We have to apply a coating to hot-dip galvanised construction work. When measuring the zinc coating thickness, we find very different values. How thick should/must the zinc layer be?

The required zinc coating thickness is described in the NEN-EN-ISO 1461:2009 – “Hot dip galvanized coatings on iron and steel articles – Specifications and test methods”. (Unless otherwise agreed by the parties concerned). The layer thickness depends, among other things, on the material thickness and the material composition of the steel products. For example, for…

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.

How does sherardising or diffusion galvanising work?

In enclosed rotating drums the metal products are heated together with zinc powder. 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. Watch out video.

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.

Is pre-treatment necessary for sherardizing?

It’s 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.

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.