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The chemical properties of Fe3O4

wallpapers Industry 2020-09-24
Ferroferric oxide, the chemical formula Fe3O4. Commonly known as black iron oxide, iron magnet, black iron oxide, it is a black crystal with magnetism, so it is also called magnetic iron oxide. It cannot be regarded as "ferrous ferrite" [Fe(FeO2)2], nor can it be considered as a mixture of ferrous oxide (FeO) and iron oxide (Fe2O3). Still, it can be regarded as suboxide A compound composed of iron and iron oxide (FeO·Fe2O3). This substance is soluble in acid solution, insoluble in water, alkali solution, ethanol, ether and other organic solvents. Natural ferroferric oxide is insoluble in acid solution and is easily oxidized to iron oxide (Fe₂O₃) in the air in a humid state. Usually used as a pigment and polishing agent, it can also be used to make audiotapes and telecommunication equipment.
Combustion of iron wire in oxygen will generate ferroferric oxide. Comparing the free energy of Gibbs generated by the standard mole of iron oxide, it is concluded that Fe3O4 has the most excellent thermodynamic stability, so the product is Fe3O4.

Iron and air will form oxides on its surface. At this time, the chemical composition of the oxide film itself is not uniform. For example, a piece of low-carbon steel can be covered by three kinds of oxide films: FeO is in contact with the metal, Fe2O3 on the side in contact with air, and Fe3O4 in the middle. More precisely, perhaps the mixture of saturated reliable solutions of three oxides constitutes the oxide film on the surface of the steel.

At the same time, the thickness of the oxide film also varies depending on different environmental conditions during oxidation. At room temperature, the thickness of the oxide on the relatively pure iron in dry air does not exceed 20 angstroms (1 angstrom = 0.1 nanometers). Still, the thickness of the oxide film in humid air increases significantly, and rust spots on the surface can be seen. At this time, the oxide deposition is layered, the side close to the metal is a dense amorphous anhydrous layer, and the side close to the air is a thick porous hydration layer.

Iron reacts with water vapour to produce Fe3O4 and hydrogen.

Fe3O4 has an anti-corrosion effect. For example, the bluing of steel parts (also called blue-burning and baking blue) is to use the oxidation effect of alkaline oxidizing solution to form a blue-black or dark blue Fe3O4 film on the surface of steel parts Used to increase corrosion resistance, gloss and aesthetics.

Trunnano is one of the world's largest producers of ferroferric oxide powder. If you have any questions or needs, please contact Dr Leo, email: brad@ihpa.net.

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