The physicochemical properties and production methods of iron oxide Fe3O4

 Overview of iron oxide Fe3O4

Ferroferric oxide is an inorganic substance with a chemical formula of Fe3O4. It is a magnetic black crystal, so it is also called magnetic iron oxide. It cannot be regarded as "ferrous ferrite" [Fe(FeO2)2], nor can it be regarded as a mixture of ferrous oxide (FeO) and iron oxide (Fe2O3), but it can be regarded as suboxide A compound composed of iron and iron oxide (FeO·Fe2O3). This substance is insoluble in water, alkali solutions, ethanol, ether and other organic solvents. The 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 audio tapes and telecommunications equipment.

Three oxides of iron: ferrous oxide (FeO), iron oxide (Fe2O3), and ferric oxide (Fe3O4).

Ferric oxide is the only iron compound that can be magnetized in the middle school stage. Fe2+ and Fe3+ are contained in ferroferric oxide. X-ray diffraction experiments show that ferroferric oxide has a trans-spinel structure, and there is never a ferrite ion FeO22- in the crystal. Ferroferric oxide, the natural mineral type is magnetite. Iron has two valences in ferroferric oxide. It has a trans-spinel structure, and the oxygen is the most densely packed cube. In addition, Fe3O4 is also a conductor. Because Fe2+ and Fe3+ are basically disorderly arranged at the octahedral position in magnetite, electrons can quickly transfer between the two oxidation states of iron, so Fe3O4 Iron solids have excellent electrical conductivity. Fe3O4 can be regarded as FeO·Fe2O3. This way of writing better shows that Fe3O4 contains Fe(Ⅱ) and Fe(Ⅲ).

The physicochemical properties and production methods of iron oxide Fe3O4

Physical properties

The black Fe3O4 is a mixed valence oxide of iron. It has a melting point of 1597℃ and a density of 5.18g/cm3. It is insoluble in water and soluble in acid solutions. It appears in the form of magnetite in nature. Strong submagnetism and high conductivity.

Ferromagnetic and ferrimagnetic materials undergo a secondary phase transition above the Curie temperature to transform into paramagnetic materials. The Curie temperature of Fe3O4 is 585℃.

The magnetic properties of materials can be divided into five categories:

(a) Diamagnetism (diamagnetism): All electrons in a substance have been paired in atomic or molecular orbits, with opposite spins, and no permanent magnetic moment.

(b) Paramagnetism: There are unpaired electrons in atoms or molecules, and there is a permanent magnetic moment, but there is no interaction between the magnetic moments.

(c) Ferromagnetism: Each atom has several unpaired electrons, and the atomic magnetic moments are relatively large, and they interact with each other, making the atomic magnetic moments parallel.

(d) Ferrimagnetism (ferrite magnetism): The magnetic moments of adjacent atoms exhibit unequal anti-parallel arrangement.

(e) Antiferromagnetism: Paramagnetism above the Néel temperature; below the Néel temperature, the magnetic moments of adjacent atoms between the magnetic moments show an equal antiparallel arrangement.

Fe3O4 has high electrical conductivity, and the unusual electrochemical properties of Fe3O4 can be attributed to the transfer of electrons between Fe2+ and Fe3+.

Chemical nature

Combustion of iron wire in oxygen will produce ferroferric oxide. Comparing the standard moles of iron oxides to generate Gibbs free energy, it is concluded that Fe3O4 has the greatest thermodynamic stability, so the product is Fe3O4.

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 greatest 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 a mixture of saturated solid 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), but the thickness of the oxide film in moist 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 vapor to produce Fe3O4 and hydrogen.

Fe3O4 has 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.

Production method

Hydrogen reduction method of α-iron oxide

Put high-purity micro-powdered α-Fe2O3 into the pan, and the powder layer should not be too thick. After putting the pan into the reaction tube, pass in high-purity nitrogen to completely replace the air. Then slowly feed the hydrogen saturated with water through the scrubber. The heating temperature is between 300 and 400°C (for example, 330°C). After confirming that the reaction is complete (usually 1 to 3 hours), cool it down, stop sending hydrogen, and replace it with nitrogen, then take out the sample. Insufficient water vapor, excessive heating temperature or excessive reduction will generate FeO, so care must be taken. Increasing the temperature of the scrubber can increase the amount of water vapor (40-60°C is appropriate). With needle-shaped α-FeO(OH) as starting material, α-Fe2O3 is obtained by heating and dehydrating. With this α-Fe2O3, needle-shaped ferroferric oxide particles can be prepared. The black audio tape uses this ferroferric oxide as the tape recording medium.

Plus legal

Iron scraps are reacted with sulfuric acid to obtain ferrous sulfate, and then caustic soda and iron oxide are added to perform an adduct reaction at 95-105°C to generate ferroferric oxide, which is filtered, dried and crushed to obtain iron oxide black.

Slow oxidation of ferrous hydroxide

By heating the aqueous solution containing ferrous hydroxide precipitation to above 70°C and performing slow oxidation, ferroferric oxide powder composed of fairly uniform regular octahedral or cubic single crystal particles with a rib length of about 0.2 μm can be obtained. Air bubbles can also be used as a means of oxidation. An oxidant like KNO3 can also be used.

Harber method

If you are proficient in the operation, you can get Fe3O4 with a stoichiometric composition of Fe3.00O4.00. In the Harber method, 220g 0.2 ammonia water is added to 2.2L FeSO4·7H2O aqueous solution and boiled under the condition of cutting off the air (you can use a capillary Round bottom flask), add a concentrated aqueous solution containing 25.5g KNO3 to the boiling.

Alkali Method

The ferrous sulfate solution is oxidized by adding alkali or the solution of ferrous salt and ferrous salt is mixed in a certain proportion and then added with alkali precipitation

In the contemporary electrification and information society, the application of magnetic materials is very extensive. As a multifunctional magnetic material, ferroferric oxide magnetic material has been widely used in tumor treatment, microwave absorbing materials, catalyst carriers, cell separation, magnetic recording materials, magnetic fluids, medicine and other fields. There are development prospects.

Fe3O4 contains Fe(Ⅱ) and Fe(Ⅲ). 

Application of iron oxide Fe3O4

Ferroferric oxide is a commonly used magnetic material.

Specially made pure ferroferric oxide is used as raw material for audio tapes and telecommunications equipment.

Natural magnetite is the raw material for iron smelting.

Used to make primers and topcoats.

Ferric oxide is the main raw material for the production of iron catalyst (a kind of catalyst).

It is very hard and can be used as abrasive. It has been widely used in the field of automobile braking, such as: brake pads, brake shoes, etc.

Ferroferric oxide has been recognized in the field of domestic welding materials, and the production of welding rods and wires is still in its infancy, and the market prospect is very broad.

Fe3O4 shows good performance in sewage treatment due to its high specific gravity and strong magnetism.

Ferroferric oxide can also be used as a pigment and polishing agent.

We can also use certain chemical reactions, such as the use of sodium nitrite, etc., to form a dense layer of ferroferric oxide on the surface of steel to prevent or slow down the corrosion of steel, such as the bluing of firearms, saw blades, etc. Blackened. Commonly known as "baked blue".

Fe3O4 can also make special electrodes. 

Iron oxide Fe3O4 price

The price of iron oxide Fe3O4 powder will vary randomly with factors such as production cost, transportation cost, international situation, and market supply and demand of iron oxide Fe3O4 powder. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for iron oxide Fe3O4 powder, please feel free to send an inquiry to get the latest price of oxide Fe3O4 iron powder.

Suppliers of iron oxide Fe3O4

As a global supplier of iron oxide Fe3O4, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including boron carbide, aluminum carbide, titanium carbide, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.

Technical Parameter of Iron Oxide Fe3O4 Powder：
Test item	01	2
Content Fe3O4≥﹪	99	99
Moisture content ≤﹪	0.7	0.7
Water Soluble ≤﹪	0.4	0.4
Residue On Sieve(325mesh)	0.3	0.3
Oil absorption (ml/100g)	21	21
PH value	7	7
Tinting strength ﹪	99	99

Other Names	Iron(II,III) oxide,Iron Oxide Fe3O4 Nanopowder,
	Fe3O4
CAS No.	1317-61-9
Compound Formula	Fe3O4
Molecular Weight	233.53
Appearance	Black Powder
Melting Point	1597 °C
Boiling Point	N/A
Density	4.8-5.1 g/cm3
Solubility in H2O	N/A
Exact Mass	231.784471