Hybrid bearings - technical features

Due to its special characteristics (light, high-strength and low wear), the preferred material silicon nitride (Si3N4) is used for most ceramic bearing applications.

The low-cost alternative is zirconium oxide (ZrO2), which has the additional advantage that its thermal expansion is similar to that of steel. A shrink-fit is not necessary, because matching problems between the shaft and housing cannot occur.

For highly corrosive media, e.g. in the chemical industry, use of silicon carbide (SiC) is advisable.

Characteristic material values

 

 

Si3N4

ZrO2

SiC

100Cr6

Thickness

ρ

g/cm³

3,2

5,9 - 6,04

3,14 - 3,2

7,85

Hardness

HV10

N/mm²

1700 - 2700

1300 - 1500

2400

700

Elastic modulus

E

GPa

300

205

410

210

Coefficient of thermal expansion

α

10-6/K

3,2

10,2

4,3

11,5

Bending strength

δB

N/mm²

800

1000 - 1500

450 - 800

> 2500

Fracture toughness

KIC

MPa m½

8

8 - 12

4 - 5

> 20

Thermal conductivity

λ

W/m * K

30 - 35

2

30-120

40 - 45

Material selection

Some examples of high-performance materials used:

Rings and rollers: Highly temperable stainless steels, e.g.:  W.-Nr: 1.4112, 1.4108, 1.4535 etc - up to +350°C 
Austenitic stainless steels, e.g.: W.-Nr:  1.4404, 1.4462, 1.4529 etc – high chem. resistance
Highly temperable stainless steels, e.g.: W.-Nr: 1.3343, Vanadis 23 etc – up to +600°C
High-performance ceramics such as Si3N4 silicon nitride, ZrO2 zirconium oxide, SiC silicon carbide - up to +1000° C
Cages + cover discs: High-performance plastics such as PEEK, PTFE, PI, PEI etc. are standard materials. They can be used from 150-260° C and are chemical- and radiation-resistant, non-magnetic, vacuum-suitable and there do not allow passage of current.
Technologies: 

Dry running properties - friction reduction - wear protection Insoluble lifetime coating 0.5 µm (lubrication) of the surfaces of the tracks and rolling elements up to +500° C, vacuum-stable up to 10-14 mbar, bio-compatible, very low coefficient of friction Higher corrosion and wear protection for all hardened rolling bearing rings of standard bearings made of 100Cr6 (chrome coating) Silver-gray chrome coating 3-5μm, HRC72, corrosion protection equivalent to 120 hour salt spray test According to DIN EN ISO 9227, vacuum-stable up to 10-14 mbar

Lubrication

Bearing greases are available for every application. We are happy to advise you in detail as to chemical resistance, work stability, FDA greases and high-temperature grease up to +260° C.

Contact our technical consultation service here..