Carbonyl iron powder is produced by the reaction of CO and iron at high temperature and pressure to produce 5 carbonyl iron oil. The product is obtained after low pressure separation. Can be shipped after annealing and oxidation treatment. When the temperature is 200 ° C and 200 bar, the reaction formula of carbonyl is as follows

 

Fe + 5CO = Fe (CO) 5

 

Iron carbonyl decomposes into Fe and CO at 300 ℃ and 1bar

 

Fe (CO) 5 = Fe + 5CO

 

During the decomposition process, because Fe can catalyze the mutual conversion of CO and CO2, NH3 is usually used as a protective gas to suppress the reaction. In this way, the presence of N element is inevitable in the carbonyl iron powder. The iron content of the product collected from the cyclone collector is generally about 97%, and the content of C and N is less than 1%. Due to the presence of impurities such as Fe2O3 and Fe3N, at the same time, the surface of iron powder will also have a certain adsorption of CO and NH3 gas. These factors cause the hardness of iron powder to be relatively large, which is often referred to as hard powder.

 

还原 Reduction of iron powder with H2 gas for 1 hour, the iron content will increase to about 99.0%, and the content of other elements will also be significantly reduced. This reduced carbonyl iron powder has slightly lower hardness and is also called soft powder.

 

Carbonyl iron powder is very active. After standing for a period of time under normal circumstances, automatic reunion will occur due to the increase of entropy. The particle size of the agglomerated iron powder increases, and the particles are sticky, which has a relatively large impact on the application of injection molding. At present, the best quality carbonyl iron powder on the market is produced by German BASF company.

 

The requirements of carbonyl iron powder are very high. When the temperature of 5 carbonyl iron decomposes, the temperature changes by 3 degrees, and the gas flow rate increases by 5%, which can obviously change the carbonyl iron powder particle size and carbon content.