To provide a spinel ferrite magnetic powder having excellent characteristics. A method for manufacturing a magnetic powder includes: melting and then quenching a glass-forming component and a spinel ferrite magnetic powder-forming component to manufacture an amorphous body; and heat-treating the amorphous body to precipitate a spinel ferrite magnetic powder. An oxygen partial pressure during the heat treatment is 1.0 kPa or less.

To provide a spinel ferrite magnetic powder having excellent characteristics. A method for manufacturing a magnetic powder includes: melting and then quenching a glass-forming component and a spinel ferrite magnetic powder-forming component to manufacture an amorphous body; and heat-treating the amorphous body to precipitate a spinel ferrite magnetic powder. An oxygen partial pressure during the heat treatment is 1.0 kPa or less.

There is provided a radio wave absorber containing a magnetic powder, and an aliphatic polyamide, in which an intensity ratio (α/γ) of a diffraction intensity α of an α crystal of the aliphatic polyamide to a diffraction intensity γ of a γ crystal of the aliphatic polyamide, which are determined by subjecting the radio wave absorber to measurement with an X-ray diffraction method, is 2.60 or less. There is also provided a radio wave absorbing article including this radio wave absorber.

An object is to provide a magnetic filler composed of the ferrite particles having a low apparent density, capable of maintaining various properties in a controllable state and a specified volume is filled with a small weight, and a resin molded product made using the magnetic filler. To achieve the object, a magnetic filler composed of the ferrite particles having an outer shell structure containing a Ti oxide and a resin laminate made using the magnetic filler are employed.

This ferrite sintered magnet comprises ferrite phases having a magnetoplumbite type crystal structure. This magnet comprises an element R, an element M, Fe, Co, B, Mn and Cr, the element R is at least one element selected from rare earth elements including Y, the element M is at least one element selected from the group consisting of Ca, Sr and Ba, with Ca being an essential element, and when an atomic composition of metallic elements is represented by R.sub.1-xM.sub.xFe.sub.m-yCo.sub.y, x, y and m satisfy formulae:
0.2≤x≤0.8  (1)
0.1≤y≤0.65  (2)
3≤m<14  (3). Additionally, a content of B is 0.1 to 0.4% by mass in terms of B.sub.2O.sub.3, a content of Mn is 0.15 to 1.02% by mass in terms of MnO, and a content of Cr is 0.02 to 2.01% by mass in terms of Cr.sub.2O.sub.3.

A magnetizable abrasive particle is presented. The magnetizable abrasive particle has a ceramic particle having an outer surface. The magnetizable abrasive particle also has a magnetic coating layer applied to the outer surface of the ceramic particle prior to sintering. The sintered magnetizable particle is responsive to a magnetic field.

A magnetizable abrasive particle is presented. The magnetizable abrasive particle has a ceramic particle having an outer surface. The magnetizable abrasive particle also has a magnetic coating layer applied to the outer surface of the ceramic particle prior to sintering. The sintered magnetizable particle is responsive to a magnetic field.

A dispersed iron oxide magnetic powder slurry, in which the average secondary particle diameter of ε-type iron oxide measured with a dynamic light scattering particle size distribution analyzer is 65 nm or less, and which has good dispersibility, is obtained by adding a quaternary ammonium salt serving as a first dispersant and an alkali to a slurry containing ε-type iron oxide particles to bring the pH at 25° C. to 11 or higher, and thereafter adding an organic compound, which is an organic acid serving as a second dispersant and having two or more carboxy groups in the molecule, and in which one type or two types of a hydroxy group and an amino group are bound to carbon that does not constitute a carboxy group other than the carboxy groups to bring the pH at 25° C. of the slurry to 4 or higher and lower than 11.

A dispersed iron oxide magnetic powder slurry, in which the average secondary particle diameter of ε-type iron oxide measured with a dynamic light scattering particle size distribution analyzer is 65 nm or less, and which has good dispersibility, is obtained by adding a quaternary ammonium salt serving as a first dispersant and an alkali to a slurry containing ε-type iron oxide particles to bring the pH at 25° C. to 11 or higher, and thereafter adding an organic compound, which is an organic acid serving as a second dispersant and having two or more carboxy groups in the molecule, and in which one type or two types of a hydroxy group and an amino group are bound to carbon that does not constitute a carboxy group other than the carboxy groups to bring the pH at 25° C. of the slurry to 4 or higher and lower than 11.

Composition for making magnetic coverings comprising at least one elastomer, at least one magnetic filler, at least one compatibilizer, wherein the at least one magnetic filler is present in the composition in an amount comprised between 90% and 300% by weight, preferably between 100% and 250% by weight based on the weight of the least one elastomer.