ZERODUR M
Heat-treated state
also Schott ZERODUR, Astronomical Mirror Glass
M = thermomechanically controlled processed
Shorter ceramization route giving lower cost and shorter lead time at somewhat wider CTE tolerance — for large mirror substrates and mounts.
Values for the M condition
Other ZERODUR tempers and conditions
ZERODUR is listed in 6 conditions; see the grade overview at ZERODUR.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed GlassDefault standard ceramized & fine-annealed ZERODUR, Expansion Class 2 | Default commercial delivery state: ceramized, fine-annealed blank with CTE 0 ± 0.10 ×10⁻⁶/K — use for general precision optics and mechanical metrology parts. | — | 30 | — | 620 HV | 1 W/m·K |
Expansion Class 1 | Tighter-CTE selection for telescope mirror blanks and stable structures where thermal drift budget is a few nanometres. | — | 30 | — | 620 HV | 1 W/m·K |
Expansion Class 0 | Premium selected class for EUV lithography optics, ring-laser gyros and length standards; long ceramization/selection cycle raises price and lead time. | — | 30 | — | 620 HV | 1 W/m·K |
Expansion Class 0 EXTREME | Highest-specification tolerance class, reserved for EUV mask blanks and ultra-stable metrology where CTE must be near-perfectly zero. | — | 30 | — | 620 HV | 1 W/m·K |
MThis page Thermomechanically controlled processed | Shorter ceramization route giving lower cost and shorter lead time at somewhat wider CTE tolerance — for large mirror substrates and mounts. | — | 30 | 0 | 620 HV | 1 W/m·K |
ZERODUR K20 | Companion glass-ceramic with a deliberate small positive CTE, chosen to CTE-match metals/coatings or as a lower-cost mechanically similar substrate. | — | 30 | — | 620 HV | 2 W/m·K |
What is ZERODUR M?
ZERODUR M is ZERODUR heat treated to M — shorter ceramization route giving lower cost and shorter lead time at somewhat wider CTE tolerance — for large mirror substrates and mounts. ZERODUR M has a tensile strength of 30 MPa (4.35 ksi), weaker than 80% of glass grades. The elastic modulus is 90 GPa (13.1 Msi). ZERODUR M has a density of 2.53 g/cm³ (0.0914 lb/in³), lighter than 66% of glass grades. Annealed Glass is the default condition FabDigit quotes; M is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 0.9 MPa·√m (0.819 ksi·√in), better than 79% of glass grades
- Stiff — 90 GPa (13.1 Msi), better than 75% of glass grades
ZERODUR M properties
Typical room-temperature values for ZERODUR M; 15 are specific to this condition. Other listed values are ZERODUR reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
ZERODUR M has a density of 2.53 g/cm³ (0.0914 lb/in³), lighter than 66% of glass grades.
Mechanical11
ZERODUR M has a tensile strength of 30 MPa (4.35 ksi), weaker than 80% of glass grades. The elastic modulus is 90 GPa (13.1 Msi).
Thermal5
ZERODUR M is rated for continuous service to 500°C (932 °F). It conducts heat at 1.5 W/m·K (0.844 BTU/hr·ft·°F), better than 59% of glass grades. Thermal expansion is 0 µm/m·K (0 µin/in·°F).
Electrical5
ZERODUR M is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (85/100), better than 65% of glass grades.
Sustainability4
Producing a kilogram of ZERODUR M takes about 90 MJ of energy and emits 6.5 kg of CO₂ — more than 66% of glass grades. Typical recycled content is 0%.
Manufacturability3
ZERODUR M's machinability is poor (20/100, better than 56% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZERODUR M
Is ZERODUR easy to machine?
Diamond grinding, core drilling, lapping and ultrasonic machining only — no conventional cutting; keep coolant flooded and avoid edge chipping, then acid-etch or fine-grind to remove subsurface damage.
Can ZERODUR be welded?
Not weldable; parts are joined by optical contacting, low-stress epoxy/silicate bonding, frit bonding or Invar/steel flexure mounts.
Can ZERODUR be formed, bent or molded?
Supplied as cast, ceramized blanks; near-net shapes (lightweighted honeycomb mirrors) are produced by machining the blank, not by hot forming, since re-heating above ~600 °C alters the crystal phase and CTE.
What surface finishes work on ZERODUR?
Polishes to sub-nanometre rms and accepts ion-beam figuring plus Al/Ag/dielectric and multilayer coatings; a light etch after grinding recovers much of the bending strength.
ZERODUR chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| SiO2network former | 54 – 58 | 55.5 |
| Al2O3 | 24 – 26 | 25.3 |
| P2O5 | 6.5 – 8.5 | 7.5 |
| Li2Oforms high-quartz solid solution crystals | 3 – 4.5 | 3.7 |
| TiO2nucleating agent | 2 – 2.6 | 2.3 |
| ZrO2nucleating agent | 1.5 – 2.2 | 1.9 |
| ZnO | 1 – 1.8 | 1.4 |
| MgO | 0.5 – 1.5 | 1 |
| Na2O | 0.2 – 0.8 | 0.5 |
| K2O | 0 – 0.8 | 0.5 |
| As2O3fining agent in classic composition; arsenic-free melts also offered | 0 – 0.6 | 0.4 |
ZERODUR M — frequently asked
What is ZERODUR M used for?
ZERODUR M is typically used for telescope mirror blanks, astronomical optics, lightweighted honeycomb mirror substrates, metrology reference plates and straightedges, ring laser gyroscope bodies and lithography stages and mask blanks. In short: zero-expansion glass-ceramic.
What is the tensile strength of ZERODUR M?
ZERODUR M has a typical tensile strength of 30 MPa (4.35 ksi) — weaker than 80% of glass grades. Strength varies by condition: see the 6 listed tempers.
Is ZERODUR M easy to machine?
Not especially — machinability is rated poor (20/100, better than 56% of glass grades). Diamond grinding, core drilling, lapping and ultrasonic machining only — no conventional cutting; keep coolant flooded and avoid edge chipping, then acid-etch or fine-grind to remove subsurface damage.
Can ZERODUR M be welded?
Not weldable; parts are joined by optical contacting, low-stress epoxy/silicate bonding, frit bonding or Invar/steel flexure mounts.
What surface finishes work on ZERODUR M?
Polishes to sub-nanometre rms and accepts ion-beam figuring plus Al/Ag/dielectric and multilayer coatings; a light etch after grinding recovers much of the bending strength.
Can ZERODUR M be formed, bent or molded?
Supplied as cast, ceramized blanks; near-net shapes (lightweighted honeycomb mirrors) are produced by machining the blank, not by hot forming, since re-heating above ~600 °C alters the crystal phase and CTE.
What is the maximum service temperature of ZERODUR M?
ZERODUR M is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ZERODUR — Zero Expansion Glass Ceramic, technical data — SCHOTT AG (2023)
- Strength of ZERODUR (TIE-33 / strength brochure) — SCHOTT AG (2021)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- Glass-ceramic property compilations (LAS system) — MatWeb / Ceramic Industry data (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.