金刚石精微粉形貌修整的研究

为提高5μm以细金刚石精微粉气流整形的质量和效率,将5μm以细的金刚石精微粉和10μm以粗的金刚石粗微粉按照一定比例混合进行气流整形。结果表明:利用10μm以粗微粉在气流带动下产生的相对精微粉较大的动能来剪切和摩擦精微粉,可以达到快速修整精微粉形貌的目的,经过2 h左右的整形处理可得到平均圆度大于0.93的产品,并且过程中不会产生二次污染。

DOE全因子实验设计法优化托吡酯微丸制备工艺

目的:优化托吡酯微丸挤出滚圆制备工艺。方法:以微丸收率(18~30目)和平均圆度系数为响应值,运用MINITAB软件设计了3因子2水平加设3个中心点的全因子实验,研究并优化工艺条件。结果:根据收率建立模型,确定滚圆速度1 100 r·min^(-1)、载料量300~400 g、滚圆时间2~3 min,对应收率可高于87%,平均圆度系数高于0.77。结论:应用DOE全因子实验设计法优化了挤出滚圆工艺。

Numerical prediction of the flow property in round turbulent jet of fiber suspension

The equation of probability distribution function for mean fiber orientation,and the equations of Reynolds averaged NavierStokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of the fibers are derived and solved numerically.The effects of fiber concentration and fiber aspect-ratio on the mean velocity profile,turbulent kinetic energy and turbulent viscosity are analyzed.The results show that the mean axial velocity gradient increases near the centerline and decreases near the outside,respectively,as the fiber concentration increases.The mean axial velocity decreases with increasing the fiber concentration at the same radial positions.The centerline mean axial velocity decreases with axial distance,and this phenomenon is more obvious as the fiber concentration increases.The turbulent kinetic energy and turbulent viscosity increase over the jet region with an increasing fiber concentration.The variation tendency of mean axial velocity,turbulence kinetic energy and turbulence viscosity with fiber aspect-ratio is the same as that with fiber concentration.The difference is that the variation with fiber concentration is more obvious than with fiber aspect-ratio.