等离子体辅助球磨对Al+C₄H₄N₄ 合成超细AlN的影响机制

The synthesis mechanism of AlN from diaminomaleonitrile (C₄H₄N₄) and aluminum (Al) by using plasma assisted ball milling (PM) was investigated, in which the conventional ball milling (CM) was also used under the same conditions for comparison. The results indicate that PM is much more favorable for the grain refinement and lattice distortion of Al, as compared with that of CM, which promotes the synthesis of nanocomposite structure between Al and C₄H₄N₄. During the process, the plasma formed in PM can promote the deammoniation of C₄H₄N₄ to decompose much more free N-containing groups than that of the CM, which accelerates to react with the activated Al powders. After 14 h milling, the conversion rate of AlN by using PM method is up to 91%, which is much higher than the value of 83% in CM process. Furthermore, a lower nitriding reaction activation energy (353.46 kJ/mol) was obtained in the Al+C₄H₄N₄ precursors by 8 h-PM process, which could achieve a full conversion temperature is about 800 ℃, but for the 8 h-CM process, a higher nitriding reaction activation energy (441.21 kJ/mol) needs a higher nitriding temperature in the Al+C₄H₄N₄ precursors, leading to the melting of Al phase and evaporation of part of C₄H₄N₄, and obviously reducing the conversion rate to 86%. The main synthesis mechanisms of AlN through the plasma assisted ball milling is a synergistic effect between high frequency pulse bombardment and transient “spark” on the powders by plasma discharge.