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Fabrication and characterisation of oxide fibre-reinforced glass matrix composites for optomechanical applications

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Title: Fabrication and characterisation of oxide fibre-reinforced glass matrix composites for optomechanical applications
Authors: Silva, Deborah Desimone
Item Type: Thesis or dissertation
Abstract: Stiff and strong ceramic fibres have been incorporated into brittle glass matrices in order to increase their mechanical strength and fracture toughness. In the present work, a novel processing technique has been investigated, in which the reinforcing fibres are “sandwiched” unidirectionally between glass slides and heat-treated for consolidation into composites by viscous flow of the glass matrix, filling the gaps between the reinforcing fibres. Highly dense and transparent composites were produced combining alumina (Nextel ™) or sapphire fibres with soda-lime silicate or borosilicate glasses. Their microstructural, optical and mechanical properties were investigated and compared to those of the unreinforced glass matrix processed under the same conditions. Moreover, a sol-gel technique was developed for coating the fibres with a ZrO2 interfacial layer. As-received and ZrO2 coated Nextel ™ and sapphire fibre-reinforced composites were produced, with fibre contents of up to 1 vol. % and total light transmittance in the range of 70 to 93 % of the matrix transmittance. Sapphire fibre-reinforced borosilicate glass composites exhibited the highest measured flexural strength (73 MPa), followed by ZrO2 coated Nextel ™ fibre-reinforced soda-lime silicate composites (0.6 vol. %), which exhibited mean flexural strength of 64 MPa. The introduction of a ZrO2 interfacial layer effectively increased the flexural strength of the composites compared to the unreinforced matrix and the as-received fibre-reinforced composites. In addition, there was evidence of fibre pullout and crack deflection upon failure during flexural and fracture toughness tests, as well as a fail-safe behaviour upon flexure, which enabled the composites to retain their integrity. A robust processing methodology was thus demonstrated of producing high quality oxide fibre-reinforced glass matrix composites, with high optical transparency and favourable fracture properties. The composites produced are promising materials for a wide range of applications, notably in the construction industry, special machinery and architecture.
Issue Date: 2011
Date Awarded: Mar-2011
URI: http://hdl.handle.net/10044/1/6414
DOI: https://doi.org/10.25560/6414
Supervisor: Boccaccini, Aldo R.
Lee, Bill
Sponsor/Funder: EU Commission and Marie Curie Fellowship
Author: Silva, Deborah Desimone
Funder's Grant Number: MEST-CT-2004-514667
Department: Materials
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Materials PhD theses

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