56results about How to "Easy to demagnetize" patented technology

A melt of an iron-based rare earth material alloy, represented by (Fe1-mTm)100-x-y-zQxRyMz, is prepared, wherein T is Co and / or Ni; Q is B and / or C; R is selected from Y (yttrium) and the rare earth elements; M is selected from Al, Si, Ti, V, Cr, Mn, Cu, Zn, Ga, Zr, Nb, Mo, Ag, Hf, Ta, W, Pt, Au and Pb; 10<=x<=30 at %; 2%<=y<10 at %; 0<=z<=10 at % and 0<=m<=0.5. The melt is fed onto a guide to form a flow of the melt thereon and move the melt onto a melt / chill roller contact region, where the melt is rapidly cooled by the chill roller to make a rapidly solidified alloy. An oxygen concentration of the melt yet to be fed onto the guide is controlled at about 3,000 ppm or less in mass percentage.

In known methods, an improvement of the coercive force is realized by allowing the Dy metal or the like to present selectively in crystal grain boundary portions of a sintered magnet. However, since these are based on a physical film formation method, e.g., sputtering, through the use of a vacuum vessel, there is a mass productivity problem when a large number of magnets are treated. Furthermore, there is a magnet cost problem from the viewpoint that, for example, an expensive, high-purity Dy metal or the like must be used as a raw material for film formation. The method for modifying grain boundaries of a Nd—Fe—B base magnet includes the step of allowing an M metal component to diffuse and penetrate from a surface of a Nd—Fe—B base sintered magnet body having a Nd-rich crystal grain boundary phase surrounding principal Nd2Fe14B crystals to the grain boundary phase through a reduction treatment of a fluoride, an oxide, or a chloride of an M metal element (where M is Pr, Dy, Tb, or Ho).

Provided is a magnetic recording medium having good electromagnetic characteristics, particularly both improved high-density recording characteristics and good durability, and particularly a C / N ratio that is markedly improved in the high-density recording region. A magnetic recording medium comprising a nonmagnetic lower layer and a magnetic layer provided in this order on a support wherein said magnetic layer comprises a ferromagnetic metal powder or a ferromagnetic hexagonal ferrite powder and a binder and has a coercive force equal to or higher than 143 kA / m. Said magnetic recording medium is a medium for recording signals having a surface recording density ranging from 0.2 to 2 Gbit / inch<2>; said support has a thickness equal to or less than 5.5 mum and a Young's modulus in the MD direction equal to or higher than 11,000 Mpa; and said support has on the reverse surface from said magnetic layer a backcoat layer, said backcoat layer having not fewer than 200 and not more than 1,000 protrusions having a height equal to or higher than 50 nm per 10,000 mum<2>.

The invention provides a magnetic grinding material. The magnetic grinding material comprises a magnetism sensing core, and a core housing structure of a grinding housing which wraps the magnetism sensing core, wherein the grinding housing comprises a binding agent and grinding material particles; the grinding material particles are adhered to the magnetism sensing core by hot melting the binding agent. According to the magnetic grinding material, the surface wrapping layer of the magnetism sensing core is reasonably designed, so that the grinding efficiency of the magnetic grinding material is improved, and the self-sharpening performance remains, and as a result, the consistency and stability of the grinding process can be ensured; the magnetism sensing material is used as the core of the magnetic grinding material; the magnetic grinding material is easy to recover. The invention further provides a preparation method of the magnetic grinding material. The preparation method comprises the steps of supplying the magnetism sensing core particles and the binding agent particles, and preparing and sintering semi-finished product, namely, small balls, of the magnetic grinding materials. According to the method, the grinding material particles and the magnetism sensing core particles are sintered through the high-temperature-sintered binding agent powder, so that the oxidizing degree of the magnetism sensing core particles can be effectively reduced. The preparation method is simple in processes, and industrial production is easily carried out.

A rotor for an electric machine excited by magnetic poles formed by one or more embedded permanent magnets includes a magnetic body and the one or more embedded permanent magnets associated with the magnetic body defining first magnetic poles and second magnetic poles of alternating magnetic polarity along a rotor direction. For at least one of the one or more embedded permanent magnets a rotor segment is arranged between the one or more embedded permanent magnets and a first surface of the magnetic body. At least one retainer element connects the rotor segment to a portion of the magnetic body.