B4C/SiC
B4C/SiC is a ceramic-matrix composite that combines boron carbide's low density (2.6 g/cm³) and extreme hardness with silicon carbide for improved toughness and easier densification.
Reference datasheet — B4C/SiC 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
B4C/SiC grades and fills
B4C/SiC is supplied in 5 conditions, soft to hard. HP is the default FabDigit quotes; the values on this page are for it.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Pressureless sintered B4C/SiC | Pick for complex near-net shapes and lower cost where a modest drop in strength versus hot-pressed is acceptable. | 205 | 0.05 | ||
HPDefault Hot-pressed B4C/SiC | Pick for maximum hardness and ballistic performance per unit mass — the standard armour and blast-nozzle grade. | 270 | 0.06 | ||
SiC matrix with 20–35 % B4C particulate | Pick when thermal conductivity, oxidation resistance and high-temperature strength matter more than minimum weight. | 280 | 0.07 | ||
Spark-plasma / field-assisted sintered B4C/SiC | Pick for fine-grained, fully dense small tiles and research/premium armour where the highest strength and toughness are needed. | 330 | 0.07 | ||
Reaction-bonded B4C/SiC/Si | Pick for large, thick or complex parts at low cost and zero sintering shrinkage; accept 8–20 % free silicon and lower hardness. |
Supply forms, finishes and certifications
Ways B4C/SiC is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Armor | Armor tile grade | Certification |
What is B4C/SiC?
B4C/SiC is a ceramic-matrix composite that combines boron carbide's low density (2.6 g/cm³) and extreme hardness with silicon carbide for improved toughness and easier densification. Engineers select it where mass-specific hardness matters — armor tiles, abrasive nozzles and wear liners — and it is supplied hot-pressed (HP), pressureless-sintered (PS), reaction-bonded (RB), spark-plasma-sintered (SPS), in SiC-rich blends and as finished armor plate, with an elastic modulus of 450 GPa and thermal conductivity of 45 W/m·K. Limits are brittleness, a practical maximum service temperature of 800 °C in air, and a machinability score of 2 — fired parts can only be diamond-ground, so cost is driven by near-net pressing. Where service above 800 °C or lower cost per part governs, plain SiC is the usual alternative. B4C/SiC has a density of 2.6 g/cm³ (0.0939 lb/in³), heavier than 83% of composite grades. B4C/SiC has a tensile strength of 270 MPa (39.2 ksi), stronger than 52% of composite grades. Elongation at break is 0.06% and the elastic modulus is 450 GPa (65.3 Msi).
What is B4C/SiC used for?
- body armor plates
- vehicle armor
- abrasive nozzles
- wear-resistant liners
Advantages
- Polishes to a fine finish — 90/100, better than 99% of composite grades
- Stiff — 450 GPa (65.3 Msi), better than 97% of composite grades
- Good corrosion resistance — 92/100, better than 94% of composite grades
- Good UV / weathering resistance — 100/100, better than 93% of composite grades
- High service temperature — 800°C (1,472 °F), better than 89% of composite grades
Limitations
- Limited ductility — 0.06%, worse than 100% of composite grades
- Difficult to machine — 2/100, worse than 100% of composite grades
- Heavy — 2.6 g/cm³ (0.0939 lb/in³), worse than 83% of composite grades
B4C/SiC properties
Typical room-temperature values for B4C/SiC-HP; bars are the position among composite grades.
Physical1
B4C/SiC has a density of 2.6 g/cm³ (0.0939 lb/in³), heavier than 83% of composite grades.
Mechanical11
B4C/SiC has a tensile strength of 270 MPa (39.2 ksi), stronger than 52% of composite grades. Elongation at break is 0.06% and the elastic modulus is 450 GPa (65.3 Msi).
Thermal6
B4C/SiC is rated for continuous service to 800°C (1,472 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 83% of composite grades. Thermal expansion is 4.6 µm/m·K (2.56 µin/in·°F).
Electrical1
B4C/SiC has an electrical resistivity of 1 Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 94% of composite grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of B4C/SiC takes about 220 MJ of energy and emits 16 kg of CO₂ — more than 50% of composite grades. Typical recycled content is 3%.
Manufacturability2
B4C/SiC's machinability is not recommended (2/100, worse than 100% of composite grades).
Common Calculations4
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 composite family
Yield strength against density for every composite grade FabDigit runs. B4C/SiC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with B4C/SiC
Is B4C/SiC easy to machine?
Green/bisque machining before final sintering is the only economical route; fired parts require resin- or metal-bond diamond grinding, ultrasonic machining or laser, and cannot be turned, drilled or EDM'd conventionally.
Can B4C/SiC be welded?
Not weldable; join by active-metal brazing (Ti/Zr-containing AgCu foils), Si-melt infiltration bonding or epoxy/polyurethane adhesive to backing plates and metal frames.
Can B4C/SiC be formed, bent or molded?
Shaped by dry/isostatic pressing, slip or gel casting, or extrusion of powder blends, then hot pressing (1900–2100 °C, 30–40 MPa), pressureless sintering (~2150 °C) or Si melt infiltration; hot pressing restricts geometry to plates and simple curves.
B4C/SiC 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 |
|---|---|---|
| B4Cmatrix phase in the default (B4C-rich) composite | 60 – 85 | 70 |
| SiCtoughening/sintering second phase; 65–80 % in SiC-rich variants | 15 – 35 | 28 |
| Sifree silicon only in reaction-bonded (RB) variants | 0 – 20 | 0 |
| Cfree/graphitic carbon sintering aid | 0 – 3 | 1 |
| Al + rare-earth/metal oxide sintering airoute dependent (Al2O3, Y2O3, TiB2 additions) | 0 – 3 | 0.5 |
| impurities (Fe, O, N) | 0 – 1.5 | 0.6 |
What surface finishes work on B4C/SiC?
Diamond lapping/polishing gives mirror surfaces for seal and optics-support faces; ballistic tiles are usually left as-ground and encapsulated in aramid/UHMWPE or rubber wrap for edge protection.
How much does B4C/SiC cost?
B4C/SiC is a high-cost composite ($$$$), 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.
B4C/SiC — frequently asked
What is B4C/SiC used for?
B4C/SiC is typically used for body armor plates, vehicle armor, abrasive nozzles and wear-resistant liners. In short: lightest hard armor ceramic; near-diamond hardness; grind-only, near-net pressed.
What is the tensile strength of B4C/SiC?
B4C/SiC has a typical tensile strength of 270 MPa (39.2 ksi) — stronger than 52% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is B4C/SiC easy to machine?
Not especially — machinability is rated not recommended (2/100, worse than 100% of composite grades). Green/bisque machining before final sintering is the only economical route; fired parts require resin- or metal-bond diamond grinding, ultrasonic machining or laser, and cannot be turned, drilled or EDM'd conventionally.
Can B4C/SiC be welded?
Not weldable; join by active-metal brazing (Ti/Zr-containing AgCu foils), Si-melt infiltration bonding or epoxy/polyurethane adhesive to backing plates and metal frames.
What surface finishes work on B4C/SiC?
Diamond lapping/polishing gives mirror surfaces for seal and optics-support faces; ballistic tiles are usually left as-ground and encapsulated in aramid/UHMWPE or rubber wrap for edge protection.
Can B4C/SiC be formed, bent or molded?
Shaped by dry/isostatic pressing, slip or gel casting, or extrusion of powder blends, then hot pressing (1900–2100 °C, 30–40 MPa), pressureless sintering (~2150 °C) or Si melt infiltration; hot pressing restricts geometry to plates and simple curves.
What is the maximum service temperature of B4C/SiC?
B4C/SiC is rated for continuous use to about 800°C (1,472 °F), and briefly to 1,600°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does B4C/SiC cost?
B4C/SiC is a high-cost composite ($$$$), 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
- ASM Engineered Materials Handbook, Vol. 4: Ceramics and Glasses — ASM International (1991)
- ASTM C1161 / C1421 — flexural strength and fracture toughness of advanced ceramics — ASTM International (2018)
- NIJ Standard-0101.06 Ballistic Resistance of Body Armor — US National Institute of Justice (2008)
- Boron carbide and SiC technical ceramic datasheets — CoorsTek / Kyocera / 3M Technical Ceramics (2023)
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.