What is galvanizing and what are the advantages of galvanizing?

Galvanizing is the process of adding zinc coating to the surface of steel or iron. Because zinc acts as a sacrificial coating, it protects the steel or iron underneath, thus extending the life of metal parts.

But galvanizing is a complex process that can be done in a variety of ways. There are different forms of galvanizing, including hot dip galvanizing and hot diffusion galvanizing, and these variations each have advantages and disadvantages. Therefore, it is helpful to understand the different forms of galvanizing before incorporating it into a prototyping or manufacturing project.

Galvanized metal is more common than you might think. Structures such as building frames, metal benches, balconies, ladders and fire escapes can all be made of galvanized metal to ensure a longer service life and adequate protection from corrosion and damage. Other examples can be found in car parts and appliances.

In addition, galvanized steel and galvanized iron can be used in different manufacturing processes, from sheet metal machining to CNC machining, making it a major process in manufacturing.

This article reviews the basics of galvanizing and answers the questions of what galvanizing is, which metals can be galvanized, the uses of galvanizing, the types of galvanizing and how galvanizing can improve metal parts.

1. What is electroplating?

Galvanizing (or galvanizing) is the process of adding a layer of zinc to the outer surface of a metal (i.e. steel or iron). The idea is to add a protective coating to the underlying metal, reducing the likelihood of corrosion or rust.

Galvanizing process varies with specific technology. However, the most important part of the process is that it usually involves enclosing steel or iron in zinc, which may be in a liquid or dust-like state. When zinc is introduced, the iron in the surrounding metal reacts with the zinc to form a tightly bonded alloy coating.

The end-to-end galvanizing process can be divided into three stages:

Prepare the surface of steel or iron

Actual plating

Galvanized finish

Galvanizing is a relatively simple coating process that produces a fairly beautiful surface coating, usually about 80 m, about three times thicker than the coating produced by electroplating.

2. Galvanized materials

The main substrates that can be galvanized are steel and iron. However, other ferrous metals can also be galvanized.

The coating material in galvanizing is always zinc. However, a similar process to galvanizing is tin plating, which uses zinc instead of tin. Tin plating is suitable for simple applications such as food storage, but is not as reliable as galvanizing: If the coating is damaged, the tin will eat away at the iron underneath.

3, galvanized type

The two most popular forms of galvanizing are hot dip galvanizing and electric galvanizing. These two methods and others are discussed below. Knowing which type of galvanizing to choose may require expert help.

1) Hot dip galvanizing

In hot dip galvanizing, the metal is immersed in a hot zinc bath at approximately 450 °C. When it is removed, the coated surface reacts with oxygen to form zinc oxide, which then reacts with carbon dioxide to form zinc carbonate. Before galvanizing, the metal must be cleaned with a caustic solution and then pickled in an acidic solution; Zinc ammonium chloride can also be used to prevent premature oxidation of metals prior to galvanizing.

2) Galvanizing

Electrogalvanizing combines galvanizing with electroplating: Current is passed through a zinc bath with a zinc anode and a steel conductor. The process produces a thinner coating than hot-dip galvanizing and also produces a brighter surface finish suitable for cosmetic applications.

3) zincizing

There are several names for this form of galvanizing: thermal diffusion galvanizing, steam galvanizing, and dry galvanizing. It involves heating steel parts to 500°C in a closed rotating drum containing zinc powder. The evaporated zinc diffuses to the surface of the steel to form a strongly bonded coating. It is ideal for small parts and components that need to be coated on the inside.

4) Galvanizing

Galvanizing is a combination of hot drop galvanizing and annealing. The hot dip galvanizing process proceeds normally before coating the metal through an air knife to remove any excess zinc. The metal is then briefly heated in an annealing furnace at 500 -- 565 °C to diffuse the iron and zinc layers and form zinc-iron alloy layers.

4, the advantages of galvanized

The purpose of galvanizing is to form a protective coating of zinc on steel or iron parts. But why is this useful? What are the main advantages of galvanizing?

Deterring corrosive substances: The zinc coating on galvanized metal prevents corrosive substances from reaching the weaker underlying substrate metal. This can extend the service life of the substrate, especially in demanding applications.

Rust prevention: Galvanized significantly delayed rust.

Create a sacrificial anode: The zinc coating is consumed by corrosive substances, so it provides protection for the underlying metal until it is completely used up. Even if the scratch penetrates the coating, the zinc will run out before the iron.

Durability: The zinc coating formed by galvanizing is tough and long-lasting, often providing decades of protection for the underlying metal.

Affordable: Galvanizing is a fairly simple and affordable procedure that provides significant benefits with minimal outlays.

Forming a thick coating: Although not suitable for all applications, galvanizing produces a thicker coating than, for example, electroplating.

5, the application of galvanized

The ability to prevent steel corrosion has made galvanizing widely used in a variety of industries.

The most common application is galvanized steel for construction: hundreds of thousands of tons of galvanized construction steel are produced each year to make structures such as building frames, street furniture, fire escapes, ladders and balconies.

Galvanized steel is also common in the auto industry, where it can be made into rust-proof parts, including much of a car's "body in white" : its skeletal base. The bumpers, beams, frame and chassis can also be made of galvanized steel.

Rust protection is a desirable feature in the telecommunications industry, where phone lines and boxes are affected by these elements every day. Galvanizing helps to prolong the service life of such articles.

6, with galvanized metal manufacturing

Galvanized materials can be widely used as galvanized metal sheets, suitable for sheet metal manufacturing processes such as bending and stamping, or galvanized metal bars, pipes and rods suitable for CNC machining and other processes.

Galvanized materials tend to be easy to work with because the zinc coating is softer than the underlying steel.

Galvanized metal can also be welded, but zinc can give off dangerous fumes, so proper ventilation is essential. Paint is not particularly effective on galvanized steel or iron unless the material has been galvanized.