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

Abstract

Abstract:Highly pure Al 4 SiC 4 powders were prepared by carbothermic reduction at 2173 K using Al 2 O 3 , SiO 2 , and graphite as raw materials. The obtained Al 4 SiC 4 powders owned hexagonal plate-like grains with a diameter of about 200-300 μm and a thickness of about 2-6 μm. Based on the experimental results, the reaction of Al 4 SiC 4 formation and grain evolution mechanisms were determined from thermodynamic and first-principles calculations. The results indicated that the synthesis of Al 4 SiC 4 by the carbothermic reduction consisted of two parts, i.e., solid-solid reactions initially followed by complex gas-solid and gas-gas reactions. The grain growth mechanism of Al 4 SiC 4 featured a two-dimensional nucleation and growth mechanism. The gas phases formed during the sintering process favored the preferential grain growth of (0010) and (1 10) planes resulting in formation of hexagonal plate-like Al 4 SiC 4 grains.

Combustion synthesis of single‐phase Al4SiC4 powder with assistance of induction heating

“…The particle size of the powder ranges from several hundred nanometers to several micrometers. The size is considerably smaller than the size reported for Al 4 SiC 4 powders synthesized by high‐temperature heat treatment or by carbothermal reduction, which can be explained by the short time the sample spent under high temperature. The shape of the particles is similar to the morphology of Al 4 SiC 4 synthesized from elemental powders by high‐temperature treatments, however some tendency to form plate‐like morphology was observed too.…”

“…Al 4 SiC 4 can be synthesized by various methods; elemental powders of Al, Si, and C or oxide powders such as Al 2 O 3 and SiO 2 , and C are often used as starting materials. The carbothermal reduction method uses cheap and widely available Al(OH) 3 , Al 2 O 3 and SiO 2 powders as starting materials, moreover natural minerals can also be used . Lee et al synthesized Al 4 SiC 4 using the carbothermal reduction method by calcination of pyrolyzed Al(OH) 3 , SiO 2 , Al 2 O 3 and phenolic resin mixture at 1750°C for 4 hours.…”

“…Lee et al synthesized Al 4 SiC 4 using the carbothermal reduction method by calcination of pyrolyzed Al(OH) 3 , SiO 2 , Al 2 O 3 and phenolic resin mixture at 1750°C for 4 hours. Xing et al obtained Al 4 SiC 4 from Al(OH) 3 , SiO 2 , Al 2 O 3 after heat treatment at 1900°C for 8 hours. In both cases, SiC and C were present as by‐products.…”

“…Aluminum silicon carbide (Al 4 SiC 4 ) has been attracting increasing attention not only in the field of refractory and hightemperature materials due to its low density, high melting temperature, high compressive stress, good thermal conductivity, ductility, and excellent oxidation resistance, [1][2][3][4] but also in the fields of photocatalysis, power, and optoelectronics as a new wide-gap semiconductor material. [5][6][7] Al 4 SiC 4 can be synthesized by various methods; elemental powders of Al, Si, and C 1,3,8,9 or oxide powders such as Al 2 O 3 and SiO 2 , and C [10][11][12] are often used as starting materials. The carbothermal reduction method uses cheap and widely available Al(OH) 3 , Al 2 O 3 and SiO 2 powders as starting materials, moreover natural minerals can also be used.…”

“…The carbothermal reduction method uses cheap and widely available Al(OH) 3 , Al 2 O 3 and SiO 2 powders as starting materials, moreover natural minerals can also be used. [10][11][12] Lee et al 10 synthesized Al 4 SiC 4 using the carbothermal reduction method by calcination of pyrolyzed Al(OH) 3 special molds and precautions are required to prevent separation of liquid Al from the reaction mixture before the reaction takes place. 13 In spite of very attractive properties of Al 4 SiC 4 , its application is still restricted by the difficulty to fabricate single phase.…”