1. As a heating element: Quartz tubes can withstand high temperatures and are often used in heating equipment, such as laboratory heating furnaces and industrial furnaces.

2. As a light source: Quartz tubes can be used to manufacture ultraviolet lamps and halogen lamps because quartz materials have good light transmittance and can transmit ultraviolet rays.

3. As a chemical reaction container: Quartz tubes have strong corrosion resistance and are suitable for various chemical reactions in chemical laboratories.

4. As an electric light source: Quartz tubes can be used to manufacture various electric light sources, such as fluorescent lamps, high-pressure mercury lamps, etc.

5. As a transmission medium: In some special industrial applications, quartz tubes can be used as transmission pipelines for gases or liquids.

6. As an optical element: The transparency of quartz tubes allows them to be used in optical instruments, such as the window material of spectrometers.

7. Used in the semiconductor industry: In the semiconductor manufacturing process, quartz tubes are used to manufacture furnace tubes for high-temperature processing of materials such as silicon wafers.

These functions of quartz tubes are due to their unique physical and chemical properties, including high temperature resistance, corrosion resistance, and good light transmittance.