A Method to Determine the Electrical Resistance of a Metallic Powder Mass under Compression

Abstract

Abstract:In this paper, a phenomenological model to predict the value of the electrical resistance of a compressed metal powder mass is proposed. The model, based on the experimental compressibility and resistivity-porosity curves, is useful in the field of the electrical resistance consolidation. In this area is often required to find out whether a certain mass of powder inside a die of specified inner section, and subjected to a certain compression, reaches a sufficiently small resistance value so that it can be consolidated by electrical means. The model also predicts the electrical resistance value of the powder mass in case of powders with no oxide layers, or after removing them mechanically or electrically by a previous activation process. The model predictions have been successfully validated through direct measurements of electrical resistance in powder aggregates both in as-received state and after electrical activation.

Resistance sintering of NdFeBCo permanent magnets and analysis of their properties

“…On the contrary, the powder from the one hour ball milling shows a reduced hardness due to the isotropic structure typical in the core as discussed above for higher electrical current densities. The reason for the two powders to show a structure change at different electrical current densities is found in the different densities revealed in Figure 7, where the higher density for the powder from 30 minutes ball milling results in less heat generation as highlighted by Chawake et al [35] and experimentally studied by Montes et al [36].…”

Numerical Simulation of Resistance Sintering of Titanium by a Porous Continuum Approach

“…Montes et al [30][31][32] have theoretically described the electrical resistivity e  at room temperature as a function of the corresponding electrical resistivity at full density 0  (i.e.…”

“…The tap porosity of titanium powder was mathematically estimated as 0.5 m   following the method presented in [30][31][32]. Heat is generated by the Joule effect as a function of the electrical resistivity and the current density.…”

Nickel Porous Compacts Obtained by Medium-Frequency Electrical Resistance Sintering

“…The powder metallurgy characteristics of the powder were completed with the measurement of its compressibility [23], and the variation of its electrical conductivity vs. porosity. For this last determination, the device shown in Figure 2 was used, according to the procedure described in [24].…”