Tadao Nozawa

Relationship between total losses under tensile stress in 3 percent Si-Fe single crystals and their orientations near

The relationship between the total loss under tensile stress and the tilt angle of the [001] out of crystal surface β was studied in 3 percent Si-Fe single crystals. The total loss largely depends upon β. When β is about 2°, the total loss under tensile stress is the smallest, and the decrease of the total loss due to tensile stress is the largest. When β is less than about 2°, the total loss increases as β decreases. In the case of perfect

Effects of scratching on losses in 3-percent Si-Fe single crystals with orientation near

The effects of scratching perpendicular to the [001] direction on losses were studied as a function of the tilt angle of the [001] out of the crystal surface β both with and without tensile stress in 3-percent Si-Fe single crystals. The reduction of the total losses by scratching becomes larger with decreasing β. The total losses of scratched samples further decrease with the application of tensile stress parallel to the [001] direction. Observations of domain structure showed that scratching causes a decrease in 180° main domain wall spacings and also the occurrence of reverse subdomains in the vicinity of the scratch. It was found that the total losses of scratched specimens are lower than those of unscratched samples for equal 180° main domain wall spacing observed in the demagnetized state. This may be because the losses of scratched samples are influenced by the dynamic behavior of reverse subdomains in addition to the function of 180° domain wall displacements, The variation of dc hysteresis loss by scratching is very small. This may be caused by the effect of the new domain configuration at the scratch line, which weakens the domain wall pinning due to free poles or internal stress caused by scratching.

Magnetic properties and dynamic domain behavior in grain-oriented 3% Si-Fe

The magnetic properties of soft magnetic materials are based on dynamic behavior of magnetic domain walls. Many domain structure studies have contributed to the progress of magnetic materials. In this paper, the present state of new development in advanced grain-oriented silicon steel is introduced through the aid of dynamic domain observation of real materials with forsterite film. The basic magnetic phenomena of material, such as the dynamic behavior of surface closure domains, domain wall pinning, and domain structure under rotating magnetization, are explained mainly through the observation of static and dynamic domain wall movements under a high-voltage scanning electron microscope. A few techniques for manufacturing the latest grain-oriented silicon steel, such as improvement in alignment with (110) [001] orientation, increase in the number of mobile domain walls, and relaxation of domain wall pinning, are also described through the observation of dynamic domain patterns. Examples of core losses are given for ideal grain-oriented silicon steel as industrial material, and future developments are predicted.

Production of very low core loss grain-oriented silicon steel

The present paper is concerned with the production of very low core loss grain-oriented silicon steel. Domain refining techniques and their mechanisms have been studied. A quantitative interpretation for the domain refining phenomena is not sufficient. However, it is anticipated that these results will be based on the same principle, that is, an interaction between tensile stress and subdomains which consists mainly of transverse domains resulted from magnetic free poles and/or internal stress. An attempt to develop grain-oriented silicon steel with almost perfect

Production of single-crystal 3% silicon-iron sheet with orientation near (110) [001]

Abstract The production of single-crystal 3% silicon iron sheet with a near (110) [001] orientation was studied. This study presented the possibility of the industrial production of grain-oriented 3% silicon steel with very high induction. This production is characterized by a unique grain-growth inhibition system for promoting secondary recrystallization. The system is composed of final annealing in a temperature gradient. Final annealing in a temperature gradient above 3°C/cm enables production of grain-oriented 3% silicon steel with a very high induction of 2.0 T.

Heatproof domain refining method using chemically etched pits on the surface of grain-oriented 3% Si-Fe

The experimental results of a new heatproof domain refining method for grain-oriented 3 % Si-Fe sheets are described. By using laser irradiation and nitric acid etching, small and shallow pits arranged in lines transverse to rolling direction were made on the surface of Si-Fe sheets. Typically the size of these pits was 0.3 mm in diameter and 0.02 mm in depth, spot distance was 0.3 mm and line distance was 5 mm. After recoating and stress relief annealing at 800°C for 2 hours, the iron losses of these Si-Fe sheets were reduced beyond 15 %. These materials reduce iron losses of wound type cores which need a high temperature annealing in the manufacturing.

Magnetic properties of FeCoV film sandwiched by thin soft-magnetic films

Soft magnetization of FeCoV thin films has been examined experimentally. The coercive force of FeCoV films decreases by more than 90% with little reduction in saturation magnetization or changes in magnetization behavior when films are sandwiched between two thin FeNiMo soft-magnetic layers making up about 2% of the total volume. It can be assumed that a magnetic wall, parallel to the film surface and formed at the interface between the soft-magnetic layer and the FeCoV layer, will readily propagate into the FeCoV layer. The thickness of the soft-magnetic layer necessary for the magnetic wall formation is thought to be about 50/spl sim/100 /spl Aring/. The reduction in coercive force seems to be related to the anisotropy of the magnetic properties of the thin soft-magnetic layer. In the case of Fe films, however, a reduction in coercive force due to the thin soft-magnetic layer never occurs. Whether the thin soft-magnetic layer has effects on the crystal structure of FeCoV or Fe layers, will be examined experimentally in the future.

Domain structures and magnetic properties of advanced grain-oriented silicon steel

Abstract The dynamic behavior of surface closure domains governing the soft magnetic properties of grain-oriented 3% silicon-iron and the basic magnetic phenomena, such as domain wall pinning, are explained mainly through the observation of static and dynamic domain wall movements under a high-voltage scanning electron microscope. Techniques for manufacturing the latest grain-oriented silicon-iron, such as improvements in the alignment of the (110)[001] orientation, increases in the number of mobile domain walls and relaxation of domain wall pinning, are also described through the observation of domain patterns.

Coercive force reduction effect in FeCoV and FeNi films due to ultrathin FeNiMo layer

The mechanism of the drastic coercive force reduction effect in essentially semi-hard FeCoV and FeNi films due to ultrathin FeNiMo layer has been examined. It is noted experimentally that a kind of a coupling of magnetic moments existing between ultrathin FeNiMo layer with anisotropic magnetization and semi-hard magnetic layer with anisotropic magnetization contributes to this drastic coercive force reducing effect.

The influence of grain-orientation on 180° domain wall spacing in (100) [001] grain-oriented 3% Si-Fe with very high permeability

Abstract A domain refining process of grain-oriented 3% Si-Fe with very high permeability was proposed. In experiments, the specimens having periodic change of the tilt angles of the [001] in a grain were prepared and the behavior of the domain structure was observed using SEM. The experimental results were explained using a simple model.