焙烧炭砖孔结构和导热系数与硅粒度变化关系

借助于X射线衍射仪、压汞仪、激光导热仪、扫描电子显微镜和能谱分析仪等测试手段，研究了分别含3种不同粒度硅粉（中位径分别为2．3、45．0、115．6μm）焙烧炭砖试样中的孔结构和导热系数的变化。结果表明，含硅粉的炭砖试样经焙烧后内部均生成pSiC、Si2N2O和石英等相，粒度过粗，试样内有单质硅残留；随着硅粉粒度的减小，生成碳化硅晶须的长径比变小。对所选用的3种粒度硅粉，随着硅粉粒度的减小，焙烧后炭砖试样的孔径分布范围逐渐变窄，小于1μm气孔孔容积变大，而平均孔径变小。受炭砖试样组成和孔结构影响，硅粉粒度变小，导热系数下降。细小气孔容积与导热系数呈反比关系，即细小气孔增多，导热系数下降。

Effect of silicon particle size on porous structure and thermal conductivity of coked carbon brick

Anthracite-based carbon brick specimens for blast furnace were prepared using calcined anthracite, graphite flake, brown corundum and silicon as raw materials. Effect of different silicon particle sizes （2.3 μm,45.0 μm,115. 6 μm） on the pore size distribution and thermal conductivity of the specimens was investigated by using X-ray diffraction （XRD）, mercury porosimeter, laser thermal conductivity instrument, scanning electron microscopy （SEM）, and electron probe microanalysis （EDS）, etc. The results indicate that the porous size distribution, mean porous size, and 1 μm porous volume are controlled by added silicon particle size. The porous size distribution becomes narrower and 1 μm porous volume gradually increases with the decrease of silicon particle size owing to the formation of ceramics phases such as Si2N2O and Q-SiC whisker in the matrix of carbon brick. The residual silicon is observed in the specimens due to the too larger silicon particle size. Meanwhile the thermal conductivity of the specimens is affected by pore structure and phase composition. The thermal conductivity decreases remarkably when 0.1μm porous volume goes up and mean porous size becomes smaller in the specimens with the addition of finer silicon particles.