碳化硅晶须双重加热合成的研究

双重加热法是低成本、大批量合成碳化硅晶须的新技术，合成温度低、合成时间短、生成率高。对以炭黑和二氧化硅微粉为原料、用双重加热法合成碳化硅晶须的工艺过程进行了研究。观察了不同合成时间、合成温度和催化剂条件下的碳化硅晶须，揭示出不同工艺参数对合成的碳化硅晶须的产出率，微观形貌、直径和长度范围的影响。结果表明，催化剂的使用可以加快反应速度，提高碳化硅晶须的生成率，合成过程为VLS。实验中初步得到的最佳经济工艺参数为：Fe2O3的用量为2％，合成时间为1．5h，合成温度为1250℃。此时的该工艺条件下碳化硅晶须的生成率可达80％，晶须平均直径为0．6μm，平均长度为30μm。

Study on the Synthesis of Silicon Carbide Whiskers by a Double-Heating Technique

The key process parameters for the double-heating synthesis of silicon carbide whiskers with carbon black and SiO2 powders as raw materials are studied. The effects of synthesis temperature, time and catalysts on the surface morphology, the average diameter and the average length of the synthesized silicon carbide whiskers are investigated. It is displayed that with the rise of the synthesis temperature, the synthesis rate, the diameter and the length increase but the final surface quality becomes worse. With increasing synthesis time the synthesis rate increases. For the double-heating technique it is demonstrated that Fe2O3 is a good catalyst and its content has a significant influence on the quality of the synthesized silicon carbide whiskers. In addition the parameters for the optimum synthesis process of silicon carbide whiskers are given.