| Dielectric barrier discharge plasma assisted high-energy ball milling combines plasma and mechanical energy, which can efficiently surmount the deficiencies of traditional ball milling such as single energy input, low efficiency and pollution. And it shows the obvious promotion effect on materials refinement and activation. In this dissertation, the history, the research status and the problems of high-energy ball milling have been reviewed. The mechanism and application in preparation of materials, in particular, in the dielectric barrier discharge plasma assisted ball milling have also been described. Then, the reason and mechanism have been analyzed for the breakdown of the electrode rods in DBDP assisted milling. In order to increase the life of electrode rod, the internal structure and external fitting way have been improved. The gas control system was designed to extend the function of the DBDP assisted mill. Based on those,we investigated the effect of DBDP assisted milling with different discharge current on W-C-Co composite powders and Si powders. And the effect of different methods of ball milling on the in-situ reduction of Al-SnO2 was also studied. Finally, the induction of solid-gas reaction by DBDP assisted milling was carried out, which can extend the applications of DBDP assisted milling.The failure analysis of electrode rods show that their breakdowns were mainly electrochemical breakdown of dielectric layer caused by creeping discharge and point discharge. Based on the interference fitting structure of electrode and dielectric layer, fillet was set at the tail of inner metal electrode and its length was shortened, which could reducing the occurrence of the point discharge and creeping discharge at those positions, and thus, the service life of electrode rods increased to 42 h under the current of 1.5A. And then the metal ferrule was added externally, reducing the current intensity of creeping discharge at the fitting portion of electrode rod and cover plate, thereby further stabilizing the life of the electrode rod. With the increase of discharge current, the life of electrode rods decreases. But compared with the life of original electrode rods, the improved ones have obviously longer life. In addition, the gas control system was designed and set up, which could control the flow and pressure of gas by the cooperation of pressure reducing value and unloading value.For DBDP assisted milling of W-C-Co powders, taking as an example of conductive material, the grain size of W was quickly fined to 50 nm or less, and W particles deform to lamellars after DBDP assisted milling for 3h. The changes of discharge current did not cause significant change in the W grain size and the thermal reaction temperature of W-C-Co composite powders. With the increase of discharge current, the composite powders become more agglomerated, which caused its powder size increases. For Si powders prepared by DBDP assisted milling for 4h, as an example of semiconductor material the increase of discharge current not only made the grain size increases but also changed the morphology of particles, which reduced the particles agglomeration and make it finer and more dispersed.With the same vacuum sintering process at 600℃, the Al-SnO2 powders prepared by DBDP assisted milling for 6h has better in-situ reduction reaction than that prepared by planetary ball milling for 40 h. DBDP assisted milling could also effectively induce the solid-gas reaction. The solid-gas reactions have been triggered by short time of DBDP assisted milling of Mg and Ti under ammonia respectively and the products in those two systems are Mg3N2, TiN and TiH2, respectively. After milling for 10 h, both of the powders could react almost completely. The discharge plasma activated and decomposed the reaction gas, as well as activated the surface of materials, which could accelerate the solid-gas reations together with the mechanical effect of high energy ball milling. |
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