Stainless steel screws are made of metal, and metal corrosion protection has four main aspects, namely the nature of the material, the environment used, the interface between the data and the environment, and the design of the improved metal structure. If a complete corrosion-resistant alloy is used to make the stainless steel screws Unless there is a special need, it is not realistic in terms of economics, or it can completely isolate the appearance of the screw 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 conditions under certain conditions, but the design of most stainless steel screws can not be fully corrected, and its maintenance role is not permanent, so this method can not basically deal with the problem, as long as it is on the interface Anti-corrosion, that is, external anti-corrosion treatment is currently the most widely used method.
Screw surface anti-corrosion treatment refers to the use of various methods to apply a maintenance layer on the metal surface. Its function is to isolate the metal from the corrosive environment, to suppress the corrosion process, or to reduce the contact between the corrosive medium and the metal surface. Or reduce the purpose of corrosion.
The maintenance layer should be able to meet the following requirements:
1, corrosion resistance, wear resistance, high hardness,
2. The structure is strict, intact, and the pores are small.
3. It is separated from the base metal and has good adhesion.
4, the average spread and a certain thickness.
The maintenance layer is usually divided into two types: metal coating and non-metal coating. The metal coating refers to the use of a highly corrosion-resistant metal or alloy to form a maintenance layer on the surface of a metal that is easily corroded. This coating is also called a coating. There are quite a number of methods and varieties for producing metal plating, 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. The maintenance layer can completely separate the base metal from the environmental medium to avoid contact corrosion of the base metal. Corrosion forms in the stainless steel standard part media.