HFB2-20SIC
Reinforced grade
HFB2-20SIC = 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.
Values for the HFB2-20SIC 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 |
HFB2-20SICThis page 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 HFB2-20SIC?
HFB2-20SIC is HfB2 in the HFB2-20SIC grade — standard aerospace UHTC formulation: SiC forms a borosilicate/SiO2 sealing scale, extending useful air exposure to ~1600–1800 °C while raising strength. The elastic modulus is 470 GPa (68.2 Msi). HFB2-20SIC has a density of 9.6 g/cm³ (0.347 lb/in³), heavier than 78% of ceramic grades. It melts at 3,380°C (6,116 °F). HP is the default condition FabDigit quotes; HFB2-20SIC is available on request or by drawing note.
Advantages
- High service temperature — 1,700°C (3,092 °F), better than 90% of ceramic grades
- Stiff — 470 GPa (68.2 Msi), better than 75% of ceramic grades
Limitations
- High embodied carbon — 110 kg CO₂/kg, worse than 99% of ceramic grades
- Heavy — 9.6 g/cm³ (0.347 lb/in³), worse than 78% of ceramic grades
HFB2-20SIC properties
Typical room-temperature values for HFB2-20SIC; 13 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
HFB2-20SIC has a density of 9.6 g/cm³ (0.347 lb/in³), heavier than 78% of ceramic grades. It melts at 3,380°C (6,116 °F).
Mechanical10
The elastic modulus is 470 GPa (68.2 Msi).
Thermal5
HFB2-20SIC is rated for continuous service to 1,700°C (3,092 °F). It conducts heat at 75 W/m·K (43.3 BTU/hr·ft·°F), better than 73% of ceramic grades. Thermal expansion is 6.2 µm/m·K (3.44 µin/in·°F).
Electrical2
HFB2-20SIC has an electrical resistivity of 2.5×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (80/100), better than 56% of ceramic grades.
Sustainability3
Producing a kilogram of HFB2-20SIC 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
HFB2-20SIC's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HFB2-20SIC
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) | — |
HFB2-20SIC — frequently asked
What is HFB2-20SIC used for?
HFB2-20SIC 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 HFB2-20SIC 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 HFB2-20SIC 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 HFB2-20SIC?
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 HFB2-20SIC 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 HFB2-20SIC?
HFB2-20SIC is rated for continuous use to about 1,700°C (3,092 °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.