Quartz glass:

Natural quartz glass (also often called “natural silica glass”) and synthetic fused silica (synthetic quartz glass) can be supplied in flat glass or in tube and rod form. Other products such as ground joints, rings, lamp bulbs, double tubes, sleeves or spirals are available on request.

Both materials have excellent thermal and optical properties. Since certain specifications do differ, we will be happy to advise you on the most suitable material for your application, taking cost into account.

Quartz glass is mainly used in optical applications or as a sight glass / inspection window for monitoring high-temperature processes.

Quartz glass tubes are used for special UV lamps. Quartz glass is also used, for example, in chemical and industrial applications. On request, we can also supply Quartz glass with special coatings.

Below are the main differences of the quartz glass types:

Flame fused Quarz glass:

Natural quartz sand (containing ≥ 99.98% SiO2) is melted in a flame containing both hydrogen and oxygen (H2/O2) to obtain a solid round rod. The quartz rod is then placed in a non-contact melting furnace to melt again. It is then formed into a rod, tube or thick-walled quartz sheet. The glass contains an abundant amount of hydroxyl (OH) due to the direct contact of hydrogen, oxygen (H2/O2) and the quartz sand. This OH content cannot be reduced by annealing and its presence lowers viscosity and infrared transmission, but does not cause sagging problems. Due to the double melting process, fused quartz glass is very homogeneous, has no draw line and the bubble content is very low. Fused quartz glass is widely used in the fibreglass, semiconductor and photovoltaic industries.

Properties and applications for flame-fused Quartz glass:

  • Mainly used for high-temperature applications, continuous working temperature 1100°C, short-term max 1240°C
  • Viewing window for high temperature furnaces, used in water disinfection applications, good transmission starting from 254nm wavelength.
  • Filter disc, protective glass for UV and infrared applications, good transmission starting from 220nm wavelength.

Electrically fused Quarz glass:

This quartz glass is a mechanically drawn electrically fused clear quartz glass. Quartz with a percentage of SiO2 ≥ 99.98% is used as raw material. Quartz glass can be drawn as tubes, rods or plates. A tube can also be cut into a crescent in the middle and then rolled into a slab. Directly drawn sheet is currently limited to a size of 2000 x 210 x 6-7 mm. To achieve larger lengths, several sheets can be welded together. They are then ground and polished to avoid weld lines. After the grinding and polishing process, the welding lines are no longer visible to the naked eye. It is also possible to maintain a good plane parallelism of, say, 0-0.5 mm for the 500 x 500 x 3 mm plates.

In the semiconductor and photovoltaic (PV) industry, the entire range of quartz glass components is used for the manufacture of quartz wash tanks and quartz boats for cleaning “wafers” and many other applications with operating temperatures up to 1000°C. Due to the increased sodium (Na) content, electrically fused quartz glass cannot be used for applications with continuous temperatures higher than 1000°C. The sodium will cause glass devitrification (due to crystallisation in the glass, transparency gradually disappears).

Properties and applications for electrically fused Quartz glass:

  • Mainly used for optical applications, continuous working temperature 1000°C, short-term max 1100°C (is lower than flame-fused quartz glass).
  • Protective glass for UV, infrared or camera applications, good transmission from 254nm wavelength onwards.
  • Protective glass for optical applications, filter discs, good transmission starting from 220nm.

Flame fused Synthethic Quarz glass:

Produced from pure silicon tetrachloride (SiC14) in a flame pyrolysis process.

Properties and applications for flame-fused synthetic Quartz glass:

  • Continuous working temperature 950°C, short-term max 1250°C.
  • Filter disc, very good transmission in the UVC range.
Quarz glass