Effect Of Kaolin Type Al₂O₃ On The Formation Mechanism Of SFCA

In this project,the sintering process mainly studied the behavior difference of kaolin and Al2O3 in the phase change process,kaolin and Al2O3 were expounded at different temperatures.In the solid phase reaction stage,TG-DSC was used to analyze the reaction process of the formation of complex calcium ferrite,and the starting temperature of the precursor compounds was determined.The phase evolution of the reaction was analyzed by in situ X ray diffraction.When the content of kaolin in the material was relatively low,the formation of Ca₂Al₂Si O₇ in the reaction process was considered as the intermediate correlation and the formation of acicular calcium ferrite.With the increase of kaolin content,Ca₂Al₂SiO₇ in the phase began to transform into CaAl₂Si₂O₈.With the increase of temperature,the content of Fe₂O₃ decreased significantly,in the process of reaction,the total heat weight loss increased and the decomposition temperature of calcium ferrite was increased.In the reaction process,the temperature range of SFCA-I is 1000¹100℃,and the content of SFCA-I reaches the maximum at about 1150℃.With the increase of sintering temperature,alumina begins to dissolve into calcium ferrite and form CaAl₂Fe₄O₁₀.With the increase of alumina content,the stability range of calcium ferrite in the reaction process is enlarged and the formation rate of calcium ferrite is increased.During the process of sintering,with the decrease of alumina content,a large number of pores began to appear in the mineral structure,and under the action of thermal stress,the cracks began to grow and expand.When Al₂O₃ content is relatively low,Al₂O₃ in the sinter mainly exists in compound calcium ferrite.During the reaction process,the content of Al2O3 continues to increase,resulting in the saturation of Al₂O₃ in SFCA,and Al₂O₃ gradually participates in the formation of glass phase.