Ceramic tubes protect, isolate and carry. They serve as thermocouple sheaths, furnace muffles, insulating bushes and fluid paths where metal would corrode, creep or conduct.
Silicon carbide tubes are the choice for burner nozzles, radiant tubes and heat exchangers above 1200°C. High conductivity and expansion of 4.0 ×10⁻⁶/K let them cycle between flame and cold air without cracking.
Silicon carbide is chosen when a part must survive abrasion, high temperature and thermal shock at the same time. Hardness reaches 2200-2500 HV, thermal conductivity of 120-200 W/m·K is several times that of steel, and expansion of 4.0 ×10⁻⁶/K keeps it in shape through fast temperature swings.
It is brittle and electrically semiconducting, so it is not used where electrical isolation matters, and its hardness makes diamond grinding the only practical finishing route.
Specifications
| Outer diameter | 3-150 mm |
| Inner diameter | 1-120 mm |
| Length | up to 600 mm |
| Minimum wall thickness | 0.5 mm |
| Concentricity | 0.02 mm |
| Bore finish | Ra 0.4 µm, honed Ra 0.2 µm |
| Ends | square cut, chamfered, flanged or closed one end |
Silicon Carbide Properties
| Composition | Sintered silicon carbide (SSiC) |
| Density | 3.10-3.15 g/cm³ |
| Vickers hardness | 2200-2500 HV |
| Flexural strength | 400-500 MPa |
| Fracture toughness | 3-4 MPa·m½ |
| Max. service temperature | 1400°C in air (1600°C inert) |
| Thermal conductivity | 120-200 W/m·K |
| Thermal expansion (20-1000°C) | 4.0 ×10⁻⁶/K |
Machining and Tolerances
Tubes are extruded, isostatically pressed or slip cast depending on size and quantity, then ground on the outside and honed internally. Long thin-wall tubes are the most distortion-prone parts we make, so we rough grind, allow the part to relax, then finish grind.
Where It Is Used
- Thermocouple protection sheaths and furnace muffles
- Insulating bushes through heated panels and vacuum chambers
- Fluid and slurry transport in corrosive or abrasive service
- Lamp, laser and UV equipment bodies
- High-voltage insulators and standoffs
Frequently Asked Questions
What is the thinnest wall you can produce?
0.5 mm is the practical floor for most materials and lengths. Below that, yield drops sharply during firing and grinding, so we review the drawing and usually suggest thickening the wall or shortening the tube.
Can you supply closed-end tubes?
Yes. Closed one end, hemispherical closed ends and reduced-tip ends for thermocouple sheaths are all produced, either formed during shaping or ground after firing.
