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<p>Iron boride coatings were developed on AISI H13 hot work tool steel using the electrochemical boriding method at temperatures of 850, 950, and 1050&#xa0;°C for durations of 2, 4, and 6&#xa0;h. The process was conducted at a current density of 200&#xa0;mA/cm<sup>2</sup>, utilizing a powder mixture containing 22.5 wt.% ferroboron (Fe-B), 70 wt.% borax (Na<sub>2</sub>B<sub>4</sub>O<sub>7</sub>), and 7.5 wt.% ammonium chloride (NH<sub>4</sub>Cl). The obtained coatings were examined using light microscopy (LM), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). Metallographic analysis revealed a distinct saw-tooth shaped interface between the boride layer and the underlying transition zone, which was consistent and uniform across the examined area. XRD results revealed the formation of a dual-phase boride layer (FeB/Fe<sub>2</sub>B) with traces of chromium and vanadium borides. The kinetics of the boriding process were evaluated using the classical parabolic growth law, demonstrating a parabolic relationship between boride layer thickness and treatment time. The activation energy required for boron diffusion throughout the boride layer was determined to be 168.4&#xa0;kJ/mol. Additionally, the microhardness and wear rate were evaluated. The boride layer reached a thickness up to 252&#xa0;µm and exhibited a microhardness of 1956 ± 67 HV<sub>0.05</sub>, representing an increase of over 300% compared to the quenched and tempered specimens, which had a microhardness of 543 ± 8 HV<sub>0.05</sub>. The findings demonstrated that the phase composition and thickness of the boride coatings are strongly influenced by the immersion time and processing temperature.</p>

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Enhancement of tribological behavior and microhardness of AISI H13 tool steel by electrochemical boriding

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月8日

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  • A. Mourad,
  • A. A. Mahdy,
  • E. S. Mosa,
  • A. Kandil,
  • M. A. Elhelaly

摘要

Iron boride coatings were developed on AISI H13 hot work tool steel using the electrochemical boriding method at temperatures of 850, 950, and 1050 °C for durations of 2, 4, and 6 h. The process was conducted at a current density of 200 mA/cm2, utilizing a powder mixture containing 22.5 wt.% ferroboron (Fe-B), 70 wt.% borax (Na2B4O7), and 7.5 wt.% ammonium chloride (NH4Cl). The obtained coatings were examined using light microscopy (LM), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). Metallographic analysis revealed a distinct saw-tooth shaped interface between the boride layer and the underlying transition zone, which was consistent and uniform across the examined area. XRD results revealed the formation of a dual-phase boride layer (FeB/Fe2B) with traces of chromium and vanadium borides. The kinetics of the boriding process were evaluated using the classical parabolic growth law, demonstrating a parabolic relationship between boride layer thickness and treatment time. The activation energy required for boron diffusion throughout the boride layer was determined to be 168.4 kJ/mol. Additionally, the microhardness and wear rate were evaluated. The boride layer reached a thickness up to 252 µm and exhibited a microhardness of 1956 ± 67 HV0.05, representing an increase of over 300% compared to the quenched and tempered specimens, which had a microhardness of 543 ± 8 HV0.05. The findings demonstrated that the phase composition and thickness of the boride coatings are strongly influenced by the immersion time and processing temperature.