电镀是一种电化学过程，也是一种氧化还原过程。电镀的基本过程是将零件浸在金属盐的溶液中作为阴极，金属板作为阳极，接直流电源后，在零件上沉积出所需的镀层。

Electroplating is not only an electrochemical process, but also a redox process. The basic process of electroplating is to immerse the parts in the solution of metal salt as the cathode and the metal plate as the anode. After connecting with the DC power supply, the required coating is deposited on the parts.

例如：镀镍时，阴极为待镀零件，阳极为纯镍板，在阴阳极分别发生如下反应：

For example, during nickel plating, the cathode is the part to be plated and the anode is pure nickel plate. The following reactions occur at the cathode and anode respectively:

阴极(镀件)：Ni2++2e→Ni(主反应)

Cathode: Ni2 + + 2e → Ni (main reaction)

2H++e→H2↑(副反应)

2H + + e → H2 ↑ (side reaction)

阳极(镍板)：Ni﹣2e→Ni2+(主反应)

Anode (nickel plate): ni-2e → Ni2 + (main reaction)

4OH-﹣4e→2H2O+O2+4e(副反应)

4OH - - 4E → 2H2O + O2 + 4E (side reaction)

不是所有的金属离子都能从水溶液中沉积出来，如果阴极上氢离子还原为氢的副反应占主要地位，则金属离子难以在阴极上析出。根据实验，金属离子自水溶液中电沉积的可能性，可从元素周期表中得到一定的规律。

Not all metal ions can be deposited from aqueous solution. If the side reaction of hydrogen ion reduction to hydrogen on the cathode is dominant, it is difficult for metal ions to precipitate on the cathode. According to the experiment, the possibility of electrodeposition of metal ions from aqueous solution can be obtained from the periodic table of elements.

阳极分为可溶性阳极和不溶性阳极，大多数阳极为与镀层相对应的可溶性阳极，如：镀锌为锌阳极，镀银为银阳极，镀锡-铅合金使用锡-铅合金阳极。但是少数电镀由于阳极溶解困难，使用不溶性阳极，如酸性镀金使用的是多为铂或钛阳极。镀液主盐离子靠添加配制好的标准含金溶液来补充。镀铬阳极使用纯铅，铅-锡合金，铅-锑合金等不溶性阳极。

The anode is divided into soluble anode and insoluble anode, most of which are soluble anode corresponding to coating, such as zinc anode for zinc plating, silver anode for silver plating, and tin lead alloy anode for tin lead alloy plating. However, due to the difficulty in anodic dissolution, insoluble anodes are used in a few electroplating processes. For example, platinum or titanium anodes are mostly used in acid gold plating. The main salt ions in the plating bath are supplemented by adding standard gold containing solution. Chromium plating anode uses pure lead, lead tin alloy, lead antimony alloy and other insoluble anode.