• Density: New ceramic has a density of 6 g/cm³, compared to 7.8 g/cm³ for insulators and 3.2 g/cm³ for conductors.
• Linear Expansion Coefficient: The new ceramic has a coefficient of 10.5×10⁻⁶ 1/°C, which is slightly different from the bearing steel SUJ2, minimizing internal clearances due to temperature changes.
• Vickers Hardness: The new ceramic has a hardness of 1280 HV.
• Elasticity: The module of longitudinal elasticity is 210 GPa with a Poisson's ratio of 0.31.
• Strength and Toughness: It has a 3-point bending strength of 1200 MPa and fracture toughness between 5 to 6 MPa･m^1/2.
• Conductivity: The new ceramic acts as an insulator.

The newly developed ceramic material is the first of its kind in Japan, designed to expand the applications of ceramic bearings. It offers similar insulation properties, strength, and durability as conventional silicon nitride (Si3N4) materials, with minimal change in acoustic value.

The new ceramic is suitable for use in electric motors, preventing electrical pitting in bearings. It is particularly effective in environments with a wide range of temperatures due to its minimal internal clearances.

• Fatigue Life: The new ceramic demonstrated more than three times the calculated fatigue life under test conditions with a contact stress of 4.2 GPa and oil bath lubrication.
• Noise Comparison: At 150°C, the new ceramic showed no significant deterioration in acoustic value after 3600 hours.
• Crushing Load Test: The new ceramic has strength equivalent to conventional Si3N4 ceramics.

Electrical pitting occurs due to arcing between the bearing raceway surface and rolling elements. The new ceramic's insulating properties help prevent this, extending bearing service life.

For more information, contact JTEKT CORPORATION at their Nagoya or Osaka head offices.