原料预处理对电热法制备碳化硼的影响

THE EFFECT OF PREPROCESSING RAW MATERIAL ON PREPARATION OF BORON CARBIDE BY ELECTROTHERMAL METHOD

以硼酸和石油焦粉为原料,采用电热法制备碳化硼。考察了三种不同的原料预处理方式(原料粉状、原料压制球团和原料压制球团并预脱水)对制备出的碳化硼质量的影响。采用X射线衍射、化学分析、扫描电镜和粒度分析对产物的物相、纯度、形貌和粒径进行了分析。研究表明,三种预处理方式中,原料经过压制球团并预脱水的预处理后所制备出的碳化硼的质量相对较优,其中碳化硼的含量为93.76%、游离碳含量仅为1.32%;产物中碳化硼的衍射峰较强,结晶好;形成的碳化硼晶粒较大,D50为27.20μm。此外,研究表明制备的碳化硼存在两种不同的形貌,一种是液-固反应形成的完形块状晶,而另一种则是气-固反应形成的长条状枝晶。

The boron carbide was prepared with electrothermic method with the boric acid and petroleum coke powder as the raw materials. In order to compare the effect of the preprocessing method of the raw materials on the quality of prepared boron carbide, the raw materials were already preprocessed with three different methods, which were powdery materials, pressed pellets, pressed pelletsand pre-dewatered, respectively. The experimental products were analyzed by XRD, chemical component, SEM-EDS and particle size. The results indicated that the product, which had higher content of boron carbide, lower content of free carbon, better crystallization and larger grain, was prepared with the raw material after pelletized and pre-dewatered. Besides, the results also found that the boron carbide was prepared with two kinds of reaction mechanism, one was solid-liquid interface reaction and the other one was gas-solid interface reaction.