Silicon Nitride
also Sintered Silicon Nitride
Silicon Nitride (Si₃N₄) is a covalent nitride ceramic supplied to ASTM F2094 and GB/T 26315 in sintered, HIPed, hot-pressed (HPSN), reaction-bonded (RBSN/SRBSN), C935 and high-thermal-conductivity (HTC) grades.
Reference datasheet — Silicon Nitride 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 Sintered condition
Silicon Nitride tempers and conditions
Silicon Nitride is supplied in 6 conditions, soft to hard. Sintered is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Reaction-bonded silicon nitride | Low-cost, near-zero-shrinkage porous grade for large refractory shapes, thermocouple sheaths, riser tubes and molten-aluminium hardware where strength is secondary. | 160 | 900 HV | 12 W/m·K | ||
Sintered reaction-bonded silicon nitride | Route that starts from cheap Si powder and then densifies; gives near-SSN properties with less shrinkage and lower raw-material cost for larger parts. | 400 | 0 | 1,450 HV | 40 W/m·K | |
SinteredDefault pressureless / gas-pressure sintered Si3N4 (SSN) | Standard dense grade for general structural, wear and high-temperature parts; best cost/performance for complex near-net shapes. | 450 | 1,500 HV | 25 W/m·K | ||
Hot isostatic pressed | Pick when defect-free, fully dense material is required — bearing balls/rollers, high-cycle-fatigue and highly stressed parts. | 550 | 1,600 HV | 30 W/m·K | ||
Uniaxially hot-pressed Si3N4 | Choose for the highest strength in simple plate/blank geometries (cutting inserts, tooling); shapes limited and properties slightly anisotropic. | 550 | 0 | 1,650 HV | 30 W/m·K | |
High-thermal-conductivity Si3N4 substrate grade | Y2O3-based, low-oxygen, coarse-β-grain grade for AMB power-module substrates: 70–100 W/m·K with substrate-grade strength and toughness. | 1,450 HV | 90 W/m·K |
Supply forms, finishes and certifications
Ways Silicon Nitride is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
C935 | Dense Si₃N₄ | Certification |
What is Silicon Nitride?
Silicon Nitride (Si₃N₄) is a covalent nitride ceramic supplied to ASTM F2094 and GB/T 26315 in sintered, HIPed, hot-pressed (HPSN), reaction-bonded (RBSN/SRBSN), C935 and high-thermal-conductivity (HTC) grades. It combines 450 MPa tensile strength, a 310 GPa modulus and good thermal-shock and rolling-contact fatigue behaviour, which makes it the standard choice for hybrid bearing balls, turbocharger rotors and glow plugs. Thermal conductivity is only 25 W/m·K, service is capped at 1200 °C, and fired parts require diamond grinding (machinability score 5), so unit cost is high. Silicon carbide is the alternative when heat spreading or hardness dominates. Silicon Nitride has a density of 3.22 g/cm³ (0.116 lb/in³), lighter than 71% of ceramic grades. It melts at 1,900°C (3,452 °F). Silicon Nitride has a tensile strength of 450 MPa (65.3 ksi), stronger than 76% of ceramic grades. Elongation at break is 0% and the elastic modulus is 310 GPa (45 Msi).
What is Silicon Nitride used for?
- Hybrid bearing balls and rollers
- Hot rolling bearings
- Turbocharger rotors
- Diesel glow plugs
- Cutting tool inserts for cast iron
- Welding locator pins and molten aluminum riser tubes
- AMB power module substrates
Advantages
- Polishes to a fine finish — 92/100, better than 89% of ceramic grades
- Good corrosion resistance — 92/100, better than 88% of ceramic grades
Silicon Nitride properties
Typical room-temperature values for Silicon Nitride-Sintered; bars are the position among ceramic grades.
Physical4
Silicon Nitride has a density of 3.22 g/cm³ (0.116 lb/in³), lighter than 71% of ceramic grades. It melts at 1,900°C (3,452 °F).
Mechanical12
Silicon Nitride has a tensile strength of 450 MPa (65.3 ksi), stronger than 76% of ceramic grades. Elongation at break is 0% and the elastic modulus is 310 GPa (45 Msi).
Thermal5
Silicon Nitride is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 55% of ceramic grades. Thermal expansion is 3.2 µm/m·K (1.78 µin/in·°F).
Electrical5
Silicon Nitride is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (92/100), better than 88% of ceramic grades.
Sustainability4
Producing a kilogram of Silicon Nitride takes about 170 MJ of energy and emits 12 kg of CO₂ — more than 59% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
Silicon Nitride's machinability is not recommended (5/100, worse than 59% of ceramic 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 ceramic family
Yield strength against density for every ceramic grade FabDigit runs. Silicon Nitride is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Silicon Nitride
Is Silicon Nitride easy to machine?
Green/bisque machining with carbide tooling is the economical route; after sintering only diamond grinding, lapping and laser/ultrasonic machining work (electrically insulating, so no EDM).
Can Silicon Nitride be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu), metallization + soldering, glass sealing or mechanical shrink-fit; AMB copper bonding is standard for substrates.
Can Silicon Nitride be formed, bent or molded?
Formed as a powder compact: uniaxial/isostatic pressing, injection moulding, slip/tape casting or extrusion, then sintered at 1650–1850 °C under N2 overpressure with ~15–18 % linear shrinkage (RBSN routes are near net shape).
Silicon Nitride 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 |
|---|---|---|
| Y2O3primary sintering aid (rare-earth oxide; may be substituted by Yb2O3/La2O3) | 0 – 8 | 4 |
| Al2O3co-additive; forms grain-boundary glass, lowers thermal conductivity | 0 – 5 | 2 |
| MgOalternative aid, mainly in hot-pressed grades | 0 – 3 | 0 |
| SiO2surface oxide on powder, part of the glass phase | 0.5 – 2.5 | 1.2 |
| Feimpurity | 0 – 0.2 | 0.05 |
| Si3N4predominantly β-Si3N4 after sintering | ≥ 88 (balance) |
What surface finishes work on Silicon Nitride?
Diamond lapping and polishing give Ra < 0.01 µm on bearing surfaces; CVD/PVD coatings, metallization or lapped-and-honed seal faces are common — no anodizing/plating without prior metallization.
Equivalent designations
Standards and trade names that resolve to Silicon Nitride in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Sintered Silicon Nitride
- Similar grades
- F2094GB/T 26315
How much does Silicon Nitride cost?
Silicon Nitride is a high-cost ceramic ($$$$), pricier than about 98% 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.
Silicon Nitride — frequently asked
What is Silicon Nitride used for?
Silicon Nitride is typically used for hybrid bearing balls and rollers, hot rolling bearings, turbocharger rotors, diesel glow plugs, cutting tool inserts for cast iron and welding locator pins and molten aluminum riser tubes. In short: high-toughness silicon nitride.
What is the tensile strength of Silicon Nitride?
Silicon Nitride has a typical tensile strength of 450 MPa (65.3 ksi) — stronger than 76% of ceramic grades. Strength varies by condition: see the 6 listed tempers.
Is Silicon Nitride easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). Green/bisque machining with carbide tooling is the economical route; after sintering only diamond grinding, lapping and laser/ultrasonic machining work (electrically insulating, so no EDM).
Can Silicon Nitride be welded?
Not weldable — join by active-metal brazing (Ti-containing Ag-Cu), metallization + soldering, glass sealing or mechanical shrink-fit; AMB copper bonding is standard for substrates.
What surface finishes work on Silicon Nitride?
Diamond lapping and polishing give Ra < 0.01 µm on bearing surfaces; CVD/PVD coatings, metallization or lapped-and-honed seal faces are common — no anodizing/plating without prior metallization.
Can Silicon Nitride be formed, bent or molded?
Formed as a powder compact: uniaxial/isostatic pressing, injection moulding, slip/tape casting or extrusion, then sintered at 1650–1850 °C under N2 overpressure with ~15–18 % linear shrinkage (RBSN routes are near net shape).
What is the maximum service temperature of Silicon Nitride?
Silicon Nitride is rated for continuous use to about 1,200°C (2,192 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Silicon Nitride cost?
Silicon Nitride is a high-cost ceramic ($$$$), pricier than about 98% 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)
- ISO 26602 — Fine ceramics: Silicon nitride materials for rolling bearing balls and rollers — ISO (2017)
- ASTM C1161 / C1421 — Flexural strength and fracture toughness of advanced ceramics — ASTM (2018)
- Silicon Nitride (Si3N4) material property sheets — CoorsTek (2023)
- Fine Ceramics — Silicon Nitride SN series — Kyocera (2023)
- SL200B / high-thermal-conductivity Si3N4 substrate data — CeramTec / Rogers curamik (2022)
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.