amics.org/lAGS Higb-Performance Glass Fiber De Although E-CR glass fibers are evolving to beco fiber glass industry. High cost and technology barriers he GFRP industry standard for most corrosion-resis- remain as factors limiting the growth of D-Glass in tant applications, improved chemical resistance was PCB applications. One of the D-Glass derivatives, SI lly obtained from boron-free C-Glass fiber fibers (Nitto Boseki Co. Ltd, Fukushima, Japan) (Na2O, CaO, Al2O3, and Sio2), which offered good introduced small amounts of alkaline earth oxides and chemical resistance against acid attack. Boron-contain- alumina at the expense of boron to improve glass ing C-Glass fiber was invented in 1943(UE. Bowes, melting and fiber-forming characteristics. However, the US 2, 308, 857, OC, 1943), which had limited use in melting and forming processes remain significantly building material insulation applications because of challenged because of its lower resistance to acidic environments due to boron T relative to E-Glass. In late 2010, PPG introduced presence in the glass. The mechanical performance of INNOFIBER LD fiber glass, a low dielectric glass fiber boron-free C-Glass fiber is inferior to E-CR Glass and that offered glass-melting and fiber-forming characteris- E-Glass, and these properties limit its use as a rein- tics that were compatible with a E-Glass manufacturing fCO ment. Further limiting the broad commercial use pla Glass is the fact that it has lower hydrolytic resis S-Glass is primarily composed of MgO, Al2O3, tance under high humidity environments at elevated and Sio2 and was first developed in the 1960s primar temperatures. Starting in the mid-1960s, boron-free ily for high-temperature and high-strength applications C-Glass fiber and E-Glass fber products served the and later in 1970s for military ballistic protection general industrial market. Because of their lower cost, applications. S-Glass is difficult to fberize due to its boron-free C-Glass fiber products are still used in com- high liquidus temperature(1470.C). Liquidus tempera- bination with E-Glass fibers in nonstructural corrosion ture, Ti, is defined as the maximum temperature above barrier applications. However, boron-free C-Glass which all crystals are dissolved in molten glass. As a volume is <10% of fibers used in GFRP today. result, S-Glass has Ti greater than TE, indicating that Continuing on the theme of corrosion resistance, the glass exhibits a negative delta T(AT-TF-TD force concrete structures in the mid-1960s. This gla- Commercial examples include the S-2 Glass products AR-Glass fibers were developed as a solution to re from AGY(Aiken, SC). S-Glass derivatives, such as HS primarily composed of Na2O, CaO, ZrO2(17-24%), glass from Sinoma Science and Technology(Nanjing, and SiOz with a small amount of Al2O3. AR-Glass Jiangsu, China), offer melting technology improve fibers offer the highest resistance against alkaline as ments over S-2 Glass . Overall, however,commercial ell as acid-attacks. High concentrations of ZrO2 in applications using S-Glass fiber input are limited due the glass and its resultant higher melting temperature to significantly higher manufacturing costs in both (TM as defined by 10 Pa-s viscosity in glass industry) melting and fiber formi lead to very high product costs, which restricts its broad In the mid-1960s, R-Glass was first developed for use in general-purpose applications military applications. The glass is primarily composed As mentioned earlier, E-Glass offers adequate elec- of MgO, Cao, Al2O3, and SiOz. In its original chem trical properties, primarily driven by the low total alkali istry, such as S-Glass, usage was limited because of its (<2%)content of the glass, for PCB applications. high melting temperature requirement. Although these When higher signal transmission speeds in electronic early chemistries created melting challenges when man devices are required, D-Glass fibers or pure silica ufacturing R-Glass fibers, newly engineered R-Glass (SiO2) fibers offer the best achievable electrical proper- compositions have overcome the melting and fiber ties as measured using dielectric constant (Dk) and forming obstacles, becoming commercially attractive for dissipation factor(Df) among all fiber glass classes large-scale production D-Glass is also easier than pure SiO2 to melt and fiber ize. However, D-Glass fiber production is limited to small commercial scale because of its very high TN Historic Higb-Modulus and Higb-Strengtb Glass Fiber Developmen (1650° C)and high forming temperature(1400°C which is approximately 200C higher than traditional As earlier stated, both S-Glass and R-Glass have boron-containing E-Glass fiber products. Fiber-forming been restricted to limited applications because of high- temperature, TF, is defined at 100 Pa s viscosity by the temperature processing challenges preventing theirAlthough E-CR glass fibers are evolving to become the GFRP industry standard for most corrosion-resis￾tant applications, improved chemical resistance was originally obtained from boron-free C-Glass fibers (Na2O, CaO, Al2O3, and SiO2), which offered good chemical resistance against acid attack. Boron-contain￾ing C-Glass fiber was invented in 1943 (U.E. Bowes, US 2,308,857, OC, 1943), which had limited use in building material insulation applications because of lower resistance to acidic environments due to boron presence in the glass. The mechanical performance of boron-free C-Glass fiber is inferior to E-CR Glass and E-Glass, and these properties limit its use as a rein￾forcement. Further limiting the broad commercial use of C-Glass is the fact that it has lower hydrolytic resis￾tance under high humidity environments at elevated temperatures. Starting in the mid-1960s, boron-free C-Glass fiber and E-Glass fiber products served the general industrial market. Because of their lower cost, boron-free C-Glass fiber products are still used in com￾bination with E-Glass fibers in nonstructural corrosion barrier applications. However, boron-free C-Glass volume is <10% of fibers used in GFRP today. Continuing on the theme of corrosion resistance, AR-Glass fibers were developed as a solution to rein￾force concrete structures in the mid-1960s. This glass is primarily composed of Na2O, CaO, ZrO2 (17–24%), and SiO2 with a small amount of Al2O3. AR-Glass fibers offer the highest resistance against alkaline — as well as acid — attacks. High concentrations of ZrO2 in the glass and its resultant higher melting temperature (TM as defined by 10 Pa
s viscosity in glass industry) lead to very high product costs, which restricts its broad use in general-purpose applications. As mentioned earlier, E-Glass offers adequate elec￾trical properties, primarily driven by the low total alkali (<2%) content of the glass, for PCB applications. When higher signal transmission speeds in electronic devices are required, D-Glass fibers or pure silica (SiO2) fibers offer the best achievable electrical proper￾ties as measured using dielectric constant (Dk) and dissipation factor (Df) among all fiber glass classes.5 D-Glass is also easier than pure SiO2 to melt and fiber￾ize. However, D-Glass fiber production is limited to a small commercial scale because of its very high TM (1650°C) and high forming temperature (1400°C) which is approximately 200°C higher than traditional boron-containing E-Glass fiber products. Fiber-forming temperature, TF, is defined at 100 Pa
s viscosity by the fiber glass industry. High cost and technology barriers remain as factors limiting the growth of D-Glass in PCB applications. One of the D-Glass derivatives, SI
fibers (Nitto Boseki Co. Ltd., Fukushima, Japan), introduced small amounts of alkaline earth oxides and alumina at the expense of boron to improve glass￾melting and fiber-forming characteristics. However, the melting and forming processes remain significantly challenged because of its significantly higher TM and TF relative to E-Glass. In late 2010, PPG introduced INNOFIBER LD fiber glass, a low dielectric glass fiber that offered glass-melting and fiber-forming characteris￾tics that were compatible with a E-Glass manufacturing platform.6,7 S-Glass is primarily composed of MgO, Al2O3, and SiO2 and was first developed in the 1960s primar￾ily for high-temperature and high-strength applications and later in 1970s for military ballistic protection applications. S-Glass is difficult to fiberize due to its high liquidus temperature (1470°C). Liquidus tempera￾ture, TL, is defined as the maximum temperature above which all crystals are dissolved in molten glass. As a result, S-Glass has TL greater than TF, indicating that the glass exhibits a negative delta T (DT = TFTL). Commercial examples include the S-2 Glass
products from AGY (Aiken, SC). S-Glass derivatives, such as HS glass from Sinoma Science and Technology (Nanjing, Jiangsu, China), offer melting technology improve￾ments over S-2 Glass. 8,9 Overall, however, commercial applications using S-Glass fiber input are limited due to significantly higher manufacturing costs in both melting and fiber forming. In the mid-1960s, R-Glass was first developed for military applications. The glass is primarily composed of MgO, CaO, Al2O3, and SiO2. In its original chem￾istry, such as S-Glass, usage was limited because of its high melting temperature requirement. Although these early chemistries created melting challenges when man￾ufacturing R-Glass fibers, newly engineered R-Glass compositions have overcome the melting and fiber￾forming obstacles, becoming commercially attractive for large-scale production. Historic High-Modulus and High-Strength Glass Fiber Development As earlier stated, both S-Glass and R-Glass have been restricted to limited applications because of high￾temperature processing challenges — preventing their www.ceramics.org/IJAGS High-Performance Glass Fiber Development 67