Hot-dip galvanizing process characteristics

利用锌对钢铁进行防腐的工艺很多，如：电镀锌工艺，锌层厚度一般控制在5～15μm；吹镀热镀锌工艺（本书专指“吹镀”、下同）的镀锌层较厚，一般在35μm以下；吊镀工艺的镀锌层厚度则在65μm以上，有的产品要求镀锌层厚度甚至高达100μm以上，对于大型钢结构及箱型截面（本书统一为“腔体工件”、下同）钢结构来说，镀锌层厚度则更大一些。

There are many processes that use zinc to prevent corrosion of steel, such as: electro-galvanizing process, the thickness of the zinc layer is generally controlled at 5 ~ 15μm; the blown hot-dip galvanizing process (this book refers to "blow plating", the same below), the galvanized layer is more Thickness, generally less than 35μm; the thickness of the galvanized layer of the hanging plating process is more than 65μm, and some products require the thickness of the galvanized layer to be as high as 100μm or more. For large steel structures and box sections (this book is unified as "cavity workpieces" ", the same below) For steel structures, the thickness of the galvanized layer is larger.

热镀锌工艺的覆盖能力好，镀锌层致密，无有机物夹杂，其腐蚀防护或者说耐腐蚀性能远远高于电镀锌；但是，对于吊镀工艺来讲，镀锌层厚度值有一个较厚的下限值，也就是说，镀锌层太薄了反而不容易做到；对于吹镀工艺来讲，根据型材、管材等的技术指标要求，镀锌层厚度的控制则相对灵活得多。

The hot-dip galvanizing process has good coverage, the galvanized layer is dense, without organic inclusions, and its corrosion protection or corrosion resistance is much higher than that of electro-galvanized; however, for the hanging plating process, the thickness of the galvanized layer has a higher value. The lower limit of thickness, that is to say, the galvanized layer is too thin, but it is not easy to achieve; for the blow plating process, according to the technical index requirements of profiles, pipes, etc., the control of the thickness of the galvanized layer is relatively more flexible .

镀锌层对钢铁的保护作用是双重的，首先，抗渗透性能良好的镀锌层将被保护的钢铁与腐蚀性环境完全隔离，从而彻底消除了钢铁发生腐蚀的一个主要条件，即“电解质”。其次，由于锌的化学活泼性高于钢铁，因而更容易被腐蚀溶解（牺牲阳极原理），一旦镀锌层出现局部损坏，钢材表面外露，锌就成了阳极，先于钢铁发生腐蚀，从而达到了保护钢材的目的。

The protective effect of the galvanized layer on steel is twofold. First, the galvanized layer with good penetration resistance completely isolates the protected steel from the corrosive environment, thereby completely eliminating one of the main conditions for steel corrosion, that is, "electrolyte" . Secondly, because zinc is more chemically active than steel, it is more likely to be corroded and dissolved (the principle of sacrificial anode). Once the galvanized layer is locally damaged and the surface of the steel is exposed, zinc becomes an anode, which corrodes before steel, so as to achieve In order to protect the steel.

在镀锌层电化学保护性、致密性、耐久性、免维护性，镀锌层与钢铁基

体结合力，镀锌层经济性，以及热镀锌工艺对工件形状、尺寸的适应性，生产的高效性等全方面进行比较，热镀锌工艺具有其他金属腐蚀防护工艺无可比拟、得天独厚的优势。

In the electrochemical protection, compactness, durability, maintenance-free of the galvanized layer, the bonding force of the galvanized layer and the steel matrix, the economics of the galvanized layer, and the adaptability of the hot-dip galvanizing process to the shape and size of the workpiece, the production Compared with all aspects such as high efficiency, the hot-dip galvanizing process has the unparalleled and unique advantages of other metal corrosion protection processes.