Zerodur – Wikipedia
Zerodur (Spelling of the manufacturer: Zerodur®) is a glass ceramic material from Schott AG, which is produced by controlled volume crystallization.
Zerodur contains a crystalline phase and a residual glass phase through which the extraordinary features of the material are determined.
These special features include an extremely low expansion coefficient, good material homogeneity, chemical resistance, long -term stability and hardly fluctuating mechanical properties.
For the production of Zerodur, parts made of glass are initially heated again. At around 800 degrees Celsius, the fabric melts are added to the fabric melts, on which tiny crystals (average size approximately 50 nanometers) grow with increasing temperature. These have the property of contracting in the event of warming. So they counteract the heat expansion of pure glass. The art of this process, which is referred to as ceramization, is to adjust the ratio of crystal phase to glass phase so that the resulting thermal expansion is minimally, even zero in certain temperature ranges. This is the case if there are about 70 percent of the melt. The ceramization process can last up to several months, depending on the size of the glass blank. [first]
The material zerodur is typically as substrate material of optical elements in astronomy, e.g. B. in comet probes, as a mirror carrier for modern astronomical large telescopes, such as. B. the very large telescope in Chile (four monolithic mirrors each 8.2 meters in diameter), the cheeky observatory in Hawaii (two segmented mirrors each 10.0 meters diameter), the Gregor sun telescope or the Gran Telescopio Canarias on La Palma ( a segmented mirror 10.4 meters in diameter) as well as used in the precision look or precision measurement technology. Zerodur becomes because of its excellent
Thermal properties also used as a material for the frame and carrier of lithography and nanomesses. An example of this is the nanopositioning and nanomesster (NMM-1) of the Technical University of Ilmenau.
Zerodur is interesting for use in space travel because of the possible reduction in the starting weight compared to other mirror materials. In the coordinate measurement technology, scales from Zerodur with fabricated long -distance divisions are used in high -precision measuring devices. [2]
Zerodur was launched in 1968. In 1971, Ceran followed, in which Zerodur glass ceramic is used for “Ceran” cookies. Since then, the material has been expanded to include numerous material variants, e.g. B. “Zerodur K20”. It is produced by thermal conversion of the semi -transparent starting material Zerodur, is thermally highly stable and does not change even over many heating cycles. “Zerodur K20” glass ceramic has a high long-term temperature stability up to 850 degrees Celsius. The material can e.g. B. are used for mechanical and optical components in high -performance lasers or are used as shape material for use in hot shape (glass, plastic). [3]
- ↑ Source: 50 years of Schott in Mainz. Quarterly booklets for culture, politics, business and history. Special edition Mainz. 22nd year, 2002.
- ↑ Length measuring system with division carriers from Zerodur. Retrieved on September 26, 2019 .
- ↑ Scott Age Zeodur
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