ALKALI GLASS FOR THE PRODUCTION OF CONTINUOUS GLASS FIBER Yu, i. kolesov and a Kolesova UDC666.189.212:666.11.016.2 A constant improvement in the technology for making continuous glass fiber and in its use in rein forcing materials requires an urgent solution to problems of reducing the cost of the initial glass. At change to a new progressive single-stage method for making reinforcing materials, the fraction or the 9 present the cost is 10-30% of the cost of making the glass fiber materials. In the next 5-7 years, with glass cost will be even higher The high cost of the initial glass for making glass fiber is determined by the use of aluminoboro silicate glass. Boric acid is used in its composition, and it is an expensive raw material. In certain countries(England, FRG)[I about 50% of all reinforcing materials for fiber glass reinforced plastics are manufactured from inexpensive alkali glass. In spite of the fact that its use causes a reduction in the productivity of fiber drawing by 20% in comparison with that obtained from aluminoborosilicate glass, the final cost of the glass fiber materials made from it is 20-25% less than that of similar material made from The VNIISPV has performed investigations with the aim of developing an alkali glass composition that would provide the same productivity as the fiber-forming process obtained with aluminoborosilicate glass The investigations resulted in the development of alkali glass No. 7, which has favorable production and use properties [2]. However, its commercial introduction exposed several TABLE 1 drawbacks: a high tendency to crystallize, producing devitrification of the glass in the feeder, and a high residual glass content, causing Glass foaming of the glass in the glass melting vessel on drawing the glass fib No. 7A The purpose of our present investigation was to develop the technology for making spheres of an alkali glass that Temperature corresponding to would not exhibit the stated drawbacks, and also to correct the chemi cal composition of the glass and the batch, and to choose a suitable 1150 1190 feeder construction. We studied the changes in the working properties gn=36 of the glass and the fiber made from it for the following compositional Strength of glass fibre in g/mm[ 210 210 Ca0, 2.5 MgO, 2 Bao, 7.5-10 R,0,"0-2 Mng04, 2 ZrO2,10-14.5 Density in g/em Chemical durability 'of glass Based on a study of the viscosity and crystallization ability of fibre: Napo leached, in mg 4.814 27 the melted glasses, and also of the strength and chemical durability surface on boiling for 3 hours of the fiber, we selected a glass composition(No 7A)that exhibited a reduction in the upper limit of crystallization by 30'C and a shift of the 19.08 16 52 working range of the fiber towards a higher temperature zone in com inIN sulfuric acid 23.719.2 in 2N sodium hydroxid 820 500 parison with glass No.7 A comparative evaluation of the technological properties of the examined glasses was made by melting them in a gas-electric tank V L Panasyuk, Chemical Control of Pro furnace of the Severodonetsk factory of fiber reinforced fiber glasses luction [ in Russian], Gizlegprom(1952). The results of the comparison are presented in Table 1, and the All-Union Scientific Research Institute of Fiber Glass Reinforced Plastics and Fiber Glass. Trans lated from Steklo i Keramika, No 1, pp 25-27, January, 1973 o 1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N.Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publis her. A copy of this article is available from the publisher for $15.00ALKALI GLASS FOR THE PRODUCTION OF CONTINUOUS GLASS FIBER Yu. I. Kolesov and A. I. Kolesova UDC 666.189.212:666.11.016.2 A constant improvement in the technology for making continuous glass fiber and in its use in rein￾forcing materials requires an urgent solution to problems of reducing the cost of the initial glass. At present the cost is 10-30% of the cost of making the glass fiber materials. In the next 5-7 years, with a change to a new progressive single-stage method for making reinforcing materials, the fraction of the glass cost will be even higher. The high cost of the initial glass for making glass fiber is determined by the use of aluminoboro￾silicate glass. Boric acid is used in its composition, and it is an expensive raw material. In certain countries (England, FRG) [1], about 50% of all reinforcing materials for fiber glass reinforced plastics are manufactured from inexpensive alkali glass. In spite of the fact that its use causes a reduction in the productivity of fiber drawing by 20% in comparison with that obtained from aluminoborosilicate glass, the final cost of the glass fiber materials made from it is 20-25% less than that of similar material made from the aluminoborosilieate glass. The VNIISPV has performed investigations with the aim of developing an alkali glass composition that would provide the same productivity as the fiber-forming process obtained with aluminoborosilicate glass. The investigations resulted in the development of alkali glass No. 7, which has favorable production and use TABLE 1 Index Glass Upper crystallization lirnit ~ Temperature corresponding to to log viscosity, in ~ log ~ = 3.2 log 77 = 3.6 Working range in ~ Density in g/era ~ Strength of glass fibre in g/mm ~ Chemical durability *of glass fibre: Na20 leached, in mg Weight loss from 5000 cm 2 of surface on boiling for 3 hours in mg: in water in 1N sulfuric acid in 2N sodium hydroxide rNo. ~A I J 1150 1190 i 1100 1188 50 52 2. 62 2. 61 210 210 4.81 4.27 19. 08 16. 52 ~.3.7 19.2 820 500 * V. L Panasyuk, Chemical Control of Pro duction [in Russian], Gizlegprom (1952). properties [2]. However, its commercial introduction exposed several drawbacks: a high tendency to crystallize, producing devitrification of the glass in the feeder, and a high residual glass content, causing foaming of the glass in the glass melting vessel on drawing the glass fiber. The purpose of our present investigation was to develop the -- commercial technology for making spheres of an alkali glass that would not exhibit the stated drawbacks, and also to correct the chemi￾cal composition of the glass and the batch, and to choose a suitable feeder construction. We studied the changes in the working properties of the glass and the fiber made from it for the following compositional range (in %): 63-64.5 SiO 2, 6-12 R~O.~, 0-2 Mn.~Ot, 2 ZrO 2, 10-14.5 CaO, 2.5 MgO, 2 BaO, 7.5-10 R20. Based on a study of the viscosity and crystallization ability of the melted glasses, and also of the strength and chemical durability Df the fiber, we selected a glass composition (No. 7A) that exhibited a reduction in the upper limit of crystallization by 30~ and a shift of the working range of the fiber towards a higher temperature zone in com￾parison with glass No. 7. A comparative evaluation of the technological properties of the examined glasses was made by melting them in a gas-electric tank furnace of the Severodonetsk factory of fiber reinforced fiber glasses. The results of the comparison are presented in Table 1, and the All-Union Scientific Research Institute of Fiber Glass Reinforced Plastics and Fiber Glass. lated from Steklo i Keramika, No. 1, pp. 25-27, January, 1973. Trans- 9 1975 Consultants Bureau, a division of Plenum Publishing Corporation, 227 g/est 17th Street, New York, N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher. A copy of this article is available from the publisher for $15.00. 41