钽电解电容器用β二氧化锰阴极材料的制备研究

【作者】 刘海涵；

【导师】 郭学益；

【作者基本信息】 中南大学 ， 有色金属冶金， 2007， 硕士

【摘要】 钽电解电容器是一种可靠性高、漏电流小、性能稳定的电子产品，广泛应用于通讯、计算机、雷达、导弹、航空航天等领域，其阴极材料为β-MnO₂。本研究通过采用化学沉淀——晶型转变法制备出了在化学纯度、粒度形貌和晶型结构均符合要求的β-MnO₂。研究的基本思路是通过化学沉淀制备粒度及形貌可控的碳酸锰，对碳酸锰进行热分解、酸洗及晶型转变后得到二氧化锰含量在99％以上的β-MnO₂。研究工作主要包括超细均分散碳酸锰制备，碳酸锰热分解生成二氧化锰过程研究以及二氧化锰晶型转变研究三个部分。在超细均分散碳酸锰化学沉淀中，通过控制加料方式、时间及温度，得到了粒度在2～3.51μm、形貌为球型的均分散碳酸锰粉末，确定了制备碳酸锰粉末的最佳工艺条件。根据碳酸锰热分解热力学分析、氧化锰分解压力lgp_o2和1／T的关系图、碳酸锰的差热分析和二氧化锰等压分解曲线，确定了碳酸锰的热分解温度范围，并且在富氧条件下二氧化锰的生成率会大大提高。实验表明，在50％富氧条件，400℃下热分解2小时，二氧化锰生成率达到82％以上。二氧化锰的晶型转变是本实验最关键的一个步骤。本研究结合二氧化锰的热重差热分析与X射线衍射分析，确定二氧化锰进行晶型转变的温度在300～450℃之间。通过对不同温度及时间条件下二氧化锰的热处理，确定了其晶型转变的最佳工艺条件为450℃下，热处理5～10小时。更多还原

【Abstract】 Tantalum capacitor is a kind of electronic product which has beenwidely applied in communication, compute, radar, missile and aviationwith high reliability, low leaky current and stable performance. Thecathode material of Tantalum capacitor isβ-MnO₂. In this research, thechemical precipitation-crystal phase transformation method was utilizedto prepareβ-MnO₂ satisfied the demand on chemical purity, particle size,morphology and crystal configuration. The basic conception of theresearch is using chemical precipitation to prepare MnCO₃ with theparticle size and morphology in control, which will be transformed intoβ-MnO₂ with the purity above 99％through heat decomposition,acid-washing and crystal phase transformation. The research consists ofthree key processes: the preparation of ultra-fine dispersed MnCO₃, theheat decomposition in which MnCO₃ was transformed into MnO₂, andthe crystal phase transformation of MnO₂.In chemical precipitation of ultra-fine dispersed MnCO₃, thedispersed MnCO₃ particles with the size between 2～3.5μm and themorphology of sphere were prepared through the control of charging style,time and temperature. The optimum technological conditions ofpreparation were determined.The temperature range of heat decomposition for MnCO₃ wasdetermined according to the thermodynamic analysis, the diagram ofdecomposition pressure lgpo₂ and 1/T for MnO₂, the DSC-TGA analysisand the isotonic decomposition curve of MnO₂, which reveals that theproduction of MnO₂ will greatly increase in the presence of oxygen withhigh concentration. The results shows that the production of MnO₂increases above 82％with the oxygen concentration as 50％and the heatdecomposition at 400℃for 2 hours.The crystal phase transformation of MnO₂ is the most significantprocess in this work. According to the DSC-TGA analysis and X-raydiffraction analysis of MnO₂, the temperature range of the crystal phasetransformation was determined as 300～450℃. On the basic of heat treating at different time and temperature, the optimum technologicalcondition of crystal phase transformation was determined as heat treatingfor 5～10 hours at 450℃.更多还原