Low-Temperature Molten Salt Synthesis and the Characterisation of Submicron-Sized Al(8)B(4)C(7) Powder

Submicron-sized (~200 nm) aluminium boron carbide (Al(8)B(4)C(7)) particles were synthesised from Al, B(4)C 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 Al(8)B(4)C(7) formation process. By using a combined salt of 95%NaCl + 5%NaF, an effective liquid reaction medium was formed, greatly facilitating the Al(8)B(4)C(7) formation. As a result, essentially phase-pure Al(8)B(4)C(7) 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.