Quartz glass
Quartz glass, also known as fused silica, is a unique type of glass that offers distinct properties, especially in high-performance and high-temperature applications. Here are the key properties of quartz glass:
- High Thermal Resistance: Like borosilicate glass, quartz glass has exceptional resistance to heat and can withstand extremely high temperatures (up to 1,000°C or more) without deforming or breaking. It has a very high melting point, typically around 1,650°C (3,002°F).
- Low Thermal Expansion: Quartz glass has an even lower coefficient of thermal expansion than borosilicate glass, which means it is less likely to expand or contract with changes in temperature. This makes it ideal for applications requiring precision and stability under varying thermal conditions.
- Optical Transparency: Quartz glass is highly transparent to ultraviolet (UV), visible, and infrared (IR) light. This makes it ideal for optical applications, such as lenses, fiber optics, and windows for lasers and high-intensity light sources.
- Chemical Inertness: Quartz glass is highly resistant to chemicals and does not easily react with acids, bases, or other aggressive substances. This makes it suitable for use in chemical processing environments, laboratory equipment, and containers that handle reactive substances.
- Electrical Insulation: Quartz glass is an excellent electrical insulator, making it useful in high-voltage and high-frequency applications, such as electrical components, insulators, and semiconductors.
- High Purity: Quartz glass has a very high level of purity, often made from natural silica (SiO₂). This makes it ideal for applications where contaminant-free materials are critical, such as in semiconductor manufacturing and high-precision optics.
- Durability: Quartz glass is hard and resistant to scratching, although it can be more brittle and prone to breaking if subjected to physical shock. However, it is more durable than most other glass types in extreme conditions, especially with regard to heat and chemical exposure.
UV Transparency: Quartz glass is particularly notable for its ability to transmit UV light, making it a key material in UV lamps, sterilization devices, and other UV-based technologies.
Due to these properties, quartz glass is widely used in fields like:
- Optical applications (e.g., lenses, mirrors, prisms)
- Semiconductor and electronics manufacturing (e.g., substrates, crucibles)
- UV and laser technologies
- Laboratories (for specialized glassware)
- High-temperature equipment (e.g., furnaces, reactors)
In summary, quartz glass is prized for its combination of thermal, chemical, and optical properties, making it suitable for highly demanding applications across several advanced industries.
Here's an overview of common technical data for fused quartz (also known as fused silica
when it's very pure).
Chemical Composition
Oxide
% by Weight
SiO₂
~99.95% – 99.999%
Derived from high-purity silica sand or synthetic processes.
Thermal Properties
Property
Value
Softening Point
~1665 °C
Annealing Point
~1180 °C
Strain Point
~1070 °C
Continuous Use Temp
>1000 °C
Thermal Expansion (20–1000 °C)
~0.55 × 10⁻⁶ /K
Thermal Shock Resistance
Very High (can handle rapid ΔT >1000 °C depending on thickness)
Mechanical Properties
Property
Value
Density
~2.2 g/cm³
Young's Modulus
~72 GPa
Poisson's Ratio
~0.17
Compressive Strength
~1100 MPa
Tensile Strength
~50 MPa (depends on surface quality)
Hardness (Mohs)
~5.5–6.5
Knoop Hardness
~570
Electrical Properties
Property
Value
Electrical Resistivity
>10¹⁶ Ω·cm at 25 °C
Dielectric Constant (1 MHz)
~3.8
Dielectric Strength
~40–50 kV/mm
Optical Properties
Property
Value
Transmission Range
~180 nm to >3,000 nm
Refractive Index (n₅₈₉)
~1.458
UV Transmission
Excellent (down to 180 nm or lower depending on purity)
Birefringence
Very low
Fluorescence
None (ideal for UV optics)
Key Advantages
- Extreme thermal resistance
- Outstanding UV and IR transparency
- Chemical inertness (resistant to most acids, except HF)
- Very low outgassing (perfect for vacuum and semiconductor use)
- Stable under high-energy radiation
