KBr HP
Other
HP = hot-pressed / forged polycrystalline KBr
Choose when larger, tougher and less cleavage-prone blanks are needed and slight far-IR scatter is acceptable.
Values for the HP condition
Other KBr tempers and conditions
KBr is listed in 3 conditions; see the grade overview at KBr.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spectroscopic-grade powder for pressed pellets | Choose for making 13 mm KBr pellets of solid samples in FTIR analysis; consumable, not an optical component. | — | 3 | 0.1 | 7 HV | 4 W/m·K |
SCDefault Single crystal, IR window / prism grade | Choose for IR windows, prisms, beamsplitter substrates and ATR optics needing maximum 0.25–25 µm clarity. | — | — | — | 6 HV | 5 W/m·K |
HPThis page Hot-pressed / forged polycrystalline KBr | Choose when larger, tougher and less cleavage-prone blanks are needed and slight far-IR scatter is acceptable. | — | — | — | 9 HV | 5 W/m·K |
What is KBr HP?
KBr HP is KBr in the HP condition — choose when larger, tougher and less cleavage-prone blanks are needed and slight far-IR scatter is acceptable. The elastic modulus is 26 GPa (3.77 Msi). KBr HP has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 51% of glass grades. It melts at 734°C (1,353 °F). SC is the default condition FabDigit quotes; HP is available on request or by drawing note.
Advantages
- Easy to machine — 60/100, better than 97% of glass grades
Limitations
- Needs corrosion protection — 5/100, worse than 98% of glass grades
- Low fracture toughness — 0.15 MPa·√m (0.137 ksi·√in), worse than 97% of glass grades
- Hard to polish — 45/100, worse than 92% of glass grades
- Low stiffness — 26 GPa (3.77 Msi), worse than 90% of glass grades
- Limited service temperature — 250°C (482 °F), worse than 83% of glass grades
KBr HP properties
Typical room-temperature values for KBr HP; 11 are specific to this condition. Other listed values are KBr reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
KBr HP has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 51% of glass grades. It melts at 734°C (1,353 °F).
Mechanical10
The elastic modulus is 26 GPa (3.77 Msi).
Thermal4
KBr HP is rated for continuous service to 250°C (482 °F). It conducts heat at 4.5 W/m·K (2.6 BTU/hr·ft·°F), better than 68% of glass grades. Thermal expansion is 43 µm/m·K (23.9 µin/in·°F).
Electrical3
KBr HP has an electrical resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (5/100), worse than 98% of glass grades.
Sustainability2
Producing a kilogram of KBr HP takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 58% of glass grades.
Manufacturability2
KBr HP's machinability is good (60/100, better than 97% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with KBr HP
Is KBr easy to machine?
Cleaves readily on {100}; saw or single-point diamond turn dry with low forces, never use water-based coolant — use dry air, kerosene or anhydrous alcohol-free oils.
Can KBr be welded?
Not weldable; assemble as a mounted optic with dry elastomer or indium seals and avoid hard clamping on the soft crystal.
Can KBr be formed, bent or molded?
Cold-pressed at ~700–1000 MPa into transparent FTIR pellets; can be hot-forged/hot-pressed near 400 °C into larger polycrystalline blanks.
What surface finishes work on KBr?
Polish with anhydrous solvents (dry ethanol/isopropanol-free oil slurries) on pitch; store desiccated, and consider parylene or thin polymer moisture-barrier coatings — conventional AR coatings adhere poorly.
KBr 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 |
|---|---|---|
| Kstoichiometric KBr | 32.5 – 33.1 | 32.85 |
| total impuritiesoptical grade typically ≥99.95 %; main contaminants Cl, SO4, Ca, H2O/OH- | ≤ 0.5 | 0.05 |
| Br | ≥ 66.8 (balance) | — |
KBr HP — frequently asked
What is KBr HP used for?
KBr HP is typically used for FTIR windows/pellets, IR spectroscopy cells and IR prisms. In short: widest IR transmission range; standard FTIR pellet material; strongly hygroscopic.
Is KBr HP easy to machine?
Reasonably — machinability is rated good (60/100, better than 97% of glass grades). Cleaves readily on {100}; saw or single-point diamond turn dry with low forces, never use water-based coolant — use dry air, kerosene or anhydrous alcohol-free oils.
Can KBr HP be welded?
Not weldable; assemble as a mounted optic with dry elastomer or indium seals and avoid hard clamping on the soft crystal.
What surface finishes work on KBr HP?
Polish with anhydrous solvents (dry ethanol/isopropanol-free oil slurries) on pitch; store desiccated, and consider parylene or thin polymer moisture-barrier coatings — conventional AR coatings adhere poorly.
Can KBr HP be formed, bent or molded?
Cold-pressed at ~700–1000 MPa into transparent FTIR pellets; can be hot-forged/hot-pressed near 400 °C into larger polycrystalline blanks.
What is the maximum service temperature of KBr HP?
KBr HP is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Potassium Bromide (KBr) optical crystal data — Crystran Ltd (2023)
- KBr IR window and lens specifications — ISP Optics / Thorlabs (2022)
- CRC Handbook of Chemistry and Physics, 102nd ed. — CRC Press (2021)
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- Refractive index dispersion of alkali halides (Li, J. Phys. Chem. Ref. Data) — NIST/AIP (1976)
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.