仲钨酸铵在微波场中的热分解特性研究

发布时间：2018-05-05 02:16

  本文选题：仲钨酸铵 + 三氧化钨　； 参考：《昆明理工大学》2015年硕士论文

【摘要】：传统煅烧制备三氧化钨的方法存在以下缺点：生产时间长,生产成本高,能耗大,产品质量难以保证的缺点。而微波煅烧制备三氧化钨的方法不仅缩短了生产时间,降低了生产成本和能耗,还得到合格率较好的产品。本文首先采用微波加热炉对仲钨酸铵进行加热,研究仲钨酸在微波场中的升温行为,分别探讨微波功率、物料量和加热时间对温度的影响,还通过微波谐振腔法测定仲钨酸铵的吸波特性。接着通过多因素正交试验确定最佳工艺条件。并且对仲钨酸铵传统制备三氧化钨的工艺进行了研究,考察了煅烧温度、热分解速度、炉管转速和炉内抽气速度对三氧化钨制备过程的影响；同时采用传统热重分析仪对仲钨酸铵进行测定,并分析了仲钨酸铵在常规条件下的热分解特性；随后在最佳工艺条件下,采用单模腔微波热重分析系统对仲钨酸铵进行微波热重分析,探讨仲钨酸铵在微波场中的热分解特性,并与仲钨酸铵常规热分解特性进行对比。最后对三氧化钨产物进行XRD和SEM表征。研究结果表明：仲钨酸铵在频率2.450GHz的微波场中具有良好的吸波特性,并且仲钨酸铵在微波场中的升温与微波功率成正比,与物料量成反比关系,物料温度随着微波加热时间的延长而逐渐升高；通过正交优化试验确定了最佳工艺条件：微波功率600W、煅烧时间12min和物料重量12g,仲钨酸铵的热分解率为90.08%。在传统制备三氧化钨的过程中,选择煅烧温度600℃、炉管转速14r/min、抽气速度3m3/min等条件,并采用合理的煅烧温度制度,可以制备出粒度细、均匀的三氧化钨；仲钨酸铵在常规条件下的热分解过程分为四个阶段：脱除结晶水、分解成无定形氨钨青铜(AATB)、转变为氨钨青铜(ATB)和分解为三氧化钨；仲钨酸铵在微波场中的热分解过程也分为四个阶段,通过与仲钨酸铵常规热分解特性的比较,可知仲钨酸铵在微波场中热分解反应更剧烈,热分解更加彻底、完全。由产物XRD可知热分解得到的产物纯度很高,杂质少,洁净度好,晶相的颗粒尺寸小,产物晶型为正交晶型；产物SEM表明结晶生长充分,颗粒均匀未出现团聚,颗粒细小,晶形呈块状分布并且发育完整。
[Abstract]:The traditional calcination method of tungsten trioxide has the following disadvantages: long production time, high production cost, high energy consumption and difficult to guarantee the product quality. The microwave calcination method not only shortens the production time, reduces the production cost and energy consumption, but also obtains the product with good qualified rate. In this paper, the heating behavior of paratungstic acid in microwave field was studied by heating ammonium paratungstate in microwave heating furnace, and the effects of microwave power, material quantity and heating time on the temperature were discussed, respectively. The absorbing characteristics of ammonium paratungstate were also measured by microwave resonator method. Then, the optimum process conditions were determined by orthogonal test of many factors. The effects of calcination temperature, thermal decomposition rate, furnace tube speed and gas extraction rate on the preparation process of tungsten trioxide were investigated. At the same time, the traditional thermogravimetric analyzer was used to determine ammonium paratungstate, and the thermal decomposition characteristics of ammonium paratungstate under conventional conditions were analyzed. The microwave thermogravimetric analysis of ammonium paratungstate was carried out in a single-mode cavity microwave thermogravimetric analysis system. The thermal decomposition characteristics of ammonium paratungstate in microwave field were discussed and compared with the conventional thermal decomposition characteristics of ammonium paratungstate. Finally, the products of tungsten trioxide were characterized by XRD and SEM. The results show that ammonium paratungstate has good absorbing characteristics in microwave field of frequency 2.450GHz, and the heating of ammonium paratungstate in microwave field is proportional to microwave power and inversely proportional to the quantity of material. The material temperature increased gradually with the increase of microwave heating time, and the optimum technological conditions were determined by orthogonal optimization test: microwave power 600W, calcination time 12min and weight of material 12g. The thermal decomposition rate of ammonium paratungstate was 90.08. In the traditional preparation of tungsten trioxide, the fine and uniform tungsten trioxide can be prepared by selecting the calcination temperature of 600 鈩，

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