Chemical & High-Temperature Ceramics
Alumina crucibles, thermocouple tubes, kiln furniture and porous filtration media for temperatures up to 1,700 °C.
Above roughly 1,200 °C the limits stop being about wear and start being about purity, porosity and thermal shock. This family exists for the duties where the part has to survive the environment rather than the abrasion.
What limits a high-temperature ceramic part
- Thermal shock. Rapid heating or cooling puts the surface into tension. Most failures in crucibles and sheaths are thermal-shock failures, not melting.
- Creep. Under continuous load at temperature, alumina slowly deforms. Higher purity and higher density resist it, which is why kiln furniture is almost always AL-99.7.
- Chemical attack. Alumina resists most acids and neutral salts but is attacked by hydrofluoric acid, hot concentrated phosphoric acid and strong alkalis above about 100 °C.
- Pore structure. For filtration, the pore size distribution matters more than the grade — and it has to stay stable through backwashing and chemical cleaning.
Typical duties
| Duty | Grade | Testing / qualification |
|---|---|---|
| Melting crucible, batch | AL-99 / 99.7 | Thermal cycling test; check chemical compatibility first |
| Thermocouple protection sheath | AL-99.7 | Closed-end, gas-tight wall; shock resistance is the limit |
| Kiln furniture, setters, rollers | AL-99.7 | Creep test under load at the working temperature |
| Furnace tube, process tube | AL-99.7 | Straightness and wall concentricity specified |
| Liquid filtration | AL-99 | Pore size 1–200 µm; flow rate measured on a coupon |
| Gas distribution / sparging | AL-92 / 99 | Bubble point and permeability specified |
What we supply
- Alumina crucibles, closed-end and open, from 10 ml to 5 litres, in AL-99 and AL-99.7
- Thermocouple protection tubes and sheaths, closed end, Ø6–40 mm
- Furnace tubes, rollers and kiln furniture to drawing
- Porous ceramic discs, plates and tubes with controlled pore size from 1 to 200 µm
- Custom high-temperature profiles, including stepped and flanged tubes
Heating and cooling rates matter more than the peak temperature. A part that would fail in one furnace survives in another simply because the ramp is slower. Give us the cycle — ramp rate, dwell, cooling — and we can specify realistically.
Specify a high-temperature part
Send the duty, the temperature cycle and the chemistry. We will confirm grade, wall thickness and wall-density requirements.
In this section
Alumina Crucibles & Thermocouple Tubes
Crucibles and sheaths fail from thermal shock and chemistry far more often than from temperature. Specifying them well means knowing the heating…
Porous Ceramic Filtration Media
Porous ceramics filter by depth as well as by surface, which is why they hold far more contaminant than a cloth or…
Send us your drawing — get a quotation with a firm lead time
PDF, DWG, STEP, IGES or a photo with the critical dimensions marked. Engineering review within one working day.