Ceramic Materials and Their Properties

There are a variety of different ceramic materials, each with their own capabilities, advantages and disadvantages; their use in bearing and rolling element applications was pioneered by many of the space agencies and continues to be at the forefront of engineering technology.

Silicon Nitride

Density 3.2 g/cm3
Linear expansion coefficient 3.1×10-6/oC
Hardness 1450Kg/mm2
Elastic modulus 310GPa
Poisson’s Ratio 0.27
Electrical Resistance 1016ȍcm

Zirconia

Density 6.05 g/cm3
Linear expansion coefficient 10.3×10-6/oC
Hardness 1300Kg/mm2
Elastic modulus 220GPa
Poisson’s Ratio 0.31
Electrical Resistance 1013ȍcm

Silicon Carbide

Density 3.1g/cm3
Linear expansion coefficient 3.9×10-6/oC
Hardness 2200Kg/mm2
Elastic modulus 380GPa
Poisson’s Ratio 0.16
Electrical Resistance 108ȍcm

Stainless Steel(440C)

Density 7.6g/cm3
Linear expansion coefficient 12.5×10-6/oC
Hardness 750Kg/mm2
Elastic modulus 200GPa
Poisson’s Ratio 0.3
Electrical Resistance 10-5ȍcm

The most common ceramic materials and their properties are listed to the left along with 440C stainless steel as a comparison to a conventional material.

Components made of ceramic materials have a number of special properties such as being strong electrical insulators and highly resistant to temperatures opening a wider range of application than was thought possible prior to their utilisation.

Aspects such as lower density gives a weight saving and an increased life. This is because centripetal force acting upon the bearing is less, therefore reducing the wear on the rolling elements.

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