Modelling and Simulation of the Electrical Resistance Sintering Process of Iron Powders

Abstract

In this paper, the process known as Electrical Resistance Sintering under Pressure is modelled, simulated and validated. This consolidation technique consists of applying a highintensity electrical current to a metallic powder mass under compression. The Joule effect acts heating and softening the powders at the time that pressure deforms and makes the powder mass to densify. The proposed model is numerically solved by the finite elements method, taking into account the electrical-thermal-mechanical coupling present in the process. The theoretical predictions are validated with data recorded by sensors installed in the electrical resistance sintering equipment during experiments with iron powders. The reasonable agreement between the theoretical and experimental curves regarding the overall porosity and electrical resistance suggests that the model reproduces the main characteristics of the process. Also, metallographic studies on porosity distribution confirm the model theoretical predictions. Once confirmed the model and simulator efficiency, the evolution of the temperature and the porosity fields in the powder mass and in the rest of elements of the system can be predicted. The influences of the processing parameters (intensity, time and pressure) as well as the die material are also analyzed and discussed.

Nickel Porous Compacts Obtained by Medium-Frequency Electrical Resistance Sintering

“…Only by means of theoretical estimation is it possible to know the achieved temperatures. Using simulators developed in previous works [13,14], it has been possible to establish that the maximum values of the mean temperatures reached, for the analyzed conditions, move in the range of 400 to 700 K. These values may seem low, but it must be considered that the local temperature may be much higher in the interparticle contact areas. Unfortunately, there are no reliable theoretical estimates for these local temperatures.…”

“…On the other hand, the diametral section of all the compacts (electrically and conventionally consolidated) was analyzed by optical microscopy (EPIPHOT 200, Nikon, Tokyo, Japan) in order to study the porosity distribution. The non-homogeneous porosity distribution is a consequence of the temperature achieved in different compact zones during the process [8,14].…”

“…The mediumfrequency technology offers a great advantage, as it allows using a DC current and smaller and lighter transformer cores, without power loss. Although this technique has not yet enjoyed a great deal of theoretical development by many researchers, some complete theoretical models and simulations of the process can be found in [13,14].…”

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

“…One of the main disadvantages of the MF-ERS technique is that it is not possible (or at least it is not easy) to measure the temperature evolution inside the compact, resulting in it being even more difficult to know the temperature distribution. The only possible way is the simulation of the process, as described in [16].…”

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

“…The main disadvantages of the ERS technique arise from operational difficulties (incomplete knowledge of how certain parameters influence the process) and the problem of achieving a homogeneous temperature distribution in the powder mass [18]. Some of the authors of this paper have studied this process, both from the experimental and theoretical points of view [19][20][21]. One of the important problems of the ERS technique refers to the durability of the ceramic dies, which was studied in [22].…”