Quart glass products can be used for a longer period of time if they are kept clean.
Even a small amount of impurities left on the surface of a product can cause the area to be devitrified when the product is heated. This also promotes devitrification of other areas and shortens the service life.
Quartz glass products are mainly used in processes where high purity is required and for high-temperature operations. Thus, this makes it all the more important to handle them in a clean work environment.
Do not handle quartz glass products with bare hands. Protect the products from dirt and dust during storage and keep them in plastic bags.
To remove stains from quarts glass products, wash them with 5% to 10% hydrofluoric acid (HF) for about 10 minutes.
After washing with hydrofluoric acid, rinse the products well and dry them.
Make sure that the products stay wet and do not dry out during washing. After washing, dry them completely.
If stains do not wash off, try a stronger hydrofluoric acid solution.
Quartz glass is highly heat resistant and withstands rapid heating and cooling more than ten times better than ordinary glass. This heat resistance, however, becomes lower as the wall becomes thicker. Large products, and especially thick opaque quartz glass products, can develop cracks when exposed to rapid temperature changes. Exercise utmost caution when there is a rapid temperature change.
The annealing point of transparent quartz glass is approximately 1190. Its distortion point is about 1090. For opaque quartz glass, they are 1080 and 1030 respectively. If products are cooled rapidly after they are used at temperatures exceeding these levels, distortions may once again be generated. Thus, exercise utmost caution, especially with large products.
Quartz glass is a material with an extremely low thermal expansion. A product can crack if a rapid temperature change occurs while a component with a different coefficient of thermal expansion is attached, fastened, or clamped to it.
Due to its low thermal conductivity, quartz glass can develop cracks when it is heated locally as it is placed near a heating element or comes in direct contact with a flame. Products that are heavy or have a long tube shape may gradually become deformed at temperatures above 1100. Attention must be paid to the way the products are supported, taking into account the viscosity of quartz glass. Caution is advised, especially for large products.
Devitrification of quartz glass refers to a change from a semi-stable glass to a crystallized stable cristobalite. This phenomenon occurs when quartz glass is used at high temperatures for an extended duration or heated with impurities attached to its surface. In practical applications, the phenomenon almost never occurs at temperatures below 1150 as long as no impurity is attached to the surface. Devitrification normally starts when the temperature rises above 1200 and is accelerated as temperatures become higher. If impurities, even in small amounts, are present on the surface of quartz glass, devitrification can easily occur even at temperatures below 1000. In particular, alkalis, such as Na, K and Ca, or metal compounds of alkaline earth in the order of less than 0.1 mg per 1 square centimeter can generate devitfification tens or hundreds of times the norm. Also, most metals, such as Al, B, Fe, Ni, Mg, Zn, Cu, Sb, and their compounds, if they are on the quartz glass, can trigger serious damage.