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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:530247 |
| Date | January 2011 |
| Creators | Silva, Deborah Desimone |
| Contributors | Boccaccini, Aldo R. ; Lee, Bill |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/6414 |
Page generated in 0.078 seconds