Co24 alloys, respectively. The oxidation mechanism of the Al-Co alloys is discussed and implications towards practical applications of these alloys at high temperatures are provided.

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“…oxide layer [16][17][18][19][20]. As transport mechanisms across this scale are typically slow, this oxide prevents the inward-diffusion of gaseous impurities and the outward-diffusion of other alloy components due to its slow growth [21,22].…”

Section: Surface Morphology Of Wc-10co-4cr Cermet Coatings Before And...mentioning

confidence: 99%

Study on Microstructure and Cyclic Oxidation Behaviour of WC–CoCr Cermet-Based Plasma-Sprayed Coatings Developed on the Austenite Steel

Alam

Das

2023

High Temperature Corrosion of mater.

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This article studies the cyclic oxidation behavior of WC-10Co-4Cr powder coatings obtained by plasma spraying on AISI316L austenitic stainless steel in an ambient air at 850°C for 50 cycles. Weight change observations of coated samples have been used to establish the oxidation kinetics, and the outcomes for the uncoated and coated specimens were compared. Utilizing scanning electron microscopy (SEM) and X-ray diffraction (XRD) the coating's microstructure has been identi ed before and after oxidation. XRD, SEM and energy dispersive spectroscopy (EDS) were utilized to analyse the scales surface-morphology of coated austenite steel samples following the oxidation cycle. The uncoated AISI 316L Steel had severe spalling, peeling-off, and sputtering from its oxide scale. Additionally, the scale is rich in Fe 2 O 3 , which contributed to the large weight gain. The ndings showed that coatings outperform uncoated materials in terms of oxidation resistance. The coating lowered the weight gain of austenite 316 steel by 84.34%. It was discovered that the protective WO 3 and Cr 2 O 3 phase generated on the oxide scale provided higher oxidation resistance.

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Formation and growth of protective alumina scales

Cited by 13 publications

References 219 publications

Alumina Scale Formation: A New Perspective

Alumina Scale Formation: A New Perspective

Oxidation of Al-Co Alloys at High Temperatures

Study on Microstructure and Cyclic Oxidation Behaviour of WC–CoCr Cermet-Based Plasma-Sprayed Coatings Developed on the Austenite Steel

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