HOT DIP GALVANIZING
This treatment ensures double protection to steel metallurgy and electrochemistry, preventing the formation of rust.
By immersion of the steel poles in a bath of molten zinc at about 450° during which determines a reaction steel/zinc which leads to a diffusion of zinc in iron with formation of Fe-Zn alloy, giving predominance of pure Zn on the surface.
The Fe-Zn alloy gives the hot dip galvanizing of particular qualities as, increased abrasion resistance and excellent corrosion resistance.
The galvanizing process ensures a protective barrier between the internal and external atmosphere and the steel along the surface of our products.
The phases of the galvanizing process are:
1. Preparation: the materials are hung by wire and / or chains / equipment to <<frames>> to allow the movement along the entire production process.
2. Degreasing: elimination of oil and fat from the surface of products by dipping in acidic degreasing solution, with added surfactants.
3. Pickling: removal of iron oxides and iron residuals of rolling, using immersion in solutions composed of hydrochloric acid (HC1) and water (H20).
4. Washing: elimination of waste acids, the previous processes, and through immersion rinsing in water.
5. Flushing: immersion of the articles in an aqueous solution of «double salt» composed of zinc chloride and ammonium chloride (ZnC12-2NH4C1).
6. Pre-heating: the articles are heated in the oven dryer at about 100-120° C so that dried the flushing salts and reduce the thermal shock at the time of immersion in hot dip galvanizing.
7. Galvanizing: immersion in a bath of molten zinc (Zn 98.5% min.) at a controlled temperature of
440-450 ° C.
8. Cooling: natural cooling in the air at room temperature.
9. Detachment and control: posting materials from the frames, quality control and finally packaging and finishing.