Study On The Improvement Of The Preparation Process Of Flaky Zinc Powder

Zinc flake is mainly used in the preparation of a variety of water-soluble inorganic coating,organic anti-corrosion coating,and zinc-rich primer.Zinc flake belongs to metallic powder with high additional value.Zinc flake was prepared by horizontal high-energy stirring ball milling and dry process.Preparation technology and performance of Zinc flake was studied and analyzed.Analysis and test of performance of Zinc flake were conducted by SEM,XRD,EDS,laser particle sizer,apparent density instrument,water covering area detector.And the theoretical model of instantaneous temperature change of Zinc powder during collision process in high-energy ball mill was investigated in this paper.Conclusions are as follows:(1)According to the single factor variable method,the effect of high-energy ball milling process parameters and dispersion process parameters on the performances of Zinc flake were studied,including stirring shaft speed,ratio of ball to powder,high-energy ball milling time,the content of modifier,dispersion speed and dispersion time.Optimum milling process parameters were obtained.The high-energy ball milling process parameters as follow:stirring shaft speed equal to 900/1300rpm;ratio of ball to powder equal to 10:1;high-energy ball milling time equal to 80 minutes;modifier dosage equal to 2.5-3.5%;drum dispersion frequency equal to 1200Hz and dispersion time equal to 2 hours.(2)Based on the Hertz collision theory,non-completely elastic collision theory and metal plastic deformation and rolling theory,the model of instantaneous tempera-ture change of Zinc flake during high-energy ball milling process was established.And the instantaneous temperature-rise of powder was calculated at different speeds and different ratio of ball to raw Zinc powder.The model of the instantaneous tempera-ture change of Zinc flake during high-energy ball milling process is △T=0.95Fap/cpπrh2lnh0/h.The higher the stirring shaft speed,the temperature-rise of Zinc flake became greater.With the ratio of ball to powder increasing,Zinc powder temperature-rise increased rapidly.The maximum Zinc powder temperature-rise during collision process in high-energy ball mill is approximately 148.6℃ when the ratio of ball to raw Zinc powder equal to 10:1 and stirring shaft speed equal to 900/1300 rpm.(3)A variety of modifiers were experimented to analyze the effect on the performances of Zinc flake.Four kinds of additives were selected for recipe reagent.Through orthogonal test and contrast test analysis,the final composite modifier formula was obtained.The final composite modifier formula is 2.5%of stearic acid,0.3%of reagent a,0.3%of reagent b and 0.1%of reagent c.Under this condition Zinc flake powder was prepared with medium particle size D50 equal to 13.12μm;bulk density equal to 0.9348 g/ml,water covering area equal to 2280.2cm2/g.