Water vapour corrosion of rare earth monosilicates for environmental barrier coating application

Nasiri, Nasrin Al; Patra, Nihar Ranjan; Jayaseelan, Daniel Doni; Lee, William

doi:10.1016/j.ceramint.2017.02.123

Cited by 81 publications

(35 citation statements)

References 15 publications

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“…However, YDS is not observed in the central regions of the deposit, where there is a larger amount of residual melt ( Figure 8B). The inference is that the reaction in the bulk of the deposit only reaches the L + Ap field (6) in Figure 9 within 250 hours, whereas that in the periphery terminated within the L + Ap+YDS field. In the context of Figure 1B and Figure 2, the depth of consumption in the bulk is lower than that needed to reduce the Ca:Si ratio of the melt below 0.23, where the onset of YDS is expected.…”

Section: Ca:si Meltmentioning

confidence: 99%

“…Disilicates are of interest because of their closely‐matched thermal expansion coefficients (CTE) with the composite and because they are in equilibrium with the SiO 2 scale that invariably forms on the underlying Si‐based bond coat. Although the volatilization resistance of disilicate coatings is superior to that of SiC, further improvements are obtained by coating the disilicate with an outer layer of an RE monosilicate because the silica activities (and thereby volatilization rate) of monosilicates are an order of magnitude lower than those of the corresponding disilicates . The monosilicates, however, exhibit significant CTE mismatch with the composite, making design of robust coatings particularly challenging.…”

Section: Introductionmentioning

confidence: 99%

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Reactions of molten silicate deposits with yttrium monosilicate

et al. 2020

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The article addresses effects of silicate deposit composition on reactions with yttrium monosilicate (YMS), a candidate environmental barrier coating for aero-engine components. Computed phase equilibria are used to predict the nature and relative proportions of reaction products and the extent of YMS consumption upon reaction with twelve deposits of varying composition at 1300°C. These predictions are compared with results of a corresponding experimental study on three exemplary deposits.Although the nature and sequence of reaction products formed (typically apatite and yttrium disilicate) depend on the Ca:Si ratio of the deposit, the degree of consumption of YMS at equilibrium is relatively insensitive to deposit composition and is predicted to proceed to a greater extent than that in yttrium disilicate. However, sluggish reaction kinetics associated with the formation of a thin apatite layer above the YMS prevents reactions from reaching their terminal equilibrium states within the experimental times investigated (250 hours). For deposit loadings of 18 mg/cm 2 (corresponding to a thickness of about 100 µm), the degree of consumption following 250 hours exposures is only about 10%-40% of the predicted terminal values, depending on deposit composition. K E Y W O R D Schemical reactions, CMAS, Environmental barrier coating, yttrium silicate 2920 | SUMMERS Et al.

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Section: Ca:si Meltmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reactions of molten silicate deposits with yttrium monosilicate

et al. 2020

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“…RE 2 SiO 5 may also decompose into RE(OH) 3 and Si(OH) 4 , as shown in Equation . Both of the reaction products are gaseous and cannot be found on the surface of the samples.…”

Section: Resultsmentioning

confidence: 99%

Robust hydrophobicity and evaporation inertness of rare‐earth monosilicates in hot steam at very high temperature

et al. 2019

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Rare‐earth oxides are intrinsically hydrophobic, and this characteristic opens new horizons for their design and diverse applications as robust hydrophobic surfaces. Here, we discover some rare‐earth (RE) monosilicates (RE2SiO5) that are hydrophobic under ambient conditions. Their hydrophobicity is positively correlated with their hot‐steam corrosion at 1400°C. RE3+ in RE2SiO5 is further found to be a hydration prohibitor, and its species can regulate hydration and volatilization at very high temperatures. These results may provide basis for innovative designs of RE silicates in harsh hot‐steam environments for robust environmental barrier coatings (EBC) or as ceramic components.

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“…10 Mullite, stabilized zirconia, mullite/stabilized zirconia composite, alumina, yttria-alumina composite, yttrium aluminum garnet, yttrium aluminate perovskite, rare earth silicates, and zirconium silicate are investigated as coating materials to resist oxidation and corrosion of SiC in water vapor containing oxidation environments. [49][50][51][52] Recently, it has been shown that Li 2 O-Al 2 O 3 -SiO 2 -based glaze resists alkali vapor corrosion. 53 These coating materials exhibit limitations despite significant success for oxidation and corrosion resistance.…”

Section: Mahapatramentioning

confidence: 99%

Review of corrosion of refractory in gaseous environment

Mahapatra

2019

Int J Applied Ceramic Tech

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Advancing high temperature technologies pushes the envelope of the service conditions to new extremes. However, corrosion of refractories substantially decreases the service life and causes unscheduled shutdown of manufacturing and processing plants. In this paper, corrosion of refractories in gaseous environments is reviewed.The corrosion mechanisms of alumina refractories, including alumino-silicates and zirconia as oxide, and silicon carbide as non-oxide refractory are emphasized due to their broad array of applications. It is shown that carbonaceous atmosphere and water vapor are detrimental for the oxide refractories. Interaction with water vapor leads to formation of the volatile species and subsequent recession of the refractories.Carbonaceous atmosphere leads to the decomposition of even mullite, which is categorized as neutral refractory due to its excellent thermochemical stability. Oxidizing atmosphere with water vapor dominates the corrosion of non-oxide refractories.Presence of impurities, even parts per million level, in the gas stream such as alkali vapor and halogens can alter the corrosion mechanisms and favor "hot corrosion."

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Water vapour corrosion of rare earth monosilicates for environmental barrier coating application

Cited by 81 publications

References 15 publications

Reactions of molten silicate deposits with yttrium monosilicate

Reactions of molten silicate deposits with yttrium monosilicate

Robust hydrophobicity and evaporation inertness of rare‐earth monosilicates in hot steam at very high temperature

Review of corrosion of refractory in gaseous environment

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