Toshio Isobe

The refractory brick and mortar for aluminium holding furnace and its baking method

This is to report on the study on the suitability of refractries for the lining of aluminium holding furnance. In this investigation, it was found that high alumina brick presented the best result. It was decided, as the result, the high alumina brick with the following properties is to be used for the actual operation.1. Chemical analysisSiO2 6.5%Al2O3 90.7%Fe2O3 1.9%TiO2 0.9%2. Reacted with molten alminium, and the content of SiO2 is slightly reduced.3. Slightly attacked by molten fluoride.4. The spalling test by rapid heating and cooling alternately more than 15 times.5. Correlative abrasion with alminium ingot 0.02g/100rev.6. Compressive strength 734kg/cm27. Apparent porosity 24.0%8. Water adsorption 8.4%9. Modulus of elasticity 5932kg/mm210. Apparent density 3.811. Thermal expansion (showed in Fig. 10)12. Water diffusion coefficient in the natural drying condition 0.0001m2/day13. Water diffusion coefficient in the forced drying condition 0.0024m2/dayIn case of lining furnace with this high alumina brick, the binder between the bricks should be half melted at 850°C, which is the finishing temperature of the furnace baking, and should be solidified at 750°C, the operating temperature of the furnace. Considering with this factor, special mortar of the following composition is to be used:Fused alumina in powder state 71.5%As best fiver 1.5%Sodium silico-fluoride 12.0%Soluble glass 15.0%Water operating amountThe furnace is reached to the operating condition without any trouble, when the above mentioned brick and mortar are used and the temperature of the furnace is raised in accordance with the temperature raising program. In this case the water content in bricks and the elongation of bricks took place during heating should be taken into consideration.

METHOD OF DETECTING CONTINUOUSLY CAST ALUMINIUM WIRE BAR DEFECTS

In studying the method of detecting hair cracks in wire bars before rolling, the specific gravity of its surface and central parts was measured.The specific gravity of the surface was lighter than the central part in defective bars, and the specific gravity of the surface was heavier than the central part in non-defective bars.The results of this study confirm the findings already ascertained by rolling mill operations.It is concluded, therefore, that one method of detection defects in wire bars is by the measuring of specific gravity of the surface and central parts.