Study On The Optimization Of Manufacturing Process And The Structure For Superfine Cu-Zn Powder Made By The Methods Of Thermal Atomization And Wet Grind

The manufacturing process of the combination between Thermal Atomization (TA) and Wet Grind (WG) were developed to prepare superfine Cu-Zn powder in this paper. Annealing heat treatment was adopted so as to improve the milling efficiency, make the powder flaky and further fine. The TA parameters that influenced the particle's size and the powder's surface properties were emphatically discussed. The milling parameters such as milling time, accumulation of milling balls, the rate of ball to powder, and the rate of powder to agent, also as the variety and the addition of milling assistant agents, were discussed in the paper. The changing laws of particle pattern, single particle's metallurgical structure of Cu-Zn powder were studies in the process of milling, as was the recrystallization annealing heat treatment process studied. This came to the better manufacturing process.The Cu-Zn powder's granularity and distribution, pattern were studied by sieving method, gravity sedimentation, SEM and TEM, also were The microstructure, particle inner metallurgical structure, component and crystal structure of Cu-Zn powder studied. The changing laws and influencing factors in the process of milling were discussed. The results indicate that the powder's main deformation mechanism is elastic-plasticity in the earlier stage of milling, and it is the reciprocal process between cracking and conglobation,welding-on in the later. There is a critical strain value for Cu-Zn powder's deformation while milling. The better milling time is 8h.The milling efficiency will reduce when the powder's deformation amount forereaches the strain value or milling time exceeds 8h. The TS powder's shape is long strip or cylindrical, and it comes to be flaky after milling; while the particle size is less than a certain meter, it is spherical. Milling assistant agents greatly influence the milling efficiency and the surface property. The main metallurgical structure of TA powder is dendrites, and it is sinewy after milling; it is even a equiaxed grain after recrystallization. BM does not only make the powder's structure sinewy, but also finer the grain. This would greatly increase particle's deficiency density of crack, bit bare and dislocation. These would be the driving force in the process of recrystallization annealing heat treatment. Milling time and annealing heat treatment are the main influencing factors for changing powder structure and fining grain. The optimum parameter of recrystallization annealing heat treatment is 400℃×1h.