One of the pretreatment methods for enamel metal is pickling, which is beneficial to remove rust and dirt on the surface, and avoid enamel defects such as scale explosion, pinholes, and focal points in the subsequent enamel process. In the pickling process, an appropriate amount of corrosion inhibitor (inhibitor) can be added, so what is the corrosion inhibitor? Under what circumstances can it be used? What precautions? The author shares based on years of industry experience, and welcomes peer discussions.

1. What is a corrosion inhibitor

The corrosion inhibitor is used to help the enamel iron billet to reduce the release of hydrogen during pickling, and at the same time reduce the consumption of acid (saving about 30%~40%). The principle of corrosion inhibitor is that its particles will be absorbed on the metal surface to form a dense layer of film to prevent acid from penetrating into the metal, which will not affect the dissolution of rust, but will reduce the dissolution of metallic iron.

2. Disadvantages of corrosion inhibitors

The biggest disadvantage of using a corrosion inhibitor is that it contaminates the metal surface. At the same time, the micro-roughness of the metal surface is greatly reduced compared with that without a corrosion inhibitor, which will weaken the adhesion between the bottom glaze and the metal. Generally, the concentration of the additive is between 0.1~2%.

3. Precautions for using corrosion inhibitors

The corrosion inhibition effect of corrosion inhibitors in pickling is only relative. If the temperature of the acid solution rises and the time is prolonged, over-corrosion of the embryo body will still occur. Therefore, the work procedures must be strictly implemented in the operation to ensure product quality. .