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Quartz fiber
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Quartz fiber is a fiber created from high-purity quartz crystals.[1][2] It is made by first softening quartz rods (in an oxyhydrogen flame)[3] and then creating filaments from the rods.[4] Since the creation of high-purity quartz crystals is an energy intensive process, quartz fiber is more expensive than alternatives (glass fiber and high-silica fiber) and has limited applications.[3]
Manufacture
[edit]Quartz fiber is made from heating quartz rods with an oxyhydrogen flame. Then, filaments are drawn out of the quartz rod, creating quartz fibers.[5] For optical fibers, germanium and phosphorus can be added to increase the refractive index.[6][7] In general, quartz fiber is made of 99.95% purity of silicon dioxide.[8]
Properties
[edit]A single quartz fiber can have a tensile strength of 5.5 gigapascals (800 ksi). Quartz fibers are chemically stable as they are not affected by halogens (for the most part). Quartz fibers also have a higher thermal resistance than S-glass or E-glass.[9] Quartz fiber also has a low coefficient of thermal expansion.[8]
Applications
[edit]
Since quartz fiber is expensive, it has limited applications.[2] It is used mainly for producing composite materials (due to having higher stability compared to glass fiber) and in electrical applications where thermal resistance and dielectric properties are important.[10] It can be used in filtration applications where alternatives such as glass fiber filters cannot be used.[3][11] Quartz fiber can also be used for physical devices (such as in quartz fiber dosimeters and quartz fiber electrometers).[12]
Quartz fibers can be used in fiber optics. This is due to a quartz fiber having the ability to transport data at a speed of 1 terabit per second,[13][14] and having a transmission loss of 1 decibel per kilometer.[15]
Similar to how fiberglass can be made, quartz fiber can be used to make composite materials by combining with a resin. The fiber can be weaved into a cloth ("quartz cloth", "silica cloth"), or chopped to a uniform length.[16] Three-dimensional quartz phenolic is an example of such a material.
See also
[edit]References
[edit]- ^ Carley, James F. (October 8, 1993). Whittington's Dictionary of Plastics, Third Edition. CRC Press. ISBN 9781566760904.
- ^ a b Wang, Ru-Min; Zheng, Shui-Rong; Zheng, Yujun George (July 14, 2011). Polymer Matrix Composites and Technology. Elsevier. ISBN 9780857092229.
- ^ a b c Rosato, Donald V.; Rosato, Dominick V. (2004). Reinforced Plastics Handbook. Elsevier. ISBN 9781856174503.
- ^ Rosato, Donald V.; Rosato, Marlene G.; Rosato, D. V. (August 31, 2000). Concise Encyclopedia of Plastics. Springer Science & Business Media. ISBN 9780792384960.
- ^ Peters, S. T. (November 27, 2013). Handbook of Composites. Springer Science & Business Media. ISBN 9781461563891.
- ^ Xinju, Lan (February 18, 2010). Laser Technology, Second Edition. CRC Press. ISBN 9781420091717.
- ^ Staff, IGIC, Inc (1994). Radiation Effects on Fiber Optics and Opto Electronics. Information Gatekeepers Inc. ISBN 9781568510750.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ a b Escudier, Marcel; Atkins, Tony (2019). A Dictionary of Mechanical Engineering (2nd ed.). Oxford University Press. doi:10.1093/acref/9780198832102.001.0001. ISBN 9780191870866.
{{cite book}}: CS1 maint: date and year (link) - ^ Defense, Us Dept Of (June 18, 1999). Composite Materials Handbook-MIL 17: Materials Usage, Design, and Analysis. CRC Press. ISBN 9781566768283.
- ^ Materials, Metal Properties Council Task Group on Commercial Opportunities for Composite; Watts, Admiral A. (1980). Commercial Opportunities for Advanced Composites. ASTM International. ISBN 9780803103023.
- ^ Brisson, Michael J.; Ekechukwu, Amy A. (2009). Beryllium: Environmental Analysis and Monitoring. Royal Society of Chemistry. ISBN 9781847559036.
- ^ Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Academic Press. ISBN 9780123526519.
- ^ "Fiber optics". ping-test.net. Retrieved March 16, 2018.
- ^ McWhan, Denis (February 23, 2012). Sand and Silicon: Science that Changed the World. OUP Oxford. ISBN 9780191627477.
- ^ Takajima, Toshi; Kajiwara, K.; McIntyre, J. E. (1994). Advanced Fiber Spinning Technology. Woodhead Publishing. ISBN 9781855731820.
- ^ "Technical Reference Handbook 2017" (PDF). JPS Composite Materials.
Quartz fiber
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History
Invention and Early Development
The earliest production of pure silica fibers occurred in France, where M. Gaudin created fused quartz fibers in 1839 by extruding molten quartz through a stream of hot air.[6][7] These initial efforts were limited to small-scale demonstrations, as the process required intense heat to melt quartz at approximately 1700°C, posing significant energy demands that restricted broader application.[7] In the early 20th century, interest in silica as a high-temperature material grew, with researchers exploring its potential for filament production from quartz crystals to support industrial needs such as precision instrumentation.[7] By the 1930s, experiments at Corning Glass Works advanced fiber-making processes by melting high-purity silica glass, addressing persistent issues with impurities in natural quartz sources that could compromise material integrity during fusion.[8] These impurities, including trace elements like aluminum and iron embedded within crystal lattices, often led to inconsistencies in early fiber quality and performance.[9] Natural occurrences of quartz whiskers—thin, fibrous crystalline forms observed in minerals such as chert and certain replacement deposits—had long inspired synthetic efforts, highlighting silica's inherent fibrous potential.[10] The shift to synthetic production accelerated in the 1940s, when flame-drawn methods enabled the creation of consistent quartz fibers by softening quartz rods in an oxyhydrogen flame and pulling them into filaments, overcoming limitations of natural variability.[7] This technique, refined for industrial viability, marked a key transition from experimental curiosities to practical materials.[8]Modern Advancements and Commercialization
World War II research significantly accelerated the demand for high-temperature resistant materials, spurring advancements in fused quartz fiber production to support military applications requiring durability under extreme conditions. Post-war efforts in the United States and Europe led to the commercialization of high-quality fused silica, with techniques developed during the conflict adapted for broader industrial use, enabling the transition from experimental to scalable manufacturing processes.[7] In the 1950s and early 1960s, companies like Saint-Gobain pioneered the development of continuous quartz filaments through oxyhydrogen flame drawing methods, which softened high-purity quartz rods to produce uniform fibers suitable for reinforcement. This innovation, initiated at Saint-Gobain's facility in Nemours, France, in 1960, marked a key advancement in achieving consistent filament quality for composite applications. Key patents from the 1960s, such as US3095642A for metal and fiber composite materials incorporating silica fibers, further supported the integration of high-purity quartz fibers into reinforced structures, enhancing their viability for high-performance uses. By the 1980s, refinements in optical-grade quartz fibers emerged through additional patents and process improvements, focusing on purity levels exceeding 99.95% to minimize signal loss in specialized applications.[11][12] Commercialization gained momentum in the 1970s with the adoption of quartz fibers in aerospace, particularly for radomes in non-civilian aircraft programs, where their electromagnetic transparency and thermal stability proved essential. A notable milestone was Saint-Gobain's 1974 collaboration with Lockheed Martin to supply quartz fibers for U.S. Space Shuttle components, demonstrating their reliability in extreme environments. The 1990s fiber optics boom indirectly boosted demand for high-purity quartz materials, though structural quartz fibers saw expanded use in composites amid the telecommunications surge. Specialized producers, including Saint-Gobain (under the Quartzel brand) and JPS Composite Materials (Astroquartz), emerged to meet these needs, with the global fused quartz fiber market projected to reach $104 million by 2031, driven by high-tech demands in aerospace, electronics, and thermal protection systems.[11][13][14]Composition and Manufacture
Raw Materials and Purification
The primary raw material for quartz fibers is synthetic quartz crystals, produced through a hydrothermal growth process that starts with high-grade silica sand or natural quartz deposits as nutrient sources.[15] In this method, nutrient quartz is dissolved in an aqueous alkali solution, such as sodium hydroxide or sodium carbonate, within a high-pressure autoclave at temperatures of 300–400°C and pressures of 700–1500 bar, allowing controlled crystallization on seed plates to form large, high-purity boules.[15] This synthetic approach achieves silicon dioxide (SiO₂) purity levels exceeding 99.99%, often reaching 99.999% or higher, which is essential for minimizing optical and mechanical defects in the resulting fibers.[16] Natural quartz deposits, while used as starting materials, are less favored due to variability in impurity content, making synthetic methods the standard for consistent quality in fiber production.[15] Purification is critical to eliminate impurities that could compromise fiber performance, particularly metallic contaminants like iron (Fe) and aluminum (Al), which can introduce absorption bands or structural weaknesses.[16] Common techniques include acid leaching, where hydrothermal or vein quartz is calcined at around 900°C to expose impurities, followed by treatment with hydrochloric acid (HCl) or sulfuric acid (H₂SO₄) under pressure to remove up to 98% of Fe and 88% of Al, achieving total impurity reductions of over 84 wt%.[17] For ultra-high purity, chemical vapor deposition (CVD) is employed post-leaching, depositing SiO₂ from silicon tetrachloride (SiCl₄) vapors to yield material with less than 10 ppm total impurities, preventing scattering or degradation in fiber applications.[16] These steps ensure the quartz is free of lattice-bound metals that natural sources often contain at levels exceeding 100 ppm.[17] Global production of synthetic quartz for fibers is concentrated in the United States, China, and Europe, where companies employ hydrothermal methods for reliability over natural extraction.[18] China leads with major producers like Feilihua Quartz Glass and Jiangsu Pacific Quartz, supported by recent investments exceeding $14 million, while Europe (e.g., Heraeus in Germany) and the U.S. focus on high-tech variants for photonics.[19][20][21] Synthetic processes are preferred globally for their scalability and purity control, supplying over 80% of semiconductor- and fiber-grade material.[18]Fiber Production Processes
The primary method for producing quartz fibers entails softening high-purity quartz rods in an oxyhydrogen flame at temperatures around 2200–2300°C, followed by mechanical drawing to create continuous filaments with diameters typically between 5 and 20 μm.[3][22][23] This process utilizes specialized equipment, including a drawing tower equipped with chucks to hold the rod, a high-precision oxyhydrogen burner to localize heating and achieve a viscous state without crystallization, and winding mechanisms to collect the filaments at controlled speeds. The rod is fed vertically into the flame, where surface tension and mechanical pull transform the softened tip into fine, uniform strands, enabling the production of high-strength, continuous yarns suitable for reinforcement applications.[7] Alternative techniques, though less prevalent for high-purity continuous quartz fibers, include steam texturizing to produce crimped variants for enhanced bulk in composites, sol-gel spinning for staple fibers, and plasma methods where plasma torches heat the quartz rods for drawing. In steam texturizing, drawn filaments are exposed to high-pressure steam jets to introduce crimp and texture, improving processability in non-woven forms. Sol-gel spinning involves preparing a spinnable silica sol from precursors like tetraethylorthosilicate through hydrolysis and polycondensation, extruding it via dry, wet, or dry-jet wet methods, and sintering the green fibers at elevated temperatures to yield high-purity SiO₂ structures, often achieving viscosities of 250–400 poise for optimal fiber formation. Plasma methods use high-temperature plasma to soften the material similarly to flames but offer potential advantages in control and purity. These methods are favored for specialized short-fiber production but face challenges in scalability and purity uniformity compared to flame drawing.[24][3] Post-processing steps are essential for practical use and include bundling individual filaments into rovings for easier handling, applying sizings such as silane-based coatings to protect against abrasion and enhance matrix adhesion, and annealing via controlled heat treatment to relieve residual stresses from drawing. These treatments occur in specialized furnaces, ensuring the fibers maintain their integrity during subsequent weaving or composite integration.[3] Quartz fiber production is notably energy-intensive, relying on high-temperature oxyhydrogen flames and precise mechanical systems, which necessitates advanced facilities and drives costs significantly higher than those for conventional glass fibers—often by a factor of several times due to the purity and thermal demands.[25][26]Properties
Mechanical and Structural Properties
Quartz fibers, primarily produced as fused variants, possess an amorphous structure derived from high-purity silica (SiO₂ content exceeding 99.9%), which contributes to their uniform and defect-minimized form.[27] In contrast, certain high-end crystalline quartz fibers feature a structured lattice, offering enhanced stability in specialized applications, though fused amorphous types dominate commercial production.[28] The density of these fibers is consistently 2.20 g/cm³ for amorphous fused quartz, providing a lightweight profile ideal for structural reinforcement.[27] Typical filament diameters range from 7 to 14 μm, enabling fine weaving and composite integration, while lengths are available as continuous strands or chopped segments of 3 to 50 mm for use in matrix reinforcements.[27][1] These dimensions ensure high aspect ratios, facilitating effective load distribution in fibrous assemblies without compromising flexibility.[29] At room temperature, quartz fibers demonstrate exceptional tensile strength, reaching up to 6 GPa for virgin filaments, which surpasses that of conventional E-glass fibers (typically 3-4 GPa).[27] The modulus of elasticity is approximately 72-78 GPa, reflecting the material's inherent rigidity.[27][29] This linear elastic behavior follows the standard stress-strain relationship:
where denotes stress, the modulus of elasticity, and the strain, underscoring the predictable deformation under load up to failure.[7]
Thermal and Chemical Properties
Quartz fibers exhibit exceptional thermal stability, enabling continuous use in environments up to 1200°C without significant degradation, with a softening point around 1700°C and a melting point exceeding that threshold where the material becomes fluid at approximately 2000–2500°C.[30] This high-temperature resilience stems from the fused silica structure, which resists devitrification until prolonged exposure above 1000°C, with crystallization occurring only after extended heating at 1100°C for several days or briefly at 1600°C. Compared to E-glass fibers, which soften around 850°C, quartz fibers maintain structural integrity at much higher temperatures, making them preferable for demanding thermal applications.[31] The coefficient of thermal expansion for quartz fibers is remarkably low at approximately 0.55 × 10^{-6} K^{-1}, far below that of metals (typically 10–20 × 10^{-6} K^{-1}), which minimizes dimensional changes under temperature variations.[1] This property, combined with low thermal conductivity of about 1.4 W/m·K at 20°C, contributes to outstanding thermal shock resistance, allowing the fibers to endure rapid temperature shifts exceeding 1000°C without cracking—for instance, from cryogenic conditions near -196°C to 1000°C.[1][32] At elevated temperatures, this thermal endurance can influence mechanical strength retention, though detailed structural effects are addressed elsewhere.[33] Chemically, quartz fibers demonstrate high inertness, resisting most acids, bases, and halogens up to 1000°C with minimal degradation in both oxidizing and reducing atmospheres.[13] They remain unaffected by common acids and gaseous halogens, except for hydrofluoric acid at room temperature or hot phosphoric acid above 300–400°C, and show limited reactivity with alkaline solutions only at temperatures exceeding 100°C.[13] This stability surpasses that of E-glass in corrosive high-temperature settings but aligns with carbon fibers in certain oxidizing environments where both maintain performance without rapid breakdown.[34]Optical and Electrical Properties
Quartz fibers, derived from fused silica, exhibit exceptional optical transparency, transmitting over 90% of light from the ultraviolet range starting at approximately 200 nm to the near-infrared up to 2.5 μm, owing to the material's high purity and amorphous structure.[35] This broad transmission window stems from minimal absorption bands in pure forms, with internal transmittance exceeding 99% for thicknesses up to 10 mm in the visible spectrum.[36] The refractive index of fused quartz is approximately 1.46 at visible wavelengths, providing a stable medium for light propagation with low dispersion.[37] In fiber form, pure quartz achieves remarkably low attenuation, around 0.2 dB/km at 1550 nm in the telecom C-band, enabling long-distance signal transmission without significant loss.[38] Fused quartz fibers display minimal birefringence, typically less than 10^{-6} in high-quality samples free of significant stress, unlike crystalline quartz, which supports their use in polarization-sensitive optics such as polarizers.[39] This low intrinsic birefringence arises from the isotropic nature of the amorphous glass, though stress-induced effects can introduce small phase differences quantified by the equation:
where is the phase difference, is the wavelength, is the birefringence, and is the path length.[40]
Electrically, quartz fibers serve as excellent insulators with a dielectric constant of about 3.8 at 1 MHz, reflecting the material's low polarizability and suitability for high-frequency applications.[41] The volume resistivity exceeds 10^{16} \Omega \cdot \mathrm{cm} at room temperature, ensuring minimal leakage currents even under prolonged exposure.[42] Breakdown strength reaches up to 20 kV/mm, allowing reliable performance in high-voltage environments without dielectric failure.[43]
In variations such as germanium-doped quartz fibers for telecommunications, attenuation remains low at approximately 0.2 dB/km in key bands like the C-band (1530–1565 nm), supporting data rates exceeding 1 Tbps through wavelength-division multiplexing.[44] These doped configurations enhance core-cladding index contrast while preserving the inherent low-loss properties of silica.[45]