Generally, the natural law of thermal expansion and cold contraction is applicable to most objects. However, the ceramic fiber module not only does not expand after being heated, but also has a shrinkage rate of less than 3 percent . The reason is derived from the structural characteristics of the ceramic fiber itself.
The microstructure of ceramic fiber is a mixed structure composed of solid fiber and air, and its microstructure is characterized in that both solid phase and gas phase exist in the form of continuous phase. In this structure, the solid matter exists in the form of fibers with a diameter of 25um and a length of 30250mm, and constitutes a continuous solid skeleton, while the gas phase exists continuously in the skeleton gap of the fiber material, and the porosity is greater than 90 percent . Therefore, the expansion of the ceramic fiber after heating will be folded by its own pores, and it will not be too obvious. This is the reason why the ceramic fiber module does not expand when heated.
During the application of the ceramic fiber module in the high temperature furnace, due to the long-term high temperature environment, the fiber filaments that make up the solid phase skeleton break due to its own weight or brittleness, resulting in the collapse of the skeleton, the aggregation of fiber filaments, and the reduction of void space. Therefore, ceramic fiber products will appear from the appearance. A certain shrinkage, the shrinkage rate is generally less than 3 percent .
Therefore, when the ceramic fiber module is applied, it is necessary to follow the principle of high refractory temperature and reasonable selection of materials to reduce the linear shrinkage of the ceramic fiber as much as possible; secondly, the ceramic fiber module plus blanket structure should be compacted as much as possible during the construction process to prevent high temperature shrinkage This leads to gaps in the furnace lining and damage to the furnace body; at the same time, it is recommended that when choosing a ceramic fiber module furnace lining, there should be a margin of ceramic fiber cotton blankets for filling the gaps later.
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