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Full-Text Articles in Engineering
Steam Oxidation Of Ytterbium Disilicate Environmental Barrier Coatings With And Without A Silicon Bond Coat, Ken A. Kane, Eugenio Garcia, Sharon Uwanyuze, Michael Lance, Kinga A. Unocic, Sanjay Sampath, Bruce A. Pint
Steam Oxidation Of Ytterbium Disilicate Environmental Barrier Coatings With And Without A Silicon Bond Coat, Ken A. Kane, Eugenio Garcia, Sharon Uwanyuze, Michael Lance, Kinga A. Unocic, Sanjay Sampath, Bruce A. Pint
Materials Science and Engineering Faculty Research & Creative Works
The current generation of multilayer Si/Yb2Si2O7 environmental barrier coatings (EBCs) are temperature limited by the melting point of Si, 1414°C. To investigate higher temperature EBCs, the cyclic steam oxidation of EBCs comprised of a single layer of ytterbium disilicate (YbDS) was compared to multilayered Si/YbDS EBCs, both deposited on SiC substrates using atmospheric plasma spray. After 500 1-h cycles at 1300°C in 90 vol%H2O-10 vol%air with a gas velocity of 1.5 cm/s, both multilayer Si/YbDS and single layer YbDS grew thinner silica scales than bare SiC, with the single layer YbDS forming the …
Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh
Mixed Electron Emission From Lead Zirconate-Titanate Ceramics, Weiming Zhang, Wayne Huebner, Stephen E. Sampayan, Mike L. Krogh
Materials Science and Engineering Faculty Research & Creative Works
Simultaneous ferroelectric and plasma emission from Pb(Zr,Ti)O3 was observed with only a negative driving pulse applied to the sample, and without an extraction potential on the electron collector. Plasma emission was a strong, inconsistent, and self-destructive process. In addition, a positive ion current was detected. Comparatively, ferroelectric emission was a relatively stable self-emission process, exhibiting no apparent delay time, and no positive ion current. The relationship between the switching and emission current of ferroelectric samples measured simultaneously cannot only be used to determine the existence of ferroelectric emission, but can also give direction to choosing suitable ferroelectric materials for …