Effect of Pulsed Electric Current on the Distribution of Pb Impurities in Oxygen-free Copper

XIONG Jiao; LI Kun; YANG Xiangjie

doi:10.3969/j.issn.1674-6457.2026.04.019

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (4) : 186-195. DOI: 10.3969/j.issn.1674-6457.2026.04.019

Copper Alloy Forming

Effect of Pulsed Electric Current on the Distribution of Pb Impurities in Oxygen-free Copper

XIONG Jiao^1,2, LI Kun^2,3, YANG Xiangjie^2,3,*

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Abstract

The work aims to systematically investigate the purification effect of pulsed electric current (PEC), an auxiliary physical field technology, on Pb impurities in an oxygen-free copper melt, to reveal the migration behavior and underlying mechanism of Pb and to develop an efficient and green purification process. With oxygen-free copper containing 1 wt.% Pb as the research object, the melt prepared in a high-frequency induction furnace was treated with PEC at varying parameters (electrode insertion depth, pulsed current intensity and frequency). The microstructure, size, area fraction and spatial distribution of Pb impurities in the treated samples were systematically characterized and quantitatively analyzed through optical microscopy (OM), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) spectrometry. The PEC effectively drived Pb impurities to overcome central segregation, achieving directional migration towards the anode and the bottom of the melt, thereby forming purified zones in the central and cathode areas. Parameter optimization experiments revealed that the optimal purification efficiency was achieved with an electrode insertion depth as 1/4 of the depth of the graphite crucible, a pulsed current of 150 A, and a frequency of 1 500 Hz, resulting in a maximum Pb removal rate of 58.75% in the central region. The underlying mechanism was primarily attributed to the combined driving forces of electromigration (electron wind force) and the reduction in electrochemical free energy induced by the current density gradient. However, when the current or frequency exceeded critical thresholds, the intense Joule heating effect induced disordered convection within the melt, consequently reducing the purification efficiency. Pulsed electric current technology can effectively achieve directional migration and selective purification of Pb impurities in oxygen-free copper melts. The impurity migration is driven synergistically by electromigration force and current density gradient force, with an optimal processing window existing. This research clarifies the key process parameters and mechanism of this technology, providing a theoretical basis and practical guidance for the green preparation of high-performance oxygen-free copper.

Key words

pulsed electric current / high-purity copper / Pb impurity / electromigration / current density gradient / purification

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XIONG Jiao, LI Kun, YANG Xiangjie. Effect of Pulsed Electric Current on the Distribution of Pb Impurities in Oxygen-free Copper[J]. Journal of Netshape Forming Engineering. 2026, 18(4): 186-195 https://doi.org/10.3969/j.issn.1674-6457.2026.04.019

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Funding

National Natural Science Foundation of China (50965015); Jiangxi Major Science and Technology R&D Special Project (20223AAE02009); Fund of Key Laboratory of Light Alloy Materials of Jiangxi Province (2024SSY05031)