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?

Zerodur is a glass-ceramic material developed by SCHOTT featuring an extremely low coefficient of thermal expansion (CTE ~0 ± 0.02 × 10⁻⁶/K). It is widely used in precision optics, astronomy, laser systems, and semiconductor inspection equipment due to its dimensional stability and excellent homogeneity.

What other low-thermal-expansion glasses exist?

Common alternatives include:

ULE® (Ultra-Low Expansion glass) – Corning
ClearCeram®-Z – Ohara
Fused silica (high-purity quartz) – low CTE but not as close to zero
Sitall/ Astrositall (Russia) – zero-expansion glass-ceramic
These materials are typically used in optical benches, mirrors, metrology systems, and thermal-stable frameworks.

Which is better for high-precision optics: Zerodur or ULE?

Both are excellent, but:

Zerodur offers better long-term dimensional stability, higher stiffness, and excellent homogeneity for large optics (e.g., telescope mirrors).
ULE has slightly lower density and is preferred for certain UV optical applications and smaller precision components.
For most ultra-precision optical mirrors and metrology systems, Zerodur is generally the preferred choice.

Does Zerodur’s performance change in cryogenic or vacuum environments?

Minimal. Zerodur maintains very low thermal expansion, stable modulus, and no outgassing under vacuum. In cryogenic conditions, its CTE curve remains extremely flat compared to other materials, making it suitable for space optics, cryo-lasers, and vacuum interferometry systems.

What grades of Zerodur glass can your company provide?

Jundro Ceramics supplies multiple grades of Zerodur glass-ceramic, including:

Standard Zerodur for optical/structural parts
Zerodur-Extreme Low Expansion (CTE-selected grades) for metrology
High-homogeneity grades for optics, laser systems, and scientific instruments
We also offer precision grinding, polishing, and 5-axis machining for custom Zerodur components.

Is Zerodur suitable for prototyping? What is the typical lead time?

Yes. Zerodur is excellent for prototyping small optical or structural components because it machines and polishes well.
Typical lead times from Jundro Ceramics:

Prototype parts: 1–3 weeks depending on complexity
High-precision optics or large blocks: 3–6 weeks
We provide material traceability, CTE certificates, and full QC reports with each batch.