Judging the quality of firebrick can be started from the following aspects:
1. Check appearance
– Dimensional accuracy: The dimensional deviation of high-quality firebricks is small. Using measuring tools to measure its length, width and height, the size in line with the standard requirements can ensure that the brick seam is uniform during the masonry, which is conducive to improving the overall stability and sealing of the masonry. For example, for firebricks with a standard size of 230mm×114mm×65mm, the size deviation should be controlled within the specified range.
– Shape regularity: Observe whether the corners of the firebrick are regular and whether the surface is flat. Firebricks with regular shape and flat surface can fit better during the masonry process, reduce gaps and avoid stress concentration. If the brick body is distorted or there is a lack of corners, it will affect the quality of the masonry.
– Color uniformity: Firebricks with uniform color are usually more stable in quality. Different colors may reflect differences in raw material composition or uneven firing processes. For example, if the color of high alumina firebrick is not uniform, it may imply that its alumina content is different in different parts, which will affect its fire resistance.
2. Physical performance test
– Refractoriness: This is a key indicator to measure the quality of refractory bricks. Through professional high temperature test equipment, test the softening and deformation of refractory brick at high temperature. Refractory bricks with high refractoriness can withstand higher temperatures, such as the refractoriness of magnesia chrome bricks up to about 2000 ° C, suitable for high temperature melting environment.
– Load softening temperature: reflects the deformation performance of refractory brick under a certain high temperature environment. Under specified pressures, refractory bricks with high load-softening temperatures hold their shape better and are more reliable in practical applications, such as bearing material weight at the bottom of the kiln. It is generally required that the load softening temperature of firebrick is higher than the temperature of its use environment.
– Porosity: Refractory bricks with low porosity are of better quality. Porosity can be calculated by measuring the volume and pore volume of the brick. Low porosity means that the brick structure is denser and better able to resist the penetration of liquids and gases, resulting in increased erosion resistance and wear resistance. For example, the porosity of fused zirconium corundum brick is low, which can effectively prevent the erosion of glass liquid in glass melting kiln.
-Density: Density is related to the material and internal structure of the firebrick. Generally speaking, firebricks with high density have relatively high strength and wear resistance. However, for some occasions that require insulation, lightweight firebricks with lower density may be selected, but other indicators such as fire resistance also need to meet the requirements.
3. Chemical performance analysis
– Chemical composition: Analysis of the content of various chemical components in firebricks, such as alumina, silicon oxide, magnesium oxide, etc. Different chemical compositions determine the properties of refractory bricks, such as high alumina content in high alumina refractory bricks, so that it has good fire resistance and corrosion resistance; The magnesia content in magnesia refractory brick is high, which is suitable for alkaline environment.
– Resistance to chemical erosion: Test the resistance to corrosion of refractory bricks by simulating the chemicals in the actual use environment. For example, in the cement industry, the sample of refractory brick is placed in a simulated cement raw material solution containing alkali, chlorine, sulfur and other components, and its change is observed. The refractory brick with strong erosion resistance can maintain better physical and chemical properties in this solution.
4. Mechanical performance evaluation
– Compressive strength: The use of pressure testing machine to test the compressive strength of refractory bricks, refractory bricks with high compressive strength can withstand greater pressure, and are not easy to be crushed under the condition of bearing the weight of materials, equipment vibration, etc. For example, the carbon bricks used at the bottom of a blast furnace need to have a high compressive strength to withstand the weight of molten iron and slag.
– Flexural strength: Measures the ability of firebricks to resist bending forces, which is important for firebricks that may be subjected to lateral forces or bending stresses. For example, in the top position of the tunnel kiln, the refractory brick needs to have a certain bending strength to prevent fracture under the stress caused by its own gravity and temperature changes.
– Wear resistance: Evaluate the wear resistance of refractory bricks by simulating the friction and erosion conditions in actual working conditions. Wear resistance test device is used to simulate the abrasion erosion of refractory brick in circulating fluidized bed boiler. Refractory brick with good abrasion resistance can maintain its size and performance under long time erosion.
