HfB2 SPS
Grade
SPS = 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.
Values for the SPS condition
Other HfB2 tempers and conditions
HfB2 is listed in 4 conditions; see the grade overview at HfB2.
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 |
SPSThis page 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 SPS?
HfB2 SPS is HfB2 in the SPS grade — choose when the highest strength and near-full density in small parts are needed; fine grain size from short, fast consolidation. The elastic modulus is 510 GPa (74 Msi). HfB2 SPS has a density of 11.15 g/cm³ (0.403 lb/in³), heavier than 80% of ceramic grades. It melts at 3,380°C (6,116 °F). HP is the default condition FabDigit quotes; SPS is available on request or by drawing note.
Advantages
- Conducts heat well — 100 W/m·K (57.8 BTU/hr·ft·°F), better than 83% of ceramic grades
- Stiff — 510 GPa (74 Msi), better than 78% of ceramic grades
Limitations
- High embodied carbon — 110 kg CO₂/kg, worse than 99% of ceramic grades
- Heavy — 11.15 g/cm³ (0.403 lb/in³), worse than 80% of ceramic grades
HfB2 SPS properties
Typical room-temperature values for HfB2 SPS; 11 are specific to this condition. Other listed values are HfB2 reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
HfB2 SPS has a density of 11.15 g/cm³ (0.403 lb/in³), heavier than 80% of ceramic grades. It melts at 3,380°C (6,116 °F).
Mechanical10
The elastic modulus is 510 GPa (74 Msi).
Thermal5
HfB2 SPS is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 100 W/m·K (57.8 BTU/hr·ft·°F), better than 83% of ceramic grades. Thermal expansion is 5.8 µm/m·K (3.22 µin/in·°F).
Electrical2
HfB2 SPS has an electrical resistivity of 9.5×10⁻⁸ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (70/100), worse than 59% of ceramic grades.
Sustainability3
Producing a kilogram of HfB2 SPS 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 SPS's machinability is not recommended (4/100, worse than 85% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HfB2 SPS
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.
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.
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) | — |
HfB2 SPS — frequently asked
What is HfB2 SPS used for?
HfB2 SPS 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 SPS easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 85% 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 SPS 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 SPS?
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 SPS 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 SPS?
HfB2 SPS 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.