what is galvanisation ?write its use
Answers
Galvanization or galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten zinc.
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.
Hot-dip galvanizing deposits a thick, robust layer of zinc iron alloys on the surface of a steel item. In the case of automobile bodies, where additional decorative coatings of paint will be applied, a thinner form of galvanizing is applied by electrogalvanizing. The hot-dip process generally does not reduce strength on a measurable scale, with the exception of high-strength steels (>1100 MPa) where hydrogen embrittlement can become a problem. This deficiency is a consideration affecting the manufacture of wire rope and other highly-stressed products.
The protection provided by hot-dip galvanizing is insufficient for products that will be constantly exposed to corrosive materials such as acids, including acid rain in outdoor uses. For these applications, more expensive stainless steel is preferred. Some nails made today are galvanized. Nonetheless, electroplating is used on its own for many outdoor applications because it is cheaper than hot-dip zinc coating and looks good when new. Another reason not to use hot-dip zinc coating is that for bolts and nuts of size M10 (US 3/8") or smaller, the thick hot-dipped coating fills in too much of the threads, which reduces strength (because the dimension of the steel prior to coating must be reduced for the fasteners to fit together). This means that for cars, bicycles, and many other light mechanical products, the practical alternative to electroplating bolts and nuts is not hot-dip zinc coating, but making the fasteners from stainless steel or (stronger but much more expensive) titanium.
The size of crystallites (grains) in galvanized coatings is a visible and aesthetic feature, known as "spangle". By varying the number of particles added for heterogeneous nucleation and the rate of cooling in a hot-dip process, the spangle can be adjusted from an apparently uniform surface (crystallites too small to see with the naked eye) to grains several centimetres wide. Visible crystallites are rare in other engineering materials, even though they are usually present.
Thermal diffusion galvanizing, or Sherardizing, provides a zinc diffusion coating on iron- or copper-based materials. Parts and zinc powder are tumbled in a sealed rotating drum. Around 300 °C (572 °F), zinc will diffuse into the substrate to form a zinc alloy. The advance surface preparation of the goods can be carried out by shot blasting. The process is also known as "dry galvanizing", because no liquids are involved; this can avoid possible problems caused by hydrogen embrittlement. The dull-grey crystal structure of the zinc diffusion coating has a good adhesion to paint, powder coatings, or rubber. It is a preferred method for coating small, complex-shaped metals, and for smoothing rough surfaces on items formed with sintered metal.
Answer:
Galvanization aur galvanizing is a process of applying a protective layer of zinc coating to steel or iron to prevent rusting
most common method is hot dip galvanizing in which the parts are submerged in a bath of molten zinc...
USES ARE::
It is done to make our utensils Rust free. also used in rims of a bicycle...
Hope so it helps u!!❤❤❤