抄録
The synthesis mechanism of Al3BC3 through carbo-thermal reduction process was investigated and the processing conditions were optimized using Al(OH)3–B2O3–C as starting materials. The mass change and phase formation of the compacts were analyzed with varying temperature. Excess Al(OH)3 and B2O3 were required compared to the stoichiometric composition due to the loss of the source materials by vaporization at 1,500–1,600°C. At 1,600°C, Al2O gas began to actively react with carbon to form Al4C3 on the carbon particles. Al, Al2O and B2O3 gases diffused through Al4C3 layer and reacted with carbon at and above 1,650°C to form Al3BC3. The formation of hexagonal terrace at the surface of synthesized powder indicated that the gases also reacted at the particle surface with carbon which diffused through the carbide layers. The reactions were completed after calcination at 1,725°C for 4 h or at 1,800°C for 1 h. Gas-solid reactions were the major synthesis mechanism. The optimum composition for the synthesis of the ternary compound was Al(OH)3:B2O3:carbon = 0.7:1.4:0.25 by weight.
