Calcium–magnesium–aluminosilicate corrosion behaviors of rare-earth disilicates at 1400°C

Liu, Jia; Zhang, Litong; Liu, Qiaomu; Cheng, Laifei; Wang, Yiguang

doi:10.1016/j.jeurceramsoc.2013.05.030

Cited by 115 publications

(49 citation statements)

References 26 publications

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“…Reactions of molten silicate deposits with RE monosilicates and disilicates exhibit significant similarities and differences. Disilicates frequently react with the deposits to form apatite, nominally of composition Ca 2 RE 8 (SiO 4 ) 6 O 2 .…”

Section: Introductionmentioning

confidence: 99%

“…In many cases, the reaction processes are sensitive to deposit composition, making the problem even more challenging to address. 9,15,16 Reactions of molten silicate deposits with RE monosilicates [17][18][19][20] and disilicates 16,[19][20][21][22][23][24][25][26] exhibit significant similarities and differences. Disilicates frequently react with the deposits to form apatite, nominally of composition Ca 2 RE 8 (SiO 4 ) 6 O 2 .…”

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: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reactions of molten silicate deposits with yttrium monosilicate

et al. 2020

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“…Siliceous debris ingested into aero‐engines produces molten deposits of calcium‐magnesium‐aluminosilicate (CMAS) glass. CMAS reacts with candidate EBC materials to form non‐protective phases . Because of mismatch in the thermal expansion coefficients of these phases relative to the underlying composite, both the deposits and the reaction products may crack upon cooling.…”

Section: Introductionmentioning

confidence: 99%

“…CMAS reacts with candidate EBC materials to form non-protective phases. [14][15][16][17][18][19][20][21][22] Because of mismatch in the thermal expansion coefficients of these phases relative to the underlying composite, both the deposits and the reaction products may crack upon cooling. Cracks can compromise the efficacy of the coating or lead to coating spallation during thermal cycling.…”

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confidence: 99%

Degradation of a SiC‐SiC composite in water vapor environments

et al. 2019

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The article examines degradation of a SiC‐based fiber composite containing Tyranno ZMI fibers in water vapor at elevated temperatures (800°C and 1100°C). Degradation is characterized through mechanical tests under cyclic and quasi‐static tensile loading in the near‐threshold regime, at stresses at or slightly above the matrix cracking limit. These tests are augmented by examinations of fracture surfaces and polished cross‐sections, measurements of fracture mirror radii, and measurements of interfacial debond toughness and sliding resistance. Degradation involves highly localized consumption of fibers through reactions of water vapor with the fibers and the BN coatings in regions adjacent to the few matrix cracks present at low stresses; the global hysteresis response and the average interfacial properties are minimally affected. Boria formed by oxidation of BN appears to play a fluxing role; it combines with silica on the fibers to form a non‐protective molten glass. Inhomogeneous fiber consumption leads to stress concentrations in the fibers and hence reduced fiber strength. Spatial variations in the degradation process occur at two length scales: at the macroscopic scale, because of cracking of the external CVI SiC overcoat and subsequent water ingress through the cracks, and at the tow‐scale, because of cracking of the CVI SiC around the tows. Parsing the kinetic processes over the two length scales remains a significant challenge.

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“…[15][16][17][18][19] Previously, most research has focused on the EBCs themselves only: studying their water vapor resistance, [9][10][11][12][15][16][17] fabrication process, 14,18,19 and hot corrosion behavior. 13,20,21 Very few works considered the failure behaviors of the entire system contained both the substrate and the EBCs. Although Kimmel et al 22 revealed that the spallation of the EBCs was one of the dominant factors that resulted in the failure of the composites with the EBCs, the spallation mechanism of the EBCs is yet clear to date.…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanism Associated with the Thermally Grown Silica Scale in Environmental Barrier Coated C/SiC Composites

Luo

Liu

et al. 2016

J. Am. Ceram. Soc.

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The barium strontium aluminosilicate and Y2Si2O7‐BSAS‐coated C/SiC composites were corroded in 50%H2O–50%O2 environments at 1250°C, respectively. It was found that the coated composites suddenly lost their strength as the corrosion time was up to 250 and 750 h, respectively. During the water vapor corrosion, a continuous silica scale was formed between the SiC bond coat and environmental barrier coatings, leading to the growth stress. The thickness of silica scale grew with the prolonged corrosion time, accompanied with the accumulation of growth stress in the silica scale. When the growth stress was greater than the bond strength between silica scale and SiC bond coat, the cracks would form and propagate along their interface, resulting in the spallation of EBCs, followed by the failure of the composites.

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Calcium–magnesium–aluminosilicate corrosion behaviors of rare-earth disilicates at 1400°C

Cited by 115 publications

References 26 publications

Reactions of molten silicate deposits with yttrium monosilicate

Reactions of molten silicate deposits with yttrium monosilicate

Degradation of a SiC‐SiC composite in water vapor environments

Failure Mechanism Associated with the Thermally Grown Silica Scale in Environmental Barrier Coated C/SiC Composites

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