Magnetic Field Generated during Electric Current-Assisted Sintering: From Health and Safety Issues to Lorentz Force Effects

Abstract

In the past decade, a renewed interest on electromagnetic processing of materials has motivated several investigations on the interaction between matter, electric and magnetic fields. These effects are primarily reconducted to the Joule heating and very little attention has been dedicated to the magnetic field contributions. The magnetic field generated during electric current-assisted sintering has not been widely investigated. Magnetism could have significant effects on sintering as it generates significant magnetic forces, resulting in inductive electrical loads and preferential heating induced by overlapping magnetic fields (i.e., proximity effect). This work summarizes the magnetic field effects in electric current-assisted processing; it focuses on health and safety issues associated with large currents (up to 0.4 MA); using FEM simulations, it computes the self-generated magnetic field during spark plasma sintering (SPS) to consolidate materials with variable magnetic permeability; and it quantifies the Lorentz force acting at interparticle contact points. The results encourage one to pay more attention to magnetic field-related effects in order to engineer and exploit their potentials.

Ultrahigh Temperature Flash Sintering of Binder-Less Tungsten Carbide within 6 s

“…To obtain the real-time temperature of the specimen over the course of experiment, a Finite Element Model (FEM) was developed by means of the COMSOL ® software [47]. FEM was reproduced as detailed in Reference [48]. The electrical and thermal boundary conditions are shown in Figure S2, axial symmetric boundary condition was assumed along the central axis.…”

Influence of the Power of Various Types of Induction Furnaces on the Shape of the Metal Bath Surface

“…On Figure 8 example meniscus shapes were compiled, created using the Wolfram Mathematic program for the aluminum alloy (70 and 130 kW) molten inside a cold crucible furnace According to the data shown in Table 2, it can be ascertained that in the case of melting alloy inside a crucible furnace, power increase from 8 to 22 kW causes the increase of liquid alloy surface from 88.1 to 155 cm 2 In the case of a cold crucible furnace, the increase of power from 70 to 130 kW causes the increase of liquid alloy surface from 280 to 330.3 cm 2 . for the Y-axis diameter of the crucible in cm) [1] Determination of the influence of the furnace operating power on zinc losses in the smelting process of the tested Al-Zn alloy…”

“…The purpose of the induction coil is the forming and shaping of an electromagnetic field (especially the magnetic component), which affects the insert. The Eddy currents induced inside the insert, aside being a source of heat, cause the creation of EM fields inside the metal (The Lorentz force) [2]. It's the result of an interaction of induced Eddy currents with the created magnetic field [3÷5].…”

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

“…Values of current intensity, voltage between the bedplates of the equipment, and upper head position were monitored during the equipment work. The rectified current waveform gives special characteristics to this technique, otherwise magnetic field effects would be significant, as described in [15].…”