Quartz glass production method

 Quartz is a special material due to its high purity silica and its mechanical, electrical, thermal, chemical and transmittance properties.Quartz glass is a special industrial technical glass with a single component of silica. The hardness of this glass can be as high as Mohs 7, with high temperature resistance, low expansion coefficient, thermal shock resistance, chemical stability and good electrical insulation properties, and can transmit ultraviolet and infrared rays. Except for hydrofluoric acid and hot phosphoric acid, it has good acid resistance to general acids.

Quartz glass is an amorphous material with a single component of silicon dioxide. Its microstructure is a simple network composed of silicon dioxide tetrahedral structural units. Due to the large chemical bond energy of Si-O and the tight structure, quartz glass It has unique properties, especially the optical properties of transparent quartz glass are very good, and it has excellent transmittance in the continuous wavelength range of ultraviolet to infrared radiation.

Quartz glass uses high-purity silica sand as the raw material, and the traditional method of production is the melting-quenching method (heating the material to the melting temperature, and then rapidly cooling to the solid phase of the glass); making transparent glass with ultra-high purity and ultraviolet transmittance requires silicon The process of vaporization, oxidation into silica and heating to dissolve.

Shengtang can meet different needs and provide customers with natural quartz glass, transparent and opaque quartz glass, which are made of different production processes and raw materials:



one-step production method

This is the most common contact processing method for producing quartz glass. Quartz sand is melted in a tungsten crucible with electric heating elements; the molten material flows from the furnace through the bottom mold to form quartz tubes, quartz discs and quartz rods. Through this production method and the selection of suitable raw materials, we can obtain finished products with high purity, good mechanical properties, temperature resistance, transmittance and low hydroxyl content.

Hydrogen-oxygen flame refining

The raw material is heated to melting by a oxyhydrogen flame, thereby obtaining a quartz lump. This quartz lump is produced into quartz tubes, quartz rods, quartz discs and square sheets after secondary processing. The hydroxyl content is stable at 150 ppm. This value does not decrease during annealing. These quartz tubes have excellent transmittance, and we can actually guarantee that there are no air bubbles in the finished product produced by this method.

Vacuum electrofusion two-step method

First, the raw materials are heated and melted in an electric melting vacuum furnace to generate quartz lumps; then, the quartz tubes, quartz rods and quartz sheets are formed by melting again in an electromagnetic furnace. All heated abrasives and crucibles used in this production method are made of high-purity graphite. The quartz glass produced by this method has excellent thermal stability, high temperature resistance, high transmittance to ultraviolet and infrared rays, and such quartz is stable and has a very low hydroxyl content (<3ppm).

Rotary Melting

The melting process takes place in a circular mould such as a drum with electrical heating in the centre and on the outer walls. When the mold starts to rotate, the quartz sand adheres to the high temperature mold wall due to centrifugal force during the rotation. This process yields quartz glass tubes of very large diameter and wall thickness.

 

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