DESIGN OF A VERTICAL STIRRED BALL MILL TO PRODUCE FLAKY METAL POWDER

Flaky metal powder provides the maximum contact area with carbon nanotube (CNT) reinforcements in CNT-reinforced metal matrix composites. The vertical stirred ball (VTB) mill turned out to be effective in the production of flaky metal powder. In this current project, the authors designed and tested a vertical stirred portable ball mill add-on using a computer numerically controlled (CNC) mill to produce flaky powder from spherical powder. The VTB mill consisted of a jar and stirring method constructed primarily of 304 stainless steel. The mill had total volume capacity of around one liter and was tested using the 304 stainless-steel grinding balls in a liquid medium containing aluminum powder. The stirring speed was controlled using the CNC mill, and thus limited by the mill’s capacity. Analysis using a scanning electron microscope (SCM) revealed that the vertical stirred ball mill provided the necessary attrition action to produce flaky powder. The starting spherical powder average diameter was 15 µm. After four hours of milling, the particles transformed into a flaky shape with an average thickness of 1 µm.