01Grading temperature
Grading temperature refers to the highest temperature at which the linear shrinkage rate is less than a given value. This temperature is expressed in °C and is separated by 50 °C. According to GB/T17911-2006, the heating permanent line change of refractory ceramic fiber products is measured. The test temperature at which the heating line shrinkage of refractory ceramic fiber boards and special-shaped hard products does not exceed 2% is the classification temperature. In GB/T3003-2006 “Refractory Ceramic Fibers and Products”, the classification temperature of ceramic fibers and products is divided into 19 levels, starting from 850℃ and ending at 1750℃.
Classification temperature represents the heat resistance index of refractory ceramic fiber board and is the most basic performance to ensure correct use.
02Bulk Density
Volume density refers to the ratio of the dry mass of the ceramic fiber board to its total volume. Generally, the volume density is in the range of 260~480kg/m3. In GB/T3003-2006 “Refractory Ceramic Fibers and Products”, the volume of the ceramic fiber board There are 8 nominal density values: 260, 280, 300, 320, 330, 360, 400 and 450kg/m3.
03 Compressive strength
Refers to the ultimate load that rigid ceramic fiber products can withstand per unit area at room temperature. Compressive strength is one of the important performance indicators to measure the quality of rigid ceramic fiber products. It can indirectly reflect the structural structure of the product, such as density, uniformity, sintering, etc.
04Heating permanent line changes
The linear expansion or contraction that remains after the refractory material is heated to a specified temperature without external force, kept warm for a certain period of time, and cooled to normal temperature. Domestic and foreign research results show that the heating line change test of ceramic fiber products requires 24 hours of heat preservation. The linear shrinkage rate of ceramic fiber products that have been tested for 24 hours reaches more than 75% of the line shrinkage after long-term use. The products can be kept warm for 24 hours. The heating wire shrinkage test results represent the heating permanent wire changes during long-term use of the product.
The heating line shrinkage of ceramic fiber is meaningless for a single fiber. It is only related to ceramic fiber products and is directly related to fiber crystallization and grain growth. At the temperature before crystallization begins, the fiber still maintains its original shape. Ceramic fiber products do not shrink when they are in a glassy state without obvious creep. As the glass fiber crystallization begins, individual fibers curl, causing the ceramic fiber product to shrink. International regulations stipulate that the test temperature at which the sample is kept at a certain temperature for 24 hours and the shrinkage rate of the heating wire does not exceed 2% is the allowable long-term use temperature of the ceramic fiber board. At this temperature, the crystal form of glass fiber crystals and polycrystalline fibers changes. The grain growth rate is slow, the fiber properties are stable, and the fiber is soft and elastic.
05Thermal conductivity
Thermal conductivity represents the thermal conductivity of a material. Its numerical value refers to the heat passed per unit area per unit time, per unit length, and the temperature difference is 1°C. Its unit is W/(m.k).
06Combustion performance
Combustion refers to the exothermic reaction of a substance under the action of an oxidizing agent, usually accompanied by the production of flame or visible light. In GB/T16400-2003 “Aluminum silicate wool and its products for thermal insulation”, it is stipulated that the combustion performance level of products with binders should reach Class A (non-combustible materials).