Back in 2000, scientists discovered zircon in rocks that showed life might have started 500 million years earlier than previously thought. This incredible compound has made a huge impact, as has its oxide, zirconia (ZrO2), used to make full ceramic bearings. Here, Chris Johnson, managing director of specialist bearing supplier, SMB Bearings, explains the three most overlooked factors concerning full ceramic bearings.
Full ceramic bearings are generally rounder, smoother and harder than steel, offering superior corrosion and heat resistance, higher dimensional stability and lower density. However, this comes at a cost. Ceramic bearings are significantly more expensive than their steel counterparts. So, when does investing in ceramic bearings become worth it?
High-value applications, like lab equipment, have exact requirements that need to be hit every time the application is used. Using the wrong components in such equipment can contaminate study conditions, or cause the study to cease altogether. This is the same with medical equipment, where the non-contaminating and non-magnetic properties of ceramic bearings prove vital.
Take Magnetic Resonance Imaging (MRI) for example, the imaging technique associated mostly with hospital MRI scanners. This technology uses a strong magnetic field to generate two- or three-dimensional images of any living subject. Standard steel bearings cannot be used in these scanners due to their magnetic properties, so ceramic bearings are the best choice to use in these high-value applications.
Similarly, as integrated circuit manufacturers strive to make their chips faster, smaller and less expensive, semiconductor fabrication equipment companies become more dependent on advanced ceramic components to achieve the desired performance. Using bearings made from silicon nitride, rather than the standard alumina (aluminum oxide), provides electrical insulation and good corrosion resistance.
Silicon nitride’s resistivity and dielectric constant are similar to that of alumina, but the material is far stronger due to its microstructure. Full ceramic bearings can accommodate the many challenging conditions present during the stages of semiconductor production; from furnace temperatures that can reach close to 1400 degrees Celsius, to clean-room 1 air quality. Suddenly, the increased costs are clearly justified.