What is reaction bonded silicon nitride tube?

Reaction bonded silicon nitride tubes, or Si3N4 tube are made by combining silicon powder with nitrogen at high temperatures to form a solid silicon nitride ceramic material with a tubular appearance.

Silicon nitride reaction bonded tube is generally gray in cylindrical shape with smooth and burr-free surface.

Reaction Bonded Silicon Nitride Tube
Reaction Bonded Silicon Nitride Tube

What is Si3N4 reaction bonded SiC?

Si3N4 bonded SiC is a new type refractory material, the applying temperature is 1400 ℃, it has better thermal stability, thermal shock, which is better than plain refractory material and recrystallization SiC.

Introduction of Si3N4 tube

Si3N4, or silicon nitride, is a ceramic material that is frequently utilized in the production of protective tubes(Si3N4 silicon nitride protection tube), which is an inorganic material ceramic and does not shrink during sintering. These tubes can be employed in harsh chemical and high-temperature environments to safeguard sensors, probes, or other equipment from damage.

Reaction bonded silicon nitride tube properties

The Si3N4 tubes are well-regarded for their exceptional thermal stability, high strength, and resistance to corrosion and wear. They can be used in a wide range of industries, including aerospace, automotive, and chemical processing.

Thermal stability

The exceptional thermal stability of Si3N4 is due to its high melting point of 1,800°C, which makes it a suitable material for use in extremely high-temperature environments.

High strength

Its high strength and toughness enable it to withstand mechanical stresses and shocks, which make it suitable for use in harsh environments.

Resistance to corrosion and wear

Silicon nitride is corrosion and wear resistant. Silicon nitride is highly chemically stable, it does not react with other inorganic acids except hydrofluoric acid,, as well as its resistance to abrasion, makes it a suitable material for use in chemical processing plants and other harsh environments.

Thermal shock resistance

It is also resistant to hot and cold shocks, heats up to 1000 degrees or more in air, cools quickly, and then heats up quickly without breaking.

Technical data of Si3N4 silicon nitride protection tube

The following table is a comparison of Si3N4 parameters made by two different processes.

(Gas Pressured Sintered Silicon Nitrides)
(High pressured Sintered Silicon Nitride)
Young’s Modulus(GPa)320315
Bend Strength(MPa)750850
Thermal Expansion Coefficient (x 10-6/℃)3.23.2
Fracture Toughness78
Maximum Temperature (℃) for application11501150
Dielectricity Constant99
Si3N4 silicon nitride protection tube technical data

The above table shows the data of reaction bonded silicon nitride tube (Si3N4) materials made by two different processes (GPS-SSN and HPSN)

The data provided includes various properties of the materials, such as density, Young’s Modulus, Bend Strength, Thermal Expansion Coefficient, Fracture Toughness, Maximum Temperature for application, and Dielectricity Constant.

GPS-SSN has a density of 3.30 g/cm³, while HPSN has a density of 3.23 g/cm³. Both materials have similar thermal expansion coefficients of 3.2 x 10^-6/℃.

In terms of mechanical properties, GPS-SSN has a higher Young’s Modulus than HPSN, with a value of 320 GPa compared to HPSN’s 315 GPa. However, HPSN has a higher Bend Strength than GPS-SSN, with a value of 850 MPa compared to GPS-SSN’s 750 MPa.

In terms of fracture toughness, HPSN has a higher value than GPS-SSN, with a fracture toughness of 8 compared to GPS-SSN’s 7.

Both materials have a maximum temperature for application of 1150℃ and a dielectricity constant of 9. Overall, the table provides information on the different physical and mechanical properties of these two materials, which could be useful for selecting the appropriate material for a particular application.


Si3N4 thermocouple protection tube properties

  • Lightweight (60% Lighter than Steel)
  • High Fracture Toughness
  • Wear Resistant
  • High Dielectric Strength
  • Corrosion Resistant
  • Low Coefficient of Thermal Expansion
  • Thermal Shock Resistance.


The series of products are widely used for measuring temperature in the fields of ceramic, metallurgy, chemical industry, etc.

In conclusion, reaction bonded silicon nitride tube(Si3N4 tube) are a reliable and durable solution for safeguarding equipment in harsh environments, The service life can last for many years with regular maintenance.

They provide high thermal stability, high strength, and resistance to corrosion and wear, excellent protection, impermeability and excellent precision, making them a popular choice for industries that operate in demanding conditions.