2024-03-07 10:31:15
In the pouring material, no addition was made α- The refractory castable of Al2O3 ultrafine powder has a gravitational force between the internal particles, which adsorbs together to form a cohesive structure and is coated with a large amount of free water, resulting in poor flow. If a large amount of ultrafine powder is added, the surface energy of the ultrafine powder is large, and the spontaneous agglomeration or adsorption energy is strong, causing the particles to adsorb together and the internal viscosity resistance to increase, affecting particle movement. Therefore, the flowability of the castable is actually worse.
That is to say, the optimal dosage of a-Al2O3 ultrafine powder is generally 3% -6%. At this point, the added ultrafine powder can be fully filled into the pores of the casting material without any deficiency or residue, causing the free water coated to be released, wetting the surface of the particles and giving them good thixotropy.
along with α- The increase in Al2O3 dosage results in a slight increase in medium temperature strength and a rapid increase in high temperature strength. Due to the low impurity content in the raw materials, there will be no liquid phase at medium temperature, and there will be no significant sintering, so the strength increase is relatively small. At high temperatures, some liquid phase and activity appear α- Al2O3 ultrafine powder reacts with minerals in cement to form crystals such as CA6 and CA2, forming a network like structure in the matrix, which greatly improves the strength after firing α- The increase in Al2O3 dosage leads to a continuous decrease in the retention rate of flexural strength after three thermal shocks, i.e. a decrease in thermal shock resistance.
Because the sintering degree of the castable increases with the increase of micro powder, the flexural strength after sintering increases, leading to a decrease in its thermal shock resistance. So, α- When the amount of Al2O3 ultrafine powder is small, its thermal shock resistance can be improved, while also reducing the strength ratio, which is beneficial for improving.
So, the amount of ultrafine powder added must be appropriate for the best.
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