Coupled Pressure-Gas Atomization Process for Fine Spherical Aluminium Alloy Powder Production

Coupled pressure-gas atomization (PGA) technique was introduced for metal powder production. In the PGA process, the melt could be pressurized to go through a melt-guiding-nozzle (MGN) with a very thin inner-diameter, thereby forming a very thin melt jet. By this way, a high yield of fine metal powder could be obtained. AlSi10Mg alloy powder was produced by the PGA process, whereby a MGN with an inner-diameter of 2 mm, together with a gas atomization pressure of (2.0±0.3) MPa and an over-pressure of (0.3±0.05)×105 Pa on the melt, was employed. In this case, a powder yield of >40% could be reached for a particle size range of <53 μm; compared with those from domestic market and imported from abroad, the AlSi10Mg alloy powder produced by the PGA process exhibited higher sphericity, smooth surface and fewer satellites; the specimens made from such powders by selective laser melting process led to tensile properties comparable to that from imported powders. The PGA technique could deal with the clogging problem when a highly viscous melt, i. e. the modified 2009 (Mod 2009) Al-alloy melt with 18%~20% Si and 5%~6% Fe, went through a MGN. At a melting temperature of 850℃, the viscous melt, driven by an over-pressure of (0.4±0.05)×105 Pa, could go through a MGN with an inner-diameter in a range of 4~2 mm; with a decreasing MGN inner-diameter, the fine powder yield increased, the particle size distribution became narrow, and the volume median diameter decreased. In the case of a MGN with an inner-diameter of 2 mm, the fine powder yield (<100 μm) could reach 80%, and the volume median diameter (d50, 3) was about 55 μm. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.