Quartz plates, as inorganic materials with high-purity silicon dioxide as the main component, are widely used in high-temperature furnaces, semiconductor processing, optical testing, laboratory heating and other scenarios. Their high-temperature resistance limit and long-term deformation risk are the core performance indicators that users are concerned about, which directly affect the accuracy and service life of equipment.

In terms of high-temperature resistance, the temperature tolerance of quartz plates needs to be distinguished between short-term and long-term working conditions: The melting point of mainstream high-purity fused quartz plates is approximately 1713℃. Short-term exposure to a high-temperature environment of 1450℃ will not cause significant structural damage, and they can maintain morphological stability even when exposed to temperatures above 1600℃ for an instant. This is due to their extremely low coefficient of thermal expansion (only 1/20 of that of ordinary glass), and almost no internal stress is generated when the temperature changes.

However, when used continuously over an extended period, the safety temperature threshold will decrease significantly. In oxidizing or inert atmospheres, the upper limit of the long-term use temperature of quartz plates is generally controlled between 1100℃ and 1200℃. Should this range be exceeded, performance will gradually decline over time. If the quartz plate contains impurities such as alkali metals and alkaline earth metals, it will further reduce the crystallization temperature. The long-term safe operating temperature of such low-purity quartz plates may drop below 900℃.

Whether it will deform after long-term use mainly depends on the temperature threshold and working conditions: Fused quartz is an amorphous glass material. When the temperature is below 1100℃, its structure is stable and it is less likely to undergo plastic deformation. However, when exposed to an environment above 1100℃ for a long time, two key changes will occur, causing deformation.

One of the changes is the crystallization phenomenon: amorphous quartz atoms will gradually arrange into an ordered crystalline structure. This process is accompanied by about 10% volume expansion, which disrupts the uniformity of the glassy state and significantly increases the brittleness of the material. Under the action of stress such as its own weight and device pressure, it is very easy to undergo slow plastic deformation, manifested as bending, indentation and other morphological changes.

The second change is high-temperature creep. Although fused quartz has a much higher creep strength than metals, the atomic diffusion movement intensifies when the temperature approaches 1200°C. Under long-term loading, continuous minor deformation occurs, with the amount of deformation accumulating over time and eventually exceeding the allowable range.

In addition to temperature, the usage environment is also a factor that can influence the risk of deformation. Corrosive atmospheres containing fluorine and chlorine can undergo chemical reactions with quartz, corroding the surface and damaging structural integrity, accelerating deformation. Although long-term sudden cooling and heating operations do not directly cause deformation, they can trigger internal microcracks and reduce the resistance of the material to deformation.

Finally, it is important to note that the high-temperature resistance of quartz plates should be evaluated in conjunction with the specific working conditions. When used over an extended period, it is essential to maintain a temperature within the safe range of 1100℃ to 1200℃ to avoid over-temperature and additional loads. In most cases, no obvious deformation will occur. Exposure to elevated temperatures or unfavourable conditions (e.g. impurities and corrosive atmospheres) over an extended period can accelerate the crystallization and creep processes, resulting in deformation and failure of the quartz plate.