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電化學(xué)反應(yīng)簡(jiǎn)介中英對(duì)照版

1488 人參與 2011年11月22日 00:37 分類 : 電泳工藝電泳原理評(píng)論

Electrochemical Reactions????????? 電化學(xué)反應(yīng)

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. 到此為止，我們已經(jīng)討論了陽(yáng)極漆和陰極漆，并且已使用了陽(yáng)離子，陰離子等術(shù)語(yǔ)，雖然陽(yáng)極和陰離子可以作為同義詞使用，其實(shí)他們是用于表示一個(gè)事物的兩個(gè)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. 帶正電荷的電極稱為陽(yáng)極，帶負(fù)電荷的電極成為陰極，水溶液中含有的帶電粒子稱為離子，離子是帶電荷的原子和分子，陰離子帶負(fù)電荷，陽(yáng)離子帶正電荷，如果大家都明白異性相吸的道理，問題就簡(jiǎn)單了，陰極帶負(fù)電：所以它排斥負(fù)電荷而吸引正電荷。 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. 溶液中帶正電荷的離子稱為陽(yáng)離子，帶負(fù)電荷的離子稱為陰離子。這樣，根據(jù)異性相吸的原理，陽(yáng)離子（帶正電荷）與陰極（帶負(fù)電荷）相互吸引，由于陰極位置相對(duì)固定，故此陽(yáng)離子便移向陰極，這種運(yùn)動(dòng)稱為遷移。 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. 帶負(fù)電荷的離子把帶正電的樹脂分子存在于陰極系統(tǒng)的溶液中。樹脂的溶解性取決于陰，陽(yáng)離子的電平衡。 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. 電泳漆沉積在陰極上時(shí)，此工藝稱為陰極電泳，帶正電荷的漆稱為陽(yáng)離子型電泳漆。故此“陰極的”極“陽(yáng)離子的”兩個(gè)術(shù)語(yǔ)即分別表示漆的沉積對(duì)象及沉積漆的帶電類型。這兩個(gè)術(shù)語(yǔ)?？苫Q使用。 The electrocoating process is known by several names: 電泳涂裝工藝在英語(yǔ)中有以下幾個(gè)名詞： 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. 跟電鍍工藝相似，比如汽車保險(xiǎn)杠度鉻，電泳，電鍍這兩種工藝都是通過利用電流產(chǎn)生沉積。不同之處在于，電鍍時(shí)沉積金屬離子，電泳時(shí)沉積有機(jī)樹脂分子。 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. 陰極電泳涂裝是一種將被涂件浸入水稀釋的涂料中，進(jìn)行類似電鍍上漆的涂漆工藝，通過在涂料中通直流電，在陰極電泳涂裝體系中，被涂件作為陰極（帶負(fù)電）。油漆固體份帶正電荷，因此被吸引到陰極。 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. 漆膜的電沉積過程同時(shí)包含有電泳，電解，電沉積，電滲等過程。對(duì)于電泳槽的操作人員來說，他們不一定要懂得這些原理，我們?cè)诖酥皇前言陔娪静壑兴l(fā)生的化學(xué)反應(yīng)以及工藝原理進(jìn)行解釋。 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. 電解是靠通電使導(dǎo)電液體分解。水電解生成氫氣和氧氣是大家最熟悉的電解例子。電解通常同時(shí)在一個(gè)或兩個(gè)電極上析出氣體。在電泳涂裝過程中這種氣體的析出卻是不利的。它對(duì)后面將要討論的重要特性“泳透力”有影響。由于氣體析出與電流成正比，因此要避免在沉積過程中突然的電流波動(dòng)，并且要將槽液電導(dǎo)率限制在特定的范圍之內(nèi)。這種電導(dǎo)的限制只是對(duì)油漆電導(dǎo)率的控制，并不考慮由于磷化液的帶入或去離子水質(zhì)量差所導(dǎo)致的雜離子污染雜質(zhì)離子物所產(chǎn)生的電導(dǎo)率作用（諸如此類污染的作用將會(huì)在下文討論） 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. 電泳是在一電勢(shì)電壓作用下。導(dǎo)電介質(zhì)中膠體離子的移動(dòng)過程。例如，發(fā)生在電泳涂裝過程中電泳的是顏料粒子及膠體樹脂粒子的運(yùn)動(dòng)(移動(dòng))，在這電勢(shì)的作用下，這些粒子靠電泳過程移向陰極。 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. 電沉積就是油漆粒子沉積在一個(gè)電極上。帶正電的粒子將聚積在陰極上，帶負(fù)電的粒子會(huì)在陽(yáng)極上聚集。由于這些帶負(fù)電的粒子（稱離子）使帶正電的樹脂保持在溶液中，它們有時(shí)被叫做平衡離子。 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. 涂料的漆基一般為陽(yáng)離子型，沉積只發(fā)生在陰極上，它是一個(gè)不可逆過程。在陽(yáng)極上不形成涂膜。 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. 電沉積的第一步是水的電化學(xué)分解（電解）。如果漆液PH值呈中性，在陰極上最初的反應(yīng)是產(chǎn)生氫氣和氫氧根離子（OH-）,這個(gè)反應(yīng)導(dǎo)致在陰極面上形成一高堿性邊界層。當(dāng)陽(yáng)離子樹脂（樹脂及顏料）與氫氧根離子反應(yīng)，變?yōu)椴蝗苡谒畷r(shí)，這就產(chǎn)生了沉積后的涂膜。但如果堿性邊界層達(dá)不到大約12的臨界PH值，將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. 電滲是要討論的最后一個(gè)過程，當(dāng)涂料固體份在陰極上沉積之后，此涂膜為半滲透性。水份從陰極附近通過沉積過程排斥出來，引起涂膜脫水，這種涂膜已具有抗物理變形性。 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. 由于沉積涂膜的不溶于水性，允許用水清洗電泳板洗掉電泳帶出的漆液。當(dāng)被涂工件從電泳槽中出來時(shí)，在其表面上附著一層未沉積的槽液，為了獲得外觀良好的電泳漆膜，必須將帶出的槽液洗掉。 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. 總之，當(dāng)加電壓于裝有導(dǎo)電溶液槽中的兩個(gè)電極時(shí)，就產(chǎn)生溶液的電解和帶電粒子的電泳，在陰極上發(fā)生聚積或沉積。這個(gè)過程一直持續(xù)到整個(gè)陰極表面被連續(xù)，均勻的涂膜所覆蓋。 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?yàn)榇穗姌O沉積膜在既定的電壓下具有一較高的電阻，所以當(dāng)所有表面及邊緣被涂膜覆蓋時(shí)，電泳沉積過程會(huì)自己停止。涂膜的厚度直接與沉積涂層的電阻成正比關(guān)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. 泳透力是一個(gè)比較性的參數(shù)。其定義是電泳涂料能使被涂裝工件的凹深處或被隱密表面被涂上的程度。電泳漆膜電阻高，則泳透力就好。 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. 泳透力是電泳工藝最重要的參數(shù)之一，如果電泳涂裝不能將防腐涂膜涂覆在用其它涂漆法所不可能達(dá)到的工件表面上，電泳涂裝將永遠(yuǎn)仍是實(shí)驗(yàn)室研究的問題。由于泳透力如此重要，讓我們探討一下一些影響泳透力的重要因素。 Variable?????????????????????????? Relationship to Throwpower 變量????????????? 與泳透力的關(guān)系

Coating Time???????? Varies Directly

電泳時(shí)間??????????????????? 直接成正比

Bath Solids??????????? Varies Directly

漆液固體份???????????????? 直接成正比

Applied Voltage??? Varies Directly

電泳電壓??????????????????? 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. 如果想獲得較高的泳透力而增加電壓則必須小心，此膜厚度也會(huì)由于電壓的增加，導(dǎo)致漆膜擊穿。當(dāng)高電流密度引起電極上氣體析出失控時(shí)，便會(huì)發(fā)生擊穿。氣體的產(chǎn)生消耗電流引致泳透力下降，則不可能使隱蔽表面涂上漆。擊穿過程也使漆膜絕緣性能受到影響。

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