HfO2 99.99
Grade
Pick for UV–IR high-refractive-index coatings, laser mirrors and gate-dielectric/ALD film work where trace metals and absorption must be minimal.
Values for the 99.99 condition
Other HfO2 tempers and conditions
HfO2 is listed in 4 conditions; see the grade overview at HfO2.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Plasma-spray / EB-PVD coating grade | Spray-dried or fused-and-crushed powder deposited as a porous, strain-tolerant thermal/environmental barrier layer on superalloys and C/C-SiC. | — | 25 | 0.1 | 550 HV | 1 W/m·K |
99.99This page optical / electronic grade (evaporation material, high-k dielectric) | Pick for UV–IR high-refractive-index coatings, laser mirrors and gate-dielectric/ALD film work where trace metals and absorption must be minimal. | — | 120 | 0.1 | 850 HV | 2 W/m·K |
99.9Default pressed & sintered monoclinic hafnia (technical grade) | Standard dense technical hafnia for crucibles, high-temperature insulators and refractory parts where thermal cycling through 1700 °C is avoided. | — | — | — | 800 HV | 2 W/m·K |
Yttria-stabilized hafnia | Choose when parts must be thermally cycled above 1700 °C — Y2O3 suppresses the monoclinic transformation and its damaging volume change. | — | — | — | 950 HV | 1 W/m·K |
What is HfO2 99.99?
HfO2 99.99 is HfO2 in the 99.99 grade — pick for UV–IR high-refractive-index coatings, laser mirrors and gate-dielectric/ALD film work where trace metals and absorption must be minimal. The elastic modulus is 250 GPa (36.3 Msi). HfO2 99.99 has a density of 9.5 g/cm³ (0.343 lb/in³), heavier than 77% of ceramic grades. It melts at 2,758°C (4,996 °F). 99.9 is the default condition FabDigit quotes; 99.99 is available on request or by drawing note.
Advantages
- Good corrosion resistance — 95/100, better than 97% of ceramic grades
- High service temperature — 2,200°C (3,992 °F), better than 96% of ceramic grades
Limitations
- High embodied carbon — 45 kg CO₂/kg, worse than 96% of ceramic grades
- Poor heat conductor — 1.8 W/m·K (1.04 BTU/hr·ft·°F), worse than 89% of ceramic grades
- Heavy — 9.5 g/cm³ (0.343 lb/in³), worse than 77% of ceramic grades
HfO2 99.99 properties
Typical room-temperature values for HfO2 99.99; 17 are specific to this condition. Other listed values are HfO2 reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
HfO2 99.99 has a density of 9.5 g/cm³ (0.343 lb/in³), heavier than 77% of ceramic grades. It melts at 2,758°C (4,996 °F).
Mechanical10
The elastic modulus is 250 GPa (36.3 Msi).
Thermal5
HfO2 99.99 is rated for continuous service to 2,200°C (3,992 °F). It conducts heat at 1.8 W/m·K (1.04 BTU/hr·ft·°F), worse than 89% of ceramic grades. Thermal expansion is 5.8 µm/m·K (3.22 µin/in·°F).
Electrical5
HfO2 99.99 is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (95/100), better than 97% of ceramic grades.
Sustainability2
Producing a kilogram of HfO2 99.99 takes about 700 MJ of energy and emits 45 kg of CO₂ — more than 95% of ceramic grades.
Manufacturability3
HfO2 99.99's machinability is not recommended (7/100, better than 63% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HfO2 99.99
Is HfO2 easy to machine?
Green/bisque machining is the only economical route; fired parts need diamond grinding, lapping and ultrasonic/laser drilling, and the high density makes stock removal slow and costly.
Can HfO2 be welded?
Not weldable — join by active-metal brazing (Ti/Zr-bearing filler), glass sealing or mechanical clamping with matched-CTE metals.
Can HfO2 be formed, bent or molded?
Uniaxial/CIP pressing, slip casting or tape casting of fine powder, then sintering at 1600–1900 °C (often HIP or a Y2O3/CaO stabilizer); allow for large firing shrinkage and avoid crossing the 1700 °C phase transformation in unstabilized bodies.
What surface finishes work on HfO2?
Diamond lap and polish for optical or sealing faces; PVD/EB evaporation and ALD are the standard routes for thin high-k and high-index films.
HfO2 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 |
|---|---|---|
| ZrO2Zr is the natural chemical twin of Hf; excluded from the purity figure by most suppliers, nuclear grades specify <1 % | ≤ 2 | 0.3 |
| SiO2 | ≤ 0.05 | 0.01 |
| Al2O3 | ≤ 0.05 | 0.01 |
| Fe2O3 | ≤ 0.02 | 0.01 |
| TiO2 | ≤ 0.02 | 0.01 |
| Y2O38–12 mol % added only in the stabilized (YSH) variant | ≈ 0 | 0 |
| HfO2monoclinic (baddeleyite-type) hafnia; purity usually quoted on a Zr-free basis | ≥ 99.5 (balance) | — |
HfO2 99.99 — frequently asked
What is HfO2 99.99 used for?
HfO2 99.99 is typically used for ultra-high-temperature coatings, high-k gate dielectrics, thermal barrier layers and nuclear control rods. In short: highest-temperature oxide here; high-k dielectric source; dense and costly.
Is HfO2 99.99 easy to machine?
Not especially — machinability is rated not recommended (7/100, better than 63% of ceramic grades). Green/bisque machining is the only economical route; fired parts need diamond grinding, lapping and ultrasonic/laser drilling, and the high density makes stock removal slow and costly.
Can HfO2 99.99 be welded?
Not weldable — join by active-metal brazing (Ti/Zr-bearing filler), glass sealing or mechanical clamping with matched-CTE metals.
What surface finishes work on HfO2 99.99?
Diamond lap and polish for optical or sealing faces; PVD/EB evaporation and ALD are the standard routes for thin high-k and high-index films.
Can HfO2 99.99 be formed, bent or molded?
Uniaxial/CIP pressing, slip casting or tape casting of fine powder, then sintering at 1600–1900 °C (often HIP or a Y2O3/CaO stabilizer); allow for large firing shrinkage and avoid crossing the 1700 °C phase transformation in unstabilized bodies.
What is the maximum service temperature of HfO2 99.99?
HfO2 99.99 is rated for continuous use to about 2,200°C (3,992 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- CRC Handbook of Chemistry and Physics — CRC Press (2020)
- NIST-JANAF Thermochemical Tables (HfO2) — NIST (1998)
- Phase Diagrams for Ceramists — HfO2–Y2O3 system — American Ceramic Society (1992)
- Hafnium oxide sputtering target / evaporation material data — Materion (2023)
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.