Effects of grinding aids vibration milling of aluminum

Abstract: Grinding aid additives are established in various industrial dry fine grinding processes, primarily to achieve either a) an increase of the production capacity, b) a decrease of the specific energy consumption or c) finer particles or a better product performance. However, even though numerous related scientific papers have already been published and a variety of grinding aids are currently applied in industrial processes, a comprehensive understanding of grinding aids is still missing. Thus, their selection and application is still mainly based on empirical knowledge. Therefore, this review gives a wide-ranging overview on grinding aids with special regard on their mechanisms of action, their impacts on the powder properties and the additive effects during lab-scale grinding. It is shown that the variety of applied substances, ground materials, target finenesses and analysis methods complicate the development of a comprehensive understanding, and how the mill type and grinding conditions influence the additive effects.

Abstract: In this chapter, authors discuss two preparation methods to precisely control the materials structure and elemental composition. These methods are classified into a “top-down” and “bottom-up” fabrication process. In “bottom-up” synthesis, the material is constructed from atom or molecules to the cluster until the designed shape is achieved, akin to building a house from bricks (simply saying from small to big). In the “top-down” synthesis, the corresponding material is reconstructed or deformed, ablated to form different structures, akin to a sculptor chiseling a block of marble to create a statute of definite shape and size.

Abstract: Flaky metal powders commonly used as paint and pigments, are generally produced by grinding in ball mills or vibration mills. The key to good quality powder production is to optimize the processing parameters. In the present work grinding of brass particles is studied in detail in a laboratory size ball mill to determine the optimal levels of the ball to material ratio, type and amount of additives, mill speed, ball load, etc. The quality of the powder is assessed on the basis of water coverage, degree of flattening and luster by visual inspection. Preliminary results in a 35 cm diameter ball mill with 30% ball load show that a material to ball ratio of 0.067 with a 0.1% dosage of stearic acid is required for good quality powder. For determining optimal mill speed and ball size a 2 2 factorial design of experiment has been followed. It has been determined that to achieve best powder quality the mill must run at 70% critical speed and the ball size must not exceed 20 mm. The quality of the powder assessed through SEM study for surface morphology and particle size analysis compares very well with the industrial samples.

Abstract: Atomized aluminium powder is ground in the presence of stearic acid in a laboratory vibration mill at different conditions in order to study the effect of feed size, additive concentration, weight ratio of the feed to grinding media and ball filling on the grinding characteristics. Feed size is found to be an insignificant variable in the range studied. While a stearic acid concentration of about 3% is desirable, higher concentrations result in a reduction in the rate of grinding. A lower weight ratio assures a higher rate of grinding whereas higher ball filling is preferable considering the increased production of fines.

Abstract: Die Harteverminderung ΔH einer Kristallflache bei Adsorption grenzflachenaktiver polarer Stoffe aus Losungen ist experimentell nachgewiesen und untersucht. — ΔH ist mit einer Abnahme der freien Grenzflachenenergie Δσ verbunden. Die ΔH Konzentrationskurven verlaufen den entsprechenden Adsorptionsisothermen parallel.H erreicht einen Minimalwert bei Sattigung der Adsorptionsschicht mit orientierten polaren Molekulen. In einer homologen Reihe nimmt der „ΔH-Effekt“ mit der Orientierungsfahigkeit der Molekule des „Harteherabsetzers“ zu (entsprechend der Traubeschen Adsorptionsregel). Der Einflus der Polaritat des umgebenden Mediums und des festen Korpers wurde ebenfalls untersucht. — Es ist auf die. Bedeutung des ΔH-Effekts zur Erleichterung der Risbildung bzw. Riserweiterung und des mechanischen Dispergierens hingewiesen worden).