Thermal conductivity/diffusivity of SiC-Mullite and SiC-SiC composites

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dc.contributor.authorRussell, Laura M.en
dc.contributor.committeechairHasselman, D. P. H.en
dc.contributor.committeememberForkner, H. R.en
dc.contributor.committeememberThomas, James R. Jr.en
dc.contributor.departmentMaterials Engineeringen
dc.date.accessioned2014-03-14T21:28:48Zen
dc.date.adate2013-02-07en
dc.date.available2014-03-14T21:28:48Zen
dc.date.issued1987-09-15en
dc.date.rdate2013-02-07en
dc.date.sdate2013-02-07en
dc.description.abstractThe purposes of this study were to determine as a function of temperature the thermal diffusivity and/or thermal conductivity of SiC-Mullite and SiC-SiC, and to explain the observed behavior in terms of changes in temperature, microstructure, composition, and/or orientation. Materials used in the SiC-Mullite study consisted of single crystal SiC whiskers (prepared from rice hulls or by the vapor-liquid-solid process) dispersed within a polycrystalline mullite matrix. During measurement of thermal diffusivity, the samples were heated to l500°C and cooled back to room temperature. No hysteresis occurred. However, both thermal diffusivity and conductivity exhibited maximum values at room temperatures, perpendicular to the hot pressing direction, at high volume percentages of SiC whiskers, and when VLS whiskers were employed. The SiC-SiC samples consisted of a crossweave of polycrystalline SiC fibers that were coated with phenolic resin and surrounded by a chemically-vapor-deposited matrix of SiC. The two types of samples examined were prepared with different amounts of resin. The matrices of the high resin samples were found to be dominated by the presence of char. Samples were cycled to 1000, 1400, and l800°C; hysteresis occurred on some of the cycles. Thermal diffusivity was highest parallel to one set of fibers. These results allow the qualitative tailoring of the heat flow properties of these ceramic composites, for particular applications, and set forth limitations on the use of the SiC-SiC composites at high temperatures.en
dc.description.degreeMaster of Scienceen
dc.format.extentix, 61 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-02072013-040116en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-02072013-040116/en
dc.identifier.urihttp://hdl.handle.net/10919/40981en
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1987.R877.pdfen
dc.relation.isformatofOCLC# 17541828en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1987.R877en
dc.subject.lcshCeramicsen
dc.subject.lcshMulliteen
dc.subject.lcshThermal diffusivityen
dc.titleThermal conductivity/diffusivity of SiC-Mullite and SiC-SiC compositesen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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