Method for mechanical processing of powders
24 July 2021
Ball milling is a process in which one or more materials are ground by spheres in suitable material set in motion by suitable systems called generically mills. During the process, the movement of the balls causes the material or materials to be treated to be subjected to strong mechanical stress caused by the impact and friction actions generated by the balls themselves. This type of process can be used to obtain various effects including the reduction of the size of a powder, the variation of the morphology, of the structure and also of the composition of the initial material.
Ball milling, although effective, allows the production of only small amounts of powders useful on a laboratory scale. To overcome this problem, an innovative and easily scalable method has been developed for the processing and/or mechanical activation of powders (metallic or non-metallic) by means of spheres bringing the jar-powder-spheres system to the resonance frequency.
The method involves the use of an acoustic resonant mixer with vertical, horizontal or combined action able to reach high accelerations ensuring an efficient energy transfer between spheres and powder. Its versatility makes it possible to obtain an effective regulation of the operating parameters, some of which can not be modified using standard methods. The method, already successfully tested on a long series of ingredients (Mg, Al, Steel, Graphite, Silicon, Metal Oxides, etc.), allows to produce potentially any type of powder with desired characteristics (structure, composition, incorporation or coating with other materials, particle shape, specific surface, level of impurity, metallic content, crystallite size, etc.).
The main advantages of the technology are:
- Lower time and production costs;
- More efficient process and activation;
- Innovative materials production;
- Process flexibility and adaptability;
The possible applications are:
- Additive manufactoring powders;
- Production of controlled reactivity materials (explosive powders);
- Multicomponent particles;
- Optimized ingredients for powder dispersive mix (cosmetics, pharmaceutics, tecnical pastes).
Referente: Politecnico di Milano