HfB2
HfB2 is an ultra-high-temperature diboride ceramic with a higher melting point than ZrB2, used where maximum thermal and ablation resistance is required.
Reference datasheet — HfB2 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the HP condition
HfB2 tempers and conditions
HfB2 is supplied in 4 conditions, soft to hard. HP is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Pressureless-sintered HfB2 | Lower-cost route for larger or more complex shapes; accepts residual porosity and lower strength than hot-pressed material. | 2,200 HV | 70 W/m·K | |||
HfB2–20 vol% SiC | Standard aerospace UHTC formulation: SiC forms a borosilicate/SiO2 sealing scale, extending useful air exposure to ~1600–1800 °C while raising strength. | 2,400 HV | 75 W/m·K | |||
HPDefault Hot-pressed monolithic HfB2 | Baseline dense monolithic UHTC for electrodes, crucibles and inert/vacuum high-temperature hardware where maximum melting point and conductivity matter. | 2,800 HV | 104 W/m·K | |||
Spark-plasma-sintered fine-grain HfB2 | Choose when the highest strength and near-full density in small parts are needed; fine grain size from short, fast consolidation. | 3,000 HV | 100 W/m·K |
What is HfB2?
HfB2 is an ultra-high-temperature diboride ceramic with a higher melting point than ZrB2, used where maximum thermal and ablation resistance is required. It is chosen for sharp hypersonic leading edges and propulsion hardware, and is supplied as hot-pressed, SPS and plasma-sprayed forms as well as the HfB2–20SiC composite; density is 11.1 g/cm³, elastic modulus 480 GPa and thermal conductivity 104 W/m·K. The main limits are high cost, high density and oxidation, which restricts bare air service to about 1100 °C unless SiC additions or coatings are used. ZrB2 is the lighter, lower-cost alternative. HfB2 has a density of 11.1 g/cm³ (0.401 lb/in³), heavier than 79% of ceramic grades. It melts at 3,380°C (6,116 °F). The elastic modulus is 480 GPa (69.6 Msi).
What is HfB2 used for?
- hypersonic sharp leading edges
- rocket propulsion components
- plasma-facing components
- UHTC research composites
Advantages
- Conducts heat well — 104 W/m·K (60.1 BTU/hr·ft·°F), better than 84% of ceramic grades
- Stiff — 480 GPa (69.6 Msi), better than 76% of ceramic grades
Limitations
- High embodied carbon — 110 kg CO₂/kg, worse than 99% of ceramic grades
- Heavy — 11.1 g/cm³ (0.401 lb/in³), worse than 79% of ceramic grades
HfB2 properties
Typical room-temperature values for HfB2-HP; bars are the position among ceramic grades.
Physical3
HfB2 has a density of 11.1 g/cm³ (0.401 lb/in³), heavier than 79% of ceramic grades. It melts at 3,380°C (6,116 °F).
Mechanical10
The elastic modulus is 480 GPa (69.6 Msi).
Thermal5
HfB2 is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 104 W/m·K (60.1 BTU/hr·ft·°F), better than 84% of ceramic grades. Thermal expansion is 5.8 µm/m·K (3.22 µin/in·°F).
Electrical2
HfB2 has an electrical resistivity of 1×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (70/100), worse than 59% of ceramic grades.
Sustainability3
Producing a kilogram of HfB2 takes about 1,500 MJ of energy and emits 110 kg of CO₂ — more than 98% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
HfB2's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Common Calculations2
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. HfB2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with HfB2
Is HfB2 easy to machine?
Green machining before sintering is preferred; dense bodies need diamond grinding, and because HfB2 is electrically conductive, wire/sinker EDM is a practical route for slots and complex profiles.
Can HfB2 be welded?
Not weldable — join by active-metal brazing (Ti/Zr-bearing filler), diffusion bonding, or co-sintering with a graded interlayer to manage CTE mismatch.
Can HfB2 be formed, bent or molded?
Consolidated by hot pressing or SPS (1900–2200 °C, 20–40 MPa) from submicron powder; pressureless sintering needs C or B4C aids to reduce surface oxides, and near-net shapes come from CIP plus green machining.
HfB2 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 |
|---|---|---|
| B | 10 – 11.5 | 10.8 |
| Zrtypical residual from Hf/Zr separation | ≤ 2 | 0.5 |
| Osurface oxide on powder | ≤ 1 | 0.4 |
| Cfrom carbothermal synthesis / sintering aid | ≤ 0.5 | 0.2 |
| Femilling contamination | ≤ 0.2 | 0.05 |
| Hfstoichiometric HfB2; commercial powders 98–99.5 % purity | ≥ 88 (balance) |
What surface finishes work on HfB2?
Diamond lapping/polishing gives a metallic mirror surface; oxidation-protective SiC- or Si-based coatings, or SiC additions, are used when air service above ~1100 °C is required.
How much does HfB2 cost?
HfB2 is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
HfB2 — frequently asked
What is HfB2 used for?
HfB2 is typically used for hypersonic sharp leading edges, rocket propulsion components, plasma-facing components and UHTC research composites. In short: highest-melting boride UHTC; conductive, EDM-machinable ceramic; denser, costlier than ZrB2.
Is HfB2 easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). Green machining before sintering is preferred; dense bodies need diamond grinding, and because HfB2 is electrically conductive, wire/sinker EDM is a practical route for slots and complex profiles.
Can HfB2 be welded?
Not weldable — join by active-metal brazing (Ti/Zr-bearing filler), diffusion bonding, or co-sintering with a graded interlayer to manage CTE mismatch.
What surface finishes work on HfB2?
Diamond lapping/polishing gives a metallic mirror surface; oxidation-protective SiC- or Si-based coatings, or SiC additions, are used when air service above ~1100 °C is required.
Can HfB2 be formed, bent or molded?
Consolidated by hot pressing or SPS (1900–2200 °C, 20–40 MPa) from submicron powder; pressureless sintering needs C or B4C aids to reduce surface oxides, and near-net shapes come from CIP plus green machining.
What is the maximum service temperature of HfB2?
HfB2 is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does HfB2 cost?
HfB2 is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Handbook of Refractory Compounds — Samsonov / Plenum (1980)
- Ultra-High Temperature Ceramics: Materials for Extreme Environment Applications — Wiley/ACerS (Fahrenholtz, Wuchina, Lee, Zhou eds.) (2014)
- Refractory diboride property compilations (HfB2, ZrB2, TiB2) — J. Am. Ceram. Soc. review papers (2007)
- Hafnium diboride powder and hot-pressed billet data — specialty UHTC powder producers (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.