Quartz Tubes
I. Definition and Material
Quartz tubes are a specialized type of industrial glass primarily made from silicon dioxide. These tubes are created from high-grade crystal stones and various other raw materials, making them a premium choice for numerous applications.
II. Classification
By Appearance and Characteristics
Transparent Quartz Tubes: These tubes typically range in diameter from 1.5mm to 300mm and are used in a variety of applications.
Ultraviolet-Filtering Quartz Tubes: Designed to filter out harmful ultraviolet rays within the wavelength range of 190nm to 320nm, they are often utilized in the production of environmentally friendly lighting.
Colored Quartz Tubes: Available in colors such as milky white and pink. Milky white tubes are commonly used in heating elements, while pearlescent tubes—a new variant of milky quartz—feature surfaces that have a pearl-like appearance.
By Grade
Quartz tubes can also be classified into different grades, including standard tubes, first-class tubes, premium tubes, and dehydroxylated tubes.
Dehydroxylated tubes have a significantly low hydroxyl content; after undergoing vacuum treatment, their hydroxyl levels can drop below 5ppm, making them suitable for applications demanding minimal hydroxyl presence, like high-pressure mercury and sodium lamps.
III. Performance Characteristics
High-Temperature Resistance
The softening point of quartz tubes is around 1730°C, allowing them to be used continuously at temperatures near 1100°C, with a maximum short-term operational temperature of up to 1450°C. For example, during closed-tube diffusion processes, they can endure temperatures around 1250°C. When heated above 1800°C, they soften and become moldable, facilitating processing.
Corrosion Resistance
Quartz tubes show very low reactivity with most acids, except for hydrofluoric acid. Their resistance to corrosive substances is significantly greater than that of ceramics and stainless steel, providing excellent chemical stability, especially at high temperatures.
Thermal Stability
These tubes have an extremely low coefficient of thermal expansion, which allows them to withstand significant temperature changes. For instance, if heated to approximately 1100°C and then submerged in water at room temperature, they will not shatter.
Light Transmission
Quartz tubes are known for their exceptional light transmission across a wide spectrum, including ultraviolet and infrared. Their visible light transmittance is over 93%, with the ultraviolet range reaching more than 80% maximum transmittance.
Electrical Insulation
The electrical resistance of quartz tubes is about 10,000 times greater than that of conventional glass, making them highly effective insulators even at elevated temperatures.
IV. Preparation and Detection
Preparation
The production process involves selecting specific parameters such as inner diameter and wall thickness based on the intended application (for example, different diameters for diffused silicon wafers).
Detection Methods
- Resistance Testing: Set the multimeter to the continuity setting, connecting the probes to both ends of the quartz tube. A functioning buzzer and a zero reading indicate that the tube is intact; if there’s no sound and the reading shows infinite resistance, this suggests potential internal damage.
- Voltage Testing: Adjust the multimeter to the AC voltage setting (250V). Connect the probes to the power source terminals. A reading around 220V indicates that the power supply voltage is functioning normally.
V. Applications
Electric Light Sources
Quartz tubes are integral in the production of various types of bulbs and lamp tubes, including high-pressure mercury, sodium, and metal halide lamps.
Semiconductor Manufacturing
In the semiconductor sector, quartz tubes are critical for processes such as diffusion and alloy production. Their high-temperature resistance and purity ensure the quality of the processes. They are frequently utilized as materials in closed-tube diffusion procedures.
Optical Communication
Due to their excellent light transmission properties and chemical stability, quartz tubes are commonly used in the production of components for optical communication systems.
Medical Applications
These tubes are utilized to manufacture components for medical devices, where precise dimensional control and bubble-free production are essential.
Heating Applications
Quartz tubes function as heating elements in devices like electric stoves, roasters, and heaters. They are also present in home appliances such as ovens and microwaves, providing efficient and high-quality heating.
Environmental Protection
Ultraviolet-filtering quartz tubes are essential for creating eco-friendly light sources, while ozone-free tubes transmit UV radiation around 253.7nm. These are vital for ozone-free UV germicidal lamps used in sterilization processes for medical devices, water purification, and food safety.
Other Industries
In addition, quartz tubes have applications in various fields including metallurgy, construction materials, chemical industries, machinery, and electrical power sectors, as well as in sensors for measuring temperature, displacement, vibration, frequency, and speed.