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Factors Affecting the Performance of Ceramic Fiber Products

Date:2018-04-12 16:09 | From:Zhengzhou Sunrise Refractory | Author:admin
Ceramic fiber products have the characteristics of high temperature resistance, small bulk density, good thermal insulation performance, good chemical stability, good thermal shock resistance, good wind erosion resistance, and convenient and rapid construction. It is the most promising energy saving and environmental protection type in the world today. Insulating and heat-insulating materials However, ceramic fibers also have some disadvantages in application: poor stability, erosion resistance, anti-air flow erosion, anti-peeling and other properties are poor, long-term exposure to high temperatures, due to the vitreous fiber crystallization and grain Factors such as growth, high temperature creep, etc., cause changes in the fiber structure - shrinkage deformation, fiber inelasticity, brittle fracture, reduced fiber strength, densification until loss of fibrous structure due to sintering, erosion with corrosive furnace gases, airflow The effects of scouring and other factors are easy to chalk off.
Ceramic fiber products are used under different conditions and their long-term use temperature is different. For example, industrial furnace operation system (continuous or intermittent kiln), fuel type, furnace atmosphere and other process conditions are all factors that affect the use temperature and service life of ceramic fiber.
At present, there is no ideal method for measuring the heat resistance of ceramic fibers. Generally, the ceramic fiber product is heated to a certain temperature, and the heat resistance of the ceramic fiber product is evaluated based on the shrinkage change and crystallinity of the sample heating line.
1, the effect of temperature on the performance of ceramic fiber products
From a thermodynamic point of view, the glassy ceramic fibers are in a metastable state. Therefore, as long as the heating is performed under certain temperature conditions, the particles will rearrange in the interior of the fiber, and the glass state will be converted into a crystalline state, and the fiber will crystallize.
When the grain size grows to be close to the fiber diameter size, the bonding force inside the fiber will be dominated by the intermolecular chemical bonds, and the grain boundary bonding between the grains will be dominant. Because the grain boundary binding force is relatively weak, it will lead to the strengthening of the brittleness of the fiber. Under the action of the external force, the fiber is easily damaged and eventually loses the fiber characteristics.
2, the use of environmental atmosphere on the performance of ceramic fiber
In the reducing atmosphere, the silica in the fiber easily reacts with CO and H2 as follows:
SiO 2 + CO→SiO↑+ CO2
SiO2 + H2→SiO↑+ H2O
As silica is reduced to volatile materials, the fiber structure slowly changes and the surface becomes rough. When mullite grains are formed inside the fiber, the fiber is easily broken, accelerating the deterioration of the fiber.
3, the impact of impurities on the performance of ceramic fibers
Some of the impurities present in ceramic fiber products, such as iron oxides, Na2O, K2O, etc., react with other components of the ceramic fiber at a lower temperature to form eutectics. The presence of eutectics destroys the fibers. In the network structure, the internal viscosity of the fiber is reduced, the crystallization activation energy to be overcome when the ion cluster is rearranged decreases, the crystallization temperature decreases, and the growth of the crystal grains is accelerated due to the presence of the eutectic, and the fiber is promoted. Powdering.

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