Silicon Nitride · grade
Silicon Nitride RBSN
Properties of the RBSN condition, compared with the other Silicon Nitride tempers.
Low-cost, near-zero-shrinkage porous grade for large refractory shapes, thermocouple sheaths, riser tubes and molten-aluminium hardware where strength is secondary.
What is Silicon Nitride RBSN?
Silicon Nitride RBSN is Silicon Nitride in the RBSN grade — low-cost, near-zero-shrinkage porous grade for large refractory shapes, thermocouple sheaths, riser tubes and molten-aluminium hardware where strength is secondary. Silicon Nitride RBSN has a tensile strength of 160 MPa (23.2 ksi), stronger than 57% of ceramic grades. Elongation at break is 0% and the elastic modulus is 165 GPa (23.9 Msi). Silicon Nitride RBSN has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 80% of ceramic grades. It melts at 1,900°C (3,452 °F). Sintered is the default condition FabDigit quotes; RBSN is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 92/100, better than 87% of ceramic grades
- Lightweight — 2.55 g/cm³ (0.0921 lb/in³), better than 80% of ceramic grades
- High service temperature — 1,350°C (2,462 °F), better than 77% of ceramic grades
Silicon Nitride RBSN properties
Typical room-temperature values for Silicon Nitride RBSN — 14 properties are specific to this condition; the rest are grade-level values shared by every Silicon Nitride temper. Each bar shows where the value sits among the ceramic grades in FabDigit's library — further right is higher.
Physical4
Silicon Nitride RBSN has a density of 2.55 g/cm³ (0.0921 lb/in³), lighter than 80% of ceramic grades. It melts at 1,900°C (3,452 °F).
Mechanical12
Silicon Nitride RBSN has a tensile strength of 160 MPa (23.2 ksi), stronger than 57% of ceramic grades. Elongation at break is 0% and the elastic modulus is 165 GPa (23.9 Msi).
Thermal5
Silicon Nitride RBSN is rated for continuous service to 1,350°C (2,462 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 58% of ceramic grades. Thermal expansion is 3 µm/m·K (1.67 µin/in·°F).
Electrical5
Silicon Nitride RBSN 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 very good (80/100), better than 55% of ceramic grades.
Sustainability4
Producing a kilogram of Silicon Nitride RBSN 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 RBSN's machinability is not recommended (12/100, better than 80% of ceramic grades).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Silicon Nitride tempers and conditions
Silicon Nitride is also supplied in 6 other conditions. The full side-by-side table is on the Silicon Nitride overview.
- SinteredDefaultStandard dense grade for general structural, wear and high-temperature parts; best cost/performance for complex near-net shapes.450 MPa tensile
- HIPedPick when defect-free, fully dense material is required — bearing balls/rollers, high-cycle-fatigue and highly stressed parts.550 MPa tensile
- C935Gas-tight, essentially zero-porosity sintered silicon nitride classified as IEC 60672-3 material group C-935 for electrical/electronic insulating parts, combining ≥600 MPa bending strength with high dielectric strength.400 MPa tensile
- RBSNLow-cost, near-zero-shrinkage porous grade for large refractory shapes, thermocouple sheaths, riser tubes and molten-aluminium hardware where strength is secondary.160 MPa tensile
- HPSNChoose for the highest strength in simple plate/blank geometries (cutting inserts, tooling); shapes limited and properties slightly anisotropic.1,650 HV
- SRBSNRoute that starts from cheap Si powder and then densifies; gives near-SSN properties with less shrinkage and lower raw-material cost for larger parts.1,450 HV
- HTCY2O3-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
Working with Silicon Nitride RBSN
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).
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.
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) | — |
Silicon Nitride RBSN — frequently asked
What is Silicon Nitride RBSN used for?
Silicon Nitride RBSN 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 RBSN?
Silicon Nitride RBSN has a typical tensile strength of 160 MPa (23.2 ksi) — stronger than 57% of ceramic grades. Strength varies by condition: see the 7 listed tempers.
Is Silicon Nitride RBSN easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 80% 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 RBSN 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 RBSN?
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 RBSN 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 RBSN?
Silicon Nitride RBSN is rated for continuous use to about 1,350°C (2,462 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Silicon Nitride RBSN?
Yes — Silicon Nitride RBSN is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.