Electrochemical Reactions 电化学反应
To this point, we have discussed anodic and cathodic paint and have used the terms anionic and cationic as well. Although the terms "cathodic" and "cationic" may be used as synonyms, they refer to two different aspects of the subject.
到此为止， 我们已经讨论了阳极漆和阴极漆，并且已使用了阳离子，阴离子等术语，虽然阳极和阴离子可以作为同义词使用， 其实他们是用于表示一个事物的两个不同方面的。
Positively charged electrodes are called
anodes while negatively charged ones are called
cathodes. A water solution contains charged particles which are called "ions". Ions are atoms or molecules with charges. Anions have negative charges, and cations have positive charges. If one remembers that opposites attract, the problem simplifies. The cathode is negative: thus, it repels negative charges and attracts positive charges.
带正电荷的电极称为阳极，带负电荷的电极成为阴极，水溶液中含有的带电粒子称为离子，离子是带电荷的原子和分子，阴离子带负电荷，阳离子带正电荷，如果大家都明白异性相吸的道理，问题就简单了，阴极带负电：所以它排斥负电荷而吸引正电荷。
The positively-charged ions in the solution are called
cations, and the negatively-charged particles are called
anions. Thus, by the principle of opposites attracting, the cations (positive charges) are attracted to the cathode (which is negative in charge). Since the cathode is relatively fixed in position, the cations move toward it. This movement is called
migration.
溶液中带正电荷的离子称为阳离子， 带负电荷的离子称为阴离子。这样，根据异性相吸的原理，阳离子（带正电荷）与阴极（带负电荷）相互吸引，由于阴极位置相对固定，故此阳离子便移向阴极，这种运动称为迁移。
Negatively-charged ions keep the positively-charged resin molecules in a cathodic system in solution. The solubility of the resin depends on the critical balance of positively and negatively charged ions.
带负电荷的离子把带正电的树脂分子存在于阴极系统的溶液中。树脂的溶解性取决于阴，阳离子的电平衡。
When paint is deposited at the cathode, the process is called
cathodic, and paint with a positive charge is called
cationic paint. Thus, the terms cathodic and cationic refer, respectively, to where the paint is deposited and the type of charge of the deposited paint. The two terms are often used interchangeably.
电泳漆沉积在阴极上时，此工艺称为阴极电泳，带正电荷的漆称为阳离子型电泳漆。故此“阴极的”极“阳离子的”两个术语即分别表示漆的沉积对象及沉积漆的带电类型。这两个术语常可互换使用。
The electrocoating process is known by several names:
电泳涂装工艺在英语中有以下几个名词：
Elpo
E-Coat
Electropainting
Electrodeposition
Electrophoretic Painting
Electrocoating is similar in process to that of electroplating, such as the application of chrome on automobile bumpers. The two processes are alike in that both use the passage of electric current for deposition. They differ, however, because electroplating deposits
metallic ions whereas electrocoating deposits
organic resin molecules.
跟电镀工艺相似，比如汽车保险杠度铬，电泳，电镀这两种工艺都是通过利用电流产生沉积。不同之处在于，电镀时沉积金属离子，电泳时沉积有机树脂分子。
Cathodic electrocoating is a paint-plating type operation in which the object to be coated is dipped into a water-thinned paint. A direct current is then passed through the paint. In the cathodic system, the article to be coated is made the cathode ( is charged negatively). The paint solids are positively charged and are, therefore, attracted to the cathode.
阴极电泳涂装是一种将被涂件浸入水稀释的涂料中，进行类似电镀上漆的涂漆工艺，通过在涂料中通直流电， 在阴极电泳涂装体系中， 被涂件作为阴极（带负电）。 油漆固体份带正电荷， 因此被吸引到阴极。
Electrodeposition of paint films simultaneously involves
electrophoresis,
electrolysis,
electrodeposition, and
electroendosmosis. Although a thorough understanding of these principles is not necessary for one to understand the operation of an electrocoat tank, they are presented here to explain the processes taking place beneath the surface of the tank.
漆膜的电沉积过程同时包含有电泳，电解，电沉积，电渗等过程。对于电泳槽的操作人员来说， 他们不一定要懂得这些原理，我们在此只是把在电泳槽中所发生的化学反应以及工艺原理进行解释。
Electrolysis is the decomposition of a conductive liquid by the passage of an electric current. The electrolysis of water into hydrogen and oxygen is perhaps the best known example of this process. Electrolysis is usually accompanied by gas evolution at one or both electrodes. Gassing is undesirable in the electrocoating process, limiting the throwing power, an important property which will be discussed later. Since gassing is proportional to current flow, sudden current surges should be avoided during deposition, and bath conductivity should be held within specified limits. These limits are set to control the conductivity of the paint only and do not consider the conductivity effects of ionizable contaminants which result from phosphate drag-in or poor quality deionized water. (The effects of these and other contaminants will be discussed later.
电解是靠通电使导电液体分解。水电解生成氢气和氧气是大家最熟悉的电解例子。电解通常同时在一个或两个电极上析出气体。在电泳涂装过程中这种气体的析出却是不利的。它对后面将要讨论的重要特性“泳透力”有影响。由于气体析出与电流成正比，因此要避免在沉积过程中突然的电流波动，并且要将槽液电导率限制在特定的范围之内。这种电导的限制只是对油漆电导率的控制， 并不考虑由于磷化液的带入或去离子水质量差所导致的杂离子污染杂质离子物所产生的电导率作用（诸如此类污染的作用将会在下文讨论）
Electrophoresis is the migration of electrically charged colloidal particles in a conductive medium under the influence of an electrical potential (voltage). Examples of electrophoresis are the movements (migration) of pigment particles and colloidal resin particles which take place in the electrocoating process. Under the influence of an electrical potential, these particles will move towards the cathode by the process of electrophoresis.
电泳是在一电势电压作用下。导电介质中胶体离子的移动过程。例如，发生在电泳涂装过程中电泳的是颜料粒子及胶体树脂粒子的运动(移动)，在这电势的作用下，这些粒子靠电泳过程移向阴极。
Electrodeposition is the precipitation of paint particles at an electrode. Positively-charged particles will coagulate at the cathode, and negatively- charged particles will collect at the anode. Since these negatively-charged particles (called ions) help keep the positively-charged resin in solution, they are sometimes referred to as counterions.
电沉积就是油漆粒子沉积在一个电极上。带正电的粒子将聚积在阴极上，带负电的粒子会在阳极上聚集。由于这些带负电的粒子（称离子）使带正电的树脂保持在溶液中，它们有时被叫做平衡离子。
The paint vehicle is usually cationic, and deposition takes place only at the cathode. It is an irreversible process. No coating can take place at the anode.
涂料的漆基一般为阳离子型，沉积只发生在阴极上，它是一个不可逆过程。在阳极上不形成涂膜。
The first step in electrodeposition is the electrochemical decomposition of water (electrolysis). If the paint bath has a neutral pH, the primary reaction at the cathode is the formation of hydrogen gas and hydroxyl ions. This reaction causes a highly-alkaline boundary layer to form in the area of the cathode. Film deposition occurs when the cations (resin and pigment) react with the hydroxyl ions to become insoluble. This condition does not occur until the alkaline layer reaches a critical pH of about 12.
电沉积的第一步是水的电化学分解（电解）。如果漆液PH值呈中性， 在阴极上最初的反应是产生氢气和氢氧根离子（OH-）,这个反应导致在阴极面上形成一高碱性边界层。当阳离子树脂（树脂及颜料）与氢氧根离子反应，变为不溶于水时，这就产生了沉积后的涂膜。但如果碱性边界层达不到大约12的临界PH值，将得不到不溶于水的涂膜。
Electroendosmosis is the final process to be discussed. As paint solids are drawn to the cathode and precipitated, the film becomes semi-permeable. Water is driven from the vicinity of the cathode through the deposited film, causing the dehydration of the film. Such a film is relatively resistant to physical distortion.
电渗是要讨论的最后一个过程，当涂料固体份在阴极上沉积之后，此涂膜为半渗透性。水份从阴极附近通过沉积过程排斥出来，引起涂膜脱水，这种涂膜已具有抗物理变形性。
The water insolubility of the deposited coating permits rinsing with water to remove bath drag-out.
Drag-out consists of non-deposited paint which loosely adheres to the coated article as it is removed from the bath. To achieve good appearance for the deposited film, the drag-out must be rinsed away.
由于沉积涂膜的不溶于水性，允许用水清洗电泳板洗掉电泳带出的漆液。当被涂工件从电泳槽中出来时，在其表面上附着一层未沉积的槽液，为了获得外观良好的电泳漆膜，必须将带出的槽液洗掉。
In summary, the application of an electrical potential to two electrodes in a bath containing a conductive solution produces electrolysis of the solution and electrophoresis of the charged particles. Coagulation or deposition, occurs at the cathode. This process continues until a continuous and even film coats the entire surface of the cathode.
总之， 当加电压于装有导电溶液槽中的两个电极时，就产生溶液的电解和带电粒子的电泳， 在阴极上发生聚积或沉积。这个过程一直持续到整个阴极表面被连续，均匀的涂膜所覆盖。
Because the electrodeposited film has a relatively high electrical resistance at a given voltage, the process stops itself when the film is nearly equal on all surfaces and edges. The film thickness is directly proportional to the resistance of the deposited coating.
因为此电极沉积膜在既定的电压下具有一较高的电阻， 所以当所有表面及边缘被涂膜覆盖时，电泳沉积过程会自己停止。涂膜的厚度直接与沉积涂层的电阻成正比关系。
Throwpower is a comparative function and is defined as the degree to which paint will coat recessed or hidden areas. Electrocoated films having a high electrical resistance exhibit good throwing power.
泳透力是一个比较性的参数。其定义是电泳涂料能使被涂装工件的凹深处或被隐密表面被涂上的程度。 电泳漆膜电阻高，则泳透力就好。
Throwpower is one of the most critical aspects of the electrodeposition process. Without the ability to deposit corrosion-inhibiting films in areas which are impossible to reach by other painting methods, electrodeposition would remain a laboratory curiosity. Since Throwpower is so important, let us examine some of the critical variables involved.
泳透力是电泳工艺最重要的参数之一，如果电泳涂装不能将防腐涂膜涂覆在用其它涂漆法所不可能达到的工件表面上，电泳涂装将永远仍是实验室研究的问题。 由于泳透力如此重要， 让我们探讨一下一些影响泳透力的重要因素。
Variable Relationship to Throwpower
变量 与泳透力的关系
- Coating Time Varies Directly
电泳时间 直接成正比
- Bath Solids Varies Directly
漆液固体份 直接成正比
- Applied Voltage Varies Directly
电泳电压 直接成正比
Caution is necessary if voltage is increased to achieve higher Throwpower. Film build also increases as voltage increases and can result in rupture of the film.
Rupture occurs when a high current density produces uncontrolled gassing at the electrode. Throwpower drops off as current is consumed in the production of gas and is not available to permit the covering of recessed areas. During rupture, the insulating properties of the film are also affected.
如果想获得较高的泳透力而增加电压则必须小心，此膜厚度也会由于电压的增加，导致漆膜击穿。 当高电流密度引起电极上气体析出失控时，便会发生击穿。气体的产生消耗电流引致泳透力下降，则不可能使隐蔽表面涂上漆。击穿过程也使漆膜绝缘性能受到影响。
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电泳漆电泳涂装电化学反应
