High purity quartz furnace tube (products) use instructions

High purity quartz furnace products are special industrial technology glass made of high purity silica, which is a very good basic material. Quartz products have a series of excellent physical and chemical properties such as:

1. High temperature resistance. The softening point temperature of quartz glass is about 1730℃. It can be used at 1150℃ for a long time and the maximum temperature for a short time can reach 1450℃.

2, corrosion resistance. In addition to hydrofluoric acid, high purity quartz furnace tube almost no chemical reaction with other acid substances, at high temperature, it can withstand sulfuric acid, nitric acid, hydrochloric acid, aqua royalty, neutral salts, carbon and sulfur erosion. Its acid resistance is 30 times of ceramic, stainless steel 150 times, especially at high temperature chemical stability, is any other engineering materials are incomparable.

3, good thermal stability. The thermal expansion coefficient of high purity quartz furnace tube is very small, and it can withstand intense temperature changes. The high purity quartz furnace tube will be heated to about 1100℃, and it will not burst into normal temperature water.

4, good light transmission performance. High purity quartz furnace tube has good transmittance in the whole spectrum band from ultraviolet to infrared, visible light transmittance is more than 93%, especially in the ultraviolet spectrum, ~ large transmittance can reach more than 80%.

5. Good electrical insulation performance. The resistance value of high purity quartz furnace tube is equivalent to ten thousand times of ordinary quartz glass, is an excellent electrical insulation material, even at high temperature also has good electrical properties.

High purity quartz furnace tubes (products) are widely used in high temperature electric furnaces because of their excellent physical and chemical properties.

Inherent Defects of high purity Quartz furnace Tubes (Matters needing Attention in Use)

Permeability loss (also known as crystallinity) is an inherent defect of high purity quartz furnace tube. From the thermodynamic point of view, the internal energy of quartz furnace tube is higher than that of crystallized quartzite, which is a thermodynamically unstable metastable state. When the temperature is higher than 1000℃, the vibration of SiO2 molecules accelerates, and crystallization is formed after a long period of rearrangement and orientation. The permeability is expressed by the growth rate of crystal nucleus. The crystallization rate of opaque quartz products at 1520℃ and transparent quartz products at 1620℃ respectively reach the maximum value. Crystallization mainly appears on the surface, followed by internal defects. The reason is that these places are easy to stain, resulting in local concentration of impurity ions, especially alkali ions (such as K, Na, Li, Ca, Mg, etc.) into the network and cause viscosity reduction, so as to promote

Accelerated loss of permeability. Because the thermal expansion coefficient and specific gravity of quartz products are similar to the crystallization product β-cristobalite, so at high temperature furnace tube continuous use, although the crystallization zone continues to expand, but the volume change is not obvious, it can still be used satisfactorily, at this time can reduce the plastic deformation of quartz furnace tube, improve the refractoriness. When the crystallization product is cooled to 800℃, a fine cracking network appears. At 200-275℃, the structure of the quartz changes from high temperature type to low temperature type (i.e., β-quartz → A-quartz), accompanied by volume fusion. If the crystallization layer is very deep, the quartz glass also breaks. Because crystallization often appears in the place of impurities, so high temperature and high purity furnace tube in use to use non-alkaline refractory materials, at the same time the use of atmosphere, and sintering volatile matter as far as possible to reduce the alkaline particles, after use, clean the inner wall of the furnace tube in time, in order to extend the service life of the furnace tube.

The inner wall of high purity quartz furnace tube (products) will cause certain pollution after a period of use. Please clean it with the following methods:

1, can use HF (hydrofluoric acid) as cleaning quartz tube reagent, of course, can also use hydrochloric acid, nitric acid or other combination of acid, acid concentration is controlled below 5%, and wear chemical protective equipment operation;

2. Strictly control the concentration and time of acid to prevent quartz tube from being washed (that is, permeable) or not clean;

3. After pickling, please use purified deionized water to clean quartz furnace tube (products). The inner surface of the quartz furnace tube is not clean enough to produce crystallization or acid fog, which affects the permeability of the quartz tube and causes damage;

4, of course, containing acid waste water can not be directly discharged, the simple method is to use plastic pipe centralized collection of these waste water, and then add liquid (or solid) alkali neutralization, to meet the requirements of environmental protection can be discharged.