Sherardizing or diffusion galvanizing is the application of a zinc layer on steel products. This zinc layer ensures that the product does not require chemical treatment. It significantly improves the durability of products that have been treated.
How does sherardizing work?
The products are heated together with zinc powder in closed rotating drums. The temperature rises to a temperature between 300 C and 500 ºC. Under these high temperatures, the zinc powder transforms into zinc vapour. This vapor reacts with the product and an even zinc layer is created.
How long has sherardizing been around?
Sherardizing is a reliable and time-honored application, which was already developed in the 1900s. Since that time, the technology has been further refined and improved. The name sherardizing refers to the developer of the technique: Sherard Cowpler-Coles.
A well-known application of sherardization are the iron coins issued in 1920. A number of these have still been preserved, without rust.
For which products is sherardization possible?
Sherardization can be applied to many steel products, systems and shapes. There is even so much that you could say that almost nothing is impossible.
Is pre-treatment necessary for sherardizing?
It is not necessary to pre-treat the products. Products that are metallic blank can be countersunk without prior application. Contamination does not have to be a problem either, it is removed beforehand by means of jet blasting, after which the sherardization process can start.
Is sherardizing a sustainable application?
Sherardising is a sustainable solution, because products last longer due to the diffusion galvanizing process. The service life is extended. In addition, it is an environmentally friendly solution. No chemical treatment is required and there is therefore no chemical waste. Because sherardizing is a so-called closed zinc process, no toxic zinc fumes are released.
How does sherardizing affect the appearance of my product?
Sherardized products have a matte gray appearance, which is often seen as an advantage.
What is surface treatment?
At SHERART we process the surface of a product or system in such a way that after treatment it will behave according to the predefined wishes and requirements of the customer. Think of protection against corrosion, but also of shape retention.
What are the advantages of surface treatment?
We can give the applied coating various properties or design our galvanizing process in various ways. This all affects the properties of the surface and the product.
Hot dip galvanizing
What is hot dip galvanizing?
Hot-dip galvanizing is a method of galvanizing that prevents corrosion and extends the life of a metal product or system. In this treatment method, a metal is immersed in a bath of molten zinc after thorough cleaning and fluxing. In this way, a durable zinc-iron alloy forms on the material, with a layer of zinc on top.
What are the disadvantages of hot dip galvanizing?
The disadvantage of hot-dip galvanizing compared to sherardization is that the risk of deformation and uneven layer thickness increases. Post-treatment is also necessary, especially for threaded fittings. Furthermore, zinc drops must be removed.
What is electroplating?
In addition to sherardizing and hot-dip galvanizing, it is also possible to galvanize steel or iron. In galvanizing, or electrolytic galvanizing, steel or iron is provided with a thin layer of zinc, nickel, aluminum, chromium or magnesium to prevent corrosion.
How does electroplating work?
Galvanization uses the galvano technique. This is also known as the electrolytic process. A thin zinc is applied to steel or iron by immersing the product in a cold chemical solution. An electric current charge bonds the different metals together.
The advantages of electroplating
Galvanizing has a number of advantages over hot-dip galvanizing:
Thin zinc layer so that post-processing of the material is not necessary
- More beautiful appearance: shiny and smooth
- Faster Adhesion
- Scratch resistant
Disadvantage of electroplating
A disadvantage of electroplating is that steel or iron is less resistant to seawater and is harmful to the environment.
What is powder coating?
Powder coating is a sustainable method of protecting and finishing surfaces. It is an electrostatic painting process in which negatively charged powder is applied to positively charged metal with a spray gun. In an oven, the powder particles become liquid and viscous. By curing it afterwards, a nice durable coating is created. The coating is scratch resistant and resistant to corrosion.
Powder coating applications
A major advantage of powder coating is that it can be applied to many products. Powder coating is mainly used in the furniture industry and construction construction. Think of products like:
- aluminum frames, windows and doors
- wood and MDF
- steel fences
- office furniture
- machine parts
- road and waterworks
What is a rubber-metal compound?
Sherardized products are excellent for rubber-metal bonding. This is because sherardized products have a microcrystalline rough surface. An adhesive primer can therefore be applied without pre-treatment. The result? A reliable rubber-metal compound that protects against corrosion and scratches.
Applications of Rubber-Metal Compounds
The use of rubber-metal compounds is mainly found in the automotive and transport industry and in the agricultural sector. Think of damper systems and vulcanized bars made of hardened steel in conveyor belts to prevent damage to agricultural products.
What is passivation?
Does galvanized steel have to be provided with a specific protective layer? Then passivation offers a solution. Passivation is a treatment in which the surface of metal is treated with a chemical solution, such as nitric acid, and then cleaned under high pressure. By passivation of metal, the original protective layer is restored.
A metal or stainless steel is passivated if the product…
- needs extra protection against corrosion
- should be more scratch resistant
- has to undergo a powder coating or lacquer treatment
- should conduct better
What is diffusion galvanizing?
In diffusion galvanizing, or sherardizing, steel or metal is protected by heating it with a zinc powder. The zinc combines with the base material by diffusion. This creates a protective layer that prevents corrosion.
The process of diffusion galvanizing
The product is heated together with the zinc powder in a rotating drum. This creates an even, heat-resistant and wear-resistant layer that contains a durable corrosion protection. The thickness of this layer is between 15 and 25 centimeters.
The advantages of diffusion galvanizing
- Protects against corrosion
- Even, adjustable layer thickness
- Heat resistant up to 600 degrees Celsius
- Excellent bonding ground
- Better for the environment