Abstract: A method for manufacturing a powder magnetic core includes: a step of preparing a soft magnetic powder and an oxide powder and preparing, as a raw material powder, a mixed powder of the soft magnetic powder and the oxide powder, the soft magnetic powder containing composite soft magnetic particles containing pure iron and an Fe-? alloy having an element ? more oxidizable than Fe, the composite soft magnetic particles each having a core-shell structure where a core is made of one of pure iron and the Fe-? alloy and a shell is made of the other, the oxide powder containing oxide particles containing at least one selected from Fe and an element ? that forms an oxide having higher electrical resistance than Fe3O4; a step of compacting the mixed powder into a green compact; and a step o sintering the green compact at 900° C. or more and 1300° C. or less.

Abstract: A method for producing a green compact, the method including a charging step of charging a raw-material powder including iron-based particles into a cavity formed by a lower punch and a die that are arranged to be movable relative to each other, a pressurizing step of pressurizing the raw-material powder charged in the cavity by the lower punch and an upper punch in order to form a green compact, the upper punch being arranged to face the lower punch, and a drawing step of drawing the green compact from the cavity by a relative movement between the green compact and the die. The drawing step is conducted while vibrations are applied to the green compact for at least part of the period from the time just before the relative movement starts to the time at which the relative movement completes.

Abstract: A powder magnetic core includes a compact including soft magnetic powder, and an insulating-resin coating that covers a portion of a surface of the compact. A ratio of an area of the insulating-resin coating to a surface area of the compact is lower than or equal to 85%, and a maximum depth of unevenness on a surface of the insulating-resin coating is smaller than or equal to 20 ?m.

Abstract: A dust core included in an axial-gap rotary electric machine. The dust core includes a sector-shaped plate-like yoke portion, and a tooth portion integrated with the yoke portion and projecting from the yoke portion. Denoting one of surfaces of the yoke portion from which the tooth portion projects as a toothed surface, the toothed surface has a concave portion provided between a peripheral edge of the tooth portion and a peripheral edge of the yoke portion.

Abstract: A method for producing a coated magnetic powder in which particle surfaces of a soft magnetic powder are coated with a silicone resin includes a preparation step of preparing a silicone emulsion by mixing a silicone resin with water containing a surfactant and dispersing the silicone resin in the water, an application step of applying the silicone emulsion onto particle surfaces of a soft magnetic powder, and a drying step of drying the soft magnetic powder after the silicone emulsion is applied.

Abstract: An iron-based powder for powder metallurgy includes an iron-based powder and a composite oxide powder, and the composite oxide contains, by mass, from 15% to 30% Si, from 9% to 18% Al, from 3% to 6% B, from 0.5% to 3% Mg, from 2% to 6% Ca, from 0.01% to 1% Sr, and from 45% to 55% O.

Abstract: An iron-based powder for powder metallurgy includes an iron-based powder and a composite oxide powder, and the composite oxide contains, by mass, from 15% to 30% Si, from 9% to 18% Al, from 3% to 6% B, from 0.5% to 3% Mg, from 2% to 6% Ca, from 0.01% to 1% Sr, and from 45% to 55% O.

Abstract: A powder compaction mold includes a die and upper and lower punches configured to fit into the die and is configured to compress a powder between the upper and lower punches to manufacture a powder compact. Of the members forming the powder compaction mold, at least one of two members in sliding contact with each other has therein a vent passage through which gas is vented from a filling space for the powder surrounded by the die and the lower punch to an outside of the powder compaction mold. The vent passage has a gas intake port that is open to a clearance section formed between the two members and connecting to the filling space.

Abstract: A compact is provided. When the compact is used for a magnetic core, a magnetic path cross section has a cross-sectional perimeter of more than 20 mm, and at least part of a surface of the compact is covered with an iron-based oxide film having an average thickness of 0.5 ?m or more and 10.0 ?m or less. Letting the proportion of the surface area of the compact to the volume of the compact be surface area/volume, the content of Fe3O4 present in the iron-based oxide film with respect to 100% by volume of the compact satisfies any one of (1) to (3): (1) less than 0.085% by volume when the (surface area/volume) is 0.40 mm?1 or less, (2) 0.12% or less by volume when the (surface area/volume) is more than 0.40 mm?1 and 0.60 mm?1 or less, and (3) 0.15% or less by volume when the (surface area/volume) is more than 0.60 mm?1.

Abstract: A dust core includes: a plurality of soft magnetic particles composed of an iron-based material; an insulating layer including a coating layer that is composed mainly of a phosphate and covers the surface of the soft magnetic particles; and insulating pieces containing a constituent material of the insulating layer, each of the insulating pieces being surrounded by at least three mutually adjacent ones of the soft magnetic particles while separated from the insulating layer.

Abstract: An iron-based powder for powder metallurgy includes an iron-based powder and a composite oxide powder, and the composite oxide contains, by mass, from 15% to 30% Si, from 9% to 18% Al, from 3% to 6% B, from 0.5% to 3% Mg, from 2% to 6% Ca, from 0.01% to 1% Sr, and from 45% to 55% O.

Abstract: An iron-based sintered body includes a metal matrix and complex oxide particles contained in the metal matrix. When a main viewing field having an area of 176 ?m×226 ?m is taken on a cross section of the iron-based sintered body and divided into a 5×5 array of 25 viewing fields each having an area of 35.2 ?m×45.2 ?m, the complex oxide particles have an average equivalent circle diameter of from 0.3 ?m to 2.5 ?m inclusive, and a value obtained by dividing the total area of the 25 viewing fields by the total number of complex oxide particles present in the 25 viewing fields is from 10 ?m2/particle to 1,000 ?m2/particle inclusive. The number of viewing fields in which no complex oxide particle is present is 4 or less out of the 25 viewing fields.

Abstract: There are provided a dust core in which, even if the surface of a heat-treated compact is ground, the insulation between soft magnetic particles on the ground surface can be ensured in the grinding step, and a method for producing the dust core. The method includes a preparation step of preparing a heat-treated compact 100 by compacting soft magnetic particles having an insulation coating and heating the resultant compact to a predetermined temperature; and a machining step of removing part of the heat-treated compact 100 using a working tool 2. The machining step is performed while an electric current is supplied with a conductive fluid 7L between the heat-treated compact 100 serving as an anode and a working tool 2 that machines the heat-treated compact 100 or a first counter electrode 5 that faces the working tool 2 with a distance therebetween, the working tool 2 or the first counter electrode 5 serving as a cathode.

Abstract: A method includes a step of compacting an insulation-coated pure iron powder or an iron-based alloy powder mainly containing iron using a die to obtain a dust core, a step of heat-treating the obtained dust core, and a step of post-machining at least one portion of the heat-treated dust core using a grinding wheel. In the post-machining step, grinding is performed in such a manner that the dust core and the grinding wheel are rotated, whereby isotropic machining marks are formed on a machined surface of the dust core.

Abstract: Provided are a soft magnetic powder for obtaining a dust core having a low iron loss, the dust core, and a method for producing a dust core. The present invention relates to a soft magnetic powder including a plurality of soft magnetic particles, each having an insulating layer. The Vickers hardness HV0.1 of a material constituting the soft magnetic particles is 300 or more, and the insulating layer contains Si, O, and at least one of an alkali metal and Mg. As long as the soft magnetic powder has such features, a material having a high electric resistance, such as an iron-based alloy, can be used. The eddy current loss can be reduced, and it is possible to effectively obtain a dust core having a low iron loss.

Abstract: There is provided a sintered body that does not readily deform during use and that allows a high flexibility for the design of surface layers, a method for manufacturing the sintered body, and an optical component including the sintered body. The method for manufacturing a sintered body includes a sintered body having a predetermined shape, the sintered body having a ceramic base material, the method for manufacturing a sintered body comprising a step for preparing a ceramic preform, a step for using a predetermined mold having an upper die and a lower die to hot-press the ceramic preform to form a pressure-sintered body, and a step for cooling the pressure-sintered body while applying a pressure load of approximately 5% or more and 100% or less (and preferably approximately 20% or more and 40% or less) of the pressure load applied during the step for forming the pressure-sintered body.

Abstract: A diffractive optical element (1) composed of a ceramic, in which the optical characteristics are enhanced by enhancing the machining precision, is composed of an infrared-transmissive ceramic, and prominent portions (11) and groove portions (12) are repeatedly formed on a surface of the diffractive optical element (1). The average value of the surface roughness Ra within an optical effective area (10) of the surface of the diffractive optical element is 0.05 ?m or less, and the difference in the surface roughness Ra within the optical effective area (10) of the surface is 0.02 ?m or less.

Abstract: A communication method for use in a radio communications system in which a mobile station sends identical data to a plurality of radio base stations in a parallel fashion. The method determines which radio base stations should stop forwarding data to an intermediate network device managing them. The intermediate network device includes a monitor and a controller. The monitor checks continuity of sequence numbers affixed to data received from each radio base station, thereby detecting missing sequence numbers. Based on the statistics of missing sequence numbers, the controller selects which radio base station should be allowed to continue its data forwarding operation. The controller then requests the other, non-selected radio base stations to stop their data forwarding operation.

Abstract: There are provided a dust core in which, even if the surface of a heat-treated compact is ground, the insulation between soft magnetic particles on the ground surface can be ensured in the grinding step, and a method for producing the dust core. The method includes a preparation step of preparing a heat-treated compact 100 by compacting soft magnetic particles having an insulation coating and heating the resultant compact to a predetermined temperature; and a machining step of removing part of the heat-treated compact 100 using a working tool 2. The machining step is performed while an electric current is supplied with a conductive fluid 7L between the heat-treated compact 100 serving as an anode and a working tool 2 that machines the heat-treated compact 100 or a first counter electrode 5 that faces the working tool 2 with a distance therebetween, the working tool 2 or the first counter electrode 5 serving as a cathode.