WC-Co非金属-金属纳米复合结构的形成与控制

FORMING & CONTROLLING OF WC-Co NONMETAL-METAL NANO-COMPOSITE STRUCTURE

制备了CoWO4/WO3 复合氧化物前驱体粉末和WC -Co非金属 -金属纳米复合粉末 ,研究了制备过程中从氧化物前驱体结构到非金属-金属纳米复合结构的赋承状态变化规律 ,以及原位反应的相变规律 .论述了纳米复合粒子、纳米复合结构的形成机理 .结果表明 :WC -Co复合粉末的一次粒径为 2 0～ 5 0nm ,其中的硬质相WC和粘结相Co具有纳米尺度的复合结构 ,组分和粒度分布极为均匀 ,适于制备高强。

The ammonium metatungstate [(NH 4) 6(H 2W 12 O 40 )·4H 2O, AMT], cobalt and grain_growth_inhibitor soluble salts were mixed and then sprayed to obtain CoWO 4/WO 3 composite oxidate precursor powder through thermal_decomposing. Nonmetal-metal nano_composite powder was prepared at 500-600 ℃ by H 2 reduction and the reactive intermediate with high_surface_area was carbonized immediately at 800-1 000 ℃. The carbon activity in CH 4/CO 2/H 2 gas was controlled to form the final nanocrystalline WC- Co composite powder. Results show that the CoWO 4/WO 3 composite oxidate precursor powder and the WC- Co nano_composite powder are all chemically homogeneous, hollow and spherical. The primary particle size of the former is 10-30 nm,and the latter is 20-50 nm, being pseudo_morphic with the former. The WC hard base_phase and the Co soft_phase form a composite structure, in which the nanocrystalline WC grains are covered homogeneously by the cobalt films and they constitute the primary particles.