Identification of electrogalvanized steel grating and hot-dip galvanized steel grating

In the past, the distinction between electrogalvanized steel grating and hot-dip galvanized steel grating mainly relied on sensory inspection of zinc spangles. Zinc spangles refer to the appearance of grains formed after the hot-dip galvanized steel grating is pulled out of the new pot and the zinc layer cools and solidifies. Therefore, the surface of hot-dip galvanized steel grating is usually rough, with typical zinc spangles, while the surface of electrogalvanized steel grating is smooth. However, with the improvement of new technologies, hot-dip galvanized steel grating no longer has the typical characteristics of ordinary zinc spangles. Sometimes the surface of hot-dip galvanized steel grating is brighter and more reflective than that of electrogalvanized steel grating. Sometimes, when a hot-dip galvanized steel grating and an electrogalvanized steel grating are placed together, it is difficult to distinguish which is the hot-dip galvanized steel grating and which is the electrogalvanized steel grating. Therefore, the two cannot be distinguished by appearance at present.

There is no identification method to distinguish these two galvanizing methods in China or even internationally, so it is necessary to study the method of distinguishing the two from the theoretical root. Find the difference between the two from the principle of galvanizing
, and distinguish them from the presence or absence of Zn-Fe alloy layer in essence. Once confirmed, it must be accurate. The principle of hot-dip galvanizing of steel grating products is to immerse the steel products after cleaning and activation in molten zinc liquid, and through the reaction and diffusion between iron and zinc, a zinc alloy coating with good adhesion is plated on the surface of the steel grating products. The formation process of the hot-dip galvanizing layer is essentially the process of forming an iron-zinc alloy between the iron matrix and the outermost pure zinc layer. Its strong adhesion also determines its excellent corrosion resistance. From the microscopic structure, it is observed as a two-layer structure.
The principle of electrogalvanizing of steel grating products is to use electrolysis to form a uniform, dense, and well-bonded metal or alloy deposition layer on the surface of the steel grating parts, and to form a coating on the surface of the steel grating, in order to achieve the process of protecting the steel grating from corrosion. Therefore, the electro-galvanized coating is a kind of coating that utilizes the directional movement of electric current from the positive electrode to the negative electrode. Zn2+ in the electrolyte nucleates, grows and deposits on the steel grating substrate under the action of potential to form a galvanized layer. In this process, there is no diffusion process between zinc and iron. From the microscopic observation, it is definitely a pure zinc layer.
In essence, hot-dip galvanizing has an iron-zinc alloy layer and a pure zinc layer, while electro-galvanizing has only a pure zinc layer. The presence or absence of an iron-zinc alloy layer in the coating is the main basis for identifying the coating method. Metallographic method and XRD method are mainly used to detect the coating to distinguish electro-galvanizing from hot-dip galvanizing.