Double SHS of W2B5 Powder from CaWO4 and B2O3
A synthesis study of W2B5 powder was carried out by double self-propagating hightemperature synthesis (D-SHS) from CaWO4, Mg and B2O3 mixture and followed by HCl leaching methods. In the first stage of SHS reaction, molar composition ratio of CaWO4:B2O3:Mg mixture was selected as 1:1:8 (SHS-1) and 1:2.5:8 (SHS-2). The both SHS products were then acid leached (HCl) at optimum conditions for 1 hour and 80 °C to eliminate MgO, Mg3B2O6 and Ca3(BO3)2 phases. The first leached products were consisted of W, WB, W2B5, and W2B phases. In the second stage of SHS process, the both leached products were reacted with the same amount of Mg and B2O3 mixture keeping previous initial ratio values (1:8 and 2.5:8). A successful SHS reaction was achieved only by using the mixture with leached SHS-2 product. After following acid leaching, the chemical composition of the leached D-SHS product was found to be 98.2 wt. % W2B5, 1.2 wt. % WB4, and 0.6 wt. % WB.
Pietro VINCENZINI, Ralf RIEDEL, Alexander G. MERZHANOV and Chang-Chun GE
S. Yazici and B. Derin, "Double SHS of W2B5 Powder from CaWO4 and B2O3", Advances in Science and Technology, Vol. 63, pp. 246-250, 2010