High thermal shock resistant alumina hollow sphere bricks are produced by using alumina hollow spheres as aggregates and adding appropriate amounts of SiO2 and silicate to the matrix, resulting in alumina hollow sphere bricks with good thermal shock stability and low re firing line change rate.
The main component of ordinary alumina hollow sphere bricks is Al2O3 (over 98%), and the matrix is composed of α - Al2O3, which is the main reason for the poor thermal stability of the product. Therefore, when determining the formula, alumina hollow spheres are still used as aggregates, and an appropriate amount of SiO2 is added to the matrix. During the firing process, a certain amount of mullite phase was formed in the matrix to replace corundum phase, thereby improving thermal shock stability. Add a certain amount of silicon wire stone to the matrix to reduce the rate of re firing line changes in the product and ensure the external dimensions of the product.
Production process:
Ingredients: Mix the binder and some clay into a slurry, and pre mix α - Al2O3 micro powder, sillimanite, and remaining clay for later use. The mixing sequence is: alumina hollow spheres - mud - pre mixed powder, mixed evenly in a non-ferrous container.
Forming and drying: Use a wooden mold to vibrate and form, naturally dry for 12 hours, then dry in a tunnel for 36 hours. The inlet temperature of the dryer is 60 ℃, and the outlet temperature is 120 ℃.
Burning: It is fired in a 20m3 inverted flame kiln, and most of the kiln loading is side loading. The lower part is loaded with standard and general types, and the upper part is loaded with different and special types. Heating rate: room temperature~800 ℃, 24h, 800-1300 ℃, 12h, 1300-1620 ℃, 6h; High temperature insulation for 8 hours, maintaining a slight positive pressure inside the kiln. Cool down for 48 hours after stopping the kiln. Inspect according to user standards after exiting the kiln. The surface of the product is white and smooth, with a regular appearance and a size qualification rate of 99%.
High thermal shock resistance alumina hollow sphere bricks can greatly improve their thermal shock stability by improving the matrix composition of alumina hollow sphere bricks, making them more resistant to petrification. The use of the bricks is very good.
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