MoSi2 for very high temperatures
Kanthal Super 1700* is a dense cermet material consisting of MoSi2 and a SiO2 phase. At high temperatures, a protecting layer of SiO2 is formed on the surface; This protective layer is the key to the outstanding oxidation resistance of this material, see the table below:
| Furnace atmosphere | Max temperature °C (F) |
| Air | 1700 (3090) |
| Nitrogen | 1600 (2910) |
| Argon, Helium | 1600 (2910) |
| Dry hydrogen, dewpoint -80°C (-86 F) | 1150 (2100) |
| Moist hydrogen, dewpoint 20°C (68 F) | 1450 (2640) |
| Endogas (e.g. 40% N2, 40% H2, 20% CO) | 1400 (2550) |
| Cracked and partially burnt ammonia | 1400 (2550) |
Porosity and brittleness is lower in the SUPER 1700 material as compared to ceramic tubes. This is in particular true at temperatures above 1200 C (2190 F). The large disadvantage of brittle fracture of ceramic tubes is therefore avoided using the SUPER 1700 material. Also the thermal conductivity of SUPER 1700 is superior to that of ceramics.
Kanthal SUPER 1700 is not influenced by electromechanical oscillations, which is of advantage as compared to metallic tubes.
While the SUPER 1700 material has a high strength at lower temperatures, at higher temperatures it becomes softer; Therefore, SUPER 1700 tubes should preferably be mounted vertically.
Tubes in Kanthal Super 1700 are available in the following sizes:
| Tube sizes, ODxID, mm/inch | Max-length, mm/inch | Thread |
| 25x15/0.98" x 0.59" | 2000/78.74 | 1/2"-1", BSP or NPT |
| 22x13/0.87" x 0.51" | 2000 | 1/2"-1", BSP or NPT |
| 18x10/0.71" x 0.39" | 2000 | 1/2"-1", BSP or NPT |
| 12x6/0.47" x 0.24" | 2000 | 1/2", BSP or NPT |
| 12x3/0.47" x 0.12" | 2000 | 1/2", BSP or NPT |
| 10x6/0.39" x 0.24" | 2000 | 1/2", BSP or NPT |
| 7x3/0.28" x 0.12" | 2000 | 1/2", BSP or NPT |
Examples of applications: As protection tubes at high temperatures. as hot gas sampling tubes, as hot gas injection tubes and as bubbler tubes in glass melting tanks.
*KANTHAL SUPER is a registered trademark of Kanthal AB