Chemical corrosion is mainly manifested in the corrosion of metals. In China, the loss caused by chemical reaction corrosion of metal materials exceeds 500 billion yuan every year, which means that 1 ton steel is corroded every minute and a half, so it is particularly important to understand chemical corrosion and protection. Most kitchen knives are made of iron. Generally speaking, there are two kinds of iron corrosion, one is oxygen absorption corrosion under weak acid or neutral conditions; One is hydrogen evolution corrosion under acidic conditions. Therefore, it is necessary to avoid putting the kitchen knife in an acidic environment and avoiding the contact between the kitchen knife and salt, which will accelerate the corrosion of the kitchen knife, and wash it with clear water after use.