【作者】 王宇；

【导师】 王耀武；

【作者基本信息】 东北大学 ， 冶金工程（专业学位）， 2020， 硕士

【摘要】 单质B是一种高质量热值、高体积热值的特殊物理化学性质的材料,是最有潜力的富燃料固体推进剂的燃料,同时在材料加工、汽车安全气囊、超导半导、军工等领域被广泛应用。Al-B合金作为一种重要的工业应用物质,主要以AlB2和AlB12两种铝硼化合物的形式存在,通常被用在铸造中的晶粒细化剂,推进器燃料替代物。目前制备单质B/Al-B合金的主要方法都存在着不同的缺点,如制备成本高、实际产量低、产品纯度不达标等,这些缺点限制了B及Al-B合金的应用。本论文主要对以NaBF4为原料,Al粉为还原剂真空铝热还原制备单质B/Al-B合金的工艺过程进行研究,对二段铝热还原含硼冰晶石的工艺进行研究,得出主要结果如下:对真空铝热还原制备单质B/Al-B合金过程可能发生的反应进行热力学计算,确定铝热反应在理论上可以进行;对参加反应的原料及产物进行饱和蒸气压计算,确定还原产物和结晶产物可以通过真空蒸馏进行分离。对以NaBF4为原料,真空铝热还原制取单质B的过程中,还原温度、保温时间及Al粉过量系数均对NaBF4的还原程度及所得还原产物B的品质产生显著影响。实验表明,在还原温度为1100℃、保温时间为60min、还原剂过量系数为-6%的条件下,可得到产物单质B的纯度约为91.21%,粒度分布均匀、平均粒径为8.1 μm左右,同时还原过程B的收得率可以达到85.40%。以NaBF4为原料,通过调整铝粉配入量可制备AlB2和AlB12合金。在真空铝热还原制备AlB2时,当还原温度超过980℃,AlB2会转变为AlB12合金。在还原温度为900℃、保温时间60 min、还原剂过量系数为-6%的条件下,即可得到AlB2含量约为92.6%的Al-B合金;在还原温度为1100℃、保温时间为75 min、还原剂过量系数为-10%的条件下,即可得到AlB12含量约为98.5%的Al-B合金。在还原制备B/Al-B合金的同时,会产生含硼量为2.51%的含硼冰晶石。通过二段铝热还原反应可使含硼冰晶石中的硼与铝形成铝硼合金,从而获得无硼冰晶石。二段铝热还原的实验结果表明,在还原温度为1000℃、铝与含硼冰晶石的物料配比大于1:1、保温时间大于30 min时,铝热还原后获得的冰晶石中硼元素含量可以降低到0.030%以下,成分上符合工业冰晶石的要求。实验结果表明以氟硼酸钠为原料,Al粉为还原剂,经两段铝热还原后可分别获得单质B/Al-B合金以及合格的冰晶石,该方法不仅缩短了流程,而且对含硼冰晶石进行了回收利用,具有一定的实际意义。更多还原

【Abstract】 Boron has been widely used in material processing,automotive airbags,superconducting,semi-conductor,military and other fields because of its special physical and chemical properties.At the same time,it is one of the most potential fuel-rich solid propellant because of its high calorific value.AlB2 and AlB12 are the two most common Al-B alloys and commonly used as grain-refining agents in casting and substitutes of propellant fuel.At present,there are still many disadvantages in producing B/Al-B alloy,such as high preparation cost,low actual output,non-conforming product purity,etc.,which limit greatly the application of B and Al-B alloys.This paper put forward a novel process for preparing B/Al-B alloy,in which sodium fluoroborate was used as the raw material,aluminum powder as the reducing agent,and B/Al-B alloys were prepared through vacuum aluminothermic reduction.The reduction process was investigated and the results are as follows:Thermodynamic calculation of the possible reactions involved during the vacuum aluminothermic reduction for preparation single-mass B/Al-B alloy process was carried out,and the theoretical reduction sequence was determined.The saturated vapor pressure calculation of the raw materials and products participating in the reaction is calculated to determine that the reduction product.The obtained product can be separated by vacuum distillation.and Al-B alloy from NaBF4.Experiments indicated that the reduction temperature,insulation time and Al powder excess coefficient had a significant effect on the reduction degree of NaBF4 and the quality of the products.During preparation of B simple substance,the B powder containing 91.21%B can be obtained when the reduction temperature is 1100℃,the insulation time is 60 min and the reduction agent overdose coefficient is-6%,the particle size of which is evenly distributed and about 8.1μm.Here the yield rate of B simple substance is about 85.40%.During the preparation of Al-B alloy,an alloy containing about 92.6%AlB2 can be obtained when the reduction temperature is 900℃,insulation time is 60min and the reduction agent excess coefficient is-6%;and the alloy containing about 98.5%was obtained when the reduction temperature is 1100℃,the insulation time is 75 min,and the reduction agent overdose coefficient is-10%.Boron-containing ice crystals,which contain about 2.51%B,were obtained as the preparation of B/Al-B alloys.The B can be removed by secondary aluminothermic reduction.Meanwhile Al-B alloy and boron-free ice crystal can be obtained.The experimental results show that the B content in the ice crystal obtained after secondary aluminothermic reduction is below 0.030%,which meets the requirements of industrial ice crystal when the ratio of aluminum and boron-containing ice crystal is greater than 1:1 and the insulation time is greater than 30min.In present study,single-mass B and Al-B alloy(AlB2 and AlB12)were prepared using sodium fluoroborate as the raw material and Al powder as a reducing agent.After two-stage aluminothermic reduction,qualified ice crystal was obtained.The present process not only shortens the production flow of B/Al-B alloys,but also recycles qualified ice crystal.更多还原