SF11 N-SF11
Grade
GB ZF11
N-SF11 = lead- and arsenic-free equivalent
Pick for new RoHS/REACH-driven designs: identical nd 1.7847 / vd 25.7 optics at ~32 % lower density, harder surface, better blue transmission.
Values for the N-SF11 condition
Other SF11 tempers and conditions
SF11 is listed in 2 conditions; see the grade overview at SF11.
- SF11
- N-SF11
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SF11Default Classic lead dense flint, fine annealed | Pick for legacy/high-index designs where the very soft, easily polished leaded flint and its exact dispersion curve must be reproduced. | — | — | — | 450 HV | 0.74 W/m·K |
N-SF11This page Lead- and arsenic-free equivalent | Pick for new RoHS/REACH-driven designs: identical nd 1.7847 / vd 25.7 optics at ~32 % lower density, harder surface, better blue transmission. | — | — | — | 590 HV | 0.95 W/m·K |
What is SF11 N-SF11?
SF11 N-SF11 is SF11 in the N-SF11 grade — pick for new RoHS/REACH-driven designs: identical nd 1.7847 / vd 25.7 optics at ~32 % lower density, harder surface, better blue transmission. SF11 N-SF11 has a tensile strength of 40 MPa (5.8 ksi), weaker than 65% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi). SF11 N-SF11 has a density of 3.22 g/cm³ (0.116 lb/in³), heavier than 64% of glass grades. SF11 is the default condition FabDigit quotes; N-SF11 is available on request or by drawing note.
Advantages
- Stiff — 92 GPa (13.3 Msi), better than 78% of glass grades
Limitations
- Poor heat conductor — 0.95 W/m·K (0.549 BTU/hr·ft·°F), worse than 80% of glass grades
SF11 N-SF11 properties
Typical room-temperature values for SF11 N-SF11; 19 are specific to this condition. Other listed values are SF11 reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
SF11 N-SF11 has a density of 3.22 g/cm³ (0.116 lb/in³), heavier than 64% of glass grades.
Mechanical12
SF11 N-SF11 has a tensile strength of 40 MPa (5.8 ksi), weaker than 65% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal5
SF11 N-SF11 is rated for continuous service to 400°C (752 °F). It conducts heat at 0.95 W/m·K (0.549 BTU/hr·ft·°F), worse than 80% of glass grades. Thermal expansion is 8.5 µm/m·K (4.72 µin/in·°F).
Electrical5
SF11 N-SF11 is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is good (60/100), worse than 68% of glass grades.
Sustainability4
Producing a kilogram of SF11 N-SF11 takes about 45 MJ of energy and emits 3.2 kg of CO₂ — less than 58% of glass grades. Typical recycled content is 5%.
Manufacturability2
SF11 N-SF11's machinability is poor (22/100, better than 59% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SF11 N-SF11
Is SF11 easy to machine?
No conventional machining — diamond core-drilling, curve generating, loose-abrasive grinding then pitch/polyurethane polishing with cerium oxide; the soft leaded surface scratches and sleeks easily, so keep swarf clean.
Can SF11 be welded?
Not weldable; joining is by optical contacting or UV/thermal-cure optical cement (NOA-type) to matched-CTE partner glasses.
Can SF11 be formed, bent or molded?
Formed by melting and precision gob pressing or by re-heat pressing of blanks near 620–700 °C, followed by fine (precision) annealing near Tg ≈ 505 °C at a few °C/h to hold refractive index and low stress birefringence.
What surface finishes work on SF11?
Polish to λ/4 or better, then AR-coat by e-beam/IAD — coating temperature must stay well under Tg; edges are blackened and lenses centered on a bell chuck.
SF11 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 |
|---|---|---|
| PbOapproximate; exact optical-melt batch is proprietary (leaded SF11/ZF11 only) | 45 – 55 | 51 |
| K2Oalkali modifier | 4 – 10 | 8 |
| Na2O | 0 – 3 | 1 |
| other oxides (BaO, ZnO, As2O3/Sb2O3 finiN-SF11 replaces PbO with TiO2/Nb2O5/ZrO2-type high-index oxides and is As/Pb-free | 0 – 5 | 2 |
| SiO2network former | ≥ 28 (balance) | — |
SF11 N-SF11 — frequently asked
What is SF11 N-SF11 used for?
SF11 N-SF11 is typically used for high-index camera lenses, prisms and beam splitters. In short: very high refractive index; leaded SF11, N-SF11 alternative.
What is the tensile strength of SF11 N-SF11?
SF11 N-SF11 has a typical tensile strength of 40 MPa (5.8 ksi) — weaker than 65% of glass grades. Strength varies by condition: see the 2 listed tempers.
Is SF11 N-SF11 easy to machine?
Not especially — machinability is rated poor (22/100, better than 59% of glass grades). No conventional machining — diamond core-drilling, curve generating, loose-abrasive grinding then pitch/polyurethane polishing with cerium oxide; the soft leaded surface scratches and sleeks easily, so keep swarf clean.
Can SF11 N-SF11 be welded?
Not weldable; joining is by optical contacting or UV/thermal-cure optical cement (NOA-type) to matched-CTE partner glasses.
What surface finishes work on SF11 N-SF11?
Polish to λ/4 or better, then AR-coat by e-beam/IAD — coating temperature must stay well under Tg; edges are blackened and lenses centered on a bell chuck.
Can SF11 N-SF11 be formed, bent or molded?
Formed by melting and precision gob pressing or by re-heat pressing of blanks near 620–700 °C, followed by fine (precision) annealing near Tg ≈ 505 °C at a few °C/h to hold refractive index and low stress birefringence.
What is the maximum service temperature of SF11 N-SF11?
SF11 N-SF11 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Optical Glass Data Sheets (SF11 / N-SF11) — SCHOTT AG (2023)
- Optical Glass Catalog (ZF / H-ZF dense flint series) — CDGM (2023)
- Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- RefractiveIndex / optical glass dispersion data (Sellmeier constants) — public optical glass databases (2024)
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.