Scientific Facts About Sintered Magnet

What is a sintered magnet?

During the forging and hot rolling processes of steel, due to the reaction between steel and oxygen in the air, a large amount of sintered magnets often form, resulting in accumulation and waste of resources. If these resources are properly utilized, production costs can be reduced and environmental protection and energy saving can be achieved. The main components of the sintered magnet are Fe2O3, Fe3O4, and FeO. Among them, the outermost layer of the sintered magnet is Fe2O3, accounting for about 10% of the thickness of the sintered magnet, preventing oxidation; the middle layer is Fe3O4, about 50%; and the innermost layer, which is in contact with iron, is FeO, about 40%.

What is the composition of a sintered magnet?

A typical sintered magnet consists of three layers: the outermost layer is Fe2O3, accounting for about 10% of the thickness of the entire sintered magnet, and its characteristics are: fine and glossy, brittle, easy to peel off; it also prevents further intense oxidation of the interior; the second layer is a mixture of Fe2O3 and FeO, usually written as Fe3O4, accounting for about 50% of the total thickness; the third layer connected to the metal body is FeO, accounting for about 40% of the thickness of the sintered magnet, and FeO is sticky and hard to remove once it adheres to the steel material.

Why does a sintered magnet appear red?

The surface of the steel sintered magnet is mainly composed of FeO, Fe3O4, and Fe2O3. Fe2O3 appears red, Fe3O4 appears black, and FeO appears blue. The various proportions of these oxides vary throughout the oxidation process, thus presenting different colors. When the proportion of Fe2O3 is higher, it appears red; when the proportion of FeO is higher, it appears bluish-gray. As a reliable NdFeB magnet supplier, we promise the products from us are high quality.

Where is the sintered magnet mainly used?

Firstly, in the chemical industry, sintered magnets are provided to chemical plants to produce iron oxide red, iron oxide yellow, ferric chloride, ferrous sulfate, etc. Among them, the liquid phase precipitation method using sintered magnet as the main raw material can produce all color phases of iron red, from yellow phase red to purple phase red.

Sintered magnet is an excellent auxiliary material for sintering. On one hand, sintered magnet has relatively larger granularity, which can improve the permeability of the sintering material layer. On the other hand, during the process where FeO in the sintered magnet combusts and oxidizes into Fe2O3, a large amount of heat is released, which can reduce the consumption of solid fuel and increase the sintering productivity. Experience shows that 8% of sintered magnet can increase production by about 2%.

Additionally, the magnet appliance is also used to manufacture sponge iron. The sponge iron produced has high Fe content, low impurities, and stable composition. Compared to sponge iron produced from ore, it does not contain gangue impurities and can be used as high-quality scrap steel raw material. Furthermore, reduced iron powder can be produced by either the coarse reduction method or the fine reduction method.