Effect of Sodium Oxide on the Properties of Refractory Castables.
01. Sodium oxide content has a great influence on the performance of castables
In the traditional production of refractory castables, many people do not pay much attention to the sodium oxide content in alumina powder, but the sodium oxide content in alumina has a great influence on the performance of refractory castables.
02.Final performance of the product
The final performance of the product is for the on-site construction effect and usage effect. Because high sodium oxide content will increase the amount of low-melting materials, it will have a great impact on the dispersion of the mud, and will have an impact on the construction performance and setting time of refractory castables.
03.The impact of granularity
Because the dissolution of sodium oxide into the solution will shorten the hydration time of pure alumina calcium cement and alumina powder slurry, the higher the sodium oxide content in alumina, the greater the impact on the surface area of the powder. At the same time, it also has a certain impact on the generation of hydrates, setting time, and the properties and microstructure of the solidified green body. The activity, completeness, surface characteristics, etc. of alumina micropowder will have a certain impact on the construction performance, causing the construction to condense too quickly or not to condense.
The particle size distribution of alumina powder also has a great influence on the performance of refractory pouring materials. The smaller the particle size, the larger the surface area. The more sodium oxide and other ions dissolve into the solution. So that the service life or corrosion resistance is reduced.
The particle size distribution of alumina powder has a great influence on the filling and accumulation degree of refractory castables. The particle size distribution of alumina powder is divided into two categories: unimodal and multimodal. Single bee distribution means that there is only one peak on the particle size distribution curve and only one mode particle size. The multimodal distribution means that there are two or more peaks on the number diameter distribution circle, that is, there are two or more mode particle sizes. The more peak particle size distribution of alumina powder, the greater the packing density, because smaller particles are easier to fill into the gaps formed by larger particles. Make refractory castables denser and more corrosion-resistant.
04. Description of the density of alumina powder
The bulk density of alumina micropowder with unimodal distribution is small. It is easier to obtain a higher volume density of refractory injection materials using alumina powder with a multimodal particle size distribution than with a unimodal particle size distribution. Aluminum oxide powder with a unimodal particle size distribution and a wider particle diameter distribution has good filling properties and high packing density.
05.Conclusion
Therefore, the sodium content of alumina powder cannot be high, otherwise it will affect the density of refractory castables.