Stainless steel fasteners are also made of metal, and there are four main methods for metal corrosion prevention, namely the nature of the material, the environment in which it is used, the contact surface between the material and the environment, and the design of improving the metal structure.
If corrosion-resistant alloys are used to manufacture stainless steel fasteners, unless there are special needs, it is not practical in terms of economics. If the appearance of the fastener is completely isolated from the environmental elements that will produce corrosion, it may not be feasible in actual operation, which is very difficult. Improving the metal structure design can improve the impact of special circumstances under certain conditions, but the design of most stainless steel fasteners cannot be fully modified, and its maintenance function is not permanent, so this method basically cannot handle the problem. Only the anti-corrosion measures on the contact surface between the material and the environment, that is, the surface anti-corrosion treatment, is currently the most widely used method.
Anti-corrosion treatment on the surface of stainless steel fasteners 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 inhibit the corrosion process or reduce the contact of corrosive media with the metal surface. To achieve the purpose of avoiding or reducing corrosion.
The stainless steel fastener maintenance layer should be able to meet the following requirements:
1. Corrosion resistance, wear resistance, and high hardness.
2. The structure is tight and intact with small pores.
3. Separation from the base metal is strong 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 a metal or alloy with strong corrosion resistance to form a maintenance layer on the surface of the easily corroded metal. This kind of coating is also called plating. There are many methods and varieties of metal coatings. Among them, electroplating is the most common method, 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 corrosion of the base metal.