Furnace-drawn silica fibres with tensile strengths >3.5GN/m2 (500 kp.s.i.) in 1 km lengths

The tensile strength of 10 km of coated silica fibres, drawn using a zirconia induction furnace and tested in 20 m gauge lengths, is reported. 4 km of fibre exhibited a minimum strength above 4.2GN/m2 (600 kp.s.i.), demonstrating for the first time the feasibility of achieving long-length unimodal strength distributions for furnace-drawn fibre. Several other kilometres resulted in near-unimodal distributions with minimum strengths of 3.5GN/m2 (500 kp.s.i.) or greater, demonstrating the consistency with which high strengths were achieved.