Set-up of amorphous powder sintering process by means of electrical discharge of capacitors

Abstract

The technique of sintering by electrical discharge of capacitors (SEDC) is investigated, using a commercial stud welding equipment adapted to be used in the sintering of amorphous powders. In this technique, pressure and the heat generated by the Joule effect from the high intensity electric current are applied simultaneously to a mass of powder. The use of this technique lies in its speed, in order to be able to maintain the initial structure of the powders. For the set-up of the equipment, it is analyzed how successive discharges affect, depending on the starting particle size, the porosity, microstructure, microhardness and resistivity of compacts generated from Metglas powders. It will be shown how successive discharges lead to improved sintering. Thus, starting from an initial porosity of 0.35, with powders of 64 μm, the porosity after the first 5 discharges decreases to 0.05 and after 35 discharges the final porosity decreases to 0.008. After sintering, these compacts reach microhardness values of up to 865 HV1 and the electrical resistivity of the powder mass decreases from 2.94 × 10⁻⁵ to 7.78 × 10⁻⁷ Ω-m.