Abstract
Submicron materials are those with particle size diameters between 0.1 and 1 μm. Submicron SiO2 generally refers to SiO2 powder with a D90 < 1 μm (D90 refers to the particle size distribution exhibited by the sample and corresponds, in this case, to 90% of the particles not exceeding a diameter of 1 μm). In this study, a new type of cement‐free iron ditch castable was prepared using dense corundum and silicon carbide as the primary raw materials with submicron SiO2 powder as the binder. The effects of submicron SiO2 powder content on the bulk density, apparent porosity, linear rate of change, compressive strength, and bending strength were investigated. The mechanism of action of the submicron SiO2 powder was also investigated by analyzing its microstructure and particle size distribution. The results revealed that (1) the submicron SiO2 powder can be used as the sole bonding agent in the preparation of cement‐free iron ditch castables; (2) in comparison to traditional castables, the cement‐free castable developed in this study demonstrated strong service performance and high‐temperature bending strength.
Highlights
Introduction e iron ditch in a blast furnace forms a fundamental component in the ironmaking process. e vast majority of blast furnace casts worldwide use Al2O3–SiC–C iron ditch castables and pure calcium aluminate cement as the bonding agent [1,2,3]
During the process of fabricating cement-bonded iron ditch castables and as a result of strong basic properties of cement, the comprising hydroxide ions can dissolve metal aluminum to produce aluminum hydroxide, which can cause metal aluminum powder to react with water to produce a large amount of hydrogen; this leads to porosity and even cracking of the material
The bonding system containing cement limits the introduction of additives such as Si3N4 [7] into the matrix, which is beneficial in improving the iron slag resistance properties and high-temperature performance. us, to solve this problem, refractory workers have carried out extensive research on cement-free combinations of iron ditch castables, and the general method of fabrication entails replacing pure calcium aluminate cement with silica sol or hydraulic hydrated alumina [8]
Summary
It should be noted that the submicron SiO2 powder adopts an amorphous morphology, and the calculation results given in equation (1) are used as reference rather than absolute calculation results. Is indicates that the high-purity submicron SiO2 powder used in this experiment has a certain solubility in water that allows it to form a true solution of SiO2 in its molecular dispersion state [17,18,19], i.e., monomolecular silicic acid (H4SiO4). Is further confirms that the SiO2 powder used in this experiment was a high-purity amorphous submicron powder Within the diffraction angle range of 10–90°, only one diffuse scattering amorphous peak was observed near 2θ 21.3°. is further confirms that the SiO2 powder used in this experiment was a high-purity amorphous submicron powder
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