method for improving the mechanical properties of sio2 glass fibers

摘要

The initial fibres are treated with an extn. soln. to dissolve out oxides other than SiO2. During or after this extn. treatment, the fibres are treated with a soln. (I) contg. colloidal- silica or -polysilicic acid, or silicates, so the wt. ratio of SiO2 w.r.t. the other oxides is increased. The colloidal soln. (I) may be used for different times and/or temp., and with different concn. of the SiO2 or silicates in soln.; and acids may be added to promote deposition of SiO2 on the fibres, esp. when using an aq. soln.(I). Soln. (I) may also contain metal cpds. so metals are also deposited on the fibres. The invention increases the SiO2 content of glass fibres, and therefore increases their strength at high temps. The SiO2 also fills the fissures caused by the extn. of other oxides, e.g. Al2O3, CaO, Na2O, K2O, so the tensile strength and toughness of the fibres are both increased. The resistance of the fibres to chemicals is also improved.