Fireclay, physical properties

Table 15-2 Physical Property Ranges of Acid Brick (Red Shale and Fireclay)...

The average particle-size distributions for a number of fireclays are shown in Table 14. Particles larger than 2(jl equivalent spherical radius are determined by a method based on settling under gravity, but for smaller particles a centrifugal method has to be employed. It is unfortunate that more information on the distribution below 2(jLis not available, since it is this fraction that contributes most to the specific surface area and related properties. Nevertheless, the data available does correlate to some extent with other physical properties. 

The following are typical physical properties of fireclay brick ... 

Fireclay Plastic Refractory. A US term defined as A fireclay material tempered with water and suitable for ramming into place to form a monolithic furnace lining that will attain satisfactory physical properties when subjected to the heat of furnace operation. 

Spalling or thermal shock damage of fireclay refractories has always been a concern of furnace designers and operators. It is not always obvious which brand of fireclay brick will exhibit the best spalling resistance from physical property data alone. Three different brands of fireclay brick are given with their physical properties and spalling loss in laboratory tests in Table 6. 

Refractory bricks in the 50% and 60% AI2O3 classes exhibit improved refractoriness over fireclay products. There are two frmdamental mineral mixtures used in producing these classes of brick, and the physical properties of the products depend, in part, on which mineral mixture was used in the manufacture. 

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