Hardware knowledge: stainless steel screw anti-corrosion method

Stainless steel screws are made of metal, and there are four main methods for metal corrosion protection, namely the nature of the material itself, the environment in which it is used, the interface between the material and the environment, and the design of improving the metal structure. If a complete corrosion-resistant alloy is used to manufacture stainless steel screws Unless there is a special need, it is not realistic in terms of economic concept, or the appearance of the screw is completely isolated from the environmental elements that will cause corrosion. It may not be feasible in practice, and it may be very difficult. Improved metal structure design can improve the impact of special circumstances under certain conditions, but the design of most stainless steel screws cannot be fully modified, and its maintenance function is not permanent. Therefore, this method cannot basically deal with the problem, as long as the interface is Anti-corrosion, that is, surface anti-corrosion treatment is currently the most widely used method.

Stainless steel screw surface anti-corrosion treatment refers to the use of various methods to apply a maintenance layer on the surface of the metal. Its function is to isolate the metal from the corrosive environment to prevent the corrosion process or reduce the contact of the corrosive medium with the metal surface , And achieve the purpose of avoiding or reducing corrosion.

The maintenance layer should be able to meet the following requests:

1, corrosion resistance, wear resistance, high hardness,

2. The structure is tight and intact, with small pores.

3. It is separated from the base metal and has good adhesion.

4. Evenly spread and have a certain thickness.

The maintenance layer is usually divided into two types: metal coating and non-metal coating. Metal coating refers to the use of metal or alloy with strong corrosion resistance to form a maintenance layer on the surface of easily corroded metal. Plating. There are many methods and varieties of metal coatings, the most common of which is electroplating, followed by molten metal immersion plating (hot dip plating) and chemical surface treatment. Non-metallic coating refers to the use of organic polymer materials such as paint and inorganic materials such as ceramics to form a maintenance layer on the surface of metal equipment or parts. This maintenance layer can completely isolate the base metal from the environmental medium and avoid the base metal from contact corrosion Corrosion is formed in the medium of stainless steel standard parts.