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The earliest known example of galvanizing of iron was found in September of 1999 by the Royal Armouries Museum on a 17th century Indian armour in their collection.
Galvanization is the process of applying a protective Zinc coating to steel or iron in order to prevent rusting. The process protects the iron or steel. We get the term from the name of Luigi Galvani, an Italian scientist.
The most common method of galvanization is hot-dip galvanization. The iron or steel is submerged in a bath of molten zinc. Other methods exist but are not as widely used as hot-dip galvanization.
Galvanization is the process of applying protective Zinc coating to steel. The origin has been described in the earlier posts but all the steps are not included. The process may vary from plant to plant but essncially consists of the following steps.
A hot alkaline solution removes dirt, oil, grease, shop oil, and soluble markings.
Dilute solutions of either hydrochloric or sulfuric acid removes surface rust and mill scale to provide a chemically clean metallic surface.
Steel is immersed in liquid flux (usually a zinc ammonium chloride solution) to remove oxides and to prevent oxidation prior to dipping into the bath of molten zinc. In the dry galvanizing process, the item is separately dipped in a liquid flux bath, removed, allowed to dry, and then galvanized. In the wet galvanizing process, the flux floats atop the molten zinc and the item passes through the flux immediately prior to galvanizing.
The article is immersed in a bath of molten zinc between 815-850 F (435-455 C). During galvanizing, the zinc metallurgically bonds to the steel, creating a series of highly abrasion-resistant zinc-iron alloy layers, commonly topped by a layer of impact-resistant pure zinc.
After the steel is withdrawn from the galvanizing bath, excess zinc is removed by draining, vibrating or—for small items—centrifuging. The galvanized item is then air-cooled or quenched in liquid.
Coating-thickness and surface-condition inspections complete the process.
The galvanizing process has existed for more than 250 years and has been a mainstay of North American industry since the 1890s. Galvanizing is used throughout various markets to provide steel with unmatched protection from the ravages of corrosion. A wide range of steel products from nails to highway guardrail to the Brooklyn Bridge’s suspension wires to NASA’s launch pad sound suppression system benefit from galvanizing’s superior corrosion protection properties.
Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. The term is derived from the name of Italian scientist Luigi Galvani.
Although galvanization can be done with electrochemical and electrodeposition processes, the most common method in current use is hot-dip galvanization, in which steel parts are submerged in a bath of molten zinc.
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