A Strong Carbon-Coated Silica Fibre

Freshly drawn silica fibre was coated with carbon by passing the still-hot filament through a chamber containing heated acetylene. As the coating thickness was increased, by increasing the temperature of the fibre or acetylene, the tensile strength of the fibre first increased and then decreased. This decrease in strength was concluded to be caused by reaction between the coating and the silica fibre. Optimum conditions were found which gave fibres with a mean strength of 500 000 lb/in.(2) (1 lb/in.(2) = 7 x 10(-2) kg/cm(2)).