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Thermodynamics and Kinetics of Silicate VaporizationSilicates are a common class of materials that are often exposed to high temperatures. The behavior of these materials needs to be understood for applications as high temperature coatings in material science as well as the constituents of lava for geological considerations. The vaporization behavior of these materials is an important aspect of their high temperature behavior and it also provides fundamental thermodynamic data. The application of Knudsen effusion mass spectrometry (KEMS) to silicates is discussed. There are several special considerations for silicates. The first is selection of an appropriate cell material, which is either nearly inert or has well-understood interactions with the silicate. The second consideration is proper measurement of the low vapor pressures. This can be circumvented by using a reducing agent to boost the vapor pressure without changing the solid composition or by working at very high temperatures. The third consideration deals with kinetic barriers to vaporization. The measurement of these barriers, as encompassed in a vaporization coefficient, is discussed. Current measured data of rare earth silicates for high temperature coating applications are discussed. In addition, data on magnesium-iron-silicates (olivine) are presented and discussed.
Document ID
20150023065
Acquisition Source
Glenn Research Center
Document Type
Presentation
Authors
Jacobson, Nathan S.
(NASA Glenn Research Center Cleveland, OH United States)
Costa, Gustavo C. C.
(Institute for Energy Analysis Oak Ridge, TN, United States)
Date Acquired
December 15, 2015
Publication Date
October 7, 2015
Subject Category
Chemistry And Materials (General)
Fluid Mechanics And Thermodynamics
Report/Patent Number
GRC-E-DAA-TN26999
Meeting Information
Meeting: Materials Science and Technology 2015 (MS&T15)
Location: Columbus, OH
Country: United States
Start Date: October 4, 2015
End Date: October 8, 2015
Sponsors: American Ceramic Society
Funding Number(s)
WBS: WBS 109492.02.03.02.02.02
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
thermodynamics
high temperature coatings
vaporization
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