The formwork is usually passivated online immediately after hot-dip galvanizing. During the passivation process, an oxidation reaction occurs at the interface between the zinc liquid surface and the passivation liquid, forming a dense and solid passivation film on the zinc liquid surface. Increase the corrosion resistance of the zinc layer. However, for steel gratings that require primer to form two layers of anti-corrosion system protection, it is difficult to tightly combine a dense and smooth passive metal passivation film with the subsequent primer. This is also premature. Affects the foaming, peeling and protective effects of organic coatings during use.

To further improve the durability of steel gratings, a composite protection system can often be formed by applying an appropriate organic coating to the surface. Considering that the surface of the hot-dip galvanized layer of the steel grating is flat, smooth and passivated, the bonding strength between the hot-dip galvanized layer and the subsequent coating system is insufficient, causing blistering in the coating. Fall off fall off. Early failure is highly likely. Selecting an appropriate primer or pretreatment process can improve the bonding strength between the zinc layer and the primer and achieve a long-term protection effect of the composite protection system.

A key technology for the protective effect of the steel grating surface protective coating system is also pre-coating surface treatment. Sandblasting is one of the most commonly used and reliable surface treatment methods for steel grating coatings. However, due to the soft surface of hot-dip galvanizing, the sandblasting pressure and particle size cause the galvanized layer of steel gratings to fall off. Sandblasting on the surface of steel grating is an effective surface treatment method by controlling the sandblasting pressure and sand particle size.

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Post time:Sep-25-2020