Paper published in Powder Technology
Nicolas' new paper "Spray drying synthesis of silicon-enriched iron micro-powder (FeSi) for additive manufacturing and potential magnetic use" has recently been published in Powder Technology !
Silicon steels, specifically Fe–6.5 wt% Si (Fe6.5Si), are essential for high-efficiency electrical machines due to their high magnetic permeability and near-zero magnetostriction. However, their extreme brittleness makes conventional processing difficult, driving the need for high-quality powders for additive manufacturing (AM) and powder injection molding (PIM). This study proposes a novel, sustainable and chemical synthesis route for silicon-enriched iron micro-powder (FeSi) powders combining ATEX-compliant spray drying with reductive calcination, utilizing recycled silicon sourced from end-of-life photovoltaic cells. The research systematically compares three iron precursors, iron nitrate (Fe(NO3)3.9H2O), iron hydroxide (Fe(OH)3) and iron oxide (Fe2O3) to determine their impact on powder morphology and yield. Spray drying parameters were optimized to produce spherical particles. Subsequent reductive calcination at 700 °C for 6 h under Ar/H2 was found to be the critical threshold to achieve phase-pure FeSi. Fe(OH)3 emerged as the superior precursor, providing the highest calcination yield (81%), the most robust spherical morphology and high chemical homogeneity, as confirmed by EDX mapping and Mössbauer spectroscopy. The successful incorporation of recycled PV‑silicon establishes a lower-temperature, sustainable alternative to traditional gas atomization. These results demonstrate a versatile framework for producing high-performance soft magnetic powders with the flowability and structural integrity required for advanced manufacturing of electrical components.
