Phase and Microstructure Transition of High Cu Content Cu-W Composite Powder Fabricated by Spray Drying

oleh: Qi Wang, Xiuqing Li, Shizhong Wei, Wenpeng Lou, Liujie Xu, Yucheng Zhou

Format: Article
Diterbitkan: MDPI AG 2022-09-01

Deskripsi

Cu-W composite powder with various W contents (0, 10, 20, and 30 wt%) has been fabricated by spray drying, calcination, and two-stage hydrogen reduction in this work. The microstructures and phase evolution of Cu-W composite powder were studied by FESEM, HRTEM, and XRD. Results show that precursor powder is composed of Cu<sub>2</sub>(OH)<sub>3</sub>NO<sub>3</sub> and H<sub>2</sub>WO<sub>4</sub>·H<sub>2</sub>O. Spherical CuWO<sub>4</sub> with a particle size of about 50 nm and micron-scale flat flake CuO were obtained when the calcination temperature was 500 °C. Through chemical vapor transport (CVT) during the reduction process, volatile WO<sub>2</sub>(OH)<sub>2</sub> continuously migrates to the copper surface and is reduced to W, resulting in a W-coated Cu structure. This coating structure can inhibit the aggregation and growth of copper particles. The particle sizes of Cu-10 wt%W, Cu-20 wt%W, and Cu-30 wt%W composite powders are 9.309 μm, 8.440 μm, and 6.290 μm, reduced by 40.51%, 46.06%, and 59.80%, respectively, compared to the particle size of pure copper powder, 15.648 μm. With increasing W content, the W-coated Cu particles gradually become denser and trend to grow from sphere to flake.