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Freeze Casting of Aqueous PAA-Stabilized Carbon Nanotube-Al2O3 Suspensions

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dc.contributor.authorKessler, Christopher S.en
dc.contributor.committeechairLu, P. Kathyen
dc.contributor.committeememberClark, David E.en
dc.contributor.committeememberLogan, Kathryn V.en
dc.contributor.departmentMaterials Science and Engineeringen
dc.date.accessioned2014-03-14T21:42:07Zen
dc.date.adate2006-10-02en
dc.date.available2014-03-14T21:42:07Zen
dc.date.issued2006-07-07en
dc.date.rdate2009-10-02en
dc.date.sdate2006-08-04en
dc.description.abstractFreeze casting is a colloidal processing technique that shows great promise for development of nanostructured materials. A ceramic nanopowder is dispersed with a polymer in water, under carefully controlled pH. The suspension is cast into a suitable mold and frozen, then de-molded and exposed to a vacuum to sublimate and remove the water. Polymer adsorption and rheology were studied to optimize and characterize a colloidal suspension of a 38 nm Al2O3 powder. The dispersant, dispersant amount, pH and solids loading were examined to determine the best conditions for freeze casting. Based on adsorption and viscosity data, optimal conditions for freeze casting were found with Poly(acrylic acid) (PAA) dispersant, at 2.00 wt% (of Al2O3), pH of 9.5, and a solids loading of 40 vol%. Carbon nanotubes (CNTs) were added to that suspension in increments of 0.14, 0.28, 0.53, 1.30 and 2.60 vol%. The viscosity increased dramatically upon addition of 1.30 vol% CNTs. The colloidal CNT-Al2O3 suspension was successfully freeze cast and the microstructure showed a very smooth fracture surface. It was determined that upon resting, the suspension undergoes a physical change which must be completed to obtain advantageous microstructure. Freeze cast Al2O3 discs with and without CNTs were measured using a concentric ring test, with strengths on the order of one MPa. The freeze cast sample was successfully debinded, but the heating profile attempted was not effective in obtaining full density.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-08042006-101646en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08042006-101646/en
dc.identifier.urihttp://hdl.handle.net/10919/44137en
dc.publisherVirginia Techen
dc.relation.haspartCKesslerThesis2.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectcarbon nanotubesen
dc.subjectdispersionen
dc.subjectrheologyen
dc.subjectdispersanten
dc.subjectPAAen
dc.subjectPMAAen
dc.subjectadsorptionen
dc.subjectnanopowderen
dc.subjectfreeze castingen
dc.subjectcolloidalen
dc.subjectnanoen
dc.titleFreeze Casting of Aqueous PAA-Stabilized Carbon Nanotube-Al2O3 Suspensionsen
dc.typeThesisen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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