Carbide and Boride Ceramics
This series holds the hardest engineering materials short of diamond: silicon carbide (2,500 HV, strength kept to 1,400 °C, thermal conductivity above 100 W/m·K), boron carbide (about 3,000 HV at a density of 2.5 g/cm³), the ultra-high-temperature borides TiB₂, ZrB₂ and HfB₂, and cemented tungsten carbide — WC grains bonded with 3–20 % cobalt into a metal-like body with 88–93 HRA hardness and a transverse rupture strength of 1,500–3,500 MPa. Silicon carbide is the seal, bearing and kiln-furniture ceramic; cemented carbide is the cutting-tool, die and wear-part material.
Popular carbide ceramic grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Silicon Carbide | 380 | 250 | 3.15 | Not recommended | Not recommended | Seal faces, bearings, nozzles, 1,400 °C |
| SSiC | — | 260 | 3.12 | Not recommended | — | Fully dense sintered SiC for hot acid service |
| RBSiC/SiSiC | — | 200 | 3.05 | Not recommended | — | Large kiln furniture and complex SiC shapes |
| B4C | — | 300 | 2.51 | Not recommended | — | Lightest hard ceramic: armor, blast nozzles |
| WC-Co | — | 1,500 | 14.9 | Not recommended | — | Cemented carbide for dies and wear parts |
| YG8 | — | 1,200 | 14.7 | Not recommended | — | Tough 8 % Co carbide for punches and dies |
| YT15 | — | 800 | 11.4 | Not recommended | — | WC-TiC-Co insert grade for turning steel |
Choose carbides and borides for
Seal faces, bearings, sleeves and nozzles in abrasive or corrosive slurry; kiln furniture, heat-exchanger tubes and wafer-handling parts to 1,600 °C; armor and blast nozzles; cutting inserts, drawing and stamping dies, punches, cold-heading tools and wear pads in cemented carbide; and cathodes or leading edges that must conduct or survive above 2,000 °C.
Look elsewhere when
An electrical insulator is required (SiC and cemented carbide conduct — use Alumina 96, Aluminum Nitride or Silicon Nitride), the part needs toughness at room temperature (Zirconia Y-TZP, or a hardened tool steel such as D2 at 60 HRC), the environment is a hot oxidizing gas above 1,600 °C with no protective silica film (Alumina 99.5), the geometry is thin and complex in a quantity of one (Macor or Boron Nitride), or the budget is for a wear part where Alumina 96 would last long enough.
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Carbide ceramic by application
- Seal faces and slurry bearings
- SSiC (Silicon Carbide) rings, sleeves and bushings lapped flat — inert in acids, thermally conductive enough to survive dry running briefly; RBSiC/SiSiC where the ring is large and the fluid is neutral.
- Kiln furniture and hot gas
- RBSiC/SiSiC beams, rollers, burner nozzles and heat-exchanger tubes to 1,350 °C; SSiC or HPSiC above that and in corrosive furnace atmospheres.
Working with carbide ceramic
- Forming & sintering
- Silicon carbide is pressed, extruded or slip-cast and sintered at 2,000–2,200 °C (SSiC) or infiltrated with molten silicon at about 1,500 °C (RBSiC/SiSiC, near zero shrinkage — the route for big shapes). Cemented carbide is pressed from WC-Co powder and liquid-phase sintered at 1,350–1,500 °C with about 18–20 % linear shrinkage; the green compact can be machined to shape before sintering.
- Grinding & lapping
- Both families are finished with diamond wheels under flood coolant; SiC seal faces are lapped to flatness within 1 µm and Ra below 0.1 µm. Cemented carbide is electrically conductive, so wire and sinker EDM cut profiles, holes and splines that grinding cannot reach — the standard route for carbide dies.
- Joining & sealing
- Carbide inserts and wear pads are brazed to steel with silver-copper or copper-zinc fillers, using a copper or tri-metal shim to absorb the expansion mismatch on large joints, or clamped mechanically. Silicon carbide is shrink-fitted into steel housings, bonded with active-metal brazes or diffusion-bonded to itself; it does not take conventional brazes.
- Tolerances & design rules
- Ground dimensions hold ±0.005 mm and as-sintered ones about ±1 %. Keep carbide in compression, radius internal corners, avoid sharp threads in SiC (use a steel insert) and design the metal housing to carry any bending load — a chipped edge on either material is a failed part.
Other ceramic series
Carbide and Boride Ceramics — frequently asked
What is carbide ceramic?
This series holds the hardest engineering materials short of diamond: silicon carbide (2,500 HV, strength kept to 1,400 °C, thermal conductivity above 100 W/m·K), boron carbide (about 3,000 HV at a density of 2.5 g/cm³), the ultra-high-temperature borides TiB₂, ZrB₂ and HfB₂, and cemented tungsten carbide — WC grains bonded with 3–20 % cobalt into a metal-like body with 88–93 HRA hardness and a transverse rupture strength of 1,500–3,500 MPa. Silicon carbide is the seal, bearing and kiln-furniture ceramic; cemented carbide is the cutting-tool, die and wear-part material.
Which grade of carbide ceramic should I use?
Silicon Carbide in its sintered form (SSiC) for seal faces, pump bearings, nozzles and anything in hot acid — fully dense, no free silicon, good to 1,600 °C. RBSiC/SiSiC (reaction-bonded, about 10 % free silicon) for large or complex shapes such as kiln beams, burner nozzles and wafer carriers; cheaper, limited to about 1,350 °C and attacked by strong alkalis. B4C when weight and hardness both matter — armor plates, blast nozzles, neutron absorbers. For cemented carbide, pick by cobalt content and the work material: YG6 (6 % Co, K class) for cast iron, non-ferrous and wear parts; YG8 and YG15 with more cobalt for punches, dies and impact; YT15 and YT5 (WC-TiC-Co, P class) for turning steel; YW1 as the universal M-class grade. In the US system C1–C4 cover cast iron and non-ferrous from roughing to finishing and C5–C8 do the same for steel. TiB2 is chosen for its electrical conductivity in aluminum smelting and evaporation boats; ZrB2 and HfB2 for hypersonic leading edges above 2,000 °C.
Which grade of carbide ceramic is easiest to machine?
ZrB2 (machinability not recommended, 8/100), then TiB2 (6/100).
Sintered SiC (SSiC) or reaction-bonded SiC (SiSiC)?
SSiC is pure, fully dense silicon carbide sintered at over 2,000 °C: usable to about 1,600 °C, immune to almost every acid including hydrofluoric, but limited in size and shape and more expensive. RBSiC/SiSiC is a silicon-carbide skeleton infiltrated with molten silicon, leaving roughly 10 % free silicon: it fires with almost no shrinkage, so kiln beams a meter long and intricate burner nozzles are practical, and it costs less. The free silicon caps service at about 1,350 °C and is attacked by hot caustics and some acid mixtures. Seals and chemical parts go SSiC; furniture and structural shapes go SiSiC.
How do YG, YT, C-grades and ISO K/P/M carbide grades relate?
They are three naming systems for the same families. Straight WC-Co grades are YG (China), C1–C4 (US) and ISO K: used for cast iron, non-ferrous metals and wear parts, with more cobalt (YG8, YG15, C1) meaning tougher and less hard, and less cobalt (YG3, YG6X, C4) meaning harder and more brittle. WC-TiC-Co grades that resist cratering when cutting steel are YT (YT5, YT15, YT30), C5–C8 and ISO P; the YW grades with added TaC are the ISO M all-rounders. Hardness runs from about 88 HRA at 20 % cobalt to 93 HRA at 3 %.