【作者】 魏琛娟；

【导师】 邹忠； 田忠良；

【作者基本信息】 中南大学 ， 材料冶金， 2011， 硕士

【摘要】 惰性阳极是成功开发铝电解新工艺的前提与关键,低温电解是解决惰性阳极耐腐蚀问题的重要途径。本论文在国家973计划课题(2005CB623703)及863计划课题(2008AA030503)的资助下,在前期研究的基础之上,以Na3AlF6-K3AlF6-AlF3熔体为研究对象,研究了KR为15-30%,A1F3为20-30wt.%的Na3AlF6-K3AlF6-AlF3熔体的初晶温度和A1203溶解度,并确定一种能够为惰性阳极提供适宜服役环境的“低温、高A1203溶解度”的电解质体系,同时,研究了电流密度、氧化铝浓度和电解温度对金属陶瓷在所确定的Na3AlF6-K3AlF6-AlF3电解质体系中电解腐蚀速率的影响,确定了适宜的电解工艺参数。主要研究结果如下：(1)深入研究KR值、A1F3含量对Na3AlF6-K3AlF6-AlF3熔体初晶温度的影响,并采用高温XRD分析手段研究了物相组成和含量随电解质组成的变化情况。得到了新型电解质Na3AlF6-K3AlF6-AlF3三元体系初晶温度的经验公式和三元凝固等温线图,其适用范围为20wt.%<[AlF3]<30wt.%,15％<KR<30%。.T=3478-1867×[KR]0.12-12.97×[AlF3]1.14+3.538×[AlF3]×[KR]0.98-0.505×[AlF3]1.24×[KR]1.23本经验公式中的相关系数为0.992。(2)在前期初晶温度的研究基础之上,研究初晶温度在850℃左右的电解质组成中熔体温度、KR值、A1F3含量对A1203溶解度的影响。并且,结合初晶温度的研究结果,确定了一种具有“低温、高A1203溶解度”特征的电解质组成：KR=185%,AlF3=26wt.%,该电解质组成的初晶温度为866℃,在熔体温度为870℃时的A1203溶解度为5.21wt.%。(3)考察了电流密度(1.00、1.30、1.60、2.00、3.00、4.00A/cm2)、氧化铝浓度(2.00%、3.00%、4.00%、5.21%)、电解温度(870、880、890℃)对22(20Ni+Cu)/(NiFe2O4-1 ONiO)金属陶瓷惰性阳极在KR为18%,A1F3为26wt.%的电解质体系中电解腐蚀的影响。研究发现：阳极腐蚀速率随着电流密度的增加,先降低后升高；随着氧化铝浓度的增大,阳极电解腐蚀程度降低；阳极电解腐率随着电解温度的升高而升高。金属陶瓷惰性阳极具有较小电解腐蚀率的电解工艺参数为：电流密度为1.60 A/cm2,氧化铝浓度处于饱和状态,电解温度为870℃时,此条件下阳极电解腐蚀速率几乎为O。更多还原

【Abstract】 The inert anode is the key in developing of the new technology for aluminum reduction. And, low-temperature aluminum electrolysis is the important ways to solve the corrosion problem of inert anode. This thesis is founded by the National High Technology Research and Development Program (863 program) and the National Basic Research Program of China (973 program). Based on Na3AlF6-K3AlF6-AlF3 system, the liquidus temperature and alumina solubility of Na3AlF6-K3AlF6-AlF3 system are studied in detail, and the research range is 20wt.%< A1F3< 30 wt.%,15%< KR<30%. Furthermore, the effects of current density, alumina content and bath temperature on corrosion rate of inert anode are researched in the Na3AlF6-K3AlF6-AlF3 system, and then technological condition can be determined, which can offer a good working environment for cermet inert anode. The main results of the thesis can be summarized as follows:(1) The influence of KR content and A1F3 content on the liquidus temperature of Na3AlF6-K3AlF6-AlF3 low temperature electrolyte is investigated. Moreover, the relation of the liquidus temperature and phase compositions is indicated. An empirical formula showing the relationship between liquidus temperature of melts and melts composition is built. The ternary isotherm diagram on liquidus temperature of Na3AlF6-K3AlF6-AlF3 melts is obtained, too. The composition limitations are 20wt.%< AlF3< 30 wt.%, and 15%< KR<30%. The empirical formula is as follows, and the correlation coefficient of empirical formula is 0.992.T= 3478-1867×[KR]0.12-12.97×[AlF3]1.14+3.538×[AlF]×[KR0.98-0.505×[AlF3]1.24×[KR]1.23 (2) The influence of bath temperature, KR content and AlF3 content on alumina solubility in Na3AlF6-K3AlF6-AlF3 system is revealed. Based on the result of liquidus temperature and alumina solubility in the Na3AlF6-K3AlF6-AlF3 system, the aluminum electrolyte with the nature of low-temperature and high-alumina solubility is obtained, which is the system KR18%, AlF36%. And the liquidus temperature of this system is 866℃. When bath temperature is 870℃, Al2O3 solubility of this system can reach 5.21%.(3) The influence of current density(1.00,1.30,1.60,2.00,3.00, 4.00A/cm2), alumina consentration(2%,3%,4%,5.21%) and bath temperature (870,880,890℃) on corrosion rate of 22(20Ni+Cu) /(NiFe2O4-10NiO) cermet inert anode are invesitigated in the system KR18%, AlF326%. When current density is 1.60A/cm2, alumina concentration reaches 5.21%, and bath temperature is 870℃, anode anti-corrosion capacity is preferably well, whose corrosion rate can meet 0 nearly.更多还原