Physical and chemical properties of ceramic fibers

Compared with traditional thermal insulation materials, ceramic fibers have many superior performance characteristics.

1. Good temperature resistance. According to the raw materials used in ceramic fibers, the maximum use temperature can be divided into low temperature type (below 900 ° C), standard type (below 1200 ° C), high temperature type (1400-1600 ° C). Fiber-like insulation materials such as rock wool and glass wool have a maximum use temperature of 500-700 ° C, which is much lower than that of ceramic fibers.

2. The thermal conductivity is small. The thermal conductivity of ceramic fibers in the high temperature zone is small and has excellent thermal insulation effect. At a temperature of 1000 ° C, the thermal conductivity is only 15% of the refractory clay bricks, and about 38% of the lightweight clay bricks. Its thermal conductivity is dependent on bulk density, temperature, slag content and fiber diameter.

First of all, the thermal conductivity of ceramic fiber decreases with the increase of bulk density, but the decreasing extent is gradually reduced. Even when the bulk density increases to a certain range, the thermal conductivity no longer decreases, but has an increasing trend. 

Second, at different temperatures, there is a minimum thermal conductivity and a corresponding minimum bulk density.

Finally, the minimum bulk density corresponded to the minimum thermal conductivity increases with increasing temperature.

3. The ceramic fiber has a small bulk density of about 90-220 kg/m3, which is only 1/5-1/3 of the lightweight refractory brick.

4. Good thermal stability. The fiber of the ceramic fiber is long and the elasticity of the product is good, so that a sharp change in temperature does not cause structural stress. In addition, the product is a fibrous interwoven porous material, and the expansion of the monomer fibers can be absorbed by the product itself. Therefore, if the construction is reasonable, it can guarantee sufficient strength and resistance to cold and heat.

5. Good chemical stability. Except for strong bases, hydrofluoric acid, and phosphoric acid, it is hardly eroded by other chemicals. Ceramic fibers have excellent chemical stability even in neutral and oxidizing environments. However, the product is easily attacked by reducing gas, alkali metal oxide and sulfide, reaction occurs to deteriorate the fiber properties. The chemical stability of ceramic fibers mainly depends on its chemical composition and the content of impurities. The data show that the pure Al2O3 fiber has the best chemical stability.