About ZERODUR® Zero Expansion Glass Ceramic

ZERODUR® Glass Ceramic Product Information

ZERODUR® glass ceramic is an inorganic, non-porous glass ceramic and has a completely non-directional, isotropic structure. Due to the perfect balance of glass and crystal phases within the material, the thermal expansion coefficient is nearly zero. As the crystalline and glass phases have chemical characteristics and hardness similar to those of optical glass, ZERODUR® glass ceramic can be processed using the same machines and tools as optical and technical glass (e.g. cutting, grinding and polishing). Due to its outstanding characteristics the brand LITHOTEC® describes these kind of ZERODUR® which is being used in lithographic and metrology applications.

ZERODUR® Glass Ceramic Benefits

SCHOTT Advanced Optics has the capability and experience of manufacturing ZERODUR® glass ceramic in small components as well as in parts with weights of several tons with extraordinary reproducibility. We also offer a zero expansion material with outstanding 3D homogeneity.

ZERODUR® glass ceramic has several outstanding properties including:

High internal quality
Low Helium permeability provides a longer life span for the components
Can be polished to a very high accuracy
Can be coated easily
Good processing behavior
Good chemical stability

ZERODUR® Glass Ceramic Key Applications

ZERODUR® zero expansion glass ceramic is the ideal material for applications, such as astronomy, lithography, measurement technology, mechanics and optical systems.

ZERODUR® Glass Ceramic Forms of Supply

ZERODUR® glass ceramic can be supplied in the form of:

Discs
Rectangular blocks
Prisms
Rods
Cut pieces measuring from a few cm up to approximately 4 m in length

Additionally, modern CNC processing equipment and a variety of grinding technologies allow the generation of complex geometries and filigree structures at the customer’s request.

If you are interested in high precision optical components made of ZERODUR® glass ceramic, please check here about our options or contact us.

ZERODUR® Glass Ceramic Specifications

Thermal Expansion Coefficient:
Individual pieces of ZERODUR® glass ceramic (discs, plates, rods) can be supplied with a mean coefficient of linear thermal expansion in the temperature range 0° to 50°C in three expansion classes as follows:

Expansion class 2 0 ± 0.10 x 10^-6 K^-1
Expansion class 1 0 ± 0.05 x 10^-6 K^-1
Expansion class 0 0 ± 0.02 x 10^-6 K^-1

ZERODUR® glass ceramic exhibits excellent homogeneity of the linear thermal expansion coefficient. Typical values are between 0.01 and 0.02 x 10^-6 K^-1.
On request homogeneities < 0.01 x 10^-6 are possible.

Internal Quality:
The following applies for the internal quality of “standard” ZERODUR® glass ceramic with typical dimensions < 500 mm:

Average number of inclusions 5/100 cm³
Maximum diameter of single inclusions 3.0 (1.4 within the critical volume)
Striae (birefringence) < 60 nm/striae
Bulk stress (birefringence) < 6 nm/cm

Further Properties:

Density 2.53 g/cm3

Thermal conductivity at 20°C 1.46 W/(m x K)

Thermal diffusivity at 20°C 0.72 x 10-6 m²/s

Thermal capacity 0.8 J/(g x K)

Young’s modulus at 20°C 90.3 GPa

Poisson’s ratio 0.243

Knoop hardness 0.1/20 620

Quality Assurance

Modern measurement equipment is used to inspect the ZERODUR^® glass ceramic parts during all stages of fabrication and at the final and most stringent inspection.

Thermal expansion coefficient:		Highly accurate dilatometer equipment (with reference standards provided by the PTB)
Geometry and shape:		Mobile and stationary 3D coordinate measurement machines with high accuracy
Surface quality:		Roughness measurement equipment
Internal quality:		Accurate measurement microscopes and stress measurement setups according to the “de Senarmont“ method
Optical homogeneity:		Interferometer with aperture up to 500 mm in diameter

Related Information

ZERODUR^® K20
Coatings
Precision CNC machined parts

ZERODUR^® - Product Flyer ZERODUR^® - Catalogue

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Advanced Optics
SCHOTT AG

Hattenbergstrasse 10
55122 Mainz
Germany

+49 (0)6131/66-1812

+49 (0)3641/2888-9047

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