硅粉对硅溶胶结合Al_2O_3-SiC-C浇注料性能的影响

Effect of silicon powder on properties of silica sol bonded Al_2O_3-SiC-C castables

以特级矾土熟料（5～3、3～1 mm）、棕刚玉（≤1 mm）、SiC（≤1 mm）、球状沥青（1～0．5 mm）、电熔白刚玉（≤0．074 mm）、活性α-Al2O3微粉、SiO2微粉、硅粉（d50＝20．81μm）为原料制备Al2O3-SiC-C浇注料，分别以质量分数为0、1％、2％、3％、4％、5％和6％的硅粉等量替代白刚玉粉，研究了硅粉对浇注料常温物理性能和抗氧化性能的影响，并采用Factsage、SEM和EPMA等手段对试样进行热力学分析和显微结构分析。结果表明：1）随着硅粉含量的增加，试样的显气孔率逐渐降低，体积密度先增大后减小，常温强度明显提高。2）硅粉可以提高浇注料的抗氧化性能，在硅粉加入量为4％（w）时，其抗氧化性能最好。3）抗氧化试验后，试样边缘部位原位反应生成的莫来石堵塞了气孔，使得试样边缘结构致密；试样过渡区域有少量的莫来石和SiO2生成，封闭了表面的气孔，进一步阻止了氧气的进入；试样中心区域有少量晶须状的SiC生成，填充在骨架结构中，起强化增韧的作用。

Al2O3-SiC-C castables were prepared using super grade bauxite （5 -3,3 -1 mm）,brown co-rundum （≤1 mm）,silicon carbide （≤1 mm）,ball pitch （1 -0.5 mm）,white fused corundum （≤0.074 mm ）,active α-Al2O3 micropowder,silica micropowder and Si powder （d50 =20.81 μm）as starting materi-als.Effect of silicon powder on cold physical properties and oxidation resistance was researched by repla-cing white corundum powder with 0,1%,2%,3%,4%,5% and 6% （in mass）of silicon powder,respec-tively.The thermodynamic and microstructure of specimens were analyzed by Factsage,SEM and EPMA. The results show that：（1）as Si powder addition increases,the apparent porosity decreases,the bulk den-sity increases first and then decreases,and the cold strength increases obviously;（2）the addition of Si can improve the oxidation resistance of castables;when the Si addition is 4%,the castable performs the best oxidation resistance;（3）the mullite generated during in-situ reaction on the edge of specimen fills the holes and makes the structure dense;in the transition region,the formation of mullite and SiO2 fills up the holes and prevents oxygen from entering.In the central area,some whisker-shaped SiC forms and fills in the in-terstices of aggregates structure,strengthening and toughening the structure.