Production of W-Yo Powders With Spherical Particles and Submicron Internal Structure Using Electric Arc Thermal Plasma

This paper presents the results of the study of the process of obtaining spheroidized powders of the W-YO system of 5–50 μm fraction, the particles of which are characterized by submicron grain size of tungsten and uniform distribution of yttrium oxide. The powders were obtained using an approach involving successive stages of plasma-chemical synthesis of nanopowders of the W-YO system, granulation of nanopowders by spray drying and plasma spheroidization of the obtained microgranules. The regularities of formation of composite nanopowders W-YO with yttrium oxide content in the range from 0.3 to 5.0 wt.% in the flow of nitrogen-hydrogen plasma have been established. The parameters and conditions of plasma-chemical synthesis have been determined, under which the complete transformation of initial reagents into target products (W and YO) with uniform distribution of yttrium oxide in synthesized nanopowders is achieved. The conditions of preparation of stable suspensions based on nanopowders of W-YO system and the process of their spray drying, providing the formation of predominantly rounded nanopowder microgranules of fraction −60 microns with maximum yield and productivity have been determined. The influence of plasma treatment parameters on the degree of spheroidization, internal structure, bulk density and fluidity of microorganisms has been established, and the possible ranges of variation of these characteristics have been determined. It is proved that the uniformity of yttrium oxide distribution in powder materials is provided at all stages of obtaining spheroidized microparticles of W-YO system – from plasma-chemical synthesis of nanopowders to processing of microgranules in the flow of electric arc thermal plasma. The possibility of significant refining of treated microgranules by gas impurities (O, N, H, C) during plasma treatment is demonstrated.