What is a Ceramic Ball Bearing?

Types of Ceramic Ball Bearings

Hybrid Bearings are made up of two materials. The balls are made from a ceramic material, usually silicon nitride Si3N4, while the inner & outer rings are made from traditional, heat-treated chrome or stainless steel. Full Ceramic Bearings on the other hand have both the inner & outer rings as well the balls manufactured from ceramic material, usually zirconium dioxide ZrO2, also known as zirconia. Nowadays, both hybrid and full ceramic bearings are considered quite affordable and are often the most economical solution when the end-user considers the cost of a failure and the total cost of ownership.

What Are Hybrid Bearings?

The most common configuration for a Hybrid Bearing is Silicon Nitride Si3N4 balls with either chrome or stainless steel rings. Compared to traditional steel balls, Si3N4 balls have the following desirable characteristics:

approximately 60% more lightweight than bearing steel
higher hardness: over 75 HRc
stiffer: higher elastic modulus
lower coefficient of thermal expansion
higher maximum operating temperature: 1000+°C
lower friction: highly polished surface finish

Another popular hybrid configuration is with zirconia ZrO2 balls instead of silicon nitride. The mechanical and thermal properties of ZrO2 are closer to that of alloy steel, which can be desirable in maintaining the bearing preload and contact angle over a broad range of operating temperatures. Consult an AST Applications Engineer for a full analysis of the operating conditions and potential failure modes.

What Are The Benefits of Hybrid Ceramic Bearings?

higher stiffness and rigidity reduces deflection
increased limiting speed (rpm)
less adhesive wear, no cold-welding
better lubricant life
lower noise levels & vibration
no electrical arcing through the balls

What Are The Applications For Hybrid Ceramic Bearings?

machine tool spindle
pumps - submersible, fuel, vacuum
dental drills
optical scanner
electric motors
aerospace applications
laboratory equipment
applications that requre higher speeds, longer life, and lower friction

What are Full Ceramic Bearings?

Full Ceramic Bearings are often the answer for extreme environments, such as high temperatures, corrosive chemicals, steam, and hard vacuum. These bearings have both the inner and outer rings in addition to the rolling elements manufactured from ceramic material. Like the balls in hybrid bearings, the rings in full ceramic bearings are typically manufactured from silicon nitride, Si₃N_4, or zirconia, ZrO₂. Retainers in full ceramic bearings are typically made from high-performance plastics such as PEEK or PTFE. Full complement versions are also available.

Characteristics	Unit	Chrome Steel	Stainless Steel	Nitrogen Enhanced Stainless Steel	Si₃N₄	ZrO₂
Density	g/cm³	7,85	7,85	7,85	3,2	6,0
Hardness	Rc	>60	>58	>60	>75	>75
E-Modulus		210	200	218	320	200
Poissons Coefficient		0,28	0,28	0,3	0,26	0,3
Expansion Coefficient	x 10^-6°C	10,9	10,1	10,1	2,9	10
Top Temperature Limit	°C	170	260	500	1000	600
Corrosion Resistance		limited	good	very good	very good	good
Electrical Conductivity		conductor	conductor	conductor	isolator	isolator
Magnetism		magnetic	magnetic	magnetic	not magnetic	not magnetic

Benefits of Full Ceramic Bearings:

resistant to acid, salt and water, and blood
non-magnetic
lower coefficient of friction
resistant to electricity
corrosion-resistant
lighter, smoother and stiffer

Applications for Full Ceramic Bearings:

MRI equipment
vacuum environments
semiconductor manufacturing
radiotherapy
food processing industrie
any extreme environment requiring non-corrosive, non-conductive or non-magnetic bearings

An AST Applications Engineer should be consulted for a full analysis of the operating conditions and potential failure modes.