Quartz glass is one of the most critical materials in modern semiconductor manufacturing, optical engineering, and industrial high-temperature systems. Its ultra-high purity, exceptional thermal stability, near-zero thermal expansion, and outstanding chemical resistance make it indispensable for extreme-temperature processes and rapid thermal cycling.
1. What Is Quartz Glass?
Quartz glass is an amorphous, ultra-high-purity SiO₂ material. FGQuartz products achieve ≥99.99% SiO₂ purity, with total metallic impurities <20 ppm and hydroxyl (OH) content <10 ppm. This extreme purity minimizes contamination and ensures stable performance in sensitive environments.
FGQuartz Product Portfolio
- Quartz Tubes: Large-diameter, thick-wall, square, and custom profiles
- Quartz Components: Rods, plates, discs, crucibles, flanges
- Custom Fabrication: Reaction kettles, special-shaped instruments, and precision assemblies
2. Why Quartz Glass Has No True “Melting Point”
As an amorphous (glassy) material, quartz glass does not melt at a sharp temperature like crystalline substances. Instead, it softens gradually over a wide range. Thermal behavior is defined by standardized viscosity reference points (measured in poise).
3. Key Thermal Reference Points (FGQuartz Verified)
| Reference Point | Temperature | Viscosity (poise) | Description & Practical Use |
|---|---|---|---|
| Strain Point | ≈1120 °C | 10¹⁴.⁵ | Below this, residual stresses become permanent. |
| Annealing Point | ≈1215 °C | 10¹³ | Ideal for stress relief after forming or machining (stresses relax in minutes to hours). |
| Max. Working Temp (Continuous) | 1200 °C | — | Recommended long-term limit to avoid sagging/devitrification in most applications. |
| Max. Working Temp (Short-term) | 1300 °C | — | Brief exposure limit without significant deformation. |
| Softening Point | ≈1683 °C | 10⁷.⁶ | Temperature where material deforms under its own weight (practical forming range). |
4. Key Material Properties Overview
FGQuartz ultra-pure quartz delivers superior performance:
Mechanical
- Young’s Modulus: 72 GPa
- Compressive Strength: 1100 MPa
- Mohs Hardness: 5.5–6.5
Thermal
- Coefficient of Thermal Expansion (20–300°C): 5.5 × 10⁻⁷ /°C
- Exceptional thermal shock resistance — withstands quenching from 1100°C to room temperature without cracking.
Optical
- Refractive Index (n_d at 589 nm): 1.4585
- UV Transmission (254 nm, 10 mm thickness): >90%
- Broad transmission range: 185–2500 nm
Electrical
- Resistivity (20°C): >10¹⁸ Ω·cm
- Dielectric Constant (1 MHz): 3.75
5. Factors Enhancing Performance
- High Purity (≥99.99% SiO₂) — Raises effective viscosity and reduces devitrification risk.
- Low OH Content (<10 ppm) — Dramatically improves high-temperature viscosity → excellent resistance to sagging in long vertical tubes (critical for semiconductor diffusion furnaces).
- Trace Impurities — Al <10 ppm, Fe <5 ppm, Na+K <5 ppm (ICP-MS verified per batch) → prevents premature weakening or contamination.
6. Primary Applications & Proven Reliability
- Semiconductor — Diffusion furnace tubes, quartz boats for CVD, annealing, oxidation.
- Photovoltaics — Polysilicon ingot growth furnaces, high-temperature shielding.
- Optics — UV lamp envelopes, laser windows, spectroscopy cells.
- Laboratory/Industrial — Acid-resistant crucibles, reaction vessels (resistant to most acids except HF).
7. FAQ
Q: What is the softening point of FGQuartz products? A: ≈1683°C. However, for long-term structural integrity in real applications, continuous use should stay ≤1200°C to prevent gradual sagging or devitrification.
Q: Can FGQuartz withstand severe thermal shock? A: Yes — its ultra-low CTE (5.5 × 10⁻⁷ /°C) allows direct transfer from 1100°C furnaces to room-temperature air without cracking.
Q: Do you offer custom dimensions and shapes? A: Yes — we specialize in tailored tubes, rods, and complex components to exact specifications.
Conclusion
Selecting quartz glass with precise thermal limits, purity, and low OH is critical for demanding high-tech processes. FGQuartz delivers ≥99.99% purity and a softening point of ≈1683°C, providing unmatched reliability in semiconductor, photovoltaic, and optical applications.
Contact FGQuartz for Detailed Specifications, Quotes, or Custom Inquiries 📧 [email protected]
