GB1495022A - Glassceramic fibres - Google Patents

Abstract

1495022 Glass-ceramic fibres UNITED KING- DOM ATOMIC ENERGY AUTHORITY 11 June 1975 [12 June 1974] 26175/74 Heading C1M Glass-ceramic fibres are made by: (i) forming into fibres a crystallizable glass comprising Al 2 O 3 , SiO 2 , 10-18% of Li 2 O, and a TiO 2 additive, the TiO 2 being present in an amount of not more than 5% by weight or not less than 8% by weight (all percentages given relative to the weight of glass excluding TiO 2 ); and (ii) crystallizing the glass fibres. When the TiO 2 content is not more than 5% by weight, the glass-ceramic formed comprises #- eucryptite and lithium metasilicate (Li 2 O.SiO 2 ), the fibres being capillary fibres. The glass used for forming such capillary fibres preferably comprises, by weight, 10-18% Li 2 O, 7À5-15% Al 2 O 3 and 65-75% SiO 2 , the glass being crystallized in a single stage (e.g. heating from ambient to 850‹ C. at 5‹ C./min., holding at 850‹ C. for 2 hours, and cooling at 5‹ C./min.). When the glass contains at least 8% by weight TiO 2 , the glass-ceramic formed is a non-capillary fibre comprising lithium metasilicate (Li 2 O.SiO 2 ) and #-spodumene as crystal phase. Such a glass preferably comprises, by weight, 9-11% TiO 2 , 10-18% Li 2 O, 15-30% Al 2 O 3 and 55-67% SiO 2 , and is crystallized in two stages (e.g. heating from ambient to 600‹ C. at 5‹ C./min., holding at 600‹ C. for 2 hours, heating at 850‹ C. at 5‹ C./min., holding at 850‹ C. for 2 hours, and cooling at 8‹ C./min.). In either embodiment, the glass is preferably formed into a rod, which is drawn down to a fibre before crystallizing.