Zerodur

Thermal expansion coefficient as low as 0 ± 0.007 × 10^-6/K

Zerodur glass-ceramic has an ultra-low coefficient of thermal expansion, which allows it to maintain excellent dimensional stability even under temperature fluctuations, with minimal changes in mechanical and thermal properties, Suitable for lightweight machining, often used in high-precision applications

Advantages

Supports High-precision machining.
Highly stable against temperature fluctuations.
High material homogeneity, purity, and structural uniformity for consistent performance.
Minimal deformation under load.
Exceptional resistance to chemicals, including acids and bases.
Outstanding vacuum compatibility.
Transparent across a wide wavelength range.
Extremely low thermal expansion coefficient: 0 ± 0.007 × 10⁻⁶/K.
Tolerates high operational temperatures.

Applications

Laser gyroscope mirrors, brackets, and components
Synchrotron X-ray mirrors
Interferometers, optical tables, and length measurement systems
Spectrometer optical components
Laser interferometers and planar wavefront sensors
Gravitational wave detectors
Optical components for satellites and astronomical telescopes (e.g., Hubble main mirror)
Ultra-precision optics and large telescope mirror substrates
X-ray telescope substrates
Ring laser gyroscope applications
Optical elements for space probes (e.g., comet probes)
Flat optics and optical flats
Low-expansion laser optics for space technology
Glass standards for high-precision optical measurement
Mechanical laser resonator parts
Fiber optic components and holders
Lightweight honeycomb satellite mirror mounts
Semiconductor lithography parts
Wafer stepper components

Zerodur Properties

Mechanical properties

Physical Properties	ZERODUR®	ZERODUR® K20
Density ρ [g/cm³]	2.53	2.53
Poisson’s ratio	0.24	0.25
CTE 25°C – 600°C	112 × 10⁻⁷/°C	62 × 10⁻⁷/°F
Knoop Hardness HK 0.1/20 (ISO9385)	620	620
Refractive index nd	1.5424	——
Abbe number vd	56.1	——
Thermal conductivity λ at 20°C [W/(m·K)]	1.46	1.63
Thermal diffusivity index at 20°C [10⁻⁶ m²/s]	0.72	——
Heat capacity cp at 20°C [J/(g·K)]	0.8	0.9
Young’s modulus E at 20°C [GPa] (mean value)	90.3	84.7
Internal transmittance Ti at 580 nm / 5 mm thickness	0.95	——
Internal transmittance Ti at 580 nm / 10 mm thickness	0.9	——
Stress optical coefficient K at λ = 589.3 nm [10⁻⁶ MPa⁻¹]	3	——
Electrical resistivity at 20°C [Ω·cm]	2.6 × 10¹³	——
Tk100 [°C], Temperature for ρ = 10⁸ [Ω·cm]	178	——

Chemical Properties

Chemical properties	ZERODUR®	ZERODUR® K20
Stain resistance	Class 0	—
Climate resistance	Class 1	—
Acid resistance class (ISO 8424)	1	—
Alkali resistance class (ISO 10629)	1	—
Hydrolytic resistance class (ISO 719)	HGB 1	—
Helium permeability at 20°C [Atoms/(cm·s·bar)]	1.6 × 10⁶	—
Helium permeability at 100°C [Atoms/(cm·s·bar)]	5.0 × 10⁷	—
Helium permeability at 200°C [Atoms/(cm·s·bar)]	7.2 × 10⁸	—

Thermal Expansion

Thermal expansion	ZERODUR®
CTE Grades	CTE (0°C–50°C)*
ZERODUR® Expansion Class 2	0 ± 0.100 × 10⁻⁶/K
ZERODUR® Expansion Class 1	0 ± 0.050 × 10⁻⁶/K
ZERODUR® Expansion Class 0	0 ± 0.020 × 10⁻⁶/K
ZERODUR® Expansion Class 0 SPECIAL	0 ± 0.010 × 10⁻⁶/K
ZERODUR® Expansion Class 0 EXTREME	0 ± 0.007 × 10⁻⁶/K
ZERODUR® TAILORED	TAILORED ± 0.020 × 10⁻⁶/K (+0.010 ~ +0.010 × 10⁻⁶/K upon request)

Note: This value is for reference only and may vary slightly depending on the batch conditions.

Machining Zerodur

Precision components made from Zerodur are typically processed using diamond grinding techniques, followed by optical polishing with chemical-mechanical methods as needed. When machining Zerodur, it is crucial to select appropriate cutting tools, control cutting speeds, and carefully manage heat to avoid material damage. After machining, thorough inspection is essential to ensure that the parts’ surfaces are free from cracks or chipping. In some cases, ultra-precision polishing may be required to achieve the desired finish and performance standards.

Jundro Ceramics leverages years of expertise in precision machining to produce high-quality Zerodur components that consistently meet or exceed customer specifications, ensuring both everyday functionality and specialized performance. If you require precision Zerodur machining, our team of experts is ready to assist you with tailored solutions. Contact us today for your machining needs.

Zerodur 5-Axis Machining

Our video shows the process of using CNC to process Zerodur Prototype

Frequently Asked Questions

What is Zerodur Glass-Ceramic?

Zerodur Glass Ceramic has excellent optical properties, a uniform internal structure, and strong tolerance to chemical substances. Its performance is comparable to Corning’s ule glass. making it ideal for precision optical and mechanical applications, such as telescopes and metrology equipment.

What are the main Applications of Zerodur?

Zerodur is commonly used in high-precision instruments, including telescopes, mirrors for scientific devices, laser optics, and semiconductor equipment, due to its exceptional dimensional stability and thermal properties.

How does Zerodur Glass-Ceramic differ from traditional ceramics?

Zerodur has a unique composition and structure that offers near-zero thermal expansion, unlike traditional ceramics that often experience significant dimensional changes with temperature fluctuations. This makes Zerodur ideal for applications requiring high stability.

Is Zerodur Glass-Ceramic resistant to thermal shock?

Yes, Zerodur has excellent resistance to thermal shock, which makes it suitable for high-temperature environments where rapid temperature changes may occur, without risking damage or distortion.

What industries use Zerodur Glass-Ceramic?

Zerodur is widely used in industries such as aerospace, optics, astronomy, and precision metrology, where high stability and thermal resistance are critical for the performance of equipment and instruments.

Can Zerodur be easily machined or processed?

Zerodur can be machined with high precision, but it requires specialized tools and techniques due to its hardness and brittleness. It is often processed using diamond cutting or grinding tools to achieve the desired shape and surface finish.

How Does Zerodur Compare to Other Glass Materials?

1. Zerodur vs. ULE Glass (Ultra-Low Expansion Glass)

Both Zerodur and ULE glass are ultra-low expansion materials, but they differ in composition and performance.

Material Type: Zerodur is a glass-ceramic, while ULE is a fused silica-based glass.
CTE Stability: Zerodur offers a thermal expansion coefficient of approximately 0 ± 0.02 × 10⁻⁶/K, slightly better than ULE’s 0.03 × 10⁻⁶/K.
Homogeneity: ULE provides excellent optical homogeneity, making it suitable for optical lenses and mirrors. Zerodur, meanwhile, excels in mechanical and dimensional stability, perfect for precision mirror substrates and metrology systems.
Machining: Zerodur can be polished and machined to sub-micron precision with very low internal stress.

👉 In short: choose Zerodur for mechanical and thermal stability, and ULE for optical transmission and homogeneity.

2. Clearceram vs. Zerodur

Clearceram (by Ohara, Japan) and Zerodur (by SCHOTT, Germany) are both premium glass-ceramics with near-zero thermal expansion.

CTE Performance: Both offer similar CTE control (~0 ± 0.02 × 10⁻⁶/K), though Clearceram-Z HS is slightly more homogeneous in large blanks.
Optical Properties: Clearceram provides excellent transparency and is often used for optical metrology and laser systems. Zerodur, with its proven long-term dimensional stability, is widely used in astronomical mirrors and semiconductor equipment.
Availability: SCHOTT has extensive experience and global supply for large Zerodur blanks, while Clearceram is more common in Japan and high-end optical systems.

👉 Both materials perform at a world-class level; Zerodur is often preferred for large-scale precision optics.

3. Ohara Microcrystalline Glass vs. SCHOTT Zerodur

Japanese Ohara microcrystalline glass and German SCHOTT Zerodur belong to the same family of ultra-stable glass-ceramics.

Material Origin: Ohara produces Clearceram and related microcrystalline materials; SCHOTT manufactures Zerodur.
Performance: Both show outstanding stability, polishability, and resistance to temperature-induced deformation.
Application Difference: Ohara materials are often chosen for small, high-precision optical instruments, while SCHOTT Zerodur dominates in large telescope mirrors, lithography stages, and aerospace optics.

👉 Both brands represent the top level of glass-ceramic technology—SCHOTT Zerodur is favored for large, structural precision components, while Ohara excels in compact optical applications.