Table 1 Performance of foreign 篼 strength lightweight refractory bricks Bulk density g/cm3 Compressive strength MPa Thermal conductivity Reburning line change (<2%) 篼 Strength Insulation bricks General insulation brick 2 Test study 2.1 Test method Production of lightweight refractory materials The method is generally divided into two types: a combustible method and a gas method. The products produced by the combustible method have high air permeability, poor heat insulation and low mechanical strength, and the products produced by the foam method can avoid the above defects, so the foam method is used to introduce the bubble material into the molding mud to stabilize it. The bubbles are then shaped, dried and fired at a certain temperature.
2.2 The use of composite expansion agent Because the heat-insulating material after molding shrinks during sintering, it is easy to cause cracks or deformation of the sample, and sometimes the density will increase due to sintering shrinkage. Therefore, kyanite is introduced to improve its sintering performance. After the sample was fired, the bulk density, porosity, compressive strength and linear shrinkage of the sample before and after sintering were measured. The properties are shown in Table 2.
Table 2 Sample Performance Sample Addition Addition Kyanite Expansion Agent Adding Composite Expansion Agent Bulk Density Porosity Rate Pressing Strength °C After Burning Line Shrinkage It can be seen from Table 2 that the A-free formula without additives is burned at 1450 °C. After the line shrinkage is apparent, the bulk density is 1.3 and the porosity is low, but the B formula with kyanite added a positive line change at 1450 ° C, while the C formula with the composite expander added is only small. The negative line change greatly improves the shrinkage of the sample, and the addition of kyanite also increases the compressive strength. Comparing the performance of the sample after burning at 1580 °C, it can be seen that the linear shrinkage of the kyanite is reduced from -3.0% to -0.5%, because the selected kyanite is rapidly decomposed in the temperature range of 1300-1450 °C. The mullite and silica produce a large volume expansion which compensates for the post-fire line shrinkage at 1450-1580 °C.
23 Adding an enhancer As can be seen from Table 2, the introduction of kyanite, although increasing the compressive strength, is still too low, in order to obtain higher strength, the addition of a reinforcing agent, the addition amount and the strength of the reinforcing agent are mutual The relationship is shown in Figure 1. It can be seen from the figure that for different density materials, the strength basically increases with the increase of the amount of reinforcing agent added, and the strength increase is not obvious when added to more than 10%, and for the sample with a bulk density of 1.3. When the amount of introduction is added to 10% or more, the strength is decreased, which is caused by the composite action with the kyanite expansion agent at the firing temperature. Therefore, it is preferable to select a 10% reinforcing agent.
The effect of the amount of composite additive added on the strength of the composite additive 3 Product performance In the actual production, a certain amount of kyanite and 10% of the reinforcing agent are introduced into the raw material, which is formed into a slurry, extruded, and dried at 1450C. Firing and testing the performance of the product are shown in Table 3.
Table 3 Product performance number Bulk density Porosity pressure strength MPa Thermal conductivity From the performance of the final product, the strength of the developed insulation brick is as high as 17.5Mpa, which is significantly higher than ordinary insulation brick, which is three times the strength of ordinary insulation brick. The product's reheating line change at 1400C is only -0.3%, so the material can be used for a long time at temperatures above 1400C.
4 The ultra-high-strength lightweight refractory brick developed by the application has small bulk density, high compressive strength and low thermal conductivity, especially anti-mechanical impact, vibration, anti-airflow material erosion and anti-erosion performance, which can greatly improve the life of the kiln. The material has the function of heavy and light double refractory products, and is an ideal energy-saving material, which can be widely used in special parts of thermal equipment used in electronics, metallurgy, building materials, petroleum, chemical industry and other industries.
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