Syalon (Si3n4) is Silicon Nitride alloy which is used as a protection sheath for Thermocouple Sensors. The Syalon sheath is an advanced ceramic which is commonly used in Incineration, Aluminium and Molten Metal industries. The sheaths offer outstanding performance and are cost effective compared Silicon Carbide (NSIC) & Cast Iron sheaths. The Syalon sheaths are strong and have a high thermal shock resistance and a high corrosion resistance.

The Syalon sheaths are suitable for use at high temperature up to 1500°C. The sheaths are available in a variety of lengths and diameter, see the table below.


  • Long service life
  • Good abrasive resistance
  • High temperature tolerance 1500°C
  • High thermal shock resistance
  • High corrosion resistance at high temperatures


Nitride Bonded Silicon Carbide (NSiC) Vs. Syalon (Si3n4)

  Nitride Bonded Silicon Carbide (NSiC) Syalon (Si3n4)
Application Aluminium Casting Aluminium Casting
Silicon Nitride (Si3n4) Content 21% 92%
Maximum Temperature 1400°C 1500°C
Estimated Lifespan 3-5 months 4-10 months
Price Lower Higher


Physical and chemical index

Types GPSN (gas pressure sintered silicon nitride)
Density >3.2g/cm3
Si3N4 content >92%
Flexural strength >600Mpa
Compressive strength >1500Mpa
Thermal conductivity (W/mk) >22
Porosity 0
Thermal expansion coeff. (RT-1000°C) 3.2
Max temperature In air 1400°C
Hardness (HRA) >92


Standard sizes (mm)

OD ID Minimum Length Maximum Length
16 8 300 600
22 12 300 900
28 16 300 1600
30 18 300 1600
45 25 300 1600