Why does steel rust?
What is the principle of steel corrosion? We can explore according to the small experiment shown in the figure below: add a small amount of calcium chloride in the first tube (calcium chloride can absorb the water vapor in the air, dry it), put a nail, plug it tightly Test tube mouth. A nail was placed in the second test tube, and the molten iron was immersed in distilled water which was boiled and rapidly cooled, and then the vegetable oil was poured to form an oil layer on the water surface. Place a nail in the third tube and add a small amount of distilled water to immerse a part of the nail in water. Three tubes were observed and recorded for a week. From the experimental results, we can find that the nails in the first and second tubes are not rusted, but the nails in the third tube are rusted, and reddish brown rust appears on the surface of the nail. It can be seen that iron rust requires the participation of water and oxygen.
Figure to explore the condition of iron rust
The corrosion process of steel products is a complex chemical reaction process. The rust is usually reddish brown, and different forms of rust are formed under different conditions. The rust is mainly composed of iron oxide hydrate (Fe2O3·nH2O) and iron hydroxide [Fe(OH)3]. The rust structure on the steel surface is loose, and it cannot prevent the internal iron from coming into contact with oxygen, water vapor, etc., and eventually the iron is completely rusted.
We understand the conditions under which steel is rusted. It is only necessary to isolate steel products from water and oxygen to prevent steel corrosion. Therefore, the easiest way to prevent iron rust is to keep the surface of the steel product clean and dry. To prevent rusting of steel, a protective layer can also be formed on the surface, such as oiling, painting, firing enamel, spray molding, and the like. In daily life, people often paint paint on cars, buckets, etc., and the machine needs to apply mineral oil. In addition, a layer of metal that is not easily rusted, such as zinc, tin, chromium, nickel, etc., may be plated on the surface of the steel by electroplating or hot plating. These metal surfaces are capable of forming a dense oxide film to prevent iron products from rusting by contact with substances such as water and air. In addition, the steel can be alloyed to change the internal structure of the steel. For example, stainless steel is added to ordinary metals such as chromium and nickel to make stainless steel, which effectively increases the rust resistance of steel products.
Steel corrosion can lose metal resources, but the principle of steel corrosion also has a positive side. For example, a deoxidizer is often used in pastry packaging, and its main component contains iron powder. The deoxidizer consumes oxygen by the principle of iron powder rust, thereby preventing food from spoiling.
At the same time, iron rust is an exothermic reaction, and people use this function to produce "self-heating posts." The main components of "self-heating post" are iron powder, vermiculite, activated carbon, inorganic salts (such as salt), water, and the like. Under natural conditions, the rate of oxidation of iron is slow, and in order to speed up the reaction, it is necessary to use iron powder having a large surface area. The role of activated carbon is to form a primary battery to promote the reaction; at the same time, using the strong adsorption of activated carbon, water is stored in its loose structure. The role of the inorganic salt is to form a primary battery with activated carbon to promote the reaction. Vermiculite is a ferro-magnesium aluminosilicate mineral that acts as a heat storage.
In the chemical laboratory, we can also make self-heating posts, weigh iron powder, activated carbon, salt, and vermiculite according to the mass ratio of 5:2:2:2. Pour the weighed iron powder, activated carbon, salt, vermiculite (the vermiculite can also be added) into the beaker, add a few drops of water, stir well with a glass rod, put it into a non-woven bag, and put it into a self-styled The bag is sealed (or sealed with a laminator) and can be removed when in use. In addition, the finer the iron powder and activated carbon particles (iron powder is preferably 100 mesh, and the activated carbon is 150 mesh), the faster the reaction, the more obvious the temperature rise.
Portable Power Station also known as Portable Power Bank. Our product regulated DC Power, AC Pass-Through Charging, Wireless Fast Charger, Bluetooth Playback, Attentive Start, Car charger, Type-C ....... Large capacity meet the needs of all kinds of equipment.
Portable Power Station,Indoor Portable Power Station,Solar Portable Power Station,Portable Power Station With Bms
Jiangsu Zhitai New Energy Technology Co.,Ltd , https://www.zhitainewenergy.com