The effects of different alumina powder solid content and admixture types on refractory castable performance are significant. The following is a detailed analysis of this effect:
1. Effect of alumina powder solid content
As the solid content of alumina powder increases, the performance of the castable will undergo a series of changes. Specifically:
Slurry viscosity: As the solid content increases, the viscosity value of the slurry gradually increases. When the solid content increases to a certain extent (such as about 80%), the viscosity will tend to increase rapidly. This is because the increase in solid content increases the number of particles in the slurry and enhances the interaction between particles, resulting in increased viscosity.
Construction performance: The increase in solid content will also affect the construction performance of the castable. Too high a solid content may cause the slurry to be too viscous and difficult to construct. Therefore, when selecting the solid content of alumina powder, it is necessary to comprehensively consider the viscosity and construction performance of the slurry.
2. Effect of admixture type
The type of admixture also has an important influence on the performance of the refractory castable. The following is an analysis of different types of admixtures:
Polycarboxylate water reducer: Polycarboxylate water reducer is a commonly used admixture that can effectively reduce the viscosity of the slurry and improve the construction performance. At the same time, it can also improve the fluidity and impermeability of the castable.
Sodium polyacrylate: Sodium polyacrylate is also a commonly used admixture that also has the effect of reducing the viscosity of the slurry. However, compared with polycarboxylate water reducer, its viscosity reduction effect may be slightly inferior.
Dispersible alumina micropowder: When dispersed alumina micropowder is used as an admixture, it can significantly improve the dispersibility of the slurry and reduce the viscosity. This is because dispersed alumina micropowder has a smaller particle size distribution and a higher specific surface area, which can more effectively fill the pores in the slurry and reduce the interaction between particles.
In practical applications, the choice of admixture needs to be determined according to the specific situation. Different admixtures have different effects on the performance of castables, so it is necessary to comprehensively consider the purpose of the castable, construction conditions, cost and other factors to make a choice.
3. Comprehensive impact analysis
Flowability: In cement-bonded corundum refractory castables, bimodal and multimodal alumina powders have faster slurry discharge speed and better flowability than unimodal alumina powders. This is mainly because bimodal and multimodal alumina powders have better particle size distribution and specific surface area, which can more effectively fill the pores in the slurry, thereby improving the flowability of the slurry.
Physical properties: Selecting appropriate alumina powders and admixtures can also significantly improve the physical properties of castables. For example, when using dispersible alumina powders as admixtures, the viscosity of the slurry can be significantly reduced and the dispersibility can be improved, thereby obtaining lower apparent porosity and higher physical properties such as flexural strength and compressive strength.
In summary, different alumina powder solid content and admixture types have a significant impact on the performance of castables. In practical applications, it is necessary to select appropriate alumina powder solid content and admixture types according to specific conditions to obtain the best castable performance.
