Material specifications & engineering data
The reference data engineers ask us for: a full material specification chart across our ceramic bodies, plus practical guidance on alumina bearing and bush wear life. Need a property that is not listed, or a value for a specific grade? Send us the application and we will confirm it.
Properties across our ceramic bodies
Typical values for guidance. Final properties depend on the exact grade, geometry, and firing schedule. Scroll the table sideways on a phone, or download the PDF above.
| Property | Unit | Normal Porcelain C-112 | Dense Cordierite C-210 | Steatite L-3 C-220 | Steatite L-5 C-221 | Cordierite Porcelain C-410 | Cordio-Sillimanite Refractory C-510 | Cordierite Refractory C-511 | High Alumina Porcelain C-610 | Alumina Ceramic C-780 |
|---|---|---|---|---|---|---|---|---|---|---|
| Physical Properties | ||||||||||
| Colour | Cream / White / Grey | Off-white | Off White | Off White (satin smooth) | White | White / Buff | Brown | Off White | Brown | |
| Specific gravity | 2.3 | 2.2 | 2.6 | 2.7 | 2.3 | 1.8-1.9 | 1.9 | 2.6 | 3.2 | |
| Water absorption | % | Less than 1 | Less than 2 | 0.5 | 0.0 | 0.0 | 22-24 | 15-20 | 0 | 0 |
| Flexural strength | kg/cm² | 800 | - | 1200 | 1400 | 800 | 300 | 300 | 1200 | 2500 |
| Compressive strength | kg/cm² | 2500 | 2500 | 4000 | 5000 | 2500 | 800 | 2000 | 3500 | 16000 |
| Young's modulus | kg/cm² ×10⁶ | 0.7 | - | 0.8 | 1.0 | 0.75 | - | - | 1.0 | 2.0 |
| Hardness | Moh's scale | 6-6.5 | - | 6-7 | 6-7 | 6-6.5 | 7-8 | - | 7.0 | 8.0 |
| Thermal Properties | ||||||||||
| Coefficient of thermal expansion (30-600°C) | ×10⁻⁶/°C | 6-7 | 4-5 | 6-7 | 6-7 | 6-7 | 4-5 | 4-5 | 5-6 | 6-8 |
| Thermal shock resistance (down shock) | °C | 200 | 500 | 250 | 300 | 400 | 500 | 750 | 300 | 250 |
| Thermal conductivity | W/m·K | 1.4-2.5 | - | 2-3 | 2-3 | 1.2-2.5 | 1.3-1.8 | 1.3-1.8 | 2-6 | 10-16 |
| Safe operating temp. | °C | 600 | 1000 | 1000 | 1050 | 600 | 1300 | 1000 | 1000 | 1100 |
| Max. temp. withstanding capacity | °C | 1200 | 1200 | 1200 | 1200 | 1200 | 1350 | 1200 | 1200 | 1200 |
| Electrical Properties | ||||||||||
| Dielectric strength | kV/mm | 8 | - | 10 | 20 | 10 | - | - | 10 | 18 |
| Dielectric constant (20°C, 1MHz) | 5.0 | - | 5.5 | 6.5 | 6.0 | - | - | 7.0 | 8.0 | |
| Volume resistivity (20°C) | Ω·cm | 10¹¹ | - | 10¹¹ | 10¹¹ | 10¹⁰ | - | - | 10¹¹ | 10¹² |
| Chemical Composition (nominal) | ||||||||||
| SiO₂ | % | 70 | 70-75 | 60-65 | 60-65 | 70-72 | 45-50 | 55-57 | 40-45 | - |
| Al₂O₃ | % | 20 | 15-17 | 15-17 | 6-7 | 23-25 | 45-50 | 30-32 | 45-50 | approx. 80 |
| MgO | % | - | 10-12 | 18-20 | 25-27 | 1-3 | 1-2 | 7-8 | - | - |
| Typical Applications | ||||||||||
| Applications | LT insulator, lamp holder, media lining block, etc. | Ferrules, high heat-shock items. | MCB plates, beads, insulators, lamp holders. | HRC square bodies, band heaters, end seal bush, grinding media, liners. | HRC round bodies, wire-wound resistor tube, different special-shape insulators, media. | Kiln furniture, hot plates, heating element support. | Bobbins, multi-hole tubes, heating element support. | High / low voltage electrical application, resistance formers. | Coil formers, wear-resistant parts. | |
Alumina bearing & bush wear life
A common question from customers replacing metal bushes with ceramic. The short version: in a clean, well-aligned, low-speed application, an alumina bush will outlast the shaft it runs on.
Bearing life depends heavily on operating conditions, but a slow, clean application is highly favourable for long life. As a worked example, a bush running at 12 RPM sees roughly 4.5 million revolutions a year, which is not particularly demanding from a ceramic wear perspective.
One point worth knowing: in many alumina-against-stainless combinations, the stainless shaft wears before the ceramic. Alumina sits around 1,500 to 2,000 HV, whereas 304 or 316 stainless is much softer at roughly 150 to 250 HV. With contamination or poor lubrication, the shaft can develop wear grooves while the ceramic stays largely unaffected.
For a typical low-speed support bush (well aligned, modest radial loads, smooth shaft finish, no abrasive product), the ceramic bush itself can be expected to last many years, often 10 or more.
Factors that affect life
- Alumina grade (95%, 99.5%, 99.8%, etc.)
- Shaft material and hardness (304, 316, hardened or coated stainless)
- Bearing load, both radial and axial
- Shaft surface finish
- Lubrication (dry, water, grease, or product-lubricated)
- Contamination (dust, abrasives, slurry, powders)
- Bearing clearance
| Operating condition | Typical service life |
|---|---|
| Light load, clean environment, polished shaft | 10-20+ years |
| Moderate load, occasional contamination | 5-10 years |
| Heavy load, dry running, abrasive contamination | 1-5 years |
| Misalignment causing edge loading | Months to a few years |
Figures are general guidance only. Send us your operating conditions for an estimate specific to your application.
Need a spec for your application?
Tell us the operating temperature, loads, and environment, and we will recommend the right body and confirm the properties that matter for your part.