Investigation of Magnetic Properties of Cryogenically Cooled Electrolyte Pure Iron Powder

The presented work investigates magnetic properties of electrolyte pure iron (Fe) powder and sintered specimen made from the Fe powder. The pure Fe powder is subjected to hydrogen environment annealing followed by cryogenic cooling in a custom designed arrangement. The iron powder used in the study has 99.87% purity and particle size of 120 mu m. Initially the iron powder is heated at 750oC in hydrogen environment in a tubular furnace for 1 hour duration. Later the Fe powder is cryogenically cooled in a vessel which is jacketed with liquid nitrogen. The iron powder is then used to make sintered specimen of 20 mm in diameter and 30 mm length. A custom made test set up is used with an electromagnet placed around the specimen to investigate initial magnetization curve and B-H loop characteristics. The set-up has the provision to apply variable DC current in the electromagnetic coil and measure magnetic flux density at one end of the specimen. Experimentation is performed on the iron powder and the compacted specimen to determine the maximum magnetic permeability, remanence, and coercivity. It is revealed that the cryogenically cooling improves maximum permeability by 32% with no significant influence on the remanent magnetic flux.