High-Temperature Furnace Fixtures and Insulators

Furnace Components

Furnaces operating at temperatures above 1600°C often incorporate heating elements manufactured from graphite, tungsten or molybdenum disilicide. There is a need to electrically insulate these heating elements from the furnace environment using high temperature ceramics.

While oxide ceramic insulators are commonly used in low temperature furnaces, they are not as well suited for high-temperature furnaces. They become highly stressed at high temperatures, especially under shorter production cycles with faster heating and cooling rates. This leads to premature component failures and increased furnace downtime


high temperature furnace components crucibles

For thermal processes at extremely high temperatures and vacuum or in inert conditions, boron nitride insulators and components present the only viable solution. Saint-Gobain's COMBAT® grade AX05 is the material of choice in these applications, with advantages including:

  • Excellent dielectric performance up to 2000°C in inert atmospheres
  • Resistant to thermal shock and fast cycling
  • Easily machined into precision components such as threaded tubes, flanges, washers and more
  • High purity and inert to minimize reactivity with other components or fired material

 Sintering Media for Ceramic Manufacturing

The inert nature and high operating temperature of BN makes it attractive as sintering media for other ceramic materials. The high thermal conductivity of boron nitride ensures even heat transfer to the sintered part, preventing shrinkage gradients that can lead to warpage in the final part. While it is popular as kiln furniture, in the form of crucibles or plates, it can also be used as a bedding-in powder.


The growing need for ceramic substrates in power electronics and LEDs is leading to growth in aluminum nitride (AlN) manufacturing. The high temperature needed to sinter AlN and its sensitivity to contamination excludes traditional sintering media, such as graphite and alumina, from this application. COMBAT® grade AX05 is particularly well suited for AlN sintering, offering benefits such as:

  • Multiple firing runs without warping of the plates
  • Easy cleanup between runs
  • Long service life
  • Reduced frequency of replacement
  • Protection against contact reaction between sintered parts and supporting media.
boron nitride sintering plates