Steel bolts are often galvanized to inhibit the formation of rust on their surface.
Galvanization is the process by which a coating of a non-corrosive metal is applied to an underlying piece of corrosive metal. The process is typically used to prevent corrosion and add strength to certain construction metals, like steel and iron, that will be exposed to weathering elements for prolonged periods. While there are several methods of galvanization employed in the metal working industry, the two most prevalent are hot dip galvanization and electrogalvanization.
Instructions
Hot Dip Galvanization
1. Prepare the hot dip. The hot dip for galvanizing steel is usually made from melted zinc. In order to maintain zinc in its liquefied form, it needs to be heated to 860 degrees Fahrenheit. A crucible or similar container able to withstand extremely high temperatures is needed to hold the melted zinc.
2. Clean the steel. Before galvanizing, remove dirt and other contaminates from the steel by soaking it in a light acid solution.
3. Remove the steel from the light acid solution and give it time to dry.
4. Submerge the steel in the hot dip bath and wait for it heat up to the same temperature as the molten zinc. A chemical reaction takes place that will permanently bond the zinc to the steel.
5. Remove the steel from the hot dip bath. It will now be coated in a layer of zinc that, once cured, will turn into zinc carbonate.
6. Soak the zinc carbonate coated steel in a chromate solution to finalize the hot dip galvanization procedure.
Electrogalvanization
7. Place a negative charge on the steel. This can done by electrically charging the steel or rubbing it with a negatively charged object.
8. Use electroplating to apply a coating of zinc to the steel. Workers accomplish this by immersing the steel in a zinc-salt solution and then running DC electricity through an anode in the solution. The anode is typically made of either zinc or lead. The electrical current puts a positive charge on the zinc ions and causes them to adhere to the steel.
9. Remove the steel from the zinc-salt solution. The electrogalvanization process should coat the steel with a thinner and more closely binding layer of zinc than would result from the hot dip galvanization procedure.
