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固相法制备Mo4.8Si3C0.6纳米粉体的反应机理研究
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Study on Formation Mechanism of Mo4.8Si3C0.6 Nanopowders Prepared by Solid-reaction Method
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    摘要:

    首先通过热力学计算探讨了合成Mo4.8Si3C0.6粉体的可能温度区间,进而以钼粉、硅粉和炭粉为主要原料,通过固相反应法来制备Mo4.8Si3C0.6粉体.采用XRD、SEM和BET等方法研究了温度对所得材料组成、比表面积、粒径和微观结构的影响.结果表明:在1 400 ~ 1 900 K温度范围内,Mo4.8Si3C0.6的标准生成吉布斯自由能较低,为-351.3~-338.1 kJ/mol;在 1 823 K,1.5 h时能够获得无杂质相的Mo4.8Si3C0.6粉体,粉体颗粒呈花状,直径约3.2 ~4.2 μm,组成花的六方片状晶粒厚度约为50~80 nm,粉体的比表面积为0.753 3 m2/g.固相法制备Mo4.8Si3C0.6粉体的反应机理为:反应温度为1 373 K时,主要产物为Mo2C;1 523 K时,主要产物为Mo5Si3,存在少量的Mo4.8Si3C0.6;当温度升高至1 673 K时,主要产物为MMo4.8Si3C0.6,仍存在部分Mo5Si3;1 823 K时,可获得无杂质相的Mo4.8Si3C0.6.

    Abstract:

    The thermodynamic calculation was used to evaluate the possible temperature range for preparing the Mo4.8Si3C0.6 powders by a solid reaction method using molybdenum,silicon and carbon powder as the main raw materials. Influence of temperature on composition,specific surface area,size and microstructure of the obtained materials was investigated by using the X-ray diffraction (XRD),scanning electron microscopy (SEM),BET,et al. The results show that the standard Gibbs free energy for the formation of Mo4.8Si3C0.6 is only -351.3 ~ -338.1 kJ/mol when the temperature range is between 1 400 ~1 900 K. Experimental results show that when the temperature keeps at 1 823 K for 1.5 h,the obtained Mo4.8Si3C0.6 powder possesses high purity,petal-liked shape with a diameter about 4.5 μm,specific surface area of 0.753 3 m2/g and particle size of about 1.23 μm. The reaction mechanism for the formation of Mo4.8Si3C0.6 powder is that,when the reaction temperature keeps at 1 373 K,the main product is Mo2C; when it reaches 1 523 K,the main product is Mo5Si3,and a small amount of Mo4.8Si3C0.6;when it rises to 1 673 K,the main product is Mo4.8Si3C0.6,and minor Mo5Si3;finally,when the temperature reaches 1 823 K,no impurities phase of Mo4.8Si3C0.6 is obtained.

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高朋召?覮,徐墨雨,谢文,吕华南,李青,彭苏华,肖汉宁.固相法制备Mo4.8Si3C0.6纳米粉体的反应机理研究[J].湖南大学学报:自然科学版,2018,45(12):85~89

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  • 在线发布日期: 2019-01-11
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