Phase equilibria in the calcia-gadolinia-silica system

David L. Poerschke; Carlos G. Levi

doi:10.1016/j.jallcom.2016.10.263

Phase equilibria in the calcia-gadolinia-silica system

David L. Poerschke, Carlos G. Levi

Chemical Engineering and Materials Science

Research output: Contribution to journal › Article › peer-review

27 Scopus citations

Abstract

The phase equilibria in the CaO-Gd₂O₃-SiO₂system were investigated by heat treating precursor-derived powders at 1400 °C and 1600 °C, determining the resulting phase assemblages, and measuring the compositions of the liquid and solid solution phases. The stable ternary phases at 1400 °C include silico-carnotite (Ca₃Gd₂Si₃O₁₂), Ca/Gd-cyclosilicate (Ca₃Gd₂Si₆O₂₆), and the apatite solid solution field extending from Gd_9.33(SiO₄)₆O₂to Ca_2.75Gd_7.25(SiO₄)₆O_1.625. Of these, only apatite remains stable to 1600 °C. The high-temperature α- and α′-Ca₂SiO₄polymorphs exhibit moderate Gd₂O₃solubility. The results are compared to the equilibria for the related CaO-Y₂O₃-SiO₂system. The implications for understanding the interaction between rare earth containing thermal barrier coatings (TBCs) and silicate deposits (CMAS) are discussed.

Original language	English (US)
Pages (from-to)	1397-1404
Number of pages	8
Journal	Journal of Alloys and Compounds
Volume	695
DOIs	https://doi.org/10.1016/j.jallcom.2016.10.263
State	Published - 2017

Bibliographical note

Funding Information:
Research supported by ONR grant N00014-16-1-2702 and NAVAIR STTR Phase II N00014-12-M-0340, both monitored by Dr. David Shifler. The work made use of the MRL Shared Experimental Facilities supported by the MRSEC Program of the NSF under Award No. DMR 1121053; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). The funding agencies were not involved in the study design, the collection, analysis and interpretation of the data, or the decision to publish. The authors are grateful to G.G.E. Seward (UCSB) for assistance with EPMA analysis, A. Velasco-Hogan and S. Molakalapalli (UCSB) for assistance with specimen preparation, and W. Zhang and N. Hatcher (QuesTek Innovations) for discussions regarding their thermodynamic assessment of the CGS system.

Publisher Copyright:
© 2016 Elsevier B.V.

Keywords

Apatite
Ceramics
Phase diagrams
Rare earth compounds
Silicates

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10.1016/j.jallcom.2016.10.263

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@article{bebbfd851108415c80cf8c01783691db,

title = "Phase equilibria in the calcia-gadolinia-silica system",

abstract = "The phase equilibria in the CaO-Gd2O3-SiO2system were investigated by heat treating precursor-derived powders at 1400 °C and 1600 °C, determining the resulting phase assemblages, and measuring the compositions of the liquid and solid solution phases. The stable ternary phases at 1400 °C include silico-carnotite (Ca3Gd2Si3O12), Ca/Gd-cyclosilicate (Ca3Gd2Si6O26), and the apatite solid solution field extending from Gd9.33(SiO4)6O2to Ca2.75Gd7.25(SiO4)6O1.625. Of these, only apatite remains stable to 1600 °C. The high-temperature α- and α′-Ca2SiO4polymorphs exhibit moderate Gd2O3solubility. The results are compared to the equilibria for the related CaO-Y2O3-SiO2system. The implications for understanding the interaction between rare earth containing thermal barrier coatings (TBCs) and silicate deposits (CMAS) are discussed.",

keywords = "Apatite, Ceramics, Phase diagrams, Rare earth compounds, Silicates",

author = "Poerschke, {David L.} and Levi, {Carlos G.}",

note = "Funding Information: Research supported by ONR grant N00014-16-1-2702 and NAVAIR STTR Phase II N00014-12-M-0340, both monitored by Dr. David Shifler. The work made use of the MRL Shared Experimental Facilities supported by the MRSEC Program of the NSF under Award No. DMR 1121053; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). The funding agencies were not involved in the study design, the collection, analysis and interpretation of the data, or the decision to publish. The authors are grateful to G.G.E. Seward (UCSB) for assistance with EPMA analysis, A. Velasco-Hogan and S. Molakalapalli (UCSB) for assistance with specimen preparation, and W. Zhang and N. Hatcher (QuesTek Innovations) for discussions regarding their thermodynamic assessment of the CGS system. Publisher Copyright: {\textcopyright} 2016 Elsevier B.V.",

year = "2017",

doi = "10.1016/j.jallcom.2016.10.263",

language = "English (US)",

volume = "695",

pages = "1397--1404",

journal = "Journal of Alloys and Compounds",

issn = "0925-8388",

publisher = "Elsevier BV",

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TY - JOUR

T1 - Phase equilibria in the calcia-gadolinia-silica system

AU - Poerschke, David L.

AU - Levi, Carlos G.

N1 - Funding Information: Research supported by ONR grant N00014-16-1-2702 and NAVAIR STTR Phase II N00014-12-M-0340, both monitored by Dr. David Shifler. The work made use of the MRL Shared Experimental Facilities supported by the MRSEC Program of the NSF under Award No. DMR 1121053; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). The funding agencies were not involved in the study design, the collection, analysis and interpretation of the data, or the decision to publish. The authors are grateful to G.G.E. Seward (UCSB) for assistance with EPMA analysis, A. Velasco-Hogan and S. Molakalapalli (UCSB) for assistance with specimen preparation, and W. Zhang and N. Hatcher (QuesTek Innovations) for discussions regarding their thermodynamic assessment of the CGS system. Publisher Copyright: © 2016 Elsevier B.V.

PY - 2017

Y1 - 2017

N2 - The phase equilibria in the CaO-Gd2O3-SiO2system were investigated by heat treating precursor-derived powders at 1400 °C and 1600 °C, determining the resulting phase assemblages, and measuring the compositions of the liquid and solid solution phases. The stable ternary phases at 1400 °C include silico-carnotite (Ca3Gd2Si3O12), Ca/Gd-cyclosilicate (Ca3Gd2Si6O26), and the apatite solid solution field extending from Gd9.33(SiO4)6O2to Ca2.75Gd7.25(SiO4)6O1.625. Of these, only apatite remains stable to 1600 °C. The high-temperature α- and α′-Ca2SiO4polymorphs exhibit moderate Gd2O3solubility. The results are compared to the equilibria for the related CaO-Y2O3-SiO2system. The implications for understanding the interaction between rare earth containing thermal barrier coatings (TBCs) and silicate deposits (CMAS) are discussed.

AB - The phase equilibria in the CaO-Gd2O3-SiO2system were investigated by heat treating precursor-derived powders at 1400 °C and 1600 °C, determining the resulting phase assemblages, and measuring the compositions of the liquid and solid solution phases. The stable ternary phases at 1400 °C include silico-carnotite (Ca3Gd2Si3O12), Ca/Gd-cyclosilicate (Ca3Gd2Si6O26), and the apatite solid solution field extending from Gd9.33(SiO4)6O2to Ca2.75Gd7.25(SiO4)6O1.625. Of these, only apatite remains stable to 1600 °C. The high-temperature α- and α′-Ca2SiO4polymorphs exhibit moderate Gd2O3solubility. The results are compared to the equilibria for the related CaO-Y2O3-SiO2system. The implications for understanding the interaction between rare earth containing thermal barrier coatings (TBCs) and silicate deposits (CMAS) are discussed.

KW - Apatite

KW - Ceramics

KW - Phase diagrams

KW - Rare earth compounds

KW - Silicates

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U2 - 10.1016/j.jallcom.2016.10.263

DO - 10.1016/j.jallcom.2016.10.263

M3 - Article

AN - SCOPUS:85006154578

SN - 0925-8388

VL - 695

SP - 1397

EP - 1404

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

ER -

Phase equilibria in the calcia-gadolinia-silica system

Abstract

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Keywords

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