【作者】 秦庆伟；

【导师】 刘业翔；

【作者基本信息】 中南大学 ， 有色金属冶金， 2004， 博士

【摘要】 惰性阳极技术是传统铝冶金工业的一次革命。它具有节能、降低投资与成本、增加产能、减少环境污染等一系列优越性,近几十年来已成为工业发达国家在铝冶金领域竞相研究开发的前沿技术。惰性阳极研究的核心在于材料的腐蚀及其控制,而腐蚀率的准确预测是实现腐蚀控制的关键。惰性阳极的腐蚀不仅与其本身的成分、结构有关,还取决于它的使用条件。本论文紧密围绕惰性阳极技术的核心,对电极材料的腐蚀进行了系统研究,取得了如下的结果: 首先,在广泛文献调研的基础上,制备出多种氧化物,分别考察其在冰晶石—氧化铝熔体中的溶解度,筛选出NiFe₂O₄用作电极基体,系统研究了该氧化物的溶解度与电解质组成、温度等参数之间的关系,明确了低温、低分子比、高氧化铝浓度对降低溶解度的重要作用。在此基础上,通过调整烧结速度,提出了制备NiFe₂O₄基金属陶瓷惰性阳极的较佳工艺。另外,还探索了NiFe₂O₄基金属陶瓷的加压烧结。金属陶瓷的其它基本性能,如抗热震性、导电性能等,对于惰性阳极的设计、安装及运行具有重要意义,也得到初步研究。 提出了NiFe₂O₄基金属陶瓷的瞬间液相连接技术。电极与金属导杆的连接是一项关键技术,关系到电极的欧姆压降和使用的耐久性。采用含金属Cu的中间层,成功进行了5%Ni—NiFe₂O₄/Fe的部分瞬间液相连接。 对5%Cu—NiFe₂O₄和5%Ni—NiFe₂O₄金属陶瓷惰性阳极的耐腐蚀性进行了初步电解评估,发现5%Ni—NiFe₂O₄比较容易实现致密化,表现出相对好的耐蚀性,确定为进一步研究的目标。在此基础上,对5%Ni—NiFe₂O₄电极的腐蚀率与电解参数的关系进行了系统深入的研究,对腐蚀破坏形貌提供了较为合理的解释,进一步明确了温度、分子比、氧化铝浓度等基本电解参数对降低腐蚀率的重要作用。 提出了基于灰关联分析的腐蚀因素分析方法。影响惰性阳极腐蚀率的因素多且相互耦合,难以统计出主次因素,不利于有效控制材料的腐蚀。根据灰关联度的计算,实现了电解参数与腐蚀率关系的量化、序化、显化。 铝电解惰性阳极的腐蚀过程十分复杂,采用机理分析法建模困难,采用传统数学模型（幂函数模型、灰预测模型、多元线性回归模型等）对铝电解惰性阳极的腐蚀率进行了预测探索,发现难以实现有效的数据处理。更多还原

【Abstract】 Inert anode would mean a technological revolution of the traditional Hall-Heroult process. If successfully developed and applied, inert anode technology could have significant energy, cost, productivity and environmental benefits for the aluminum industry. Over the last few decades, inert anode technology has been one of the research frontiers in the realm of aluminum smelting in developed country. The core of the inert anode technology is the corrosion and corrosion control of anode materials. However, the accurate prediction of corrosion rates holds the key to corrosion control. The corrosion rates of inert anodes are not only related to composition and microstructure of materials, but also related to operating parameters. Aimed at the core of inert anode technology, the primary thrusts of the thesis were to develop an inert anode and evaluate its corrosion behavior systematically. The main results are as follows:Firstly, several metal oxides （ceramic） were prepared based on extensive review and discussion of the open published literature. Proper ceramic composition—NiFe₂O₄ was screened from solubilities performance tests and measured systematically. The effects of low temperature, low cryolitic ratio （CR）, and high Al₂O₃ concentration in the performance of minimizing solubilities of NiFe₂O₄ ceramic were determined.Based on the solubilities performance, NiFe₂O₄ cermet materials with excellent microstructure were produced successfully by the powder metallurgy technique. The technically feasible manufacturing process used for the fabrication of inert anodes was brought forward by adjusting sintering speed. In addition, hot pressing of 5%Ni—NiFe₂O₄ cermet was also evaluated for densification of inert anodes. Some basic properties were also measured for the cermet anode materials, for example, thermal shock resistance and electrical conductivity. Such measurements are vitally important to the design, placement, and operation of inert anodes in Hall cells.The partial transient liquid phase （PTLP） bonding of NiFe₂O₄ cermet materials was proposed. The establishment of joining techniques is one of the most important subjects for inert anode technology. The technique isvery important to the voltage drop and durabilities. The partial transient liquid phase （PTLP） bonding of cermet materials were performed successfully at high temperature with Cu-containing interlayer.The corrosion and the behavior of 5%Cu—NiFe2O4 and 5%Ni — NiFe2O4 cermet in cryolite — alumina melts were investigated elementarily. The results showed that 5%Ni — NiFe2O4 cermet had relative low corrosion rates due to high relative densities. The corrosion behavior of 5%Ni—NiFe2O4 cermet anodes in cryolite—alumina melts were investigated systematically as a function of some operating parameters. The corrosion mechanisms of NiFe2O4 cermet anodes were proposed and the corrosion behaviors were explained successfully. The effects of temperature, cryolitic ratio, and A12O3 concentration on the corrosion rates were determined again.Grey realational analysis was proposed to evaluate the effect of operating parameters to corrosion rates of inert anodes. The reliable distinguishment of effect factors was a fundamental requirement for the effective control of corrosion. In inert anode system, the effect factors are coupling and cannot be varied independently. The classical statistical methods were not efficient enough to solve such complex problems and find out the main factors. The grey relational grade ranks the correlation extent of effect factors in the corrosion processes.The corrosion prediction of inert anodes based on mechanism analysises was very difficult because of the complexities of corrosion. The conventional mathematical models （power function model, gray theory model, multiple regression model, et al.） were established with experimental data. The results showed that the conventional mathematical modes had unfeasible corrosion data processing.The artificial neural network （ANN） model was established with experimental data considering the nonlinear relationship of operating parameters and corrosion rates. A corrosion prediction system was developed based on Visual C++ ADO Programming. Furthermore, genetic algorithm coding in real number was engaged to optimize the operating parameters and target parameters. The excellent transplantability and modularization make it convenient for corrosionprediction of other anode materials. The successful development of the system is an innovative creation in aluminum industry. It not only indicated the reliability of functional simulation, but also laid a firm foundation for optimal operation of innovative electrolysis cells. The successful prediction of corrosion rates greatly promoted the self-reliant innovation capability in the inert anode technology.更多还原