Study on Manufacturing Aluminium Powder by Atomization

Abstract

Much of coarse aluminium powder for thermit reaction has been produced by the cross jet method. But the fine powder is less produced thereby. Recently, demands for fine aluminium powder are increasing gradually and it is urgently requested that vertical atomization for molten aluminium is developed and brought to industrialization, because the vertical atomization is said to be preferable for manufacturing fine metal powder.This experiment was carried out to investigate the fundamental behavior of vertical atomization, comparing it with the conventional cross jet method. The results derived from this experiment are as follows.1) It is fully possible that the minus 200mesh fine aluminium powder is produced more than 50 percent of the whole atomized powder by vertical atomization. On the other hand it is not easy to take out minus 200mesh fine powder more than 30 percent by cross jet mothod.2) In order to obtain a given distribution, the vertical atomization requires much lower air pressure than the cross jet method.3) In vertical atomizing the air jet forms a closed air curtain beneath the nozzle tip and a back pressure takes place. It prevents the settling of the molten aluminium. Then the unit manufacturing capacity of the vertical atomization is 50-60 percent of that of the cross jet method.4) The disintegration by the cross jet is almost impossible, when sprayed by air compressed at a pressure lower than 2kg/cm2.5) In the case of the vertical atomization by using a small bore strainer, the molten aluminium is apt to solidify in the strainer to the cooling by the air jet.