Thread Content
Combined with the background related to the liquid ammonia corrosion reaction mentioned earlier, the corrosion of materials by liquid ammonia can be divided into two categories: metal and non-metal, as follows:: 1. Corroded metal materials copper and copper alloys: Ammonia can form stable copper ammonia complex ions with copper 3)4] 2+, directly destroys the metal surface layer, and is one of the most corroded materials in a liquid ammonia environment. Galvanized metal, zinc and zinc alloys: Ammonia will react with zinc to form a zinc ammonia complex, which will destroy the structure of the galvanized layer and the zinc material itself, causing continued corrosion. Low melting point metals such as aluminum and tin: Liquid ammonia also has a significant corrosive effect on this type of metal, and long-term contact may cause material damage. Carbon steel/low alloy steel: In a liquid ammonia environment mixed with trace amounts of oxygen and impurities, stress corrosion cracking will occur. This corrosion risk will be greatly reduced in high-purity liquid ammonia. 2. Corroded non-metallic materials Most conventional non-metallic materials corrode slightly in pure liquid ammonia, but some materials that are not alkali-resistant, such as ordinary alkali-resistant rubber and some alkali-resistant resins, will suffer from swelling, degradation and failure when exposed to high concentrations of liquid ammonia for a long time. Industrial liquid ammonia pipelines and storage tanks are generally made of carbon steel. By controlling the purity of liquid ammonia and adding a small amount of water, the stress corrosion problem of carbon steel can be effectively avoided.