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Product Information

Bearing balls (Si3N4)
Ceramics balls that sustain high-performance bearings

Bearing balls (Si<sub>3</sub>N<sub>4</sub>)

Outline

Toshiba Materials offers silicon nitride (Si3N4) fine ceramics that have high strength, high stiffness and high abrasion resistance for various structural parts. In particular, they essential materials for high-performance bearings and are applied to many bearings in diversified fields.

Advantages

  • High strength
  • High abrasion resistance
  • High stiffness
  • Excellent corrosion resistance

Applications

Required properties Application examples
High speed Machining tools, turbo chargers,
HDD spindle motors (also abrasion resistance)
Corrosion resistant Chemical plant equipment,
semiconductor-manufacturing equipment
(acid resistant & alkaline resistant)
High temperature Heat treatment furnace parts (Heat resistant)
High vacuum Turbo molecular pumps (Low dust)
High insulation Electric motors (anti-electric corrosion)
Ultra-low temperature Turbo pumps for space shuttles
(resistant to liquid oxygen & hydrogen)

Application example 1) Ceramic ball bearings were applied to turbo pumps for space shuttles.

Our fine ceramics TSN-03NH is the only one approved ceramic material to be applicable to ceramics balls and rollers for space shuttles.

for space shuttles

Application example 2) Racing car axle bearings

Employed in Mitsubishi Pajero cars (Paris - Dakar rally in 1998)

Employed in Mitsubishi Pajero cars (Paris - Dakar rally in 1998)

Application example 3) Speed car bearings

Ceramic bearings were applied to speed cars as wheel bearings. They endured high contact stress and showed excellent performance, and the car achieved a speed as high as Mach 1.
They were applied to F1 car bearings from the year 2002.

Speed car

List of classified properties

Properties Measurement
method		 Unit Class TSN-03NH
on average
I II III
Bending strength Three-point bending
(on average)		 MPa >900 >800 >600 1100
Weibull coefficient   >12 >9 >7 20
Hardness Vickers hardness HV20 kg   >1460 >1360 >1300 1500
Fracture toughness IFR method MPa
m1/2		 >6.0 >5.0 >5.0 7.0
Pore sizes
(sectional observation)		 Observation by microscope and SEM μm <10 <10 <25 ＜1

Our fine ceramics have cleared ASTM "class I" requirements, which means they maintain industry-leading level.
We offer from 1/16" to 1-5/8" bearing balls.

Comparison of properties with steel bearings

Item Unit Silicon
nitride		 Bearing
steel		 Advantages of
ceramic bearings
Heat resistance °C 800 180 A heavier load will be endured at elevated temperatures.
Density Mg/m3 3.24 7.8 Centrifugal load induced by rolling bodies (balls or rollers) will be reduced, which means serviceable life will be increased and temperature elevation will be prevented.
Thermal expansion
coefficient		 /°C 3.2×10-6 12.5×10-6 Change of internal clearance by temperature rise will be minimized, which sustains minimal vibration and change of preload.
Hardness HV 1500 750 Deformation of the parts at the rolling contact points will be minimized, which means high stiffness.
Young's modulus GPa 310 208
Poisson's ratio   0.29 0.3
Corrosion resistance   Good Poor Ceramic materials can be used in extreme circumstances such as acid or alkaline solutions.
Magnetism   Non-magnetic Ferro-magnetic Fluctuation in rotation velocity caused by magnetization in a strong magnetic field will be suppressed.
Electrical conductivity   Insulator Conductor Electric pitting will be prevented (electric motors).
Molecular bonding
state of materials		   Covalent bonding Metallic bonding Seizure by lack of lubricant oil at rolling contact points will be minimized.

FAQ

FAQ on Silicon nitride fine ceramics

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