Influence of nozzle gas inlets on properties of GTD222 superalloy powders for additive manufacturing

The GTD222 superalloy powders for the additive manufacturing were prepared by the vacuum inert gas atomization (VIGA) with the close-coupled nozzle system in this paper. The effects of nozzle gas inlets on the chemical composition, particle size distribution, sphericility, fluidity, loose packed density, and surface morphology of the GTD222 superalloy powders were studied. The results show that, using the nozzle with an “outer straight inner tangent” structure enhances the suction effect of the nozzle and improves the stability of the closed-coupled gas atomization process. In addition, the tangent inlet system enhances the gas shear effect, therefore improves the yield of the fine powders (15~53 μm). The optimized process parameters are found in the conditions of 200 ℃ superheat and 3 MPa atomization pressure. The oxygen mass fraction of the powders prepared in the optimized conditions is 0.02%, the medium diameter is 57.98 μm, the degree of sphericility is 0.77, the fluidity is 26.15 g/(50 s), and the loose packed density is 4.63 g/cm³, which meet the requirements of the metal additive manufacturing technology.