TiB_2-SiC复合粉末的碳热还原法合成及其表征

Preparation and Characterization of TiB_2-SiC Composite Powder by Carbothermal Reduction Method

以TiO2、B4C、炭黑和硅溶胶为原料,采用碳热还原法合成了TiB2-SiC超细复合粉末。对碳热还原反应过程进行了热力学分析和计算,采用XRD和SEM等研究了反应温度对合成TiB2-SiC复合粉末的物相组成和显微形貌的影响,并对合成的TiB2-SiC复合粉末的氧化性能进行了探讨。结果表明:TiB2-SiC复合粉末合成的适宜条件为在1600℃保温1 h。在反应过程中,TiB2先于SiC形成,所合成的复合粉末由球状、片状、短棒状颗粒以及晶须等多样化结构组成。TiB2-SiC复合粉末的氧化过程中,首先是TiB2优先与氧发生反应生成TiO2和B2O3,然后是SiC与氧反应生成SiO2和CO,氧化产物中没有发现低熔点B2O3的存在。

TiB2-SiC composite powder were synthesized by carbothermal reduction method using TiO2, B4C, carbon black and silica sol as raw materials. The thermodynamic analysis and calculation were performed systematically during the reaction. The effect of reaction temperature on the phase composition and morphology of TiB2-SIC composite powder was investigated by X-ray diffraction and scanning electron microscope. The oxidation resistance properties of TiB2-SiC composite powder were discussed. The results showed that the suitable condition for synthesizing TiB2-SiC composite powder is at 1600℃ for 1 h. In the reaction process, TiB2 formed ahead SiC. The composite powder are composed of round-like, plate-shaped , short rod-like particles and whiskers. In the oxidation process, TiB2 reacts in priority with O2 to form TiO2 and B2O3 ,then SiC reacts with O2 to form SiO2 and CO. Low melting glass phase of B2O3 can not be found in the oxidized product.