Magnetic cores in amorphous state are usually produced by placing together very thin amorphous ribbons from a material obtained by the melt-spinning technique. The new patented method produces the amorphous material by mechanical alloying, a traditional process in the powder metallurgy field. This technique allows a higher control on the amorphisation process and the properties of the amorphous obtained powders. These powders are then consolidated by the very quick process known as Electrical Resistance Sintering (also Electrical Discharge Consolidation/Sintering can be used). A final amorphous material, without the typical frontier between ribbons of melt spinned materials, which clearly affect properties, is obtained.
Description of the technology
The University of Huelva, in collaboration with Univ. of Seville and CSIC, has developed an alternative fabrication method of different parts with the function of magnetic core. The method is based on the powder metallurgy route instead of the melt-spinning technique. Amorphous powder are produced by mechanical alloying and then, Field Assisted Sintering Techniques (FAST) are used to consolidate them, preserving the amorphous state. This process reduces production costs, has a higher industrial-production flexibility, and allows, because of inhibiting the material devitrification, reducing the amount of metalloids, therefore improving final-parts magnetic properties.
Mechanical alloying is a process produced in a ball mill where the initially crystalline powders with the desired composition are milled. The continuous interaction with milling balls makes the powders to became nanocrystalline or amorphous depending on the milling conditions, mainly time. The main innovation of the described method is the way to consolidate this amorphous powder with the condition of preserving the amorphous state. Field Assisted Sintering Techniques, as Electrical Resistance Sintering or Electrical Discharge Consolidation/Sintering, are techniques where the sintering process is carried out in a very quick way, even less than one second, therefore being possible to preserve the amorphous state. On the other hand, the technique allows obtaining magnetic cores with the desired final geometry.
Main advantages of its use
- The main advantage of the method is its lower cost and higher flexibility for industrial production.
- Also, the devitrification tendency is lower, and the presence of metalloids can be diminished or avoided, therefore improving magnetic properties.
- The method can also use as starting material amorphous ribbons, just by mechanically milling them before starting with the electrical consolidation.
- Different FAST techniques can be used to consolidate the material.
- Obtained magnetic cores could have a completely amorphous or nanocystalline character.
- Magnetic cores are used electrical, electromechanical and magnetic devices, for instance: electromagnets, transformers, electric motors, generators, inductors, magnetic recording heads and magnetic assemblies. Many sector are continuously using such devices in their products, and therefore, makers of such devices could be interested in the developed method.