| 摘要 |
PURPOSE:To perform floation of the nonmetallic inclusions in molten steel effectively in porous refractories to be installed in a molten steel vessel in order to form bubbles in molten steel by specifying the relations between pore sizes and the spaces among the pores. CONSTITUTION:The equationI(sigma: surface tension, g: gravity acceleration, rho: the specific gravity of molten steel, rhog: specific gravity of gas) holds for the diameters db of the bubbles formed from the pores of a diameter (d) of porous refractories, in accordance with water model experiment. Here, rho>=rhog and therefore if rho-rhog rho, the equation II is obtained. To prevent the bubbles formed from the pores from joining to the bubbles from the adjacent pores and from growing to large bubbles, it is necessary to make the spaces P among the pores larger than the diameter (db), that is, to satisfy the equation III. To produce such porous refractories, plural pieces of mask plates made of a thermofusible of combustible blank material of >=d diameter are placed by leaving >=P among each other. Next, fluid refractories are coated on the blank body 3 of the spaces between the mask plates and these and mask plates are heated, whereby the mask plates are removed and the fluid refractories are sintered. |
