ZERODUR® Zero Expansion Glass Ceramic
ZERODUR® is a zero expansion, non-porous glass ceramic with extraordinary properties. It is widely used in applications where unavoidable temperature changes could influence critical size and distance accuracies. ZERODUR® has become a performance and quality-determining factor in many spectacular applications within modern technologies.
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.
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.
Innovations & Advantages
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.
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
- 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
Current and Potential Domains of Application
ZERODUR® zero expansion glass ceramic is the ideal material for applications such as astronomy, lithography, measurement technology, mechanics and optical systems.