SELF-COMBUSTION REACTIONS INDUCED BY MECHANICAL ACTIVATION - FORMATION OF ALUMINUM NITRIDE FROM ALUMINUM GRAPHITE POWDER MIXTURE

The powers of aluminum metal and natural graphite mixed in various molar ratios (Al/C = 7/0-0/7) were ground in a planetary ball mill. When the mixtures thus activated mechanically were exposed to air, exothermic reactions spontaneously occurred in two successive steps, evolving red heat initially and then white heat. The main product was aluminum carbide in the first step and aluminum nitride as well as carbide in the second step. From the measurements of XPS spectra and the lattice constants, it was concluded that the aluminum nitride obtained is solid solution with the composition of (Al2OC)(1-x)(AlN)(x). The effects of mixing ratio of Al to C, grinding time, and gas atmosphere on the formation of aluminum nitride are discussed.