functions of galvanisation
Answers
Explanation:
Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.
Galvanisation
How does galvanisation prevent rusting?
Galvanizing protects from rust in a number of ways:
It forms a barrier that prevents corrosive substances from reaching the underlying steel or iron.
The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc.
The zinc protects its base metal by corroding before iron.
The zinc surface reacts with the atmosphere to form a compact, adherent patina that is insoluble in rainwater.
Read more about rust prevention.
Potted history of galvanisation
GalvanisationIn 1780, an Italian, Luigi Galvani, discovered the electrical phenomenon of the twitching of a frog’s leg muscles when contacted by two dissimilar metals, namely copper and iron. Galvani incorrectly concluded that the source of the electricity was in the frog’s leg. The term galvanisation (or galvanization) began to appear in the lexicon, connected partly to the work carried out by Michael Faraday.
In 1824, Sir Humphrey Davy showed that when two dissimilar metals were connected electrically and immersed in water, the corrosion of one was accelerated while the other received a degree of protection.
In 1829 Henry Palmer of the London Dock Company was granted a patent for ‘indented or corrugated metallic sheets’, his discovery would have a dramatic impact on industrial design and galvanizing.
In 1836, Sorel in France took out the first of numerous patents for a process of coating steel by dipping it in molten zinc after first cleaning it. He provided the process with its name ‘galvanizing’. In addition to Sorel’s patent of 1836, A British patent for a similar process was granted in 1837 to William Crawford.
Although uncertain, the first use of galvanized corrugated iron is believed to be for the Navy at Pembroke Docks, Wales in 1844.
In mid-nineteen century Britain sheets of galvanized corrugated iron were seen to be exciting and glamorous. The concept of adding rigidity to iron sheets not only allowed for the construction of wide-span roofs without the need for cumbersome load bearing walls but they also looked new in a built environment dominated by stone and timber. The silvery reflective material was a sign of progress and success of industry.
Learn more
Hot dip galvanizing
Galvanizing process
The galvanised coating
History of galvanizing
Sacrificial protection
Galvanise steel
Galvanizing process
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Answer:
What is galvanization?
Steel and iron articles are corroded easily due to atmospheric reaction. To prevent corrosion few methods are adapted. Galvanisation is one among them.
Definition :
Galvanization is the process of applying a protective layer of zinc on a metal. It is a very common method of preventing the rusting of iron. This can be done by dipping the metal to be protected in hot, molten zinc or by the process of electroplating.
The protection of iron and steel from corrosion by coating with molten zinc. has been proved for a hundred and fifty years.
The zinc coating protects from the atmosphere the part’s surface, avoiding corrosion and weathering.
How does it help?
Galvanization helps extend the life of steel parts by forming a membrane between the metal and the air, preventing the accumulation of iron oxide on the steel layer. Galvanization also offers superior corrosion resistance to environmentally exposed parts.
Steps involved in the process
The galvanizing process consists of three basic steps, namely
Surface preparation
Fuxing
Galvanizing.
Material is loaded onto jigs before being immersed in molten zinc at about 450 degrees until the working temperature is the same as zinc. During this process, the molten zinc reacts to a series of zinc/iron alloys with the steel surface.
Disadvantages
The disadvantages of galvanization are listed below
It only provides protection from corrosion for a limited amount of time since the zinc layer is eaten up in the process.
It is not very effective in highly corrosive areas (where cadmium coating can be used instead).