1961 Volume 11 Issue 2 Pages 107-124
In the previous report, it is stated that the non-metallic hardspots in aluminium is considered to be made from aluminium oxide or reacted brick. The reaction between aluminium alloy and fire brick is non studied. In the experiment, a hole is made on a piece of fire brick and aluminium alloy is put in it. Then the brick is heated up to 900°C and held for 40 hours.
After reaction, the brick is cut and the section of brick and alloy is observed. And then, the hardness and weight of reacted brick and remained metal are measured.
The findings are as follows:
(1) The reaction between brick and pure aluminium and Silumin (Al-12%Si alloy) is less remarkable than that between brick and Lautal (Al-3%Cu-9%Si alloy) and Hydronalium (Al-4%Mg alloy). The reacted brick is changed in its quality.
(2) Magnesia brick shows no reaction against alloys.
(3) The reaction between carborundum brick and alloys is lower than that with alumina brick. From this, it is considered that the higher the content of Al2O3 in brick, the more the reaction. But, between pure aluminium and Al2O390%B brick and Hydronalium and Al2O3B brick, the reaction is very small. These cases are considered to be exeptional.
(5) Some A bricks are not reacted in this experiment, though these have been reacted in practical use, when many hardspots have appeared in the metal.
(6) The change in weight of the brick shows the same result as obtained by the observation of the section of it. This seems to show how the reaction has been made. The change in weight of the remained metal is inverse to the degree of reaction. It is also considered to show how the reaction has been made.
(7) The hardness of the reacted brick is about 300Hv-900Hv, while that in lustered position is about 700Hv-5000Hv. The high hardness is considered to be due to SiC or Al2O3 elements.
(8) The hardness of remained metal is not much changed, though that of much reacted one is rather high.
(9) The hardness of slag and oxides is about 200Hv-900Hv. This is same as the hardness of non-metallic hardspots. Thus, it is considered that the slag and oxides are non-metallic.
