Roles of composition and temperature in silicate deposit-induced recession of yttrium disilicate

William D. Summers, David L. Poerschke, Daesung Park, John H. Shaw, Frank W. Zok, Carlos G. Levi

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Reactions between silicate deposits and environmental barrier coatings (EBCs) for SiC/SiC composites can severely degrade coating performance. The goal of the present study is to elucidate effects of deposit composition and exposure temperature and time on the recession of yttrium disilicate (YDS), a candidate EBC material. Phase equilibrium calculations are used to predict reactions of YDS with deposits of twelve different compositions at 1300 °C and 1400 °C; experimental observations are reported for three exemplary compositions at both temperatures and compared with the thermodynamic predictions. For initial deposit thicknesses of about 100 μm, recession depths reach terminal values after exposures of about 100 h. Terminal recession depths are sensitive to deposit composition but are only weakly affected by temperature. Deposits with high initial Ca:Si ratios react most severely with YDS, forming thick layers containing apatite interpenetrated by residual melt, whereas reactions with deposits that have Ca:Si ratios below a threshold for apatite formation are more benign, albeit still significant.

Original languageEnglish (US)
Pages (from-to)34-46
Number of pages13
JournalActa Materialia
Volume160
DOIs
StatePublished - Nov 2018

Bibliographical note

Funding Information:
Research supported by Pratt & Whitney Center of Excellence in Composites at the University of California Santa Barbara. DP received support from ONR grants N00014-16-1-2702 and N00014-17-C-2034 , monitored by Dr. D.A. Shifler. The research made use of the MRL Shared Experimental Facilities, a member of the NSF-funded Materials Research Facilities Network ( www.mrfn.org ) supported by the MRSEC Program of the NSF under Award No. DMR 1121053 . The authors are grateful to Dr. T. Bhatia-Kashyap of P&W for helpful discussions.

Funding Information:
Research supported by Pratt & Whitney Center of Excellence in Composites at the University of California Santa Barbara. DP received support from ONR grants N00014-16-1-2702 and N00014-17-C-2034, monitored by Dr. D.A. Shifler. The research made use of the MRL Shared Experimental Facilities, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) supported by the MRSEC Program of the NSF under Award No. DMR 1121053. The authors are grateful to Dr. T. Bhatia-Kashyap of P&W for helpful discussions.

Publisher Copyright:
© 2018 Acta Materialia Inc.

Keywords

  • CMAS
  • Environmental barrier coatings
  • SiC/SiC composites
  • Yttrium disilicate

Fingerprint

Dive into the research topics of 'Roles of composition and temperature in silicate deposit-induced recession of yttrium disilicate'. Together they form a unique fingerprint.

Cite this