KCl HF
Grade
HF = hot-forged / press-forged polycrystalline KCl
Grain-refined by hot forging (~400–600 °C) to raise yield and flexural strength several-fold; used for large high-power CO₂ laser windows that cannot be supported as fragile single crystals.
Values for the HF condition
Other KCl tempers and conditions
KCl is listed in 3 conditions; see the grade overview at KCl.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SCDefault Single crystal, Bridgman/Czochralski grown, optical grade | Standard optical-grade single crystal for IR windows, prisms and FTIR cells where cost and broad transmission matter more than strength. | — | 2 | 2 | 9 HV | 7 W/m·K |
Reactive-atmosphere-processed low-absorption single crystal | Grown/purified under HCl reactive atmosphere to strip OH⁻ and metal impurities; pick for high-average-power 10.6 µm CO₂ laser windows. | — | 2 | 2 | 9 HV | 7 W/m·K |
HFThis page Hot-forged / press-forged polycrystalline KCl | Grain-refined by hot forging (~400–600 °C) to raise yield and flexural strength several-fold; used for large high-power CO₂ laser windows that cannot be supported as fragile single crystals. | — | 12 | 3 | 15 HV | 6 W/m·K |
What is KCl HF?
KCl HF is KCl in the HF grade — grain-refined by hot forging (~400–600 °C) to raise yield and flexural strength several-fold; used for large high-power CO₂ laser windows that cannot be supported as fragile single crystals. KCl HF has a tensile strength of 12 MPa (1.74 ksi), weaker than 92% of glass grades. Elongation at break is 3% and the elastic modulus is 30 GPa (4.35 Msi). KCl HF has a density of 1.98 g/cm³ (0.0717 lb/in³), lighter than 100% of glass grades. It melts at 771°C (1,420 °F). SC is the default condition FabDigit quotes; HF is available on request or by drawing note.
Advantages
- Lightweight — 1.98 g/cm³ (0.0717 lb/in³), better than 100% of glass grades
- Easy to machine — 65/100, better than 98% of glass grades
- Ductile — tolerates forming and impact — 3%, better than 90% of glass grades
Limitations
- Needs corrosion protection — 5/100, worse than 98% of glass grades
- Hard to polish — 45/100, worse than 92% of glass grades
- Low stiffness — 30 GPa (4.35 Msi), worse than 86% of glass grades
- Low fracture toughness — 0.5 MPa·√m (0.455 ksi·√in), worse than 76% of glass grades
KCl HF properties
Typical room-temperature values for KCl HF; 17 are specific to this condition. Other listed values are KCl reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
KCl HF has a density of 1.98 g/cm³ (0.0717 lb/in³), lighter than 100% of glass grades. It melts at 771°C (1,420 °F).
Mechanical13
KCl HF has a tensile strength of 12 MPa (1.74 ksi), weaker than 92% of glass grades. Elongation at break is 3% and the elastic modulus is 30 GPa (4.35 Msi).
Thermal5
KCl HF is rated for continuous service to 450°C (842 °F). It conducts heat at 6.3 W/m·K (3.64 BTU/hr·ft·°F), better than 73% of glass grades. Thermal expansion is 36 µm/m·K (20 µin/in·°F).
Electrical3
KCl HF has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (5/100), worse than 98% of glass grades.
Sustainability3
Producing a kilogram of KCl HF takes about 40 MJ of energy and emits 3 kg of CO₂ — less than 69% of glass grades. Typical recycled content is 20%.
Manufacturability2
KCl HF's machinability is good (65/100, better than 98% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with KCl HF
Is KCl easy to machine?
Cuts easily with dry diamond saws or single-point diamond turning at light depth of cut; never use water-based coolant — cleave planes {100} make it prone to chipping.
Can KCl be welded?
Not weldable; parts are cemented or mechanically clamped with compliant (indium/PTFE) seats to avoid stress-induced fracture.
Can KCl be formed, bent or molded?
Bulk blanks are Bridgman/Czochralski grown; large windows can be hot press-forged at 400–600 °C to refine grains and raise strength.
What surface finishes work on KCl?
Polish with dry or anhydrous (alcohol/kerosene) slurries in a low-humidity room; AR or moisture-barrier coatings (e.g. ThF₄/ZnSe, parylene) are standard for field use.
KCl 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 KCl | 52.3 – 52.6 | 52.45 |
| total metallic impuritiesoptical grade, typically ≤20–50 ppm; OH⁻ minimized in RAP material | ≤ 0.01 | 0 |
| Cl | balance | — |
KCl HF — frequently asked
What is KCl HF used for?
KCl HF is typically used for CO2 laser windows, IR spectroscopy optics and IR prisms. In short: low-absorption CO2 laser window; lower cost than KBr; hygroscopic, purge required.
What is the tensile strength of KCl HF?
KCl HF has a typical tensile strength of 12 MPa (1.74 ksi) — weaker than 92% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is KCl HF easy to machine?
Reasonably — machinability is rated good (65/100, better than 98% of glass grades). Cuts easily with dry diamond saws or single-point diamond turning at light depth of cut; never use water-based coolant — cleave planes {100} make it prone to chipping.
Can KCl HF be welded?
Not weldable; parts are cemented or mechanically clamped with compliant (indium/PTFE) seats to avoid stress-induced fracture.
What surface finishes work on KCl HF?
Polish with dry or anhydrous (alcohol/kerosene) slurries in a low-humidity room; AR or moisture-barrier coatings (e.g. ThF₄/ZnSe, parylene) are standard for field use.
Can KCl HF be formed, bent or molded?
Bulk blanks are Bridgman/Czochralski grown; large windows can be hot press-forged at 400–600 °C to refine grains and raise strength.
What is the maximum service temperature of KCl HF?
KCl HF is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Potassium Chloride (KCl) optical material data — Crystran Ltd (2023)
- KCl Kristalle — Kenndaten — Korth Kristalle GmbH (2022)
- Handbook of Optical Constants of Solids — Academic Press (Palik, ed.) (1998)
- Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- CRC Handbook of Chemistry and Physics, 102nd ed. — CRC Press (2021)
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.