Abstract
Submicron-sized (~200 nm) aluminium boron carbide (Al8B4C7) particles were synthesised from Al, B4C and carbon black raw materials in a molten NaCl-based salt at a relatively low temperature. The effects of the salt type/assembly and the firing temperature on the synthesis process were examined, and the relevant reaction mechanisms discussed. The molten salt played an important role in the Al8B4C7 formation process. By using a combined salt of 95%NaCl + 5%NaF, an effective liquid reaction medium was formed, greatly facilitating the Al8B4C7 formation. As a result, essentially phase-pure Al8B4C7 was obtained after 6 h of firing at 1250 °C. This temperature was 350–550 °C lower than that required by the conventional direct reaction and thermal reduction methods.
Highlights
B4 C and C were mixed in the stoichiometric molar ratios of 8:1:6 (1.35:0.35:0.53 g in a powder batch) corresponding to Equation (1), and they were further combined with 20 g binary salt of
350–550 ◦ C lower than that required by the conventional synthesis routes [11,13,14,15,16,17,18,19,20,21], demonstrating the great advantage and feasibility of the molten salt synthesis (MSS) technique developed in this work
Al8 B4 C7 particles with an average size of about 200 nm were successfully synthesised after 6 h of firing in NaCl-NaF at 1250 ◦ C, from Al, B4 C and C starting powders
Summary
Ternary carbides are an important class of high-performance non-oxide ceramics that have attracted great research interest, especially during the past decade. To fabricate high-performance Al8 B4 C7 -based bulk ceramics, high-quality Al8 B4 C7 powder often needs to be used In this regard, several synthesis methods/techniques have been developed to date, among which the thermal reduction and direct reaction methods have been investigated most extensively. As a response to this, in the present work, a molten salt synthesis (MSS) method, used previously to prepare oxide and binary carbide powders [23,24,25], was further developed and extended to synthesise high-quality submicron-sized Al8 B4 C7 powder at a much lower temperature, from Al, B4 C and C starting materials. Based on the experimental results, the synthesis/formation mechanism of Al8 B4 C7 was discussed
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