Zinc coating / Galvanisation

Zinc coating

What is galvanization?

Galvanisation is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanising, in which parts are submerged in a bath of molten zinc. Galvanising protects in three ways:

  • It forms a coating of zinc which, when intact, prevents corrosive substances from reaching the underlying steel or iron; it offers thus exceptional protection from rust.
  • The zinc serves as a sacrificial anode so that even if there are scrathches on the coating, the remaining zinc protects the underlying metal.
  • The zinc coating protects its base metal by corroding before iron; galvansisng is suitable only for ferrous metals. For better results, it is possible to apply chromates over zinc. This increases durability and contributes to the corrosion protection. Zinc coating bolts

Zinc coating for bolts

Zinc metal has a number of characteristics that make it suitable for use as a coating for protecting iron and steel products from corrosion. Its excellent corrosion resistance in most environments accounts for its successful use as a protective coating on a variety of products and in many exposure conditions. The excellent field performance of zinc coatings results from their ability to form dense, adherent corrosion product films and a rate of corrosion considerably below that of ferrous materials, some 10 to 100 times slower, depending upon the environment. While a fresh zinc surface is quite reactive when subject to the atmosphere, a thin film of corrosion products develops rapidly, greatly reducing the rate of further corrosion.

The various types of zinc plating can be identified by the color produced by the different formulations. Each color offers different levels of corrosion protection:

  • Yellow Zinc; This type of zinc coating is commonly used in the automotive industry and offers an average level of protection against corrosion.
  • Black Zinc; Black zinc coatings are available as a black oxide that can actually be olive-drab in color, or as a pure black coating. The former however, normally provides slightly better corrosion resistance.
  • Clear or Blue Zinc; This coating formulation tends to offer fewer amounts of corrosion protection, although it’s regarded as being more environmentally friendly.
  • Acid Zinc; Acid zinc plating differs from other types of zinc plating, as it does not introduce cyanide into the plating bath. A key advantage of acid zinc is that it can be effective for use on hard-to-plate substrates.

types of zinc coating

Zinc coating Sydney

Elite Plating Pty Ltd
113 Woodpark Rd Smithfield NSW 2164, Sydney

All Chrome Bits
11/ 15 Childs Road,
Chipping Norton NSW 2170, Sydney

Zinc coating Perth

Osborne Plating
36 Howe Street,
Osborne Park WA 6017, Perth

AAEP PTY LTD
Unit: 2 & 3
Address: 29 Gillam Drive KELMSCOTT Western Australia 6111, Perth

 

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