Sintered Silicon Carbide (RBSC / SSiC / Re-crystallized)

Overview

Sintered silicon carbide is the engineered SiC powder family designed as feedstock for three distinct ceramic-densification routes that together serve the highest-value end-markets in the SiC industry: precision mechanical seals, IGBT and SiC-MOSFET ceramic substrates, ballistic armour, semiconductor wafer carriers, and high-temperature kiln furniture.

Reaction-bonded SiC (RBSC, also "siliconised SiC") uses a coarse-fine bimodal SiC powder formulation: F240 (D50 45 ± 3.0 μm) coarse aggregate plus F1200 (D50 4.5 ± 0.3 μm) fine fraction, mixed with carbon binder and shaped (slip-cast, extruded, isostatically pressed, or injection-moulded). The shaped green body is then infiltrated with molten silicon at 1450°C in a vacuum or inert atmosphere; the molten Si reacts with the carbon binder to form additional in-situ SiC that bonds the original SiC grains into a near-net-shape body at 99.2% theoretical density. The advantage is near-zero firing shrinkage (large, complex shapes can be manufactured to final dimension without machining).

Pressureless-sintered SiC (SSiC) uses ultra-fine sub-micron SiC powder (W63 to W0.5, D50 44.5 → 0.5 μm) blended with 0.5–1.0% boron and 0.5–1.5% carbon sintering aids. The blend is granulated, isostatically pressed (CIP) to green-body density 55–58%, and sintered at 2050°C in argon to give a fully dense ≥99.5% SiC body. Mechanical properties are best-in-class: 4-point flexural strength 350–500 MPa, hardness HV 25 GPa, fracture toughness 3.5–4.5 MPa·m^0.5.

Re-crystallized SiC (R-SiC, RS-grade) uses a bimodal coarse + ultra-fine powder formulation (RS100 0–350 mesh coarse fraction + RS07 D50 1.8–3.5 μm fine fraction). The mixture is shaped, then sintered at 1750°C through an evaporation-condensation mechanism: the ultra-fine fraction evaporates and re-deposits at coarse-particle necks, building a continuous SiC skeleton at 12–18% open porosity. The product is used as electric heating elements (operating to 1450°C in air) and kiln furniture for sanitaryware, technical-ceramic, and electric-porcelain firing.

All three routes are supplied as engineered powders with SiC purity ≥98.5–99.5%, specific gravity ≥3.16, Fe₂O₃ ≤0.20%, free-C ≤0.20%. Packaging is 25 kg foil-lined moisture-sealed bag or 200 kg drum.

Technical Specifications

Applications

Mechanical Seal Faces (Chemical Pumps, Slurry Pumps, Boiler Feedwater)

SSiC W7–W14 powders sintered to dense seal-face blanks. Withstand 98% H₂SO₄, 50% NaOH at 200°C, hydrofluoric acid, hot organic solvents. Combined with carbon-graphite as the running counter-face gives the industry-standard chemical-pump mechanical seal. Service life 5–10× tungsten-carbide seals at half the wear-rate; 30 % of all centrifugal-pump replacement seals are now SSiC.

Ballistic Armour Tiles (Body Armour Level III/IV, Vehicle, Aircraft Under-Body)

SSiC W3.5 powders sintered to flat 4–10 mm armour tiles, then bonded to a polyethylene or aramid backing for the complete armour panel. Resists 7.62 mm AP and 14.5 mm AP threats at lower areal density than alumina or boron carbide tiles. The US, EU, and Chinese defence ministries qualify SSiC armour tiles for body armour and vehicle hull plating.

IGBT / SiC-MOSFET Ceramic Substrates (Power Module Heat Spreader)

SSiC W1–W3.5 ultra-fine powder sintered to high-thermal-conductivity (270 W/m·K) substrates for direct-bonded-copper (DBC) IGBT and SiC-MOSFET power modules. Service temperature 200°C continuous (with derating) makes SSiC the substrate of choice for traction-inverter, solar-inverter, and high-power-density industrial drives. Competes with Si₃N₄ (cheaper but lower thermal conductivity) and AlN (higher thermal conductivity but lower fracture toughness).

Semiconductor Wafer Carriers, Diffusion-Furnace Boats, Plasma-Etch Parts

SSiC sintered components for the semiconductor fab: 200 mm and 300 mm wafer carriers, diffusion-furnace boats, plasma-etch chamber rings and showerheads. Trace-metal contamination specs are stringent — total Fe + Al + Ca + Na + K below 50 ppm for many semiconductor-grade applications.

Kiln Furniture for Fine-Ceramic Firing (Sanitaryware, Technical Ceramic, Electric Porcelain)

R-SiC RS07 + RS100 bi-modal powder sintered to plates, posts, beams, saggers for high-temperature kiln furniture. Service temperature 1450°C in air, 1650°C in inert. The 12–18% open porosity gives excellent thermal-shock resistance (rapid heating-cooling cycle survival), making R-SiC the dominant choice for fast-firing tunnel kilns in ceramic factories.

Reaction-Bonded SiC Components (Burner Nozzles, Large Heat-Exchanger Tubes)

RBSC F240 + F1200 bimodal formulation for large, complex shapes that pressureless sintering cannot make: burner nozzles for heavy industrial furnaces, kiln-internal heat-exchanger tubes, large flue-gas desulphurisation spray nozzles, propeller blades for marine pumps. Near-net-shape manufacture (no firing shrinkage) gives manufacturing cost 30–50% below SSiC for equivalent-volume parts.

Electric Heating Elements (1450°C Service in Air)

R-SiC RS07 powder sintered to rod-, tube-, U-shape, and spiral electric heating elements. Used in laboratory furnaces, ceramic-firing kilns, glass-tempering furnaces, and heat-treatment furnaces. Service life 2000+ hours at 1450°C in air.

Aerospace and Defence

RBSC and SSiC components for rocket nozzle throats (re-entry heat shielding), space-telescope optical mirrors (low thermal expansion, high stiffness), satellite structural components, hypersonic vehicle leading-edge tiles.

Selection Guide: RBSC vs SSiC vs R-SiC

Choose RBSC for: large complex shapes (>50 mm any dimension); near-net-shape manufacture priority; thermal-cycling environments (better thermal-shock resistance than SSiC); low-pressure mechanical seals; burner nozzles and heat-exchanger tubes; budget-conscious applications. Sintered density 3.05 g/cm³ (95 % theoretical); SiC content 88–92% (residual free Si 8–12%).

Choose SSiC for: highest mechanical performance (flexural strength, hardness, fracture toughness); chemical-attack-resistant mechanical seals; ballistic armour; power-electronics ceramic substrates; semiconductor wafer-handling parts; any application demanding ≥99 % final SiC content. Sintered density 3.15 g/cm³ (>98 % theoretical); SiC content ≥99.5%.

Choose R-SiC for: kiln furniture and electric heating elements requiring open-porosity microstructure; thermal-shock-cycling applications (porosity absorbs thermal stress); service temperature 1450–1600°C in air; cost-optimised refractory parts. Sintered density 2.6 g/cm³ (open porosity 12–18%).

Equivalent Grades

• Saint-Gobain Hexoloy SA / SE — pressureless-sintered SSiC, global premium
• Coorstek SC-30 / SC-35 — North American SSiC
• NGK Insulators (Japan) — kiln furniture R-SiC, premium grade
• Kyocera SC-201 — Japanese SSiC for semiconductor parts
• 3M Boron-Sintered Silicon Carbide — North American premium
• Morgan Advanced Materials Hexoloy — UK / Global premium SSiC
• Generic Chinese sintering-grade SiC — RBSC / SSiC / R-SiC commodity, Shandong / Ningxia origin