Rheological properties of tap-hole materials were characterized by using a capillary rheo-meter method. The materials were extruded through a capillary of a die with different speeds and resistance was measured. The resistance increased with time and kept a maximum value during the material extruding through the capillary. Shear rate and shear stress were calculated from the extrusion speed and the resistance, respectively. From the relation between the shear stress and the shear rate, the tap-hole materials were found to behave as Bingham fluid. On the other hand, injection pressure changes of a tap-hole material with time in a real blast furnace were measured. By comparison of table tests and the injection pressure changes, the materials were estimated to inject into the furnace in the shape of strings, which were diameter of around 80mm and length of around 30m, and heaped up at the free space in the furnace.

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Effect and behavior of Al4SiC4 added to the MgO-C brick were investigated and discussed. The following conclusions were obtained. （1）The mass and strength increase gradually and the porosity decreases in the MgO-C brick with addition of Al4SiC4 above 1000℃. （2）Al4SiC4 reacts with CO gas to form spinel（MgAl2O4）and SiC above 1000℃. The formed SiC also reacts with CO gas to form forsterite（Mg2SiO4） above 1200℃. These reactions involve the increase of mass and volume which cause the texture densification. （3）The bricks containing Al4SiC4 have high slaking resistance after heating, because Al4C3 and AlN are not formed in the reaction processes. （4）It is found that Al（g）, SiO（g）and Mg（g）form in the brick texture at the high temperature. The gases are considered to disperse and condense in the pore, and then the texture is densified efficiently.

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