ZnS HP (Hot-pressed ZnS)
Other
also Cleartran, Irtran-2
Legacy/low-cost route for small IR windows and lenses where fine grain size gives good hardness but visible scatter and slightly lower LWIR transmission are acceptable.
Values for the HP condition
What is ZnS HP?
ZnS HP is ZnS in the HP condition — legacy/low-cost route for small IR windows and lenses where fine grain size gives good hardness but visible scatter and slightly lower LWIR transmission are acceptable. The elastic modulus is 87.6 GPa (12.7 Msi). ZnS HP has a density of 4.08 g/cm³ (0.147 lb/in³), heavier than 73% of glass grades. It melts at 1,830°C (3,326 °F).
Advantages
- Conducts heat well — 27.2 W/m·K (15.7 BTU/hr·ft·°F), better than 90% of glass grades
- Tough — resists crack growth — 1 MPa·√m (0.91 ksi·√in), better than 87% of glass grades
- Easy to machine — 45/100, better than 85% of glass grades
Limitations
- High embodied carbon — 30 kg CO₂/kg, worse than 82% of glass grades
ZnS HP properties
Typical room-temperature values for ZnS HP; 9 are specific to this condition. Other listed values are ZnS reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
ZnS HP has a density of 4.08 g/cm³ (0.147 lb/in³), heavier than 73% of glass grades. It melts at 1,830°C (3,326 °F).
Mechanical10
The elastic modulus is 87.6 GPa (12.7 Msi).
Thermal5
ZnS HP is rated for continuous service to 350°C (662 °F). It conducts heat at 27.2 W/m·K (15.7 BTU/hr·ft·°F), better than 90% of glass grades. Thermal expansion is 6.6 µm/m·K (3.67 µin/in·°F).
Electrical3
ZnS HP has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 74% of glass grades.
Sustainability4
Producing a kilogram of ZnS HP takes about 450 MJ of energy and emits 30 kg of CO₂ — more than 84% of glass grades. Typical recycled content is 0%.
Manufacturability3
ZnS HP's machinability is fair (45/100, better than 85% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZnS HP
Is ZnS easy to machine?
Soft and brittle — grind and lap with diamond, or single-point diamond turn to optical figure; use light loads and wet cutting to avoid chipping and to control toxic ZnS dust.
Can ZnS be welded?
Not weldable; joined only by optical contacting, epoxy/edge bonding or metal-to-glass style mounting in compliant retainers.
Can ZnS be formed, bent or molded?
Net shape is set by CVD deposition onto a mandrel (flat plates or domes), optionally followed by HIP for the multispectral grade; no plastic forming is possible.
What surface finishes work on ZnS?
Polishes to <20 Å rms with pitch/colloidal silica but scratches easily — almost always finished with AR/DLC or hard carbon coatings for durability and to cut the ~28 % Fresnel loss.
ZnS 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 |
|---|---|---|
| Znstoichiometric ZnS | 66.8 – 67.5 | 67.1 |
| S | ≥ 32.5 (balance) | — |
ZnS HP — frequently asked
What is ZnS HP used for?
ZnS HP is typically used for IR domes and windows, multispectral optics, missile seeker domes and thermal imaging. In short: rugged multispectral IR window; visible through far-IR transmission; tougher, cheaper than ZnSe.
Is ZnS HP easy to machine?
Reasonably — machinability is rated fair (45/100, better than 85% of glass grades). Soft and brittle — grind and lap with diamond, or single-point diamond turn to optical figure; use light loads and wet cutting to avoid chipping and to control toxic ZnS dust.
Can ZnS HP be welded?
Not weldable; joined only by optical contacting, epoxy/edge bonding or metal-to-glass style mounting in compliant retainers.
What surface finishes work on ZnS HP?
Polishes to <20 Å rms with pitch/colloidal silica but scratches easily — almost always finished with AR/DLC or hard carbon coatings for durability and to cut the ~28 % Fresnel loss.
Can ZnS HP be formed, bent or molded?
Net shape is set by CVD deposition onto a mandrel (flat plates or domes), optionally followed by HIP for the multispectral grade; no plastic forming is possible.
What is the maximum service temperature of ZnS HP?
ZnS HP 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
- CVD Zinc Sulfide and Multispectral ZnS optical material data — II-VI / Coherent (2022)
- Cleartran multispectral zinc sulfide — Dow / Rohm and Haas Advanced Materials (2008)
- Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- Handbook of Optical Constants of Solids — Academic Press (1998)
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.