Synthesis of tungsten nanopowders: Comparison of milling, SHS, MASHS and milling-induced chemical processes

• Tungsten nanopowders were synthesized by various methods.
• An oxygen content lower than 10 at% has been obtained.
• Maximal purity was obtained with a 10’ milling before SHS.
• Introducing mechanical activation before SHS improves the yield.

Synthesis of tungsten nanopowders was studied using milling of micrometric tungsten, then using the WO3–Mg thermitic reaction, using SHS (Self-propagating High-temperature Synthesis), milling induced chemical reaction (MICR), and MASHS (Mechanically Activated SHS). Reactions are studied by measuring temperature and pressure inside the milling jar (during MICR), or by analyzing the temperature profile along the sample during the reaction propagation by infrared thermography (SHS, MASHS). After reaction, samples were analyzed by AFM or SEM, by XRD, and BET. MASHS seems to possess optimum conditions with a pre-milling before SHS of 10 min, which yielded the highest tungsten purity, together with a grain size corresponding to our aim.

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