电偶腐蚀速度的测定 - 图文

实验三：电偶腐蚀速度的测定

一、 试验目的：

1.掌握电偶腐蚀测试原理；

2.掌握电极电位、耦合电流的测量方法； 3.掌握实验分析方法。

二、实验原理：

当两种金属或合金相接触在溶液中可以发现在该液中电，位较负的金属腐蚀速度加大，而电位较正的金属受到保护，这种现象就是电偶腐蚀。金属或合金制成电极，应用电偶腐蚀计测量，便可测定其各个电极开路电位，耦合电位，回路电流等值。 三、仪器药品

电偶腐蚀计，金属电极（Fe，紫铜，黄铜），饱和甘汞电极，烧杯，量筒，天平 砂纸，滤纸，酒精棉，pH试纸，NaCl， 四、实验内容及步骤

1． 将各电极用水砂纸打磨光亮，用酒精棉擦干待用； 2． 配制100毫升3％NaCl溶液，连接电偶腐蚀计线路；

3． 测定各电极在3％NaCl溶液中相对于石墨电极的自腐蚀电位，填入表格； 4． 测Fe－紫铜和黄铜－紫铜电偶电流随时间的变化

待电极自腐蚀电位稳定后接通电路，测定电偶电流随时间的变化情况，直到电流比较稳定时为止，测量耦合电极相对于参比电极的电位。电偶电流最初随时间变化较快，可适当缩小记录时间间隔，15秒或半分钟计一次数。 五、实验数据及结果处理

1． 所有测量数据记录于表格中

自腐蚀电位：Fe：-0.595V 黄铜：-0.208V 紫铜：-0.192V 耦合电位： Fe－紫铜：-0.552V 黄铜－紫铜：-0.218V Fe－紫铜电偶电流随时间变化

t/s12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879600602604606608610Ig(Fe-Cu)/mA154.9131.8121.4111.2100.493.788.38279.277.9757268.366.86462.961.659.558.156.855.354.352.65251.249.848.948.347.847.146.245.144.54443.242.942.241.441.140.540.339.138.638.3383837.937.23736.335.635.535.134.934.434.83433.533.433.433.332.532.532.332.131.832.23231.231.630.330.230.229.729.929.629.329.329.219.819.819.819.819.820.1t/s8081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159590592594596598Ig(Fe-Cu)/mA29.128.728.528.428.528.328.12827.928.127.927.928.127.227.627.827.427.327.127.526.426.426.526.426.426.226.226.426.325.826.126.125.625.625.625.425.625.425.325.225.225.525.22524.824.824.725.124.624.624.624.524.624.424.524.524.324.324.224.224.124.424.42423.723.623.823.623.623.623.523.623.523.523.523.523.423.523.423.419.920.219.819.919.8t/s160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239580582584586588Ig(Fe-Cu)/mA23.423.223.223.223.223.523.223.222.922.922.922.922.922.922.922.823.222.823.22322.72322.722.72322.722.622.622.722.622.622.622.622.622.622.622.622.622.622.722.722.622.622.622.922.722.922.62322.722.922.922.722.922.722.722.722.723232322.722.722.723232322.7232322.7232322.722.922.722.922.722.922.720.120.120.320.220.2 t/s240242244246248250252254256258260262264266268270272274276278280282284286288290292294296298300302304306308310312314316318320322324326328330332334336338340342344346348350352354356358360362364366368370372374376378380382384386388390392394396398570572574576578Ig(Fe-Cu)/mA22.922.922.722.622.622.622.622.622.622.622.622.622.622.622.622.622.622.722.722.822.82323.223.523.62423.824.324.524.624.925.225.225.626.125.926.326.526.626.927.127.627.327.427.427.427.427.827.427.527.527.627.627.527.627.627.627.627.527.527.327.327.227.52726.626.526.526.526.426.426.226.226.225.925.925.726.125.925.620.420.220.220.220.2t/s400402404406408410412414416418420422424426428430432434436438440442444446448450452454456458460462464466468470472474476478480482484486488490492494496498500502504506508510512514516518520522524526528530532534536538540542544546548550552554556558560562564566568Ig(Fe-Cu)/mA25.625.525.425.425.225.22524.824.825.124.624.624.524.624.524.324.224.524.423.823.823.623.623.523.523.523.523.423.223.42322.922.822.82322.622.622.622.522.522.522.422.322.222.222.422.222.222.222.221.921.821.821.821.822.121.921.821.621.521.621.721.521.421.521.321.321.221.221.221.521.420.620.620.620.620.620.620.520.520.520.420.520.420.4黄铜－紫铜电偶电流随时间变化

t/s12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485Ig(Cu-Cu)t/s3.53.43.33.13.12.92.82.72.72.92.52.62.52.52.52.52.52.52.42.52.52.52.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.32.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.38687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169604Ig(Cu-Cu)/t/s2.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240242244246248250252254256258260262264266606Ig(Cu-Cu)/t/s2.42.42.42.42.42.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52268270272274276278280282284286288290292294296298300302304306308310312314316318320322324326328330332334336338340342344346348350352354356358360362364366368370372374376378380382384386388390392394396398400402404406408410412414416418420422424426428430432434608Ig(Cu-Cu)/t/s2.52.52.52.52.52.62.62.62.62.62.62.62.62.62.62.62.62.62.62.62.62.62.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.52.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.32.22.22.22.22.22.22.22.22.22.22.22.22.22.22.22.12.12.12.12.12436438440442444446448450452454456458460462464466468470472474476478480482484486488490492494496498500502504506508510512514516518520522524526528530532534536538540542544546548550552554556558560562564566568570572574576578580582584586588590592594596598600602610Ig(Cu-Cu)/mA2.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.12.22.22.22.22.22.22.22.22.22.22.222222222222222222222． 将Fe－紫铜和黄铜－紫铜电偶电流随时间的变化绘制在同一张图中；

Ig(Fe-Cu) Ig(Cu-Cu)1601401201008060402000100200300400500600700Ig/mAt (s)

3． 结果及讨论

1. 测量个电极开路电位时，其电位一直浮动不定，这是由于金属表面的极化和由

于阴、阳极反应生成表面膜或腐蚀产物的影响。

2. 两金属电极电位差越大，其测量电流Ig越大，试验中Fe-紫铜电偶为-0.552V，

大于紫铜-黄铜电偶的耦合电位，所以其测量的Ig也大于后者。

3. 随着反应的进行，Ig均随时间而减小，反应初始时Ig下降迅速，之后，随着

极化的进行，由于电极外侧生成钝化膜等原因，电流都逐渐减小，之后趋于平稳，中间也有波动起伏的过程。

4. 电极是否打磨干净会影响试验中电流的稳定和大小，但整体Ig-t变化趋势不变。

参考文献

1、《实验电化学》王圣平 编 中国地质大学出版社 2、《腐蚀电化学原理》第一版 曹楚南 编

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