Study of the influence of conditions of synthesis on magnetic characteristics of composite materials based on iron powders

Abstract

The influence of synthesis conditions on the magnetic characteristics of composite materials based on iron powders ASC 100.29 (Sweden) and LiaoNing (China) is investigated. The surface of metallic iron powders is encapsulated by an insulating ferrite coating, consisting of iron oxides and phosphides. The synthesis was carried out at a temperature of 150 °C from a gaseous medium in a special reactor at a pressure of 1 atm. Insulating oxide coatings were applied both to the initial iron powder without treatment, and to previously annealed powders in an inert atmosphere and in a mixture of hydrogen-argon. To conduct studies of magnetic characteristics, cores in the form of rings were made by pressing method. The dependence of induction vs. magnitude of the magnetic field, magnetization reversal losses (hysteresis losses) in the full and in the private loop were recorded by an express magnetometer. The value of losses was calculated by the hysteresis loops area. The results show that composite low-frequency magnetic materials based on metallic iron ASC 100.29 and LiaoNing powders have similar values of magnetic parameters – almost identical B = f(H) dependencies, but the magnetization reversal losses for ASC 100.29 are significantly lower than for LiaoNing powder under equal insulating coatings synthesis conditions. It is possible to use such materials as magnetic cores in various electrical devices, such as cores of high-frequency transformers and a number of electrical machines. Since such materials can operate at frequencies from 1 kHz and higher, this will significantly reduce the overall dimensions and increase the efficiency of electrical products.

Investigation of the frequency characteristics of composite iron powders with insulating oxide coatings

“…It has been established that annealing of finished cores made of composite material allows one to reduce losses and increase the induction of the material by 5-8%, which actually agrees with [2][3][4]. Figure 3 shows the dependence of hysteresis losses on induction for a full cycle at a magnetization reversal frequency of 1, 2, and 5 kHz for a low-frequency material based on ASC100.29 with a grain size of d> 100 μm.…”

“…Magnetically soft materials include ferro-and ferrimagnets with low coercive force, high values of the initial and maximum magnetic permeability, and low losses for magnetization reversal in dc and ac fields [4,8,10]. Depending on the characteristics of devices, electrical machines and other devices, the following requirements are imposed on SMM:…”

Optimization of the method of oxide coating of metallic iron powder particles

“…In terms of other certification parameters the powders are identical. As a comparison in fulfillment of international contracts, electromagnetic characteristics were investigated on cores obtained by pressing from ready-made industrial iron powders of well-known firms Atomet1001HP (Canada) with 99.4% purity and Micrometals (USA) with 99% purity, on particles of which the manufacturer itself has already applied dielectric layers [3,10,16]. From the analysis of the above research results it follows that the powder ASC100.29, the particles of which are covered with oxide layers, and composites based on it have a number of advantages.…”

“…As follows from the above consideration, the known methods of encapsulating iron powder with a thin oxide layer, namely by mechanical deposition of the oxide layer, formation of the oxide layer as a result of decomposition of sulfates and metal nitrides and formation of the oxide layer from the gas oxide layer, create poor quality coating and are ineffective [7,[10][11][12].…”

“…In this regard, a combined method of obtaining oxide coatings on the surface of iron particles was proposed [2,4,5,8,10]. The proposed new method is based on the combined use of the above methods.…”