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硫酸铵对纯铜腐蚀过程影响机理的研究
李坤
第一作者单位中国科学院海洋研究所
学位类型博士
导师陈卓元
2018-05-10
学位授予单位中国科学院大学
学位授予地点中国科学院海洋研究所
学位名称理学博士
关键词 腐蚀 硫酸铵 氧化亚铜
摘要

硫酸铵广泛存在于工业大气、农村大气及雾霾中,其存在会加速铜的腐蚀。本文主要研究了硫酸铵存在条件下铜的腐蚀机理,具体研究内容如下:

1)针对目前实验中铜的最主要的腐蚀产物—氧化亚铜不能准确定量测定的问题,改进了传统的高锰酸钾滴定法,具体包括装置除氧、腐蚀产物溶解、铜试样清洗、亚铜离子的氧化和滴定五个步骤,其中除了滴定步骤可以在有氧环境中进行外,其他四个步骤通过通高纯氮气以保持无氧环境。这个方法可以对整个铜试样表面腐蚀产物中的氧化亚铜进行定量分析,不存在均匀性问题,准确度较高,误差范围在±3%以内。

2)铜在硫酸铵本体溶液中的腐蚀机理研究。在本体溶液中,铜的腐蚀产物为氧化亚铜和碱式硫酸铜,其中氧化亚铜为主要腐蚀产物。具有层状结构的氧化亚铜首先在铜表面生成,随后生成的蓝色晶体为碱式硫酸铜,弥散在氧化亚铜层表面上。机理研究结果表明:铜的腐蚀是电化学腐蚀和化学腐蚀协同作用的结果,其中铜失去电子变成Cu+离子的过程为电化学反应,而溶液中游离Cu2+与铜基体发生反应生成氧化亚铜的过程是化学反应。这个化学反应可以消耗铜基体,很大程度上促进Cu的腐蚀。研究表明,Cu(NH3)n2+是存在于硫酸铵溶液中的重要的中间体,它可以释放出游离的Cu2+,促进铜表面腐蚀产物的生成。研究还发现NH4+的存在不仅可以促进铜的腐蚀,还能一定程度上阻碍铜腐蚀产物的生成,这种双重作用是由于铜氨络合效应导致的。

3)硫酸铵盐粒导致的铜的大气腐蚀机理研究。本部分研究了硫酸铵粒度、沉积量以及相对湿度对铜的大气腐蚀的影响。结果表明:盐粒粒度越小、沉积量越大、相对湿度越大,铜的腐蚀越严重。另外,硫酸铵盐粒导致的铜的大气腐蚀催化机制有两个,一个为铜氨络合效应促进铜的电化学腐蚀,另一个为Cu+Cu2+相互转换,促进了铜的化学腐蚀。游离铜离子的量对铜的腐蚀速率有很大影响。

其他摘要

Ammonium sulfate, widely exists in industrial atmosphere, rural atmosphere and haze, and its existence will accelerate the corrosion of copper. In this dissertation, the corrosion mechanism of Cu was investigated with the presence of ammonium sulfate. The main works of this dissertation are presented as follows:

(1) The traditional potassium permanganate titration method was improved in response to that the amount of cuprous oxide, which is the most important corrosion product of copper, cannot be determined accurately before, viz. deaeration of electrolyte, dissolution of the corrosion products, specimen rinsing, oxidation of cuprous ions and titration, the high-purity nitrogen flow is bubbled throughout the whole process to maintain the oxygen-free environment except for the titration. This high accurate method with the error range of ±3% can quantitatively analyze the cuprous oxide in the corrosion product regardless of uniformity of corrosion.

(2) The corrosion behavior of copper in the bulky solution of ammonium sulfate. The corrosion product generated in bulky solution are main of cuprous oxide and basic copper sulfate, in which the cuprous oxide is the major phase. The layer-structrued cuprous oxide is generated on the cooper surface on the outset, The subsequently generated blue crystal is basic copper sulfate, which disperse unnifromly on cuprous oxide. It is found that the corrosion of copper was the synergistic effect of electrochemical and chemical corrosion, in which the process of copper losing one electron is an electrochemical reaction, and the free Cu2+ reacting with the copper matrix to form Cu2O is regarding as a chemical reaction. The chemical reaction would consume the copper matrix and promote the corrosion of copper to a great extent. In addition, the Cu(NH3)n2+ is a critical intermediate for free Cu2+ supplyment, by which the corrosion products generation on the copper surface is promoted. The dual effect of NH4+ is accelerating copper corrosion and hindering the formation of copper corrosion products, both of which are caused by the copper-ammonium complexation.

(3) Atmospheric corrosion mechanism of copper caused by ammonium sulfate particles. The effect of particle size, deposition amount of ammonium sulfate and relative humidity of exposure atmosphere on the corrosion of copper are studied. The decrease of particle size, the increase of deposition amount and relative humidity would all promote the corrosion of copper. In addition, there are two catalytic mechanisms for the atmospheric corrosion of copper caused by ammonium sulfate particles. One is the copper-ammonium complexation effect to promote the electrochemical corrosion of copper, and the other is the mutual conversion of Cu+ with Cu2+, which promotes the chemical corrosion of copper. The amount of free copper ions has a great influence on the corrosion rate of copper.

学科门类理学
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/154543
专题海洋腐蚀与防护研究发展中心
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李坤. 硫酸铵对纯铜腐蚀过程影响机理的研究[D]. 中国科学院海洋研究所. 中国科学院大学,2018.
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