N-SF11-FA
Heat-treated state
N-SF11-FA = n-SF11 fine/precision annealed
Choose the slow, precision-annealed material for high-accuracy imaging and interferometric optics: index homogeneity and internal stress birefringence are markedly better than coarse annealed stock.
Values for the N-SF11-FA condition
Other N-SF11 tempers and conditions
N-SF11 is listed in 3 conditions; see the grade overview at N-SF11.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
N-SF11Default Lead- and arsenic-free heavy flint, standard (coarse) annealed… | Pick the standard coarse-annealed block or strip as the default lead- and arsenic-free high-index flint for achromatic cemented doublets and high-power lenses. | — | 45 | 0 | 470 HV | 0.75 W/m·K |
N-SF11-FAThis page N-SF11 fine/precision annealed | Choose the slow, precision-annealed material for high-accuracy imaging and interferometric optics: index homogeneity and internal stress birefringence are markedly better than coarse annealed stock. | — | 45 | 0 | 470 HV | 0.75 W/m·K |
Classic lead-containing heavy flint | Use the classic lead-containing heavy flint only for legacy designs or when lower thermal expansion and more stable index versus temperature are required; about 50% PbO restricts it under RoHS. | — | — | — | 420 HV | 0.74 W/m·K |
What is N-SF11-FA?
N-SF11-FA is N-SF11 heat treated to N-SF11-FA — choose the slow, precision-annealed material for high-accuracy imaging and interferometric optics: index homogeneity and internal stress birefringence are markedly better than coarse annealed stock. N-SF11-FA has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi). N-SF11-FA has a density of 3.2 g/cm³ (0.116 lb/in³), heavier than 61% of glass grades. N-SF11 is the default condition FabDigit quotes; N-SF11-FA 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 — 0.75 W/m·K (0.433 BTU/hr·ft·°F), worse than 92% of glass grades
N-SF11-FA properties
Typical room-temperature values for N-SF11-FA; 17 are specific to this condition. Other listed values are N-SF11 reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
N-SF11-FA has a density of 3.2 g/cm³ (0.116 lb/in³), heavier than 61% of glass grades.
Mechanical13
N-SF11-FA has a tensile strength of 45 MPa (6.53 ksi), weaker than 56% of glass grades. Elongation at break is 0% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal5
N-SF11-FA is rated for continuous service to 350°C (662 °F). It conducts heat at 0.75 W/m·K (0.433 BTU/hr·ft·°F), worse than 92% of glass grades. Thermal expansion is 8.5 µm/m·K (4.72 µin/in·°F).
Electrical2
N-SF11-FA has an electrical 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 N-SF11-FA takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 58% of glass grades. Typical recycled content is 20%.
Manufacturability2
N-SF11-FA's machinability is poor (15/100, worse than 54% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with N-SF11-FA
Is N-SF11 easy to machine?
Not conventionally machinable: shape by diamond-wheel curve generating, precision lapping and pitch or polyurethane polishing. The material is relatively soft and scratches readily, so control abrasive grit size and pressure and support edges to prevent chipping.
Can N-SF11 be welded?
Not weldable; elements are held by optical cement (UV or thermal cure), optical contact, or mechanical mounts. Allow for cement-layer stress caused by CTE mismatch with crown glasses.
Can N-SF11 be formed, bent or molded?
Melted in crucible or continuous furnaces and formed into strip or pressed blanks, then annealed. The low softening point allows precision moulding of aspheres in graphite moulds under inert atmosphere.
What surface finishes work on N-SF11?
AR-coat as soon as possible after polishing: single-surface reflection is about 7%, so an uncoated element loses roughly 14% across both faces. Clean with neutral solvents only and store dry.
N-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.
| Element | Spec limit (wt %) |
|---|---|
| TiO2main high-index/high-dispersion component, lead-free flint | — |
| Nb2O5raises refractive index and dispersion | — |
| BaOadjusts refractive index and melting behavior | — |
| Na2Oalkali oxide flux | — |
| K2Oalkali oxide flux | — |
| ZrO2improves chemical durability (small addition) | — |
| PbON-SF11 Pb- and As-free; legacy SF11 has about 50 wt% PbO | ≈ 0 |
| SiO2network former, balance; exact formulation proprietary | balance |
N-SF11-FA — frequently asked
What is N-SF11-FA used for?
N-SF11-FA is typically used for achromatic doublets, camera lenses, prisms and optical instruments. In short: high index, high dispersion; lead-free SF11 replacement.
What is the tensile strength of N-SF11-FA?
N-SF11-FA has a typical tensile strength of 45 MPa (6.53 ksi) — weaker than 56% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is N-SF11-FA easy to machine?
Not especially — machinability is rated poor (15/100, worse than 54% of glass grades). Not conventionally machinable: shape by diamond-wheel curve generating, precision lapping and pitch or polyurethane polishing. The material is relatively soft and scratches readily, so control abrasive grit size and pressure and support edges to prevent chipping.
Can N-SF11-FA be welded?
Not weldable; elements are held by optical cement (UV or thermal cure), optical contact, or mechanical mounts. Allow for cement-layer stress caused by CTE mismatch with crown glasses.
What surface finishes work on N-SF11-FA?
AR-coat as soon as possible after polishing: single-surface reflection is about 7%, so an uncoated element loses roughly 14% across both faces. Clean with neutral solvents only and store dry.
Can N-SF11-FA be formed, bent or molded?
Melted in crucible or continuous furnaces and formed into strip or pressed blanks, then annealed. The low softening point allows precision moulding of aspheres in graphite moulds under inert atmosphere.
What is the maximum service temperature of N-SF11-FA?
N-SF11-FA is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- N-SF11 Optical Glass Data Sheet — SCHOTT AG (2023)
- Optical Glass Collection Datasheets / TIE technical information — SCHOTT AG (2022)
- ASM Engineered Materials Handbook, Vol.4: Ceramics and Glasses — ASM International (1991)
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.