Influence of Processing Parameters on the Conduct of Electrical Resistance Sintering of Iron Powders

Abstract

The influence of the applied pressure and electrical parameters on the macrostructure of specimens consolidated by the medium-frequency electrical resistance sintering technique (MF-ERS) is analysed in this work. This technique is based on the application of pressure to a mass of conductive powder that, simultaneously, is being crossed by a high intensity and low voltage electric current. The simultaneous action of the pressure and the heat released by the Joule effect causes the densification and consolidation of the powder mass in a very short time. The effect of the current intensity and heating time on the global porosity, the porosity distribution, and the microhardness of sintered compacts is studied for two applied pressures (100 and 150 MPa). For the different experiments of electrical consolidation, a commercially available pure iron powder was chosen. For comparison purposes, the properties of the compacts consolidated by MF-ERS are compared with the results obtained by the conventional powder metallurgy route (cold pressing and furnace sintering). Results show that, as expected, higher current intensities and dwelling times, as well as higher pressures and the consolidation of compacts with lower aspects ratios, produce denser materials.

Ultrasonic Assisted Sintering Using Heat Converted from Mechanical Energy

“…In-depth explanation for the high hardness needs further symmetrical investigation. Before closing, it is worth mentioning that many FAST variants have recently been developed to improve efficiency of sintering further, such as medium-frequency electrical resistance sintering (MF-ERS), it uses medium frequency electric current to achieve sintering within one second [40][41][42]. Compare with the MF-ERS method, UAS utilizes the mechanical energy as heat source; broadly, there are three similarities between UAS and MF-ERS: (1) Short processing time in one or two seconds.…”

Medium-Frequency Electrical Resistance Sintering of Soft Magnetic Powder Metallurgy Iron Parts

“…Thus, porosity distribution, microhardness, electrical resistivity and hysteresis curves of MF-ERS Fe compacts were determined and compared with those measured in a compact prepared by the conventional PM route of cold pressing and vacuum furnace sintering, and with a fully dense compact processed by double press and sinter cycle in hydrogen atmosphere. The study is an extension of the work in [14], looking for practical uses (in this case, the magnetic applications) taking advantages of the MF-ERS technique.…”