Zirconia is the ceramic for chemical and magnetic duty: it resists almost every fluid, insulates, and expands with heat at nearly the same rate as steel — which keeps clearance predictable in a full-ceramic bearing.
| Designations | ZrO2 · zirconium dioxide · yttria-stabilised zirconia (Y-TZP) |
|---|---|
| Density | 6.00 g/cm³ |
| Hardness | ≈1200 HV |
| Max service temperature | ≈400 °C |
| Thermal expansion | ≈10×10⁻⁶/K — close to bearing steel |
| Corrosion resistance | Excellent against acids, alkalis, solvents, seawater |
| Magnetic | Non-magnetic |
| Electrical | Insulating |
| Relative cost | 6–10× steel |
Zirconia is tougher than most technical ceramics — its transformation-toughening mechanism absorbs energy at a crack tip — and it expands with heat at almost the same rate as steel. In a full-ceramic bearing that second property matters as much as the first: clearance stays predictable across the temperature range, so a zirconia bearing does not lose preload the way a silicon nitride one can.
Its weakness is thermal shock. A zirconia part that is heated or cooled quickly develops a temperature gradient and can crack. In a pump that runs at a steady temperature this is irrelevant; in a bearing that sees steam cleaning followed by cold water, it is decisive.
Choose silicon nitride for speed: it is a third lighter and roughly 25% harder, and it tolerates thermal shock better. Choose zirconia for chemistry, for non-magnetic requirements, and where the clearance must stay predictable with temperature because its expansion matches steel. Both are insulators; both are brittle compared with steel.
| Property | ZrO2 | Si3N4 | 316 stainless |
|---|---|---|---|
| Hardness | ≈1200 HV | ≈1500 HV | 25–30 HRC |
| Density g/cm³ | 6.00 | 3.20 | 8.00 |
| Max temp | ≈400 °C | ≈400 °C bearing | 300 °C |
| Thermal shock | Moderate — sensitive | Good | n/a |
| Thermal expansion | ≈10×10⁻⁶/K | ≈3.2×10⁻⁶/K | ≈16×10⁻⁶/K |
| Load capacity | Good | Good | Low |
| Relative cost | 6–10× | 8–15× | 3–4× |
The classic full-ceramic application: immersed, corrosive, light load.
Read →Non-magnetic, insulating positions near sensors and magnets.
Read →6000/6200 series in ZrO2 with PTFE or PEEK cages.
Read →When speed and thermal shock matter more than expansion match.
Read →No. Zirconia is non-magnetic and insulating, which is why it appears in MRI-adjacent equipment, sensors and electron-beam instruments where a steel bearing would disturb the field.
Yes, at low load and moderate speed, usually with a PTFE transfer film or a self-lubricating cage. Dry running raises the temperature quickly, and zirconia's thermal shock sensitivity is the limit.
Almost always thermal shock or mechanical impact, not fatigue. Steam cleaning a warm bearing with cold water, or pressing a ring by its raceway, are the two common causes.
Yes — it is one of the best metallic-free options for immersed seawater duty, provided the load is modest and the temperature is steady.
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