Electromagnetic properties of high-carbon ferrochrome powders decarburized in solid phase by microwave heating

• High-carbon ferrochrome powders present diamagnetism.
• We study the effect of temperature and time on electromagnetic properties.
• The relative permittivity and permeability exhibit an opposite change trend.
• The absorption peak shifts to lower frequency with the increasing temperature.

During solid-phase decarburization, the changes of the electromagnetic properties can reflect the variation degree of material components. High-carbon ferrochrome powders (HCFCP) with addition of CaCO3 were decarburized in solid phase by microwave heating and the electromagnetic properties of the decarburized materials were investigated. With increasing in heating temperature from 1173 to 1473 K, the relative permittivity of the decarburized materials increases initially and then decreases, whereas the relative permeability exhibits an opposite change trend. As holding time ranges from 40 to 60 min at 1273 K, the relative permittivity and dielectric loss factor tend to decrease while the relative permeability and magnetic loss factor tend to increase, corresponding to the maximum mean velocity of decarburization. In microwave fields, electromagnetic properties of the decarburized materials principally vary with carbon content, C-vacancies and crystal structure, and their changes in turn affect the interaction of microwaves with the decarburized materials.