마그네타이트와 금속(Ti, Al)의 기계적 합금화에 의한 복합분말의 합성

Abstract

Recently, it has been found that mechanical alloying (MA) facilitates the nanocomposites formation of metal-metal oxide systems through solid-state reduction during ball milling. In this work, we studied the MA effect of Fe3O4-M (M = Al, Ti) systems, where pure metals are used as reducing agents. It is found that composite powders in which Al2O3 and TiO2 are dispersed in α-Fe matrix with nano-sized grains are obtained by mechanical alloying of Fe3O4 with Al and Ti for 25 and 75 hours, respectively. It is suggested that the large negative heat associated with the chemical reduction of magnetite by aluminum is responsible for the shorter MA time for composite powder formation in Fe3O4-Al system. X-ray diffraction results show that the reduction of magnetite by Al and Ti is a relatively simple reaction, involving one intermediate phase of FeAl2O4 or Fe3Ti3O10. The average grain size of α-Fe in Fe-TiO2 composite powders is in the range of 30 nm. From magnetic measurement, we can also obtain indirect information about the details of the solid-state reduction process during MA.