BNP 2 ceramic is an ideal solution for bearings in harsh environments with corrosive substances and high temperatures.
Bearings made of ceramics such as BNP 2 are superior to their stainless steel equivalents in crucial ways, whether the bearing needs to achieve a higher level of revolutions per minute (rpm), should be as light a weight as possible or continue functioning in extreme environments where it may be in contact with corrosive substances or be subject to high temperatures and pressures.
The composite substance is essentially a mixture of boron nitride and aluminium nitride. This composite has a thermal conductivity that is five times that of aluminium oxide or alumina – one of the most common and cheapest ceramics on the market. In addition, it has a flexural strength similar to alumina’s.
BNP 2 can be employed up to temperatures of 1,020 degrees Celsius in an oxidising environment and to 1,900 degrees Celsius in an inert environment. It has a zero open porosity, making it superior in this characteristic to metals such as calcium, magnesium, chromium and iron – the last four of which are components elements in many stainless steels.
This ceramic has a smooth surface comparable with glass. This results in a very low friction coefficient and so makes it a preferred substance for use in bearings where the reduction of friction is vital. Such a ceramic ball bearing will need less lubricant over time to prolong its use. It also has a far superior hardness to equivalent bearings made of steel and so will have a far long useful lifetime.
The weight of such ceramic bearings is just one third of a comparable bearing made of steel. It is also highly resistant to corrosive substances such as acids that may be found in many industrial and research environments. These bearings are also resistant to any corrosion from salt water or seawater.
Hybrid bearings made of ceramic and steel have applications in machine tools and electric motors, especially in wind energy installations. These are essentially ceramic bearings surrounded by inner and outer rings of steel. These are used in place of 100% steel for their fast operation and in place of 100% ceramic to ensure a greater overall density that produces a higher centripetal force. In the wind energy application, the electrical insulating properties of the ceramic mean that the creation of welds, and hence high noise levels, can be avoided when an electric current passes through the motor’s bearings.
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