1. The thermophysical properties of quartz materials

(1) Low thermal conductivity

At room temperature, its thermal conductivity is approximately 1.4 W/(m·K), which is significantly lower than that of metals. This results in a relatively slow rate of heat transfer from the interior to the surface of the glass plate, enabling the formation of a temperature difference between the interior and exterior.

(2) Small coefficient of thermal expansion

It is approximately 5.5×10⁻⁷/℃, only 1/10 of that of ordinary glass. Its thermal shock resistance is superior to that of most glass materials, but it is brittle and has low fracture toughness.

(3) Limit in thermal shock resistance temperature difference

The safe thermal shock temperature difference for ordinary quartz glass is approximately 200 to 300 degrees Celsius. This means that the instantaneous temperature difference should not exceed this range. If it does, there is a risk of cracking or breaking due to thermal stress.

2. Feasibility of rapid cooling and analysis of cooling methods

The rapid cooling of quartz glass plates requires an external cooling medium to accelerate heat dissipation. Common methods include:

(1) Air-cooling

Principle: The heat on the surface of the glass plate is carried away by high-speed airflow, which is suitable for medium and low-temperature sections.

Advantage: The equipment is simple and there is no risk of liquid leakage. The cooling rate can be controlled by adjusting the wind speed.

Limitation: The coefficient of convective heat transfer is low, which limits the cooling efficiency in the high-temperature section. If wind speeds are too high, this can lead to significant temperature variations in specific areas.

(2) Water cooling

Principle: The heat is removed indirectly via water passing through the metal cooling sleeve located outside the glass plate, which facilitates cooling.

Advantage: High heat transfer coefficient and fast cooling rate.

Limitation: Direct contact with high-temperature quartz should be avoided as it may cause sudden local cooling. The thermal expansion of the cooling jacket needs to be matched with quartz to prevent compressive stress.

(3) Composite cooling (air cooling + water cooling)

The high-temperature section utilizes air cooling to regulate the initial cooling rate, while the medium and low-temperature sections transition to water cooling to enhance cooling efficiency and safety. It has the potential to reduce cooling times and enhance the uniformity of thermal stress distribution.

3. The key factors affecting cooling performance

(1) Glass plate structure design

An increase in thickness will result in a longer heat conduction path and a slower cooling rate. The glass plate with grooves is susceptible to stress concentration, and its structure needs to be optimized to ensure uniform heat dissipation.

(2) Initial temperature and cooling rate

The higher the initial temperature, the slower the initial cooling rate required.

Quartz glass plates are capable of rapid cooling, but this can only be achieved if the scientific design is based on material properties. This means that the selection of cooling methods must be reasonable, and should combine air and water cooling. It is imperative to strictly control the cooling rate and the temperature difference between the inside and outside. In order to reduce the risk of thermal stress, it is essential to optimize the structure and materials. The implementation of these measures will reduce cooling times while extending the service life of the glass plate, thereby enhancing the production efficiency of the equipment.