摘 要

银有着良好的光泽度，具有极佳的观赏性并且相对其他贵金属价格较低，因此银首饰已经成为一类非常受欢迎的饰品。但是，银首饰在佩戴过程中会被人体汗液腐蚀变色，影响银首饰的观感，这对银首饰的推广有着很大影响。目前国内外对抗变色银合金的开发做了很多研究，但是对银合金腐蚀变色机理的研究还不够深入。本文以银合金腐蚀变色机理为研究起点，在探究银合金腐蚀变色机理后，初步确定了银合金所添加的元素（铜、锌、镍），对添加这些元素的银合金耐腐蚀抗变色性能作出进一步的研究。本文的目的是通过对铜、锌和镍元素含量的优化，制备出一种能在人工汗液和硫化钠溶液中具有良好耐腐蚀抗变色能力的银合金。

本文还对在人工汗液和硫化钠溶液中腐蚀后的银合金进行研究。采用了金相分析、扫描电镜、X射线衍射、分光光度计法等分析手段研究了银合金腐蚀后的表面形貌、产物组成以及变色程度。在实验研究的基础上，得出以下结论：

1.本文中制备的银合金耐腐蚀抗变色能力都优于传统925银和纯银，分析可知主要是由于加入镍元素，使得银合金在腐蚀过程中生成的Ni₄S₃能够有效降低银与腐蚀液继续反应，起到提高银合金耐腐蚀性的作用。

2.本文中，在用分光光度法测量银合金试样的变色程度后，确定了在人工汗液和硫化钠溶液中银合金抗变色最好和最差的试样。将结果与Design -Expert软件的预测值对比，表明实验结果可信度较高。继续用Design -Expert软件优化银合金成分，确定了在人工汗液和硫化钠溶液中最优的银合金成分，分别是：在人工汗液中抗变色性能最优成分为92.5%银、5.426%铜、1.874%锌和0.200%镍。在硫化钠溶液抗变色性能最优成分为92.5%银、4.123%铜、2.897%锌和0.481%镍。

关键词：银合金，腐蚀机理，耐腐蚀能力，抗变色性能

Abstract

Silver has a good gloss, is very ornamental and is relatively cheap compared to other precious metals, so silver jewelry has become a very popular accessory. However, silver jewelry will be corroded and discolored by human sweat during the wearing process, which affects the perception of silver jewelry, which has a great influence on the promotion of silver jewelry. At present, many studies have been done on the development of anti-chromic silver alloys at home and abroad, but the research on the mechanism of corrosion and discoloration of silver alloys is not deep enough. In this paper, the mechanism of corrosion and discoloration of silver alloy is taken as the research starting point. After exploring the mechanism of corrosion and discoloration of silver alloy, the elements added by silver alloy (copper, zinc and nickel) are preliminarily determined, and the corrosion resistance and discoloration resistance of silver alloy with these elements are made. Further research. The purpose of this paper is to prepare a silver alloy with good corrosion resistance and discoloration resistance in artificial sweat and sodium sulfide solution by optimizing the content of copper, zinc and nickel. The silver alloy after corrosion in artificial sweat and sodium sulfide solution was also studied. The surface morphology, product composition and discoloration degree of the silver alloy after corrosion were studied by means of metallographic analysis, scanning electron microscopy, X-ray diffraction and spectrophotometry. Based on the experimental research, the following conclusions are drawn: 1. The corrosion resistance and anti-tarnishing ability of the silver alloy prepared in this experiment are superior to those of traditional 925 silver and sterling silver. The analysis is mainly due to the addition of nickel element, so that the Ni4S3 formed by the silver alloy during the corrosion process can effectively reduce the silver and corrosion solution. The reaction serves to improve the corrosion resistance of the silver alloy. 2. In this experiment, after measuring the degree of discoloration of silver alloy samples by spectrophotometry, the best and worst samples of silver alloys in artificial sweat and sodium sulfide solution were determined. Comparing the results with the predicted values ​​of the Design-Expert software indicates that the experimental results are highly reliable. Continue to use the Design-Expert software to optimize the composition of the silver alloy, and determine the optimal silver alloy composition in artificial sweat and sodium sulfide solution, respectively: the optimal composition for anti-tarnishing in artificial sweat is 92.5% silver, 5.426% copper, 1.874% zinc and 0.200% nickel. The optimum composition for anti-tarnishing properties in sodium sulfide solution is 92.5% silver, 4.123% copper, 2.897% zinc, and 0.481% nickel.

Key Words：silver alloy, corrosion mechanism, corrosion resistance, anti-tarnish performance

目录

第1章 绪论 1

1.1引言 1

1.1.1首饰银背景 1

1.1.2银合金应用存在问题 1

1.2银腐蚀的基本原理 2

1.2.1银与硫化氢的反应 2

1.2.2银与氧的反应 3

1.2.3银与硫化物溶液反应 4

1.2.4环境因素对银变色的影响 4

1.3提高银合金耐腐蚀抗变色性的途径及国内外研究现状 6

（1）贵金属合金化 6

（2）稀土合金化 6

1.4本论文的研究目的、内容及意义 8

1.4.1论文的研究目的 8

1.4.2研究内容和意义 9

1.4.3对社会环境的影响 9

第二章 实验流程与测试方法 10

2.1实验方案确立 10

2.1.1合金成分的确定 10

2.1.2影响因素的选择 10

2.1.3实验方案的确立 11

2.2试样的制备 11

2.2.1银合金的制备 11

2.2.2腐蚀试样的制备 11

2.3腐蚀变色实验 11

2.3.1试样在人工汗液中的腐蚀变色实验 11

2.3.2试样在Na₂S溶液中的腐蚀变色实验 12

2.4分析测试手段 12

2.4.1金相显微分析 12

2.4.2扫描电镜（SEM）分析 12

2.4.3X射线衍射（XRD）分析 12

2.4.4分光光度法分析 13

第三章 实验结果及分析 14

3.1银合金在人工汗液浸泡的分析结果 14

3.1.1银合金在人工汗液浸泡后的金相分析 14

3.1.2银合金在人工汗液浸泡后的扫描电镜分析 17

3.1.3 银合金在人工汗液浸泡后的XRD分析 18

3.1.4 银合金在人工汗液浸泡后分光度测试结果 19

3.1.5 耐人工汗液腐蚀的银合金成分优化 20

3.2 银合金在Na₂S溶液浸泡的分析结果 21

3.2.1 银合金在Na₂S溶液浸泡后的金相分析 21

3.2.2 银合金在Na₂S溶液浸泡后的扫描电镜分析 24

3.2.3 银合金在Na₂S溶液浸泡后的XRD分析 24

3.2.4 银合金在Na₂S溶液浸泡后分光度测试结果 25

3.2.5 耐硫化钠腐蚀的银合金成分优化 27

第4章 结论与展望 28

4.1结论 28

4.2展望 28

参考文献 29

致谢 31

附录1论文所用原材料费用一览表 32

附录2论文测试及分析费用一览表 33