Research of Preparation Boron Carbide Micro Powder by Combustion Synthesis Method

Abstract

本文提出采用燃烧合成法制备超细B4C微米粉的新思路，研究了还原剂镁配入量、氧化硼配入量以及坯样压力对反应的影响。结果表明：2B2O3+C+6Mg=B4C+6MgO体系的绝热温度为2750 K，体系可以进行自蔓延反应；自蔓延燃烧产物主要由MgO、B4C和少量Mg3B2O6相组成；采用盐酸浸出可有效除去MgO和Mg3B2O6得到纯净的B4C相；随着氧化硼配料量增加燃烧产物中Mg3B2O6含量会增加，但产物粒度无明显变化；随镁配料量增加自蔓延产物中MgO含量上升，同时有利于B4C的合成，当Mg过量5%~15%时产品粒度存在最小值；制样压力的增加，可显著细化产品粒度；不同的碳源类型对产品的微观形貌、粒度大小以及产品纯度均存在明显的影响。 This paper presents a new method for the preparation of micron boron carbide powder through combustion synthesis method. In the preset work, the effect of process conditions on the product quality was systematically studied. The results show that: The adiabatic temperature of 2B2O3+C+6Mg=B4C+6MgO system is 2750 K, and the self-propagating reactions can occur spontaneously. Self-propagating reaction product mainly contains MgO, B4C and Mg3B2O6. Hydrochloric acid leaching process can effectively remove the impurity phase MgO and Mg3B2O6, thus pure B4C was obtained. The improvement of B2O3 caused the increase of Mg3B2O6 content in product, and had no significant effect on the product particle size. The improvement of Mg caused the increase of MgO content in product, and was conducive to the synthesis of B4C; when Mg excesses 5% to 15%, the product size exists a minimum value. The increase of sample making pressure can remarkably refine product granularity. Different carbon source types have significant influence on the micromorphology, particle size and purity of the product.