B4C/SiC RB (Reaction-bonded B4C/SiC/Si)
Grade
Pick for large, thick or complex parts at low cost and zero sintering shrinkage; accept 8–20 % free silicon and lower hardness.
Values for the RB condition
Other B4C/SiC grades and fills
B4C/SiC is listed in 5 conditions; see the grade overview at B4C/SiC.
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 | — |
RBThis page 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. | — | — | — | — |
What is B4C/SiC RB?
B4C/SiC RB is B4C/SiC in the RB grade — pick for large, thick or complex parts at low cost and zero sintering shrinkage; accept 8–20 % free silicon and lower hardness. B4C/SiC RB 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 380 GPa (55.1 Msi). B4C/SiC RB has a density of 2.6 g/cm³ (0.0939 lb/in³), heavier than 83% of composite grades. HP is the default condition FabDigit quotes; RB is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 90/100, better than 99% of composite grades
- Stiff — 380 GPa (55.1 Msi), better than 95% of composite grades
- High service temperature — 1,200°C (2,192 °F), better than 94% 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
Limitations
- Limited ductility — 0.06%, worse than 100% of composite grades
- Difficult to machine — 5/100, worse than 97% of composite grades
- Heavy — 2.6 g/cm³ (0.0939 lb/in³), worse than 83% of composite grades
B4C/SiC RB properties
Typical room-temperature values for B4C/SiC RB; 10 are specific to this condition. Other listed values are B4C/SiC reference data and may not represent this condition. Bars are the position among composite grades.
Physical1
B4C/SiC RB has a density of 2.6 g/cm³ (0.0939 lb/in³), heavier than 83% of composite grades.
Mechanical11
B4C/SiC RB 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 380 GPa (55.1 Msi).
Thermal6
B4C/SiC RB is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 90 W/m·K (52 BTU/hr·ft·°F), better than 89% of composite grades. Thermal expansion is 5 µm/m·K (2.78 µin/in·°F).
Electrical1
B4C/SiC RB has an electrical resistivity of 0.002 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 RB 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 RB's machinability is not recommended (5/100, worse than 97% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B4C/SiC RB
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.
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.
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 |
B4C/SiC RB — frequently asked
What is B4C/SiC RB used for?
B4C/SiC RB 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 RB?
B4C/SiC RB 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 RB easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 97% 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 RB 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 RB?
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 RB 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 RB?
B4C/SiC RB is rated for continuous use to about 1,200°C (2,192 °F), and briefly to 1,600°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.