Tantalum powder can be reused or recycled, which can significantly reduce the price of items made with tantalum utilizing additive manufacturing. This study looked at oxygen content, particle shape, apparent density, tap density, and flowability of tantalum powder throughout cycling to assess the effects of reuse of the tantalum powder on the features of tantalum components and scaffolds. Also, with tantalum powder reused more than 30 cycles, the effect of reuse time on the mechanical characteristics of tantalum components and scaffolds produced by electron beam powder bed fusion (EB-PBF) was examined. The findings showed that the apparent density, tap density, and fluidity of the tantalum powder did not vary significantly as the number of cycles increased.During many reuses, the powder grew less spherical, and after 25 reuses, some particles had obvious deformation and a rough surface. However, after 15 reuse cycles, the plasticity of the dense tantalum decreased due to a rise in the oxygen content of the tantalum powder, and some possible microdefects started to show up in the tantalum samples made using the EB-PBF process. However, the number of uses within the research range had no effect on the tensile strength of dense tantalum components.
Reuse's impact on the powder's properties
With an increase in the quantity of reuse cycles, the tantalum powder's oxygen content rose. The leveling of the substrate before to the EB-PBF process, as well as the subsequent powder recycling procedure, were the key times when the powder was exposed to air and the oxygen content increased. The findings in figure 4 show that during the course of 30 reuse cycles, the oxygen concentration of the tantalum powder increased by 4.7 ppm per EB-PBF operation. Due to the tantalum particles being heated and melted with an electron beam in a high vacuum atmosphere during the EB-PBF process, the oxygen content grew gradually.
no discernible alteration in average particle size after 30 reuses. There are various causes for the slight change in particle size with increasing reuse cycles, including: The number of small particles was reduced due to the thin layer thickness (50 m) and scraping of the coarse powder; the number of large particles was increased due to splashing, adhesion, and remelting; and the number of small particles was decreased due to preferential melting of the fine-grained powder particles. As a result, the particle size only marginally increased. The average particle size was less after reuse because the big particles were screened out and the adhering powder particles were separated.The tantalum powder's D10, D50, and D90 alterations all followed the same pattern during the whole EB-PBF process, hence the particle size distribution barely changed and the original particle distribution was preserved.
The substrate was heated with an electron beam to 700 °C before to the EB-PBF procedure. The powder bed was then kept at a temperature over 660 °C for the duration of the EB-PBF procedure. The tantalum particles' modest surface roughening and deformation were thus anticipated, especially during the drawn-out EB-PBF process. Moreover, during the EB-PBF process, some particles near the construction components were heated to a high temperature, which could cause the particles to exhibit visible deformation and surface roughness. During the recovery process, the high-pressure air jets created concave areas on the powder particle surface.some of these characteristics. In particular, faults took longer to manifest than in the Ti-6Al-4V powder after 25 reuse cycles [15, 19]. With more powder reuse cycles, it is anticipated that there would be more surface flaws, which will increase surface roughness and particle distortion.
Conclusion 1. After 30 iterations of the EB-PBF process, the tantalum powder's oxygen content increased from 0.004 to 0.018 weight percent. After several reuse cycles, the tantalum powder's fluidity, particle size, apparent density, and tap density did not significantly alter.
2. After 20 rounds of reuse, the tantalum powder particles were spherical and had a smooth surface. After more than 25 reuses, a slight deformation in particle shape was noticed, and during the EB-PBF process, large and small particles fused.
