水雾化铁粉的粒径对工艺性能的影响

EFFECT OF PARTICLE SIZE ON THE PROPERTIES OF WATER-ATOMIZED IRON POWDER

通过筛分分级得到0.147 mm（100目）以下的4种不同粒度的水雾纯铁粉粉末,研究了颗粒粒径对铁粉流动性、松装密度、压缩性和压坯孔隙结构的影响。结果表明,随着颗粒粒径的减小,铁粉的流动性降低、松装密度增大。应用方程F=（16πr2Pφm）/（Nmφ）对不同粒径的颗粒进行了受力分析,表明大颗粒压制时平均受到的压力比小颗粒的大。使用艾西压制方程对铁粉压制密度进行拟合分析,表明不同粒度的铁粉都能很好的符合艾西方程,其压缩系数β在0.002 178~0.002 323之间,颗粒粒径大的粉末其压缩系数大,压缩性好。在总孔隙度相当的情况下,粉末粒径小的压坯其孔隙尺寸较小、孔隙数量较多、孔隙的分布较均匀。

By screening water atomized iron powder,four powders with different particle size below 0.147 mm were obtained.Effects of particle size on fluid ability,loose density,compressibility and porosity of the powder were investigated.The results show that with decrease of particle size,the iron powder shows lower fluid ability and higher loose density.Stress analysis using equation F=（16πr2Pφm）/（Nmφ）reveals that the larger the particle size,the higher the compressibility.Regression analysis shows compact density of iron powder with different partical size fits the compression equation well.The value of compression coefficient β is between 0.002 178 and 0.002 323.Higher compressibility is obtained for iron powder with a higher compression coefficient.For compacted green parts with roughly the same total porosity,with decrease of particle size,the pore size decreases,porosity increases and pore distribution becomes more uniform.