Nitride of Silicon Si3N4 for bearings of black color.
Advantages in comparison with usual bearings:
- the rolling bodies are excellent electric isolators
- the rolling bodies have smaller weight and, accordingly, lower inertia
- lower friction at high speeds
- at insufficient amount of greasing between nitride of silicon and steel there is no break of an oil film
- longer service life of the bearing in the polluted environments
- the rolling bodies have lower thermal expansion
Mechanical properties of ceramics:
- density (g/cm3) - 3.20~3.30
- factor of linear expansion (10-6/K) - 37655
- the module of elasticity (GPa) - 450~520
- poisson's ratio - 0.26
- hardness (HRC) - 75~80
- hardness (Hv) - 1500~1800 (above steel in 2 times)
- durabilities on a bend (MPa) - 800~1000
- heat conductivity (W/m*K) - 35 (same as at steel)
Physical properties of ceramics:
- working temperature (degrees centigrade) - 800~1500 (at steel 250~300)
- corrosion resistance - high
- factor of friction качения on steel without greasing - 0.03(at steel 0.09)
- coefficient of rolling friction on steel without greasing (oil fog) - 0.008 (at steel 0.02)
- magnetizability - not magnetize (steel is magnetized and leaves products of deterioration in the bearing)
- centrifugal forces - there is less than steel in 2,5 times
- allocation of temperature at work - is lower some steel in 2 times
- stability of the sizes - do not vary in general
- electroconductivity - isolator
- electric resistance - (Om*mm2/m) - 1018
