ZERODUR® Catalogue
22Pages

ADVANCED OPTICS ZERODUR®- CATALOG ZERODUR® Glass Ceramic Temperature stable precision and quality in series

ZERODUR® Contents 1. ZERODUR® has Extraordinary Properties 4 2. Thermal Properties 6 3. Internal Quality 10 4. Mechanical Properties 12 5. Optical Properties 14 6. Electrical Properties 16 7. Chemical Properties 17 8. Helium Permeability 18 9. Forms of Supply and Tolerances 19 10. Necessary Data for Quotation Preparation 20 CONTENTS ZERODUR®

4 1. ZERODUR has Extraordinary Properties ZERODUR® is a zero expansion glass ceramic with extraordinary properties. It is widely used in applications where unavoidable temperature changes could influence critical size and distance accuracies. The most important properties of ZERODUR® are: • an extremely low thermal expansion coefficient • excellent homogeneity of thermal expansion • high internal quality • good workability • polishable to a high accuracy • excellent chemical stability All these properties can be realized in small components as well as in parts with weights of several tons...

5 ZERODUR PROPERTIES ® The ZERODUR® manufacturing sequence is based on established and proven methods used in the production of high homogeneity optical glasses. Therefore ZERODUR® itself is a material of the highest homogeneity, and even in large pieces with dimensions of several meters exhibits thermal and mechanical characteristics with nearly unmeasureable deviations. Optimized melting, casting and annealing procedures are the requirements to produce ZERODUR® in high quantities with reproducable excellent quality. Homogeneity and quality in large quantities ZERODUR® has a completely...

THERMAL PROPERTIES 6 2. Thermal Properties The most important and significant properties of the glass ceramic ZERODUR® are the extremely small coefficient of linear thermal expansion as well as the homogeneity of this coefficient throughout the entire piece. Individual pieces of ZERODUR® can be supplied with a mean coefficient of linear thermal expansion á in the temperature range 0°C to 50°C in three expansion classes as follows: Expansion class 0 0 ± 0.02·10-6/K Expansion class 1 0 ± 0.05·10-6/K Expansion class 2 0 ± 0.10·10-6/K If not otherwise expressly specified, expansion class 2...

7 ZERODUR THERMAL PROPERTIES ® The stated tolerances for homogeneity of linear expansion can be guaranteed in the following weight classes for each part, provided that the diameter of the part is at least twice its thickness: up to 18.0 tons 0.03 · 10-6/K up to 6.0 tons 0.02 · 10-6/K up to 0.3 tons 0.01 · 10-6/K In certain applications, the total change of length of a ZERODUR® part within a specified temperature interval is vital to its function (such as laser gyroscopes). In the region of -50°C to +100°C, the total change in length is usually smaller than 10 · 10-6, based on the total...

ZERODUR® THERMAL PROPERTIES 8 Thermal conductivity Specific heat capacity Specific heat capacity cp at 20°C [J/(g·K)] 0.80 Figure 4: Thermal conductivity of ZERODUR® as a function of temperature. Figure 5: Specific heat capacity of ZERODUR® as a function of temperature Thermal conductivity ë at 20°C [W/(m · K)] 1.46 Thermal diffusivity index a at 20°C [10-6 m2/s] 0.72 ë [W/(m·K)] 0°C 100°C 10 5 1 0.5 0.1 0.05 0.01 0 100 200 300 400 temperature [K] 500 cp [J/(g· K)] 0° C 101 100 10-1 10-2 10-3 10-4 10-5 1 5 10 50 100 500 temperature [K] 1000

9 ZERODUR THERMAL PROPERTIES ® ZERODUR® may be used as a mechanical component as well as a window at temperatures up to 600 °C. Slight changes may arise in the linear thermal expansion coefficient á (0°C, 50°C) that can affect components of the highest optical precision, due to temperature treatments by the customer or user. If the final cooling rate RE differs from the initial cooling rate RP, especially in the temperature range of 320°C to 130°C, the change of the linear thermal expansion coefficient á (0°C, 50°C) can be estimated by using the following equation: Maximum application...

ZERODUR® INTERNAL QUALITY 10 3. Internal Quality The internal quality of ZERODUR® is essentially determined through • Inclusions • Bulk stress • Striae Inclusions in ZERODUR® cannot be completely avoided. As a rule they are mainly bubbles and to some extent individual particles. They have no effect on the function of ZERODUR® as a substrate material for surfaces of the highest quality insofar as they lie completely within the volume. The probability that individual inclusions lie in the optically finished mirror surface is very low. Specifying the volume range in which the final functional...

11 ZERODUR INTERNAL QUALITY ® We invite inquiries for requirements that go beyond the mentioned inclusion, striae, and bulk stress specifications. If no quality is specified upon order entry, ZERODUR® is supplied in standard quality. Special requirements (higher quality level) Standard Class 4 Bulk stress birefringence [nm/cm] for parts with diameters or diagonals < 500mm 6 4 < 2000 mm 12 10 < 4000 mm 15 12 Table 2: Quality levels for bulk stress in ZERODUR® Table 3: Quality levels for stress birefringence caused by striae in ZERODUR® Standard Class 4 Class 3 Class 2 Class 1 Stress...

ZERODUR® MECHANICAL PROPERTIES 12 4. Mechanical Properties Since 1973, 400 mm long gauge blocks maintained at 20 °C made from ZERODUR® have been interferometrically connected to a wavelength standard at the PTB (Physikalisch- Technische Bundesanstalt, Germany). Interpolation formulas that have been derived from previous measurements on the basis of theoretical consideration allow predictions to be made for the expected change in the length of ZERODUR® relation to time. In a formal analogy to the thermal linear expansion coefficient á the following applies: Length stability over time The...