Rust If you leave a piece of iron in a damp place for a period of time, it will form a layer of rust, just like someone painted it with reddish paint. So, what is rust? Why does steel rust? Rust is an oxide of iron, which is formed when iron combines with oxides dissolved in water. This means that if there is no water vapor in the air, or no water at all, or no dissolved oxygen in the water, rust will not form. When a drop of rain falls on the shiny iron surface, it will remain clean for a short time. However, before long, iron and oxygen in the water began to combine to form iron oxide, which is rust. Water drops will turn red and rust will be suspended in water. When the water droplets evaporate, rust will remain on the surface, forming a reddish rust layer. Once rust is formed, it will spread even in dry air. This is because rough rust is easy to condense water vapor in the air, and water vapor absorbs water vapor and stores it, which is why it is much easier to prevent iron from rusting than to prevent rust from expanding. Because steel products often need to be stored for a long time, preventing rust has become an important issue. Sometimes, people have to paint or stick plastic films on these items to prevent them from rusting. However, if it is necessary to keep the inside of the retired warship from rusting, what should I do? Relevant departments in some countries have solved this problem with dehumidifiers. To be exact, these machines can exhaust the wet air in the cabin and replace it with dry air, so that the iron will not rust. Ordinary steel gradually changes color in humid air, and a reddish-brown substance is generated on the surface. This phenomenon is called rust of steel. Its essence is that iron reacts with oxygen and water vapor in the air to generate hydrates of various oxides of iron. The composition of rust is complex, and it is usually expressed simply by Fe2O3 xH2O. Rust is a fragile and porous substance, which can't protect the iron in the inner layer from corrosion, so over time, steel products may rust into a pile of useless waste products. It is particularly serious that steel will soon rust in water vapor containing acid gas and chlorine gas, or when it comes into contact with electrolyte solution. According to statistics, tens of millions of tons of steel have become rust in every country in the world, and the losses caused by the destruction of steel products, such as production stoppage, product quality decline, environmental pollution, harm to human health and even serious accidents, are incalculable. Therefore, the rust prevention of steel has important economic and social significance. In fact, the main corrosion of steel is electrochemical corrosion. In humid air, the surface of steel is covered with an extremely thin water film due to adsorption, and weak ionization of water produces a small amount of H+ and OH-. At the same time, due to the dissolution of CO2 in the air, H+ in the water increases H2O+CO2H2CO3H++HCO3-, which forms a thin film of electrolyte solution on the surface, and forms numerous tiny primary cells with iron and impurities or carbon in steel. Among them, iron is the negative electrode and carbon is the positive electrode, and the galvanic cell reaction occurs: (-) Fe-2e = Fe2+ (+) 2h+2e = 2h2h = H2 ↑ With the decrease of H+ concentration, the ionization equilibrium of water moves to the right, and the concentration of OH- gradually increases, so that OH- and Fe2+combine to generate Fe(OH)2. Fe2++2OH-=Fe(OH)2↓ Fe(OH)2 is oxidized by oxygen in the air to form iron hydroxide 4Fe(OH)2+O2+2H2O=4Fe(OH)3↓ which causes corrosion on the steel surface. Hydrogen is released in the above corrosion process, which is called hydrogen evolution corrosion. Hydrogen evolution corrosion occurs in strongly acidic medium. If the electrolyte film formed on the surface of steel is weakly acidic or neutral, iron is still oxidized to Fe2+ at the negative electrode, and the main reaction at the positive electrode is that the electrons obtained by oxygen dissolving in the water film are reduced: (-) Fe-2e = Fe2+(+) 2H2O+O2+4e = 4oh-the dissolution of oxygen in the air promotes the corrosion of steel. The actual corrosion of metals such as steel is mainly this oxygen absorption corrosion. Traditional Chinese medicine rust: introduction to the efficacy of rust: rust (notes on materia medica), iron coat with different names (Puji prescription) and iron wire powder (health care experience set). The source is the reddish-brown rust layer produced by iron oxidation exposed to air. Processing "Rihuazi Materia Medica": calcining, flying, removing the coarse red juice, and drying. Sexual taste 1 materia medica: hard taste, cold gas. ② "Ben Feng Jingyuan": pungent, cold and non-toxic. Returning to the Classic of Materia Medica: Starting with Taiyin Lung and Foot Yangming Stomach Meridian. Indications-The effect of rust is to clear away heat and toxic materials, calm the heart and calm the liver. It can be used for treating sores, aphtha, heavy tongue, scabies, scald, poisonous insect sting and epilepsy. ① Compendium of Materia Medica: Treating scabies and applying oil. Spiders, insects, etc. Crush the garlic. 2 "Rihuazi Herbal Medicine": treating epilepsy, calming the mind and calming the nerves, and calming the five internal organs. It turns the temples black. (3) Peach blossom: rusty water, heavy medicinal properties, and the best way to cool off summer heat. 4 "Outline": calming the liver and reducing fever, eliminating sores and swelling, and sores on the mouth and tongue. Vinegar grinds centipede bite. ⑤ Materia Medica: eliminating furuncle, eliminating evil sores, expelling wind and tinea, and dispersing beriberi. Jiayou recipe is used to treat typhoid and chest obstruction, and it is ground into Chengqi decoction. 4 "Classic meets the original": the woman does not receive yin after childbirth, and takes it with borneol. Newt, centipede bite, garlic. ⑦ Drug Forest Compendium: Regulating the mind and calming the nerves, detoxifying and clearing away heat. Rotten iron wears red clothes and paints sores. Usage and dosage: external use: powder or daub, internal use: powder mixed with water. Scheme ① Treatment method of boils: nail the rust in the wall or soil for many years, wash it, calcine it with ash fire, quench it with vinegar, and wait until it is cool, scrape it with a knife, calcine it with fire, quench it with vinegar, scrape it before, repeatedly bake it, and wrap it with gauze. When someone has this syndrome, just poke the sore open and pick the powder instead of taking it as ointment. ("Puji Fang") 2 Treatment of furuncle: iron powder, with human milk and apply it. ("Puji Fang") 3 Treat the redness and swelling of the feet and legs, which is as hot as fire. The common name is red wind: apply it with rusty water and solve it. ("Shengji Fang") 4 Treatment of severe tongue swelling: rust lock burning red, rust, grinding, water swallowing. (edited by Sheng Sheng) ⑤ Treatment of boils caused by fire in soup: Bamboo burns oil, which is the same as rust. ("Ji De Tang Experience Prescription") 6 Treatment of wind itching and rash: rust and water. ⑦ Treatment of internal heat nocturnal emission: Take one yuan in cold water for three times. Famous experts discuss the Classic of Materia Medica: rust, hard taste and cold gas. Malignant scabies and scabies are caused by damp heat; Spiders and insects bite, poison gas hurts blood, industry can remove damp heat, and cold can remove poison gas, so it is also the Lord. Another secret method is to grind people buried in the open air very finely. Together with Venenum Bufonis, Brain and Musk Deer, the needle is inserted into the boil to the root, and then the medicine is inserted to pull out the root of the boil.