As mentioned before, ceramic fiber module is different from other materials, which is not suitable for the principle of thermal expansion and cold contraction. On the contrary, it will shrink to a certain extent when heated at high temperature. Let’s look at it from a physical point of view.

Shrinkage of ceramic fiber during heating is a very important characteristic, which is directly related to crystal evolution and grain growth. At the temperature before crystallization, the refractory fibers did not shrink, but when the temperature increased to the crystallization temperature, the fibers shrank.

The crystallization signals the beginning of shrinkage and presents itself as the beginning of a process called crimp. The curl or deformation of a single fiber is the mechanism that causes the aggregate to contract. Grain growth When the crystalline phase begins to precipitate, a very fine grain structure begins to form, which grows with the extension of time and the increase of temperature.

As the grain grows, the strength of a single fiber becomes weaker when its size approaches the diameter of a single fiber. With the delay of time will continue to shrink, will reduce the effective length of the fiber, long-term use will produce overall shrinkage.

It is worth noting that at 1200℃, the shrinkage rate of ceramic fiber of grade 1400 (high alumina content) is higher than that of grade 1260. At 1400 ° C, the rate of contraction at 1400 ° C is much lower than at 1260 ° C.

Therefore, in the practical application, not only the use temperature of the product should be considered, but also the shrinkage rate under a certain working temperature should be taken into account to comprehensively select materials, instead of blindly pursuing the high temperature grade, such as in the furnace temperature of 1000 degrees, 1260 high-purity use effect and durability are higher than 1400 high-aluminum fiber. At 1200 ° C, the high aluminium and low zirconium types have the best combined effect.


