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When standard steel bearings corrode, seize, or fail under electrical interference, engineers and DIY builders turn to silicon nitride full ceramic ball bearings. These bearings are designed for applications where moisture, chemicals, high temperatures, or electromagnetic fields make metallic components impractical — from marine hardware and chemical processing equipment to high-frequency spindles and medical devices.
Each bearing in this listing is a full complement design, meaning the entire rolling element set consists of Si₃N₄ (silicon nitride) ceramic balls with a ceramic inner and outer race — no steel components in the load path. Available sizes span inner diameters from 5 mm (0.20 in) to 50 mm (1.97 in) and outer diameters from 16 mm (0.63 in) to 80 mm (3.15 in), covering the 6900, 6800, 606, 608, 625, 688, 6200, and 6000 series.
Typical use cases include saltwater-exposed fishing reels and boat hardware, semiconductor fab equipment requiring non-contaminating bearings, high-speed dental or lab spindles, and RC vehicle wheel hubs where weight reduction and corrosion resistance matter. The full ceramic construction also suits applications requiring electrical insulation, such as motor test rigs and MRI-adjacent machinery.
Both races and all rolling elements are silicon nitride ceramic — no steel in the load path. This eliminates galvanic corrosion and makes the bearing fully non-magnetic and electrically non-conductive.
Si₃N₄ withstands exposure to saltwater, acids, alkalis, and most industrial solvents that would rapidly degrade carbon steel or even stainless steel bearings.
Silicon nitride retains structural integrity at temperatures typically up to 800 °C (1472 °F) in dry conditions, far exceeding the limits of standard bearing steel, making these suitable for oven conveyor systems and high-heat spindles.
Full ceramic construction provides high electrical resistivity, preventing current passage through the bearing — critical for electric motor test benches, welding equipment, and MRI-adjacent applications.
Si₃N₄ is approximately 60% lighter than bearing steel by density. At high RPM, lighter rolling elements generate lower centrifugal forces, reducing race wear and enabling higher speed ratings compared to all-steel equivalents.
Covers 6900, 6800, 606, 608, 625, 688, 6200, and 6000 series with bore sizes from 5 mm to 50 mm (0.20–1.97 in). Select your exact series and dimension from the variant options above.
| Material — Races | Silicon Nitride (Si₃N₄) Ceramic |
|---|---|
| Material — Rolling Elements | Silicon Nitride (Si₃N₄) Ceramic |
| Bearing Type | Full Complement Deep Groove Ball Bearing |
| Series Available | 6900, 6800, 606, 608, 625, 688, 6200, 6000 |
| Bore Diameter (ID) Range | 5 mm – 50 mm (0.20 in – 1.97 in) |
| Outer Diameter (OD) Range | 16 mm – 80 mm (0.63 in – 3.15 in) |
| Width Range | 5 mm – 20 mm (0.20 in – 0.79 in) |
| Lubrication | See variant options |
| Seal / Shield Type | See variant options |
| Max Operating Temperature | Typically up to 800 °C (dry, unlubricated) |
| Electrical Resistivity | Non-conductive (full ceramic) |
| Magnetic Properties | Non-magnetic |
| Dimensional Standard | ISO 15 / JIS B 1512 metric series |
| Packing Quantity | 1 pcs per unit (see variant options for bulk) |
Match the bore (inner diameter), outer diameter, and width to your housing and shaft dimensions. The variant name format is: Series / ID×OD×Width mm — for example, "6902 / 15×28×7mm" means a 6902-series bearing with a 15 mm bore, 28 mm OD, and 7 mm width. Measure your existing bearing or shaft seat before selecting.
Silicon nitride has a hardness of approximately 1,500 HV and a compressive strength exceeding 3,000 MPa, making it harder than most bearing steels. However, ceramic is more brittle under impact or shock loads compared to steel. These bearings are well-suited for steady radial and axial loads but should be evaluated carefully for applications with frequent shock or vibration.
Yes. Si₃N₄ ceramic is chemically inert to saltwater, making these bearings a reliable choice for fishing reels, boat hardware, underwater ROVs, and other marine applications where steel bearings would corrode rapidly. No additional corrosion-inhibiting coating is required on the ceramic surfaces.
Yes, provided the series and dimensions match. These bearings follow standard ISO metric envelope dimensions (bore, OD, width), so a 6902 ceramic bearing will fit any housing designed for a standard 6902 steel bearing with the same 15×28×7 mm dimensions. Always verify all three dimensions before ordering.
Full ceramic bearings are electrically non-conductive and non-magnetic, making them suitable for use near MRI equipment, in electric motor test rigs, and in semiconductor fabrication tools where metallic contamination or current leakage through the bearing must be avoided. Confirm your specific insulation requirements with your equipment manufacturer.
Full ceramic bearings can operate with minimal lubrication or dry in certain high-temperature or clean-room environments where lubricants would degrade or contaminate the process. For general use, a ceramic-compatible grease (PTFE-based or perfluoropolyether) is recommended. Avoid petroleum-based greases at elevated temperatures as they may carbonize. Contact us to confirm lubrication recommendations for your specific operating conditions.
These designations refer to different dimensional series with varying OD-to-bore ratios. The 6900 series has a narrower cross-section (lighter, more compact), the 6200 series has a wider cross-section (higher load capacity for the same bore), and the 6000 and 6800 series fall in between. Choose based on your space constraints and load requirements. The 606, 608, 625, and 688 are specific miniature sizes outside the standard numbered series.
