Screws are made of metal, and there are four main ways in which metal can be protected from corrosion.

That is, the properties of the material itself, the environment in which it is used.

The interface between the data and the environment, and the design of the improved metal structure.

It is not economically feasible to manufacture stainless steel screws from a complete corrosion resistant alloy unless specifically required.

Or completely isolating the surface of the screw from the corrosive environmental elements, which may not be feasible in practice and may be very difficult.

Improving the design of metal structures can improve the effects of special conditions in certain conditions,

However, the design of most stainless steel screws can not be fully corrected, and their maintenance is not permanent, so this method can not solve the basic problem, as long as the interface of the prevention?

Screw surface corrosion prevention treatment refers to the use of various methods to impose a maintenance layer on the metal surface.

Its role is to isolate the metal and corrosive environment, in order to prevent the generation of corrosion process.

Or reduce the corrosive medium and metal surface contact, and to avoid or reduce the purpose of corrosion.

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The maintenance layer shall be able to meet the following requirements:

1. Corrosion resistance, wear resistance, high hardness,
2. The structure is tight, intact, and the pores are small.
3. Strongly separated from the base metal and good adhesion.
4. It is evenly spread and has a certain thickness.

Maintenance layer is usually divided into metal coating and non-metal coating two types, metal coating refers to the use of corrosion resistance of metal or alloy in easy to corrode metal surface to form a maintenance layer, this coating is also called coating.

There are quite a few methods and varieties of metal plating, the most common of which is electroplating, followed by molten metal dip (hot dip) and chemical surface treatment.

Nonmetallic coating refers to the use of organic polymer materials, such as paint, and inorganic materials.

Such as ceramics, on the surface of metal equipment or parts to form a maintenance layer.

The maintenance layer can completely isolate the matrix metal from the environmental medium, and avoid the corrosion of the matrix metal in the stainless steel standard medium due to contact corrosion.