| 摘要 |
PROBLEM TO BE SOLVED: To secure an execution property by specifying the interval between the upper face and lower face, the area of the lower face, the area of the upper face, and the permeability coefficient respectively, and providing a two-layer structure of an upper layer and a base layer having the prescribed thickness. SOLUTION: An upper face and a lower face are made practically parallel with each other, both faces are unified into a rectangular, square, or regular polygonal shape, and the labor required for maintenance is sharply reduced. A ceramic aggregate is baked with a ceramic sintered material, the scratch strength of the upper face is made equal to or higher than that of the lower face, and the density of the upper face side is made larger than that of the lower face side. The shock resistance of the upper face side is made larger than that of the lower face side, and the average grain size of an upper layer is made smaller than the maximum grain size of a base layer. The interval between the upper face and the lower face is set to 40-80mm, the area of the lower face is set to 90-1600cm<2> , the area of the upper face is set to 90-98% of the area of the lower face, and the permeability coefficient is set to 1×10<-2> /sec or above. This ceramic block is formed into a two-layer structure of the upper layer and the base layer having the thickness of 2-10mm.
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