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Technical Ceramic Materials Compared
Fourteen grades that shops in this network machine, on one page. Typical published values for common commercial grades, so use them to shortlist, then quote against the datasheet for the specific blank.
Start from the property, not the name
Most selection mistakes come from copying a grade off an old drawing. Find the line that describes your failure mode instead.
- Highest fracture toughnessZirconia 3Y-TZP, then ATZ and silicon nitride. Read the guide
- Highest hardness and abrasive wearSintered silicon carbide, then alumina 99.8%. Read the guide
- Best thermal conductivity with insulationAluminium nitride, then Shapal for machinable work. Read the guide
- Best thermal shock resistanceCordierite for low stress, silicon nitride for loaded parts. Read the guide
- Highest dielectric strengthMacor and boron nitride, then high purity alumina. Read the guide
- Plasma and particle performanceAlumina 99.5% and above, or a coated grade. Read the guide
- Fastest route to a finished partMacor, Shapal or boron nitride, machined with no firing step. Read the guide
- Lowest cost for a structural partAlumina 96%, from stock plate or tube where possible. Read the guide
Full property table
Grouped by family. Hardness is Vickers, strength is flexural, temperature is a practical maximum in air unless noted.
Oxide ceramics
| Grade | Density g/cm3 | Flexural MPa | Toughness MPa m^0.5 | Hardness HV | Modulus GPa | Max temp deg C | Thermal W/mK | Expansion ppm/K | Dielectric kV/mm |
|---|---|---|---|---|---|---|---|---|---|
| Alumina 96% | 3.7 | 330 | 3.5 | 1300 | 300 | 1500 | 24 | 8.2 | 17 |
| Alumina 99.5% | 3.9 | 380 | 4.0 | 1500 | 370 | 1600 | 30 | 8.0 | 18 |
| Alumina 99.8% | 3.9 | 400 | 4.2 | 1600 | 380 | 1700 | 33 | 8.1 | 20 |
| ZTA (zirconia toughened alumina) | 4.1 | 700 | 6.0 | 1450 | 340 | 1500 | 20 | 8.5 | 15 |
| Zirconia 3Y-TZP | 6.0 | 1000 | 10 | 1250 | 210 | 1000 | 2.5 | 10.5 | 12 |
| ATZ (alumina toughened zirconia) | 5.5 | 1100 | 8.0 | 1400 | 250 | 1100 | 3.0 | 10.0 | 12 |
| Cordierite | 2.3 | 110 | Low | 700 | 70 | 1300 | 3 | 2.0 | 12 |
- Alumina 96%. The default. Insulators, wear parts, fixtures, and the easiest grade to metallise and braze.
- Alumina 99.5%. Vacuum, plasma and dielectric work where the glassy phase in 96% would be attacked.
- Alumina 99.8%. Plasma facing semiconductor parts and anywhere particle generation is the failure mode.
- ZTA (zirconia toughened alumina). An alumina part that keeps cracking, when full zirconia is too expensive.
- Zirconia 3Y-TZP. The toughest common grade. Plungers, blades, dies, thin sections, medical parts.
- ATZ (alumina toughened zirconia). Zirconia toughness with better hardness and ageing resistance.
- Cordierite. Thermal shock above everything else. Kiln furniture, setters, burner parts.
Non-oxide ceramics
| Grade | Density g/cm3 | Flexural MPa | Toughness MPa m^0.5 | Hardness HV | Modulus GPa | Max temp deg C | Thermal W/mK | Expansion ppm/K | Dielectric kV/mm |
|---|---|---|---|---|---|---|---|---|---|
| Silicon carbide, sintered | 3.1 | 450 | 3.5 | 2500 | 410 | 1600 | 120 | 4.0 | Semiconducting |
| Silicon carbide, reaction bonded | 3.0 | 350 | 3.5 | 2300 | 380 | 1350 | 130 | 4.3 | Conductive |
| Silicon nitride | 3.2 | 850 | 6.5 | 1500 | 310 | 1200 | 28 | 3.2 | 14 |
| Aluminium nitride | 3.3 | 320 | 3.0 | 1100 | 330 | 1000 in air | 180 | 4.5 | 17 |
- Silicon carbide, sintered. Abrasive wear, seal faces, aggressive chemistry, and parts that must not deflect.
- Silicon carbide, reaction bonded. Cheaper SiC for large shapes. Free silicon limits temperature and chemical resistance.
- Silicon nitride. Thermal shock, impact and rolling contact. Bearing elements and hot section parts.
- Aluminium nitride. An insulator that moves heat. Chucks, heat spreaders, power electronics.
Machinable ceramics
| Grade | Density g/cm3 | Flexural MPa | Toughness MPa m^0.5 | Hardness HV | Modulus GPa | Max temp deg C | Thermal W/mK | Expansion ppm/K | Dielectric kV/mm |
|---|---|---|---|---|---|---|---|---|---|
| Boron nitride, hot pressed | 2.1 | 60 | Low | Very soft | 40 | 900 in air | 30 to 60 | 1 to 4 | 35 |
| Macor | 2.5 | 94 | 1.5 | 250 | 67 | 800 | 1.5 | 9.3 | 40 |
| Shapal Hi M Soft | 2.9 | 300 | 3.0 | 390 | 190 | 1900 inert | 90 | 5.2 | 40 |
- Boron nitride, hot pressed. Very high temperature in inert atmosphere, self lubricating, machines like chalk.
- Macor. Fast, complex, low stress parts. No firing step, so the machined part is finished.
- Shapal Hi M Soft. Machinable and thermally conductive. Prototype heat spreaders and fixtures.
How to read this table without getting burned
Four things the numbers do not tell you.
- Grades varyTwo suppliers can both sell 99.5% alumina and deliver different density and grain size. For anything demanding, specify those as well as the purity.
- Strength is statisticalA brittle material fails from its worst flaw, not its average one. Two parts from the same lot can differ, which is what the Weibull modulus describes.
- Surface condition changes strengthA coarsely ground part is weaker than a lapped one in the same material, because grinding leaves microcracks below the surface.
- Availability beats theoryThe best grade on paper is the wrong choice if it is not stocked near your part size. Ask before you specify.
Not sure which line is yours?
Describe the environment and the failure you are trying to avoid. We read it, shortlist a grade and route, then match you with up to 3 shops that machine it. Reply within 24 business hours.