Oxidation of Cr2AlC coatings in the temperature range of 1230 to 1410°C

Hajas, D.; Baben, Moritz to; Hallstedt, Bengt; Iskandar, Riza; Mayer, J.; Schneider, Jochen M.

doi:10.1016/j.surfcoat.2011.03.086

Cited by 88 publications

(43 citation statements)

References 41 publications

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“…Another study examined scales formed on sputter coatings of Cr 2 AlC during oxidation at 1230-1410°C for various times [18]. TGA (thermo-gravimetric analyses) revealed near-parabolic kinetics, and grain structure was revealed by means of FIB-XTEM (focused ion beam, cross sectional transmission electron microscopy).…”

Section: Resultsmentioning

confidence: 99%

Oxygen diffusivity in alumina scales grown on Al-MAX phases

Smialek

2015

Corrosion Science

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a b s t r a c t Ti 3 AlC 2 , Ti 2 AlC, and Cr 2 AlC are oxidation resistant MAX phase compounds distinguished by the formation of protective Al 2 O 3 scales with well controlled kinetics. A modified Wagner treatment was used to calculate interfacial grain boundary diffusivity from scale growth rates and corresponding interfacial grain size, based on the pressure dependence of oxygen vacancies and diffusivity. MAX phase data from the literature yielded grain boundary diffusivity nearly coincident with that for Zr-doped FeCrAl (and many other FeCrAl alloys), suggesting similar oxidation mechanisms. The consolidated body of diffusivity data was consistent with an activation energy of 375 ± 25 kJ/mol.Published by Elsevier Ltd.

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Section: Resultsmentioning

confidence: 99%

Oxygen diffusivity in alumina scales grown on Al-MAX phases

Smialek

2015

Corrosion Science

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“…Using the scale thickening (Table II) and grain coarsening data (Fig. 6a) 3,[9][10][11]34,35 Thus, it is likely that oxygen grain boundary diffusivity is also the rate controlling mechanism for the formation of Al 2 O 3 scales on MoAlB.…”

Section: -33 B) Evidence For Bubble Formation And/or Oxide Bucklingmentioning

confidence: 99%

Isothermal and Cyclic Oxidation of MoAlB in Air from 1100°C to 1400°C

Kota

Zapata-Solvas

Chen

et al. 2017

J. Electrochem. Soc.

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Like many FeCrAl-based alloys, and some MAX phases, the atomically laminated boride, MoAlB, forms slow-growing, adherent Al 2 O 3 scales when heated in air to 1350 • C. Herein the oxidation of MoAlB ceramics in air was studied in the 1100-1400 • C temperature range for up to 200 h. At 1400 • C, the oxide scale was heavily cracked and spalled. At 1100 • C, and up to 20 h, mass loss was recorded. At 1300 • C and 1350 • C, subparabolic, approximately cubic kinetics were observed, as a result of growth and coarsening of the Al 2 O 3 grains in the oxide scale. At 1200 • C, the weight gain kinetics were nearly linear, while the oxide thickening kinetics were approximately cubic likely due to cubic growth of Al 2 O 3 and concurrent volatility of constituents in the oxide scale. The cyclic oxidation resistance was also good for up to 125, 1-hour, cycles at 1200 • C. Analysis of grain coarsening and scale thickening kinetics suggest that oxygen grain boundary diffusivity is the rate controlling mechanism for the growth of Al 2 O 3 scales at 1300 • C and 1350 • C. Dimensional changes at samples' corners after long oxidation at T > 1200 • C may limit the maximum operational temperature of MoAlB.

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“…Cr 2 AlC, compared to the commonly discussed Ti 2 AlC and V 2 AlC, has a higher bulk modulus of 36% and 17%, respectively 20 , and superior performance for self-healing applications 21 . Therefore, it is chosen as a model MAX phase system in this investigation.…”

Section: Introductionmentioning

confidence: 98%

Nanometre-scale 3D defects in Cr2AlC thin films

Chen

Mušić

Shang

et al. 2017

Sci Rep

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MAX-phase Cr2AlC containing thin films were synthesized by magnetron sputtering in an industrial system. Nanometre-scale 3D defects are observed near the boundary between regions of Cr2AlC and of the disordered solid solution (CrAl)xCy. Shrinkage of the Cr-Cr interplanar distance and elongation of the Cr-Al distance in the vicinity of the defects are detected using transmission electron microscopy. The here observed deformation surrounding the defects was described using density functional theory by comparing the DOS of bulk Cr2AlC with the DOS of a strained and unstrained Cr2AlC(0001) surface. From the partial density of states analysis, it can be learned that Cr-C bonds are stronger than Cr-Al bonds in bulk Cr2AlC. Upon Cr2AlC(0001) surface formation, both bonds are weakened. While the Cr-C bonds recover their bulk strength as Cr2AlC(0001) is strained, the Cr-Al bonds experience only a partial recovery, still being weaker than their bulk counterparts. Hence, the strain induced bond strengthening in Cr2AlC(0001) is larger for Cr d – C p bonds than for Cr d – Al p bonds. The here observed changes in bonding due to the formation of a strained surface are consistent with the experimentally observed elongation of the Cr-Al distance in the vicinity of nm-scale 3D defects in Cr2AlC thin films.

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Oxidation of Cr2AlC coatings in the temperature range of 1230 to 1410°C

Cited by 88 publications

References 41 publications

Oxygen diffusivity in alumina scales grown on Al-MAX phases

Oxygen diffusivity in alumina scales grown on Al-MAX phases

Isothermal and Cyclic Oxidation of MoAlB in Air from 1100°C to 1400°C

Nanometre-scale 3D defects in Cr2AlC thin films

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