High Temperature Bearings

Ceramic bearings are ideal for high temperature environments such as furnace applications Full ceramic bearings We stock full ceramic bearings, also known as full complement bearings, suitable for temperatures above 300°C. Customers can also use them at high temperatures below this limit, in which case problems may arise with the lubricant, for example, due to contamination. Our full complement ZrO2 full ceramic bearings can be used at temperatures up to 400°C, while our full complement Si3N4 bearings have been successfully used at temperatures in excess of 800°C. It is impossible to provide grease or oil suitable for these temperatures, but luckily our full ceramic bearings can operate without lubricant. This is also an advantage in high temperature vacuum applications. Both types of full ceramic bearings maintain good strength up to their upper temperature limits.

Inch Size Silicon Carbide Bearings

Silicon Carbide delivers ball bearings incredibly high corrosion-resistance.Range in bore diameters from 0.09375 inch to 4.5 inches. Silicon carbide ball bearings are used less frequently than other ceramic materials. Due to its raw material cost and processing difficulty. Silicon carbide has the best heat and corrosion resistance of all ceramic materials. Silicon carbide ball bearings are best suited for low loads, low to medium speeds and highly corrosive environments. Silicon carbide (SiC) is a lightweight ceramic material with high strength properties comparable to diamond. It has excellent thermal conductivity, low thermal expansion, and is resistant to acid corrosion. Silicon carbide is an excellent ceramic material for applications requiring good erosion and wear resistance. AUB can supply rings and bearing products made of SiC as well as other SiC parts. Bearings made of other ceramic materials such as ZrO2 and Si3N4 are also available.

Inch Size Silicon Nitride Bearings

The weight of Si3N4 bearings is only about 40% of that of steel bearings. Silicon nitride ceramic bearings have high hardness, very smooth wear surfaces and can run without lubrication, so they are often used where very low rotational resistance is important. Their coefficient of friction is very low compared to steel bearings or even hybrid bearings. Si3N4 bearings have a coefficient of friction of approximately 0.001 in lightly loaded air at ambient temperature.Unlike zirconia, silicon nitride has a low coefficient of expansion, so care should be taken when selecting a suitable shaft for high temperature applications, as steel shafts expand much more than silicon nitride inner rings, which can lead to ring fracture. Also, the steel housing expands much more than the silicon nitride outer ring, resulting in a looser fit at high temperatures.

Inch Size Zirconia Bearings

ZrO2 or zirconium dioxide is a tough ceramic material with expansion properties very similar to steel. This is an advantage when considering shaft and housing suitability for high temperature applications. Although we often refer to these bearings as Zirconia bearings, they are made from ZrO2 stabilized with yttrium oxide, which gives the material greater strength and greater fracture resistance at room temperature. This is sometimes called YSZ or YTZP. Zirconia bearings are about 70% of the weight of steel bearings.Zirconia bearings have high hardness, very smooth wear surfaces and can run without lubrication, so they are often used where very low rotational resistance is important. Their coefficient of friction is very low compared to steel bearings or even hybrid bearings. ZrO2 bearings have a coefficient of friction of approximately 0.0012 at ambient temperature and lightly loaded air.

Metric Size Silicon Carbide Bearings

Silicon Carbide delivers incredibly high corrosion-resistance.Range in bore diameters from 2 mm to 106 mm. Silicon carbide ball bearings are used less frequently than other ceramic materials. Due to its raw material cost and processing difficulty. Silicon carbide has the best heat and corrosion resistance of all ceramic materials. Silicon carbide ball bearings are best suited for low loads, low to medium speeds and highly corrosive environments. Silicon carbide (SiC) is a lightweight ceramic material with high strength properties comparable to diamond. It has excellent thermal conductivity, low thermal expansion, and is resistant to acid corrosion. Silicon carbide is an excellent ceramic material for applications requiring good erosion and wear resistance. AUB can supply rings and bearing products made of SiC as well as other SiC parts. Bearings made of other ceramic materials such as ZrO2 and Si3N4 are also available.

Metric Size Silicon Nitride Bearings

Metric Size Zirconia Bearings

ZrO2 or zirconium dioxide is a tough ceramic material with expansion properties very similar to steel. This is an advantage when considering shaft and housing suitability for high temperature applications. Zirconia bearings weigh approximately 70% of steel bearings. Zirconia bearings have high hardness, very smooth wear surfaces and can run without lubrication, so they are often used where very low rotational resistance is important. Their coefficient of friction is very low compared to steel bearings or even hybrid bearings. ZrO2 bearings have a coefficient of friction of approximately 0.0012 at ambient temperature and lightly loaded air.

All bearings have temperature limits. Typically, the material weakens above a certain temperature and the bearing can no longer withstand any meaningful load or speed. Chromium steel bearings can withstand temperatures up to 150°C, while grade 440 stainless steel bearings can be used at temperatures up to 300°C if a suitable lubricant is used. Above these temperatures, ceramic materials are required.Ceramic bearings are ideal for high temperature environments such as furnace applications Full ceramic bearings.

We stock full ceramic bearings, also known as full complement bearings, suitable for temperatures above 300°C. Customers can also use them at high temperatures below this limit, in which case problems may arise with the lubricant, for example, due to contamination. Our full complement ZrO2 full ceramic bearings can be used at temperatures up to 400°C, while our full complement Si3N4 bearings have been successfully used at temperatures in excess of 800°C. It is impossible to provide grease or oil suitable for these temperatures, but luckily our full ceramic bearings can operate without lubricant. This is also an advantage in high temperature vacuum applications. Both types of full ceramic bearings maintain good strength up to their upper temperature limits.

ZrO2 or zirconia has a similar thermal expansion rate to steel, so attention should be paid to the internal clearance of the bearing to ensure adequate clearance at the highest operating temperature. This is less of an issue with silicon nitride due to its very low thermal expansion, but calculations should still be made to ensure that the bearing has sufficient residual clearance. This low expansion should be taken into account when considering shafts and housings for use with Si3N4 bearings at elevated temperatures. These fits can change significantly if the shaft or housing is made of a material with a higher coefficient of expansion, such as 316 stainless steel.

Our all-ceramic bearings can be equipped with ball cages and seals made of PEEK or PTFE, but they limit the maximum temperature to about 250°C. It may be preferable to use looser radial clearance at high temperatures, especially when the inner ring temperature may be higher than the outer ring temperature, as this will reduce the radial clearance of the bearing. Our high temperature ceramic bearings come standard with a looser C3 radial clearance.