Effect of interfacial thermal conductance and fiber orientation on the thermal diffusivity/conductivity of unidirectional fiber-reinforced ceramic matrix composites

Simple item page
dc.contributor.authorBhatt, Hemanshu D.en
dc.contributor.committeechairHasselman, D. P. H.en
dc.contributor.committeememberThomas, James R. Jr.en
dc.contributor.committeememberDesu, Seshu B.en
dc.contributor.committeememberEiss, Norman S. Jr.en
dc.contributor.committeememberStinchcomb, Wayne W.en
dc.contributor.departmentMaterials Engineering Scienceen
dc.date.accessioned2014-03-14T21:16:37Zen
dc.date.adate2008-07-28en
dc.date.available2014-03-14T21:16:37Zen
dc.date.issued1992-02-06en
dc.date.rdate2008-07-28en
dc.date.sdate2008-07-28en
dc.description.abstractThe role of an interfacial barrier at the fiber-matrix interface in the heat conduction behavior of an uniaxial silicon carbide fiber-reinforced reaction-bonded silicon nitride and the effect of fiber orientation on the heat conduction characteristics of carbon fiber-reinforced borosilicate glass was investigated. In the study of the effect of an interfacial thermal barrier, a composite with fibers having a carbon-rich coating of about 3 J.l m was chosen as the reference material. The fiber-matrix interface was then modified by preferential oxidation of the carbon coating on the fibers, using fibers with no carbon coating and using hotisostatic-pressing (HIP) after nitridation. The formation of an interfacial gap at the interface due to thermal expansion mismatch between the fiber and the matrix in reference and HIP'd composites, and removal of carbon coating for oxidized composites, resulted in the dependence of thermal diffusivity/conductivity on the surrounding . atmosphere. This effect was attributed to gaseous heat transfer at the interface. However, no atmospheric effects were observed for composites with fibers without the carbon coating due to very strong bonding between the fiber and the matrix. HIP'ing increased the thermal diffusivity/conductivity of the composites due to densification of the matrix, crystallization of the fibers and increased physical contact at the interface. Removal of the interfacial carbon layer by preferential oxidation lowered the interfacial conductance considerably, due to decrease in the direct thermal contact between the fibers and the matrix. Interfacial contact conductance determined from measurements made in vacuum for reference and HIP'd composites increased rapidly with increasing temperature in accordance with interfacial gap closure. These observations indicate that the heat conduction behavior of all the composites investigated was strongly affected by the existence of an interfacial thermal barrier, for heat transfer transverse to the fiber direction.en
dc.description.degreePh. D.en
dc.format.extentxi, 146 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-07282008-135034en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07282008-135034/en
dc.identifier.urihttp://hdl.handle.net/10919/38928en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1992.B427.pdfen
dc.relation.isformatofOCLC# 25734498en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1992.B427en
dc.subject.lcshCeramic fibers -- Thermal propertiesen
dc.subject.lcshCeramic-matrix composites -- Mathematical modelsen
dc.subject.lcshFiber-reinforced ceramics -- Thermal propertiesen
dc.titleEffect of interfacial thermal conductance and fiber orientation on the thermal diffusivity/conductivity of unidirectional fiber-reinforced ceramic matrix compositesen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Engineering Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
LD5655.V856_1992.B427.pdf
Size:
18.37 MB
Format:
Adobe Portable Document Format
Download

Collections

Doctoral Dissertations