Robax
also Schott Robax, Stove Glass
Robax is a transparent low-expansion glass-ceramic panel material engineered for rapid thermal cycling, rated for service to 700 °C.
Reference datasheet — Robax is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed Glass condition
Robax tempers and conditions
Robax is supplied in 2 conditions, soft to hard. Annealed Glass is the default FabDigit quotes; the values on this page are for it.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed GlassDefault as-ceramized transparent Robax panel, no coating | Standard choice for fireplace and stove viewing windows, oven doors and furnace sight glasses where clear vision and thermal-shock resistance are needed. | 35 | 0 | 590 HV | 2 W/m·K | |
transparent LAS glass-ceramic (Nippon Electric Glass equivalent) | Functionally interchangeable Asian-sourced transparent glass-ceramic; usually cheaper in China/Japan supply chains with slightly lower density and marginally negative CTE. | 45 | 0 | 620 HV | 2 W/m·K |
Supply forms, finishes and certifications
Ways Robax is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
IR-COATED | ROBAX IR | Supply form |
What is Robax?
Robax is a transparent low-expansion glass-ceramic panel material engineered for rapid thermal cycling, rated for service to 700 °C. Engineers use it where a viewing window must survive direct flame contact and thermal shock, supplied as flat or roller-formed curved panels, plain, IR-coated, or as the NEOCERAM-N0 variant. It is ceramized at the factory and cannot be re-formed, tempered, or scored and snapped; cutting is limited to diamond grinding, waterjet or laser. Borosilicate is the cheaper choice where peak temperature stays well below this range. Robax has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 64% of glass grades. Robax has a tensile strength of 35 MPa (5.08 ksi), weaker than 75% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
What is Robax used for?
- Fireplace and stove door panels
- Cooktop panels
- Wood and pellet stove viewing windows
- Furnace and kiln sight glasses
- Commercial and pizza oven windows
- Gas fire viewing panels
- IR and halogen heater covers
Advantages
- Tough — resists crack growth — 0.9 MPa·√m (0.819 ksi·√in), better than 79% of glass grades
- Stiff — 92 GPa (13.3 Msi), better than 78% of glass grades
- High service temperature — 700°C (1,292 °F), better than 76% of glass grades
Limitations
- Difficult to machine — 6/100, worse than 87% of glass grades
Robax properties
Typical room-temperature values for Robax-Annealed Glass; bars are the position among glass grades.
Physical4
Robax has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 64% of glass grades.
Mechanical13
Robax has a tensile strength of 35 MPa (5.08 ksi), weaker than 75% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal5
Robax is rated for continuous service to 700°C (1,292 °F). It conducts heat at 1.6 W/m·K (0.924 BTU/hr·ft·°F), better than 62% of glass grades. Thermal expansion is 0.1 µm/m·K (0.0556 µin/in·°F).
Electrical5
Robax is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (85/100), better than 65% of glass grades.
Sustainability4
Producing a kilogram of Robax takes about 30 MJ of energy and emits 2.2 kg of CO₂ — less than 79% of glass grades. Typical recycled content is 0%.
Manufacturability3
Robax's machinability is not recommended (6/100, worse than 87% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. Robax is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Robax
Is Robax easy to machine?
Diamond grinding, water-jet or CO2/fiber laser cutting only; no scoring-and-snapping like soda-lime, and edges must be seamed/ground to remove flaws.
Can Robax be welded?
Not weldable; joined mechanically with gaskets or with high-temperature silicone/ceramic adhesives and rope seals.
Can Robax be formed, bent or molded?
Supplied as flat or roller-formed curved panels ceramized at the factory; end users cannot re-form or temper it — near-zero CTE means it is not (and need not be) thermally toughened.
Robax 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 |
|---|---|---|
| Al2O3 | 17 – 21 | 19 |
| Li2Oforms β-quartz solid solution → near-zero CTE | 3 – 4.5 | 3.7 |
| MgO | 0.5 – 2 | 1 |
| ZnO | 0.5 – 2.5 | 1.5 |
| TiO2nucleating agent | 1.5 – 3 | 2.3 |
| ZrO2nucleating agent | 1 – 2.5 | 1.8 |
| Na2O+K2Oresidual alkalis | 0.2 – 1.5 | 0.8 |
| BaO | 0 – 2 | 0.8 |
| fining agents (SnO2/As2O3-free modern ba | 0 – 1 | 0.3 |
| SiO2network former | ≥ 63 (balance) |
What surface finishes work on Robax?
Screen-printed ceramic decoration, anti-reflective or IR-reflective sputtered coatings, and fine polishing are all possible; avoid HF-based cleaners and abrasive pads on coated faces.
Equivalent designations
Standards and trade names that resolve to Robax in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Schott RobaxStove Glass
How much does Robax cost?
Robax is a standard-cost glass ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Robax — frequently asked
What is Robax used for?
Robax is typically used for fireplace and stove door panels, cooktop panels, wood and pellet stove viewing windows, furnace and kiln sight glasses, commercial and pizza oven windows and gas fire viewing panels. In short: transparent fireproof ceramic.
What is the tensile strength of Robax?
Robax has a typical tensile strength of 35 MPa (5.08 ksi) — weaker than 75% of glass grades. Strength varies by condition: see the 2 listed tempers.
Is Robax easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 87% of glass grades). Diamond grinding, water-jet or CO2/fiber laser cutting only; no scoring-and-snapping like soda-lime, and edges must be seamed/ground to remove flaws.
Can Robax be welded?
Not weldable; joined mechanically with gaskets or with high-temperature silicone/ceramic adhesives and rope seals.
What surface finishes work on Robax?
Screen-printed ceramic decoration, anti-reflective or IR-reflective sputtered coatings, and fine polishing are all possible; avoid HF-based cleaners and abrasive pads on coated faces.
Can Robax be formed, bent or molded?
Supplied as flat or roller-formed curved panels ceramized at the factory; end users cannot re-form or temper it — near-zero CTE means it is not (and need not be) thermally toughened.
What is the maximum service temperature of Robax?
Robax is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Robax cost?
Robax is a standard-cost glass ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ROBAX transparent glass-ceramic — technical data — SCHOTT AG (2023)
- NEOCERAM N-0 / N-11 glass-ceramic data sheet — Nippon Electric Glass (2021)
- ASM Engineered Materials Handbook Vol. 4 — Ceramics and Glasses (glass-ceramics chapter) — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.