Silicon Nitride Ceramics (Si₃N₄) | Bearings, Degassing Rotors & Wear Parts

Q: How does silicon nitride compare with alumina and silicon carbide?

Si3N4 has roughly twice the fracture toughness of alumina (6.5–8.0 vs 3–4 MPa·m1/2) and far better resistance to mechanical shock and thermal shock. Silicon carbide is superior in chemical and plasma resistance and at higher temperatures, but it is more brittle in impact service. In practice: choose Si3N4 for contact, impact and rolling loads, SiC for corrosive and plasma environments, and alumina where cost is decisive.

Q: Why use silicon nitride balls in hybrid bearings?

Si3N4 balls weigh about 60% less than steel balls, are electrically insulating and non-magnetic, and have a mirror-smooth, lubricant-friendly surface. Hybrid bearings run cooler, last longer in high-speed or contaminated environments and survive lubricant starvation — which is why they are standard in electric motors, machine-tool spindles and wind turbines.

Q: What foundry parts do you make for aluminum processing?

We manufacture gas-pressure sintered Si3N4 degassing rotors and shafts, riser and pouring tubes, thermocouple protection tubes, strainer cages and ladle hardware. Compared with graphite, our silicon nitride parts resist oxidation and molten-aluminum attack, giving several times the service life in continuous degassing and casting lines.

Q: Can you machine silicon nitride to our drawings?

Yes. We diamond-grind, lap and polish sintered Si3N4 to customer prints, holding ±0.005 mm on critical features. Send a STEP or DXF file plus quantity — we reply with a priced proposal, material certificate and dimensional inspection report for every shipment.

Silicon nitride hybrid ball bearing with ceramic balls

Material Overview

Built for Impact, Shock and Rolling Contact

Silicon nitride is the only structural ceramic that combines steel-like fracture toughness with the hardness, insulation and corrosion resistance of a technical ceramic. Drop it, quench it, run it at high speed against hardened steel — Si₃N₄ keeps going, which is why bearing makers and aluminum foundries specify it where every alternative fails.

Flexural strength 700–900 MPa with fracture toughness 6.5–8.0 MPa·m¹ᐟ²
Thermal-shock resistant — survives rapid quenching from 600–800 °C
About 60% lighter than bearing steel, electrically insulating and non-magnetic
Resists molten aluminum, most acids and alkalis, and repeated impact loads
Diamond-ground and lapped to ±0.005 mm on critical features

Typical Properties

Silicon Nitride Technical Data

Property (typical)	DA-SN (sintered)	DA-SN-B (bearing grade)
Bulk density (g/cm³)	3.20–3.26	3.22–3.26
Flexural strength (MPa, RT)	700–900	800–1000
Fracture toughness (MPa·m¹ᐟ²)	6.5–8.0	7.0–8.0
Thermal conductivity (W/m·K, 20 °C)	15–23	16–23
C.T.E. (10⁻⁶/K, 20–1000 °C)	3.2–3.5	3.2–3.5
Hardness (HV)	1500–1700	1600–1700
Max. service temperature (°C)	≈ 1200 (air) / ≈ 1400 (inert)	≈ 1200 (air)

Typical values for reference; custom specifications and full test reports available on request.

Product Series by Application

Silicon Nitride Components by Industry

Bearings

Balls & Hybrid Bearings

Precision Si₃N₄ balls and complete hybrid bearings for electric motors, machine-tool spindles, wind turbines and food-safe washdown environments.

Foundry & Aluminum

Rotors, Risers & Ladle Parts

Degassing rotors and shafts, riser and pouring tubes, strainer cages and ladle hardware with several times the life of graphite in molten aluminum.

Thermal Sensing

Thermocouple Tubes

Thermocouple protection tubes and furnace hardware that tolerate quenching, oxidation and abrasive dust in metallurgical and heat-treat plants.

Sealing

Seal Rings & Washers

Seal rings, washer rings and bushings for pumps handling slurries, hot media or dry-running duty where steel seals gall and alumina cracks.

Wear Protection

Wear Plates & Liners

Wear plates, lining tiles, locators and guide pins for high-wear machinery — 1500–1700 HV hardness with the toughness to take impact.

Custom Machined

Ground-to-Print Parts

Nozzles, valve balls, fixtures and complex ground geometries produced from STEP / DXF drawings with full inspection reports.

Real Product Photos

Silicon Nitride Product Gallery

Actual production parts from our facility — send us your drawing or target application and we will quote the same.

Machined silicon nitride locator rings and cages — Machined locator rings & cages

Silicon nitride seal rings and washer rings — Seal rings & washer rings

Silicon nitride bearing and grinding balls — Si₃N₄ bearing & grinding balls

Silicon nitride aluminum degassing rotor and shaft — Aluminum degassing rotor & shaft

Silicon nitride riser and pouring tube — Riser & pouring tubes

Silicon nitride thermocouple protection tubes — Thermocouple protection tubes

Silicon nitride foundry strainer and riser cages — Foundry strainer & riser cages

Silicon nitride wear plates and lining tiles — Wear plates & lining tiles

Silicon nitride ceramic nozzles for foundry — Nozzles for foundry & metallurgy

Complete silicon nitride hybrid bearings — Full-ceramic & hybrid bearings

Long silicon nitride thermocouple protection tube — Long thermocouple protection tube

Frequently Asked Questions

Silicon Nitride Questions, Answered

What is silicon nitride used for?

Silicon nitride is the structural ceramic of choice wherever parts must survive impact, thermal shock and rolling contact. Its largest application groups are hybrid and full-ceramic ball bearings, aluminum-foundry equipment such as degassing rotors, riser tubes and thermocouple protection tubes, plus seal rings, wear plates and machined fixtures. It is also specified in automotive and new-energy components where steel or alumina wear out too quickly.

How does silicon nitride compare with alumina and silicon carbide?

Si₃N₄ has roughly twice the fracture toughness of alumina (6.5–8.0 vs 3–4 MPa·m¹ᐟ²) and far better resistance to mechanical shock and thermal shock. Silicon carbide is superior in chemical and plasma resistance and at higher temperatures, but it is more brittle in impact service. In practice: choose Si₃N₄ for contact, impact and rolling loads, SiC for corrosive and plasma environments, and alumina where cost is decisive.

Why use silicon nitride balls in hybrid bearings?

Si₃N₄ balls weigh about 60% less than steel balls, are electrically insulating and non-magnetic, and have a mirror-smooth, lubricant-friendly surface. Hybrid bearings run cooler, last longer in high-speed or contaminated environments and survive lubricant starvation — which is why they are standard in electric motors, machine-tool spindles and wind turbines.

What foundry parts do you make for aluminum processing?

We manufacture gas-pressure sintered Si₃N₄ degassing rotors and shafts, riser and pouring tubes, thermocouple protection tubes, strainer cages and ladle hardware. Compared with graphite, our silicon nitride parts resist oxidation and molten-aluminum attack, giving several times the service life in continuous degassing and casting lines.

Can you machine silicon nitride to our drawings?

Yes. We diamond-grind, lap and polish sintered Si₃N₄ to customer prints, holding ±0.005 mm on critical features. Send a STEP or DXF file plus quantity — we reply with a priced proposal, material certificate and dimensional inspection report for every shipment.

High-Strength Silicon Nitride Ceramics (Si₃N₄)