镀锌钢结构怎样进行表面处理和涂漆？
天物彩板集团专注彩涂卷行业17年——镀锌钢结构表面处理和涂漆_钢结构工程配套彩涂卷板_山西天物集团彩板请拨打网站上方电话咨询
一般来说，需要防腐涂层的钢材主要有热浸镀锌钢和热喷镀锌钢。锌是一种活性金属。镀锌层的目的是为钢材提供阴极保护和防锈功能，与富锌底漆相同。
与裸钢相比，涂有锌金属涂层的表面有以下区别：
1.无论是热浸镀锌钢还是热喷镀锌钢，其表面通常都是光滑的，因此不可能像裸钢一样喷射干净，以满足一定的粗糙度要求；
2.经过一段时间的暴露后，活性锌表面会产生锌盐；
3.活性锌易与某些油性涂料（如醇酸、酚醛等）中的脂肪酸或其他涂料中的某些活性成分皂化；
4.由于已提供锌金属涂层进行保护，涂层后的保护涂层系统可相应变薄。
市场上最常用的热浸镀锌钢和热喷镀锌钢表面底漆主要有以下两种：
1、乙烯磷化底漆，又称蚀刻底漆、洗涤底漆，是一种含磷酸的特种涂料。磷化底漆形成的膜（8-15微米）牢固附着在金属表面，起到磷化和钝化作用。
磷化底漆目前很少使用，因为它含有锌、铬黄和高铅含量。通常仅在耐久性要求不高时使用。涂有醇酸、酚醛、环氧酯等低级油漆。
2.环氧通用底漆。一些制造商也将其称为环氧多功能底漆。为有色金属光滑表面（含镀锌表面）专用底漆。加强了油漆的附着力，以确保其附着力。目前，这种底漆是市场上的主流。
Generally, the steels requiring anti-corrosion coating mainly include hot-dip galvanized steel and hot sprayed galvanized steel. Zinc is an active metal. The purpose of coating zinc coating is to provide cathodic protection and rust prevention function
for steel, which is the same as that of zinc rich primer.
The surface coated with zinc metal coating has the following differences compared with bare steel:
1. Whether hot-dip galvanized steel or hot sprayed galvanized steel, the surface is usually smooth, so it is impossible to spray clean like bare steel
to meet certain roughness requirements;
2. The active zinc surface will produce zinc salt after a period of exposure;
3. Active zinc is easy to saponify with fatty acids in some oily paints (such as alkyd, phenolic, etc.) or some active components
in other paints;
4. Since zinc metal coating has been provided for protection, the protective coating system after coating can be thinned accordingly.
In the market, the most commonly recommended primers for hot-dip galvanized steel and hot
sprayed galvanized steel surfaces mainly include the following two types:
1. Ethylene phosphating primer, also known as etching primer and washing primer, is a special paint containing phosphoric acid. The film (8-15 microns) formed by phosphating
primer is firmly attached to the metal surface and plays the role of phosphating and passivation.
Phosphating primer is rarely used at present because it contains zinc, chrome yellow and high lead content. It is usually only used when durability
requirements are not high. It is coated with alkyd, phenolic, epoxy ester and other low-grade paints.
2. Epoxy general purpose primer. Some manufacturers also call it epoxy multifunctional primer. It is a kind of primer specially designed for smooth
non-ferrous metal surface (including galvanized surface). The adhesion of the paint is strengthened to ensure its adhesion strength. At present, this kind of primer is the mainstream in the market.
