Synthesis of mono-phase, hexagonal plate-like Al₄SiC₄ powder via a carbothermal reduction process

Abstract

Mono-phase and hexagonal plate-like Al4SiC4 powders were successfully synthesized using a mixture of Al(OH)3, SiO2 and phenolic resin via the carbothermal reduction process. Two-step reaction was compartmentally observed during calcination; the carbothermal reduction of SiO2 between 1300 and 1600°C and that of Al2O3 above 1500°C. X-ray diffraction data indicated the orientation of the compacted powders along c-axis due to the stacking of plate-like Al4SiC4 powders. Microscopic observation showed that the synthesized powders were mainly hexagonal platelets. The main synthetic mechanism of the ternary carbide powder during the carbothermal reduction process was gas-solid reaction. Possible reaction mechanisms which are responsible for the synthesis of Al4SiC4 by the carbothermal reduction process are discussed.

Synthesis of Al4SiC4 powders via carbothermic reduction: Reaction and grain growth mechanisms

“…At the same time, the generated SiO(g) can immediately react with carbon and CO(g) to form SiC according to the following reactions [17,18]:…”

“…Hence, most of reported research work focused on the synthesis of this ternary ceramic. There are mainly three kinds of powder mixtures used to synthesize the Al 4 SiC 4 powders or bulk, i.e., (1) using aluminum, silicon, and carbon powders as raw materials [11][12][13], (2) using Al 4 C 3 and SiC powders as raw materials [14,15], and (3) using Al 2 O 3 , SiO 2 , and C as raw materials by carbothermic reduction [16][17][18][19][20]. The former two reactant mixtures require expensive and active metal powders or carbides as starting materials.…”

“…Furthermore, it has been found that the synthesized Al 4 SiC 4 powders through carbothermic reduction usually have plate-like grains [16,17]. For the reaction mechanism, Lee et al [17,18] reported that gas-solid reactions occur in the initial stage and gas-gas reactions in the latter stage by carbothermic reduction by using Al(OH) 3 , SiO 2 , and phenolic resin as starting materials. However, Yu et al [20] argued that some solid-liquid reactions also occur as well during the synthesis and proposed that the metal phases such as Al and Si with low melting points are formed and wrap the Al 4 SiC 4 particles, which accelerate the nucleation of Al 4 SiC 4 grains.…”

Synthesis of Al₃BC₃ particulates by carbo-thermal reduction process—Parameter optimization and mechanism analysis

“…However, in spite of the importance of the process, the synthesis of ternary carbides using carbothermal reduction process has been scarcely investigated. 18), 19) Especially, the synthesis of Al 3 BC 3 by the process has never been reported.…”

Synthesis of Al4SiC4 powders from kaolin grog, aluminum and carbon black by carbothermal reaction

“…Various methods for synthesis of Al 4 SiC 4 have been developed by using different raw materials and processes, such as elements (Al+C+Si) [6], carbides (Al 4 C 3 , SiC) [7] or silicon-containing polymers [2], oxides and hydroxides [8][9] and also synthesized from laser processing [10], solid state reaction [11] and hot-pressing [2]. For the most methods, it was required expensive element powders or humidity-sensitive Al 4 C 3 powders as raw materials.…”