General Information About Fused Quartz / Quartz Glass
1. What is fused quartz glass?
Fused quartz glass, also called quartz glass or fused silica, is a high-purity amorphous SiO₂ material with exceptional thermal, optical, and chemical properties. FGQuartz products use natural quartz crystal with ≥99.99% SiO₂.
2. Is fused quartz the same as quartz glass?
Yes. Industry terms “fused quartz,” “quartz glass,” and “fused silica” are interchangeable. All refer to ultra-pure SiO₂ used for high-temperature, optical, and semiconductor applications.
3. What is the chemical purity of FGQuartz fused quartz?
FGQuartz fused quartz has:
- SiO₂ ≥99.99%
- Total metallic impurities <20 ppm
- OH <10 ppm
- Na+K <5 ppm, Fe <5 ppm, Al <10 ppm
4. Is quartz glass chemically resistant?
Yes. Resistant to most acids (except HF and hot phosphoric), bases, salts, and organic solvents. Ideal for labware, chemical processing, and semiconductor wet benches.
5. What industries use fused quartz?
- Semiconductors (furnaces, quartz boats)
- Optics and photonics (UV/laser windows, lenses)
- Laboratory equipment
- Photovoltaics, LEDs, optical fibers
- Aerospace and defense
6. What is the maximum operating temperature of quartz glass?
- Continuous: 1200°C
- Short-term: 1300°C
- Softening point: 1680°C
- Annealing point: 1215°C
- Strain point: 1120°C
7. Can fused quartz withstand rapid thermal cycling?
Yes. Ultra-low thermal expansion (≈0.55 ×10⁻⁶/°C) allows rapid changes from 1100°C to room temperature without cracking.
8. What is the thermal expansion coefficient of fused quartz?
≈0.55 × 10⁻⁶ /°C, significantly lower than borosilicate glass (~3.3 ×10⁻⁶/°C), ensuring dimensional stability.
9. How does quartz glass compare to borosilicate glass?
Quartz glass offers higher temperature resistance, lower thermal expansion, excellent UV transmission, and ultra-pure chemical stability.
10. How does quartz glass compare to sapphire or alumina ceramics?
- Sapphire: Higher melting point (~1800°C) but poorer UV transmission, higher cost, higher CTE
- Alumina: High temperature, opaque, higher expansion
- Quartz: Cost-effective for UV, thermal shock, and high-purity applications
Optical Properties and Applications
11. What is the UV-Vis-NIR transmission of fused quartz?
90% from 185 nm (deep UV) to 2500 nm (near IR), low absorption and minimal fluorescence.
12. Can quartz glass be used in UV lasers and excimer lasers?
Yes. High transmission and low impurities make it ideal for UV lithography, laser optics, and spectroscopy applications.
13. What is the refractive index of fused quartz?
Approximately 1.4585 at 589 nm. Low dispersion ensures precision optical performance.
14. Is quartz glass suitable for optical windows and lenses?
Yes. Ultra-high purity, low absorption, and high transmission make it perfect for precision lenses, windows, and prisms.
15. Can fused quartz be used for photonics and fiber optics?
Yes. It is widely used for fiber optic preforms, WDM components, UV light guides, and high-power laser systems.
16. Does quartz glass require special coatings for optical use?
Optional thin-film coatings (AR, HR) can enhance optical performance. FGQuartz supports custom coating services.
17. What is the surface quality of polished quartz glass?
Polished fused quartz can achieve surface roughness Ra ≤ 0.2 nm using CMP (Chemical Mechanical Polishing).
Mechanical Properties
18. What is the bending strength of fused quartz?
Approximately 67 MPa at 20°C.
19. What is the tensile strength?
Around 48 MPa.
20. What is the Young’s modulus?
72 GPa, indicating high stiffness for dimensional stability.
21. How hard is quartz glass?
Mohs hardness 5.5–6.5. Brittle material; avoid impact and localized stress.
Machining, Fabrication, and Custom Services
22. Does FGQuartz offer CNC machining and fabrication?
Yes. Services include CNC milling, drilling, flame polishing, precision grinding, ultrasonic cutting, welding, and annealing for custom components.
23. What tolerances can be achieved?
Custom parts can reach ±0.01 mm for critical dimensions.
24. Can FGQuartz produce complex custom shapes?
Yes. Tubes, rods, plates, non-round shapes, and micro-structured components are supported.
25. Are specialty coatings available?
Yes. Anti-reflective (AR), high-reflective (HR), and dielectric/metal coatings can be applied.
26. How long is the lead time for custom orders?
Typically 3–6 weeks depending on complexity, tolerances, and order volume. Prototypes may be faster.
Handling, Cleaning, and Safety
27. How should quartz glass be handled?
Wear clean gloves to prevent oils/fingerprints. Avoid impact, scratches, or sudden thermal shocks.
28. How should quartz glass be cleaned?
Use deionized water, isopropyl alcohol, or mild detergents. For critical cases, ammonium bifluoride (7–10%) for ≤10 min followed by thorough rinsing.
29. Can quartz glass be etched or chemically modified?
Yes, using HF or controlled chemical processes, but only with proper safety and handling.
30. How does FGQuartz ensure quality and traceability?
Every component undergoes rigorous QA with dimensional metrology (CMM), surface inspection, optical transmission testing, and full traceable documentation (CoC).