Study On The Influence Of Silica Sol On The Structure And Properties Of Bauxite-based Refractories

In recent years,with the development of high-temperature industry technology,not only is the material required to have good high-temperature mechanical properties,but also the work performance under severe conditions such as resistance to rapid cold and rapid heat,which puts forward higher requirements for the quality of refractory materials,especially bauxite-based refractories widely used in high-temperature industry.Study proves that silica sol has influence on improving the high-temperature performance of amorphous refractories,especially for the thermal shock resistance,but there are relatively few studies on the shaped refractories with different bonding systems.Therefore,this article explores its influence on the structure and performance of the material by introducing silica sol into the bauxite-based refractories,and hopes that it will provide some reference for the production and application of silica sol in bauxite-based refractories in the future.This paper is an improvement based on the production process of bauxite-based refractories.The effect of silica sol on the structure and properties of bauxite aggregate and matrix was studied.By adopting the method of adding?-Al₂O₃micropowder separately first,the influence of different silica sol addition amount on the structure and properties of alumina-based refractories was studied.3-1mm bauxite clinker particles,with impregnated in silica sol,were used to study the influence of structure and properties of the bauxite-based refractories,focusing on the effect of silica sol on the thermal shock resistance of the material,the results show that:Using different concentrations of silica sol to impregnate the bauxite aggregate,the surface of the aggregate becomes smoother.Due to the different concentration of silica sol,the thickness and distribution characteristics of the silica sol on the surface of the aggregate are also different.Adding silica sol to the matrix will cause slight expansion of the matrix sample after calcination at high temperature,reducing its density.Silica sol is introduced into bauxite-based refractories by adopting the method of adding?-Al₂O₃ micropowder separately first.Generally,it is unfavorable to the cold strength of the sample.With the increase of silica sol addition amount,the linear change rate after firing and the apparent porosity of the sample increases,but the volume density decreases,and the cold compressive strength,cold modulus of rupture and high temperature modulus of rupture will all increase first and then decrease.When the amount of silica sol addition is 1.5 wt%,the cold strength is the highest.When the amount of silica sol is 3.0 wt%,the high temperature modulus of rupture is the highest.With the increase of calcination temperature,the cold compressive strength and high temperature modulus of rupture of the sample increase first and then decrease.When the calcination temperature is 1450?,the cold compressive strength and high temperature modulus of rupture of the sample are the highest.The amount of silica sol addition and the calcination temperature have little effect on refractoriness under load which is not less than 1580?.The thermal shock resistance of samples after firing at 1400?and thermal shock is improved with the increase of silica sol addition.the thermal shock resistance of samples after firing at 1450?and 1500?and thermal shock first increase and then reduce with the increase of silica sol addition.When the amount of silica sol addition is 1.5 wt%,the thermal shock resistance is the best.Silica sol can reduce the temperature of mullization,and then promote the formation of in-situ mullite.The temperature range of silica sol participating in mullization is in the range of1400-1450?.The bauxite-based refractories prepared by using 3-1mm bauxite clinker particles impregnated with silica sol as aggregate.With the temperature increasing,the cold compressive strength and cold modulus of rupture of the samples increase first and then decrease.The optimum firing temperature is 1450?.With the increase of silica sol concentration,the linear change rate of the sample after firing at 1450?and apparent porosity increase,but the bulk density,the cold compressive strength and cold modulus of rupture decrease,and high temperature modulus of rupture of the sample,refractoriness under load and thermal shock resistance are improved.When the mass fraction of Si O₂ in the silica sol used for aggregate impregnation is15%,the refractory with the optimum comprehensive performance can be prepared after firing at 1450?.