Effect of powder size on the moldability and pore characteristics of porous tungsten by injection molding

Component shape and pore structure are crucial to the application of porous tungsten, and are significantly affected by the powder size. In this work, porous tungsten with complex shape and controllable pore structure were prepared by the combination of jet milling and injection molding, and the effects of powder size (5, 2 and 0.6 μm) on jet milling, injection molding and pore structure were systematically investigated. The results showed that in contrast to the complete dispersion observed with micron-sized powders, ultrafine powder still had residual agglomerations after jet milling, which further led to a relatively low critical solid loading (47 %) and moldability index (${\alpha }_{\mathrm{stv}}$=1.85) during injection molding. For porous pore structure, finer powder was more conducive to obtain smaller pore size and more complex pore structure. At the same porosity (27 %), with the decrease of powder size, the pore size decreased from 1028 nm to 552 nm and 350 nm, and the corresponding fractal dimension increased from 2.19 to 2.84 and 2.99. In contrast, the compressive strength increased as the powder size decreased, rising from 488 MPa to 640 MPa and 883 MPa. The establishment of the relationship between powder size, moldability, and pore characteristics provides valuable insights for the raw powder selection and pore structure control, which is of great significance for the precise preparation and application promotion of porous tungsten.