Effects of CaO addition on the CuW composite containing micro- and nano-sized tungsten particles synthesized via aluminothermic coupling with silicothermic reduction

Abstract

CuW composite fabricated by powder metallurgy using ultrafine metal powders as raw materials has the disadvantages such as uneven microstructure and low compactness. A novel method of synthesizing an as-cast CuW composite ingot via an aluminothermic coupling with silicothermic reduction is presented; a low-melting-point CaO–Al2O3–SiO2 slag is formed by adding CaO as a slag former, effectively reducing Al2O3 inclusion in the CuW composite. In this study, the effects of CaO addition on the novel synthesis of the CuW composite via the aluminothermic coupling with silicothermic reduction are investigated. The result shows that CaO affects the removal of large particles (≥6 µm) but not the removal of small particles (≤4 µm). With the increase in the ratio of CaO ranging from 0 to 1.0, the inclusions in the CuW composites gradually transform from Al2O3 to calcium aluminates, which are conducive to the separation of the metal and slag. The contents of Si and O in the CuW composites gradually decrease from 9.40 and 14.00% to 6.10 and 3.50%, respectively, while those of Al and Ca gradually increase from 2.54 and 0.02% to 3.83 and 0.26%, respectively.