Zerodur®, a registered trademark of Schott AG, is a glass ceramic. Used in large, professional telescopes, it is the material of choice for mirrors. What makes Zerodur® special is that it features extremely low expansion on exposure to changing temperature. The material is relatively hard and should be treated with a special polish. Zerodur® has to be handled gently as far as cementing is concerned – at temperatures above 100 °C, it loses its zero expansion.

Product information

Zerodur® is a glass ceramic with an extremely low coefficient of thermal expansion.

Zerodur®’s key properties

  • Virtual zero expansion with outstanding 3D homogeneity
  • High inner quality
  • Good machinability
  • Excellent polishability
  • Highly affinity for coatings
  • Low helium permeability
  • Non-porous
  • Good chemical resistance

Distinguishing features

  • Very hard for grinding
  • Colour reddish brown
  • Homogeneous (no striae) / only detectable on workpieces polished on both sides

Further details available on request

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