彩涂板基板被腐蚀的原因和常见现象

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（1） 在镀锌板的整个寿命周期中，首先腐蚀的是表面镀锌层的氧化，产生“白锈”。久而久之，表面的“白锈”与潮湿空气中的二氧化碳等杂质进一步反应，形成“黑点”。当镀锌板长期使用，镀锌层腐蚀严重时，钢基失去锌的“牺牲防腐”功能，开始氧化，形成“红锈”。一旦钢基开始氧化，腐蚀速度就会变得非常快，“镀锌板也就结束了它的寿命。
（2） 此外，镀锌板有两种特殊的腐蚀状态，称为“黑色转变”。一是由于锌层中铅等元素的影响，使用一段时间后，锌花的暗处会变黑。发黑的锌层对钢基体仍有保护作用，但对使用寿命有一定影响。在铅被停止使用，锑被用于促进锌花的形成之后，这种情况得到了很大的改善。另一种情况是，在镀锌板的运输过程中，由于卷取张力小，钢带层之间的松脱，钢圈与滑轨接触的部位会相互摩擦产生氧化。当白色氧化物被磨掉后，镀锌板表面会产生黑点，从而损坏钝化膜，减少镀锌层，大大降低镀锌板的使用寿命，同时也会影响外观。
（3） 镀锌板在干燥或无污染环境中的耐蚀性很好。但在污染环境下，使用寿命会大大缩短，因此有必要将预涂后的涂料加工成彩板。

(1) In the whole life cycle of galvanized sheet, the first corrosion is the oxidation of zinc coating on the surface, resulting in "white rust". After a long time, the "white rust" on the surface further reacts with carbon dioxide and other impurities in the humid air, forming "black spots". When the galvanized sheet has been used for a long time, and the galvanized layer is corroded seriously, the steel base loses the "sacrificial corrosion protection" function of zinc, and then it begins to oxidize, forming "red rust". Once the steel base begins to oxidize, the corrosion rate becomes very fast, "the galvanized sheet also ends its life.

(2) In addition, there are two special corrosion conditions of galvanized sheet called "black transformation". One is that due to the influence of lead and other elements in the zinc coating after a period of use, the dull part of the zinc flower will turn black. The blackened zinc coating still has a protective effect on the steel base, but has a certain impact on the service life. This situation has been greatly improved after the lead was stopped and antimony was used to promote the formation of zinc flower. Another situation is that in the transportation of galvanized sheet, due to the small coiling tension, the looseness between the steel strip layers, the parts where the steel coil contacts the skid will rub against each other and produce oxidation. After the white oxide is rubbed off, the galvanized sheet surface will produce black spots, which will damage the passivation film, reduce the galvanized layer, greatly reduce the life of the galvanized sheet, and the appearance will also be affected.
(3) The corrosion resistance of galvanized sheet in dry or pollution-free environment is very good. However, in the polluted environment, the service life will be greatly shortened, so it is necessary to use the pre coating after being processed into a color plate.