About this Abstract |
| Meeting |
MS&T25: Materials Science & Technology
|
| Symposium
|
Engineering Ceramics: Microstructure-Property-Performance Relations and Applications
|
| Presentation Title |
Mechanistic effect of ytterbium monosilicate on the microstructural evolution of ytterbium disilicate coatings in extreme environments |
| Author(s) |
Ebenezer B. Owusu, Acacio Rincόn Romero, Oriol Gavalda-Diaz, K. T. Voisey |
| On-Site Speaker (Planned) |
Ebenezer B. Owusu |
| Abstract Scope |
Ytterbium disilicate's (YbDS) properties like coefficient of thermal expansion (3.2 – 4.5 x 10-6 °C-1) which matches silicon-carbide ceramic-matrix-composite’s (4.5-5.5 x 10-6 °C-1) make it promising for manufacturing environmental barrier coatings. However, the performance of YbDS against steam and molten calcium-magnesium-alumininium-silicate (CMAS) degradation falls short of ytterbium monosilicate’s (YbMS). Engineering YbDS with certain quantity of YbMS may enhance the performance. In this research, atmospheric plasma-sprayed YbDS coatings with YbMS contents of 3 wt. % (S1), 14 wt. % (S2) and 85 wt. % (S3) were exposed to combined 1 m/s velocity-steam and 5 mg/cm-2 CMAS for 96 h at 1350 °C. Microstructure of S1 showed dispersed apatite phases, whereas S2 and S3 formed dense apatite layers that retarded CMAS infiltration, however, vertical cracks formed in the apatite layer of S3 after the exposure. Tailoring YbDS coatings to have YbMS content of about 14 wt. % could improve its corrosion resistance. |