Si3N4/SiCw
Si3N4/SiCw is a silicon nitride matrix composite reinforced with 10–30% SiC whiskers (SiCw10, SiCw20, SiCw30) and densified by hot pressing, gas-pressure sintering or HIP.
Reference datasheet — Si3N4/SiCw 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 SiCw20 condition
Si3N4/SiCw grades and fills
Si3N4/SiCw is supplied in 6 conditions, soft to hard. SiCw20 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
GPS/PLS | Lowest-cost route for near-net complex parts; residual porosity and more sintering aid reduce strength and creep resistance. | 380 | 0.13 | ||
10 vol% SiC whisker reinforced | Low whisker loading: easiest to densify and machine, modest toughness gain over monolithic Si3N4. | 450 | 0.14 | ||
SiCw20Default 20 vol% SiC whisker reinforced, hot pressed | Standard commercial loading — best balance of toughness, strength and densification; the grade used for cutting inserts and hot-section parts. | 500 | 0.15 | ||
30 vol% SiC whisker reinforced | Maximum toughness and thermal conductivity; harder to densify so residual porosity can cap the bend strength. | 520 | 0.16 | ||
Hot pressed | Choose for full density and maximum strength in simple plate/billet shapes; whiskers align normal to the pressing axis giving anisotropic properties. | 540 | 0.17 | ||
Hot isostatic pressed | Pick when near-zero porosity, isotropic properties and highest Weibull modulus are needed for complex shapes. | 560 | 0.17 |
What is Si3N4/SiCw?
Si3N4/SiCw is a silicon nitride matrix composite reinforced with 10–30% SiC whiskers (SiCw10, SiCw20, SiCw30) and densified by hot pressing, gas-pressure sintering or HIP. The whiskers raise fracture toughness, creep resistance and high-temperature strength retention over monolithic Si3N4, giving 320 GPa modulus, 32 W/m·K conductivity, 3.22 g/cm³ density and service to 1300 °C. Machinability is rated 4: fired material accepts only diamond grinding, ultrasonic machining or EDM, and whisker alignment from pressing makes properties anisotropic. Whisker dispersion and press tooling add cost, so sintered monolithic Si3N4 is the simpler alternative when toughness allows. Si3N4/SiCw has a density of 3.22 g/cm³ (0.116 lb/in³), heavier than 91% of composite grades. Si3N4/SiCw has a tensile strength of 500 MPa (72.5 ksi), stronger than 66% of composite grades. Elongation at break is 0.15% and the elastic modulus is 320 GPa (46.4 Msi).
What is Si3N4/SiCw used for?
- turbocharger rotors
- high-temperature bearings
- cutting tools
- engine valve components
Advantages
- Polishes to a fine finish — 90/100, better than 99% of composite grades
- High service temperature — 1,300°C (2,372 °F), better than 97% of composite grades
- Stiff — 320 GPa (46.4 Msi), better than 93% of composite grades
- Good UV / weathering resistance — 100/100, better than 93% of composite grades
- Conducts heat well — 32 W/m·K (18.5 BTU/hr·ft·°F), better than 80% of composite grades
Limitations
- Difficult to machine — 4/100, worse than 99% of composite grades
- Limited ductility — 0.15%, worse than 98% of composite grades
- Heavy — 3.22 g/cm³ (0.116 lb/in³), worse than 91% of composite grades
- High embodied carbon — 30 kg CO₂/kg, worse than 80% of composite grades
Si3N4/SiCw properties
Typical room-temperature values for Si3N4/SiCw-SiCw20; bars are the position among composite grades.
Physical1
Si3N4/SiCw has a density of 3.22 g/cm³ (0.116 lb/in³), heavier than 91% of composite grades.
Mechanical11
Si3N4/SiCw has a tensile strength of 500 MPa (72.5 ksi), stronger than 66% of composite grades. Elongation at break is 0.15% and the elastic modulus is 320 GPa (46.4 Msi).
Thermal6
Si3N4/SiCw is rated for continuous service to 1,300°C (2,372 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), better than 80% of composite grades. Thermal expansion is 3.4 µm/m·K (1.89 µin/in·°F).
Electrical3
Si3N4/SiCw has an electrical resistivity of 1×10⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 77% of composite grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of Si3N4/SiCw takes about 400 MJ of energy and emits 30 kg of CO₂ — more than 77% of composite grades. Typical recycled content is 0%.
Manufacturability2
Si3N4/SiCw's machinability is not recommended (4/100, worse than 99% 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. Si3N4/SiCw is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Si3N4/SiCw
Is Si3N4/SiCw easy to machine?
Green/pre-sintered machining where possible; fired material needs diamond grinding, ultrasonic or EDM (SiCw content can make it conductive enough for wire EDM), with ample coolant to avoid surface microcracking.
Can Si3N4/SiCw be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu filler), diffusion bonding or glass-ceramic sealing, matching CTE to avoid residual stress.
Can Si3N4/SiCw be formed, bent or molded?
Whisker slurry mixing/dispersion is critical; densified by hot pressing 1700–1800 °C/20–30 MPa in N2, or by GPS + post-HIP for complex geometry; whisker alignment during pressing creates anisotropy.
Si3N4/SiCw 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 |
|---|---|---|
| SiC whiskervol %; β-SiC whiskers, 0.1–1 µm dia, L/D 10–50 | 10 – 30 | 20 |
| Y2O3sintering aid, forms Y-Si-O-N grain boundary phase | 3 – 8 | 6 |
| Al2O3sintering aid (may be replaced by MgO or Yb2O3) | 1 – 4 | 2 |
| Si3N4α-Si3N4 matrix powder, converts to β-Si3N4 on sintering | balance |
What surface finishes work on Si3N4/SiCw?
Diamond lapping/polishing to Ra < 0.05 µm; edge honing for cutting inserts; optional oxidation pre-treatment or CVD SiC/oxide coating for long-term high-temperature service.
How much does Si3N4/SiCw cost?
Si3N4/SiCw is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Si3N4/SiCw — frequently asked
What is Si3N4/SiCw used for?
Si3N4/SiCw is typically used for turbocharger rotors, high-temperature bearings, cutting tools and engine valve components. In short: whisker-toughened silicon nitride; creep-resistant to 1300 °C; EDM-machinable ceramic composite.
What is the tensile strength of Si3N4/SiCw?
Si3N4/SiCw has a typical tensile strength of 500 MPa (72.5 ksi) — stronger than 66% of composite grades. Strength varies by condition: see the 6 listed tempers.
Is Si3N4/SiCw easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 99% of composite grades). Green/pre-sintered machining where possible; fired material needs diamond grinding, ultrasonic or EDM (SiCw content can make it conductive enough for wire EDM), with ample coolant to avoid surface microcracking.
Can Si3N4/SiCw be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu filler), diffusion bonding or glass-ceramic sealing, matching CTE to avoid residual stress.
What surface finishes work on Si3N4/SiCw?
Diamond lapping/polishing to Ra < 0.05 µm; edge honing for cutting inserts; optional oxidation pre-treatment or CVD SiC/oxide coating for long-term high-temperature service.
Can Si3N4/SiCw be formed, bent or molded?
Whisker slurry mixing/dispersion is critical; densified by hot pressing 1700–1800 °C/20–30 MPa in N2, or by GPS + post-HIP for complex geometry; whisker alignment during pressing creates anisotropy.
What is the maximum service temperature of Si3N4/SiCw?
Si3N4/SiCw is rated for continuous use to about 1,300°C (2,372 °F), and briefly to 1,500°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Si3N4/SiCw cost?
Si3N4/SiCw is a high-cost composite ($$$$), 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)
- Ceramic Matrix Composites: Microstructure, Properties and Applications — Woodhead Publishing (2006)
- ASTM C1421 Fracture Toughness of Advanced Ceramics — ASTM (2018)
- Technical ceramics silicon nitride datasheets — CoorsTek / Kyocera (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.