Silica sol plays several important roles in refractory materials, mainly including the following aspects:
Bonding Effect: Silica sol has excellent bonding properties. During the preparation of refractory materials, it can firmly bond various refractory aggregates, powder particles and other components together. During the drying and heat treatment processes, the silica sol loses water to form silica gel, which is then converted into amorphous silica. Tough chemical bonds are formed between the particles, endowing the refractory materials with high strength at room temperature and flexural strength, ensuring that the refractory materials are not prone to cracking and spalling during use.
Improving Densification: The particle size of silica sol particles is small, and they can fill the tiny pores between the particles of refractory materials, effectively reducing the porosity of the refractory materials and improving their densification. This not only enhances the mechanical strength of the refractory materials but also reduces the erosion channels of molten slag, gases, etc. on the refractory materials at high temperatures, improving the erosion resistance and permeability resistance of the refractory materials and extending the service life of the refractory materials.
Improving High-temperature Performance: Silica sol undergoes processes such as crystal structure transformation and sintering at high temperatures, which helps to improve the high-temperature stability of refractory materials. On the one hand, the silica network structure formed by silica sol can inhibit the grain growth and crystal structure transformation of other components in the refractory materials at high temperatures, enabling the refractory materials to maintain good structural stability at high temperatures. On the other hand, silica sol can reduce the thermal expansion coefficient of the refractory materials and improve their thermal shock resistance, allowing the refractory materials to withstand frequent temperature changes without cracking.
Promoting Sintering: During the heating process, silica sol undergoes dehydration and polymerization reactions. The generated silica has high reactivity and can chemically react with other components in the refractory materials at relatively low temperatures, promoting the sintering process of the refractory materials. This helps to reduce the sintering temperature of the refractory materials, saving energy, and at the same time, improving the density and performance of the refractory materials.
