Intensive grinding of powders in an electro-magneto-mechanical mill

The paper presents the results of high-energy grinding in the electro-magne to-mechanical (EMM) mill. Ground powder is treated in a very specific and i ntensive way owing to several field forces operating simultaneously in the EMM mill. The grinding power in the centre of the mill's working chamber is in the order of 2 MW/m(3), which is much more than in ordinary mills. Ther efore, the grinding time is very short, i.e., several tens of seconds. The self-disintegrated Fe-Al-Si powders of 155 mum on average undergo size redu ction to 8 mum after 120 s. Over 25% of the total weight get the size of le ss than 1.3 mum Very hard materials, such as SiC and B4C reduce their grain size over 30 times after 120 s of grinding in the EMM mill. The results of the grinding of Fe2O3 powder are even better. In ball mills, vibration and planetary mills, similar results can be achieved after a period several hu ndreds times longer. The treatment of Fe-Al-Si powder presented here is int ended as the preparation procedure for sintering, plasma spraying or laser surface alloying. (C) 2001 Elsevier Science S.A. All rights reserved.