Surface requirements for hot-dip galvanizing
Preliminary preparation of the steel surface is the key to the formation of a good quality galvanized coating. The main condition for steel is cleanliness. This will give a good reaction of iron and liquid zinc in the zinc bath. To avoid uncovered areas on the coating, it is necessary to eliminate various impurities, rust to the process of galvanizing.
A direct impact on the production of thickened zinc coating has a rough steel surface, which appears as a result of incorrect cleaning processes. To avoid poor adhesion of zinc should be removed from the sand cast surfaces.
The oxide mixture can be removed using a sandblasting method.
Due to the different degree of surface rusting, the time spent on the cleaning process is different, as a result, there are types of surfaces with different thicknesses.
In the process of steel welding, welding slag is retained on the surface. It should be removed before the galvanizing process due to the impossibility of its removal during chemical cleaning.
The presence of welding slag in the zinc bath is fraught with defects in the coating, and this is a direct path to rust of the goods.