Good quality used widely Si3N4 Ceramic balls

1.High temperature resistant
2.Corrosion resistant
3.Longer lasting
4.ISO9001 certificate
5.Plenty of stock

Size Range: 0.4mm~140mm

Grade: G5~G60

Compared with steel ball, Si3N4 ball has following advantages:

1. 59% lighter than steel ball, which means less centrifugal force and less wear on the groove during high speed and acceleration.

2. 44% larger elastic modulus, which means less deformation under load

3. Harder with Rockwell hardness as 78

4. Smaller friction coefficient

5. Only 1/4 coefficient of thermal expansion of steel, can endure sharp fluctuation of temperature

6. Superior surface finish can be achieved, Ra could be 4~6 nm

7. Can endure high temperature with high hardness and strength up to 1050°C

8. Never rust, and can roll without lubrication.

9. More corrosion resistant than steel.

10. Free of metal contamination.

11. Non-magnetic

12. Electric isolation

13. No adhesive-wear with metal

14. Contact angular is very large with molten and nearly no reaction

All above combination makes Si3N4 to be first choice for high-demand bearing ball material and valve ball

Si₃N₄ is considered as a suitable material for high speed hybrid bearing in ultra high-speed precision spindles of machine tools or in jet turbines of aircraft due to its desirable properties such as lower density, higher hardness, higher elastic modulus, excellent thermal and chemical stability compared to the traditional bearing steel, and higher fracture toughness than the other advanced ceramics so that the hybrid ceramic bearing with Si₃N₄ as bearing balls has outstanding advantages of a longer bearing service life (2-5 times of steel bearing), higher running speed (up to 5 x 10⁶ DN), favorable failure mode (failure of Si₃N₄ is generally by spalling like steel ball due to its higher toughness rather than by catastrophic failure like the other lower toughness ceramics), higher overall accuracy and quality,higher heat resistance, and non-magnetic property etc. Silicon nitride has seen wide usage in the bearing industry in the last 10 years.

Now the difficulty and the price of ceramic ball bearings all depend on the production technology of ceramic balls. Outside, the ceramic ball bearings have been researched since 1960s-1970s. In this period, the main producer of hot-pressed Si₃N₄ bland ball (marked NC-132) is Norton The hot-press technology is restricted into the producing disk-like Si₃N₄ blank balls, and the blank balls must be cut to square shape using diamond saw blade, then grinded to near spherical polyhedron, and then processed to G16 ceramic balls by rough grinding, fine grinding and finishing. Si₃N₄ is superhard and wear-resistant, so it can only be cut and grinded by a few grinding materials such as diamond etc. It can be imagined that the cost of producing Si₃N₄ balls from hot-pressed Si₃N₄ is so high that it can not be accepted in many applications.

In 1980s, gas pressure sintering (GPS) and hot isostatic pressing(HIP) have been successfully applied in the producing of ceramics. Si₃N₄ biscuit is molded to spherical shape before sintering, this can overcome a series of shortcomings of hot-pressed Si₃N₄, the cost falls down a lot, ceramic ball bearings have been widely used in the electrical main arbor, and the application expands gradually to high-speed and high-precision fields such as the main arbor of machine tool and dental drill etc. However, the ceramic ball blank is not completely spherical shape, normally near spherical shape with an annulus or similar sphere with a flat head, the processing cost is still high.

The ceramic balls we produced use superfine high-pure home-made Si₃N₄ powders, the uniformly mixed powders are molded to near net size, and then sintered by GPS-HIP, the produced ceramic balls have excellent material performance and good spherical shape, this highly reduces the processing cost and shortens the processing periods from formerly several hundreds of hours to current several tens of hours, furthermore, we have explored a complete set of technology of processing ceramic balls, established a complete production line, and now we can produce large batches of kinds of gauges of G5 ceramic balls, and some gauges can be processed to G3.