镀锌板电镀前的一些注意问题

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镀锌板制造商指出，在电镀之前，必须对零件表面进行除油（也称为脱脂）除油效果直接影响电镀质量工件表面的油主要是各种碳氢化合物，有些不与碱反应，不能皂化，所以称为不皂化油，除去这些油只能通过乳化或溶解来实现；其他油则与碱皂化，称为皂化油可通过皂化、乳化和溶解去除常用的除油方法有物理机械法、有机溶剂法、化学法、电化学法以及上述方法的组合。
电化学脱脂是在直流电作用下，以零件为阳极或阴极，不锈钢板、镍板、镀镍钢板或钛板为第二电极，在碱性溶液中去除零件表面油污的过程电化学除油液与碱性化学除油液相似，但彩铝板生产厂家指出，主要依靠电解强化除油效果一般来说，电化学除油比化学除油更有效、更快、更彻底。
除了化学油的皂化和乳化作用外，镀锌板制造商认为它还具有电化学作用在电解条件下，电极的极化降低了油与溶液的界面张力，溶液在零件表面的润湿性增加，油膜与金属的粘附性降低，油渍易剥离分散到溶液中乳化移除。在电化学脱脂过程中，阳极和阴极表面都有大量的气体沉淀当部分为阴极（阴极脱脂）时，在其表面进行还原反应，并将氢分离出来；当部分为阳极（阳极脱脂）时，在其表面进行氧化反应，并将氧分离出来。
在电解过程中，从金属与溶液的界面释放的氧或氢会在溶液中乳化由于小气泡容易吸附在油膜表面，随着气泡的增大和长大，这些气泡将油膜撕成小油滴带到液体表面同时，搅拌溶液，加速零件表面油污的去除。

The galvanized sheet manufacturer points out that before electroplating, oil removal, also known as degreasing, must be carried out on the surface of the parts. The effect of oil removal directly affects the electroplating quality. The oil on the surface of the workpiece is mainly various hydrocarbons, some of which do not react with alkali and cannot be saponified, so it is called unsaponifiable oil, and the removal of such oil can only be realized by emulsification or dissolution; while other oils have saponification with alkali, called saponification oil, which can be removed by saponification, emulsification and dissolution. The commonly used oil removal methods include physical mechanical method, organic solvent method, chemical method, electrochemical method and the combination of the above methods.

Electrochemical degreasing is a process of removing oil stains on the surface of parts in alkaline solution with parts as anode or cathode, stainless steel plate, nickel plate, nickel plated steel plate or titanium plate as the second electrode under the action of direct current. The electrochemical oil removal fluid is similar to the alkaline chemical oil removal fluid, but the color aluminum plate manufacturer points out that it mainly relies on the electrolysis to strengthen the oil removal effect. Generally, the electrochemical oil removal is more effective, faster and more thorough than the chemical oil removal.
In addition to the saponification and emulsification of chemical oil, galvanizing plate manufacturers believe that it also has electrochemical effect. Under the condition of electrolysis, the polarization of the electrode reduces the interfacial tension between the oil and the solution, the wettability of the solution on the part surface increases, the adhesion between the oil film and the metal decreases, and the oil stain is easy to peel off and disperse to the solution for emulsification and removal. In the electrochemical degreasing process, there are a lot of gas precipitates on the surface of both anode and cathode. When the part is cathode (cathodic degreasing), the reduction reaction is carried out on its surface, and hydrogen is separated out; when the part is anode (anodic degreasing), the oxidation reaction is carried out on its surface, and oxygen is separated out.
During electrolysis, oxygen or hydrogen released from the interface between metal and solution will emulsify in solution. Because the small bubbles are easy to adsorb on the surface of the oil film, with the increase and growth of bubbles, these bubbles tear the oil film into small oil drops and bring them to the liquid surface. At the same time, they stir the solution and accelerate the removal of oil stains on the surface of parts.