The units presented on these websites are included in our standard program and are partially available from stock. Along with the units described, we also produce intermediate sizes and special units according to your drawings and specifications, units for the semiconductor industry as well as diffusion trays, caps, push rods etc.






The material “Quartz glass“

QGT quartz glass units and apparatuses are produced from one of the most valuable materials that industry and research have available. Quartz glass is melted from pure, crystalline quartz, meaning from the purest possible silicon dioxide. The fields of application are: laboratories, industry, research and the semiconductor industry. Quartz glass offers special advantages with respect to its thermal behaviour due to extremely low expansion, high transformation and softening pint temperature, the best possible elasticity and thermal shock resistance, low heat conductivity, low electrical conductivity, low dielectric loss, excellent transmittance form the ultra-violet to infrared spectral range.




Chemical properties and behaviour of quartz glass

Quartz glass is exceptionally resistant to water, acids, saline solutions and other aggressive substances. It is only attacked by hydrofluoric acids. Quartz glass reacts sensitively to alkali and alkaline-earth compounds, because, already with only a trace, these promote devitrification at temperatures above 900C. consequently, fingerprints and water spots should be removed by means of alcohol or demineralised water before heating. After that, the units should not be touched by your bare hands again.

 

· Hydrolytic stability according to
  DIN 12111

1st Hydrolysis class:
Base release       mg Na2O
                             2g grit


· Acid resistance according
to DIN 12116

1st Acid class:
Weight loss < 0,1 mg/dm
Surface


· Alkali resistance according to DIN 52322
1st Alkali class:
Weight loss approx. 50 mg/dm
Surface


· Chemical purity
Foreign elements in quartz glass
— in weight ppm —

AL10-22Fe0,01 - 0,03
As< 0,4K0,1 - 0,7
Au< 0,001Li0,5 - 1
Ca0,2 - 1Mg0,1 - 0,2
Cr0,06Na0,2 - 1
Cu0,02 - 0,05Sb0,05

— The OH content of quartz glass is below 30 ppm— 


· Physical properties (at 20°C)
Density 2.2 g/cm3
Modulus of elasticity 7,3 x 104 N/mm2
Compressive strength 1150 N/mm2
Tensile strength 50 N/mm2
Flexible strength 67 N/mm2
Torsional strength 30 N/mm2
Average corfficient of linear expansion
      60-300°C 4,5-5,9 x 10-7/°C
Lower release temperature 1120°
Upper release temperature 1220°
Max. service temperature,
continuous 1100°
temporary 1300°


· Electrical properties
Specific electrical resistance

Temperature CSpec. elec. resistance
201018
1001016
2004 x 1013
4001010
8006,3 x 106
1000106
12001,3 x 105

Electrical breakdown field strength

20°C250-400 kV/cm
500°C40-50 kV/cm




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