Enrichment of W₂B₅ from WO₃ and B₂O₃ by double SHS method

A second self-propagating high-temperature synthesis (SHS) was carried out to enrich the W₂B₅ content in the SHS product containing a mixture of various tungsten boride compounds. In the experiment, the process called Double-SHS (D-SHS) was conducted in two steps. In the first SHS reaction, an initial molar composition ratio of WO₃:B₂O₃:Mg mixture was selected as 1:3:8. The product was then hot-leached with hydrochloric acid to eliminate MgO and Mg₃B₂O₆ phases. The leached product, consisting of 72.6 wt.% W₂B₅, 16.1 wt.% WB, 8.4 wt.% W₂B, and 2.9 wt.% W, was again reacted with the Mg and B₂O₃ mixture by second SHS. After another acid leaching step, W₂B₅ content in the D-SHS product was found to be 98.2 wt.%. The study showed that D-SHS is an effective method for boron enrichment in the tungsten compounds.