247 results about "Magnetic media" patented technology

An apparatus, in accordance with one aspect of the present invention, includes a magnetic head having an array of transducers, the transducers comprising data elements, at least two first servo readers positioned toward a first end of the array and at least two second servo readers positioned toward a second end of the array. The array is symmetrical about a centerpoint of the array, such that a distance between a center of an innermost one of the first servo readers and a center of the data element closest thereto is the same as a distance between a center of an innermost one of the second servo readers and a center of the data element closest thereto, and such that a distance between a center of an outermost one of the first servo readers and the center of the data element closest thereto is the same as a distance between a center of an outermost one of the second servo readers and the center of the data element closest thereto.

The invention provides a double-magnetic-source micro-nano magnetic medium sealing device and a gas turbine, and relates to the technical field of sealing devices.The double-magnetic-source micro-nano magnetic medium sealing device comprises an outer rotor, an inner rotor, a first sealing assembly and a second sealing assembly; the first sealing assembly and the second sealing assembly are matched with the cavity and comprise first pole shoes, permanent magnets and second pole shoes which are sequentially arranged in the first direction, and the magnetic pole direction of the permanent magnets and the direction where the pivoting axis of the inner rotor is located are the first direction. The polarity of the permanent magnet of the first sealing assembly and the polarity of the permanent magnet of the second sealing assembly are opposite, and the permanent magnet of the first sealing assembly and the permanent magnet of the second sealing assembly are spaced in the radial direction of the inner rotor. Micro-nano magnetic media are adsorbed between the first pole shoe of the first sealing assembly and the first pole shoe of the second sealing assembly and between the second pole shoe of the first sealing assembly and the second pole shoe of the second sealing assembly. According to the invention, the stroke of a magnetic loop is shortened by adopting double magnetic sources, the magnetic field intensity at a sealing gap is increased, and the pressure resistance of a micro-nano magnetic medium under a high-speed working condition is improved.

An apparatus, in accordance with one aspect of the present invention, includes a magnetic head having an array of transducers, the transducers comprising data elements, at least two first servo readers positioned toward a first end of the array and at least two second servo readers positioned toward a second end of the array. The array is symmetrical about a centerpoint of the array, such that a distance between a center of an innermost one of the first servo readers and a center of the data element closest thereto is the same as a distance between a center of an innermost one of the second servo readers and a center of the data element closest thereto, and such that a distance between a center of an outermost one of the first servo readers and the center of the data element closest thereto is the same as a distance between a center of an outermost one of the second servo readers and the center of the data element closest thereto.

The invention provides a multi-waveform magnetic field generating device for magnetic hyperthermia. The multi-waveform magnetic field generating device comprises a power supply module, a BUCK voltage regulating circuit, a multi-waveform signal generating circuit, a power amplifying circuit, a series resonance inverter circuit, an induction coil, a water cooling module, a temperature acquisition module, a DSP microprocessor and a TFT display screen. The power supply module is combined with BUCK to supply power to the device; the multi-waveform signal generation circuit, the power amplification circuit and the series resonance inverter circuit are used for generating an alternating magnetic field to act on a magnetic medium to generate a heat effect and realize magnetic hyperthermia; the water cooling module is used for reducing the temperature of the induction coil; the temperature acquisition module acquires temperature data of a treatment area and performs output control on the Buck voltage regulation circuit by using the DSP microprocessor so as to regulate the output power of the power amplification circuit powered by the BUCK voltage regulation circuit and realize intelligent temperature control of the magnetofluid; the problems that in the prior art, a magnetic field generation device is single in induction waveform and poor in heat generation effect are solved.

The invention relates to a pressure and temperature multifunctional sensor for energy collection and a manufacturing method thereof, the pressure and temperature multifunctional sensor adopts a double-layer composite structure: an upper wire coil layer is composed of a liquid metal coil embedded in a PDMS substrate, silver paint and a wire connected with the silver paint, and a lower magnetic fiber network layer is formed by weaving magnetic liquid crystal elastomer LCE composite fibers; the two are structurally integrated through a bonding layer; a coil conductive loop in the upper wire coil layer is formed on the surface of the PDMS substrate through a direct-writing printing technology, and packaging protection is completed through secondary pouring of PDMS; the LCE composite fiber takes an LCE hollow fiber tube as an external carrier, magnetorheological fluid is filled in the LCE composite fiber to serve as a magnetic medium, and two ends of the LCE composite fiber are sealed and packaged by adopting a compound of neodymium iron boron magnetic particles and PDMS (Polydimethylsiloxane). The sensor provided by the invention not only can realize pressure and temperature sensing, but also can be used as an energy collection device, provides a new solution for sustainable development of wearable equipment and sensors, and has a wide application prospect.

Methods and apparatus of identifying a substrate suitable for a magnetic medium of a data storage device configured for magnetic recording are described. In an aspect, the method includes determining a roll-off value, a ski-jump value, and a radial-waviness value, each associated with an outer diameter (OD) edge region of a data surface of the substrate, and determining a calculated minimum fly height between a slider of the data storage device and a data surface of the substrate in the OD edge region based on the roll-off value, the ski-jump value, and the radial-waviness value. The method further includes comparing the calculated minimum fly height and a fly height threshold, and determining whether to utilize the substrate for the magnetic medium based on the comparison of the calculated minimum fly height and the fly height threshold.

The utility model discloses a vertical magnetic cyclone precipitation combined device which comprises a secondary precipitation tank and a cyclone separator arranged in the secondary precipitation tank, the upper part of the cyclone separator is a cylindrical barrel, the lower part of the cyclone separator is of a conical structure, and an underflow outlet is formed in the bottom of the conical structure; a rotary magnetic system capable of generating spiral downward magnetic field force is arranged outside the cylindrical barrel; the inner wall of the cylindrical barrel is provided with a spiral magnetic conductive piece used for magnetism gathering and current stabilizing. A central overflow barrel is mounted in the cylindrical barrel, and an overflow discharge hole communicated with the secondary precipitation tank is formed in the top of the central overflow barrel; the side surface of the cylindrical barrel is connected with a tangential mud inlet pipe which is connected with a water inlet; a water outlet is formed in the top of the secondary precipitation tank. The device can be used for recovering a magnetic medium in magnetic coagulating sedimentation or a magnetic biofilm carrier in a magnetic biochemical system. The device has the characteristics of reasonable structural design, low energy consumption and wide application range, and is high in separation and recovery efficiency of the magnetic medium and the magnetic biofilm carrier.

The invention discloses a vertical ring magnetic separation device adopting a saddle-shaped coil and a magnetic separation method of the vertical ring magnetic separation device, and relates to the technical field of mine metallurgy, the vertical ring magnetic separation device comprises an integral support, a magnet system, a rotating ring, a feeding assembly and a discharging assembly, and the magnet system is fixedly arranged on the integral support and surrounds part of the rotating ring; the magnet system comprises at least one saddle-shaped coil, and the arc-shaped face, facing the rotating ring, of the saddle-shaped coil is matched with the ring face of the rotating ring. The saddle-shaped coil is adopted, the arc-shaped working face of the saddle-shaped coil is matched with the height space of the annular contour of the rotating ring, magnetic field distribution is fundamentally optimized, magnetic field energy is highly concentrated and accurately acts on a magnetic medium filled in the rotating ring, the field intensity far exceeding that of a traditional runway-shaped coil can be obtained, and the collecting capacity of weak magnetic minerals is remarkably improved; the optimization of the magnetic field further reduces the dependence on the magnetic conductive yoke, so that the overall structure weight of the magnet system is reduced, and the cost is reduced.

Mode hop detection is provided. A device includes circuitry to receive, from a reader element an indication of one or more properties of a magnetic medium detected by the reader element. The device includes circuitry to determine an envelope of the signal. The device includes circuitry to adjust, responsive to the envelope, a current provided to a laser configured to heat the magnetic medium.

The present disclosure generally relates to a magnetic media drive comprising a magnetic recording head. The magnetic recording head comprises a main pole disposed at a media facing surface (MFS), a shield disposed at the MFS, a spin blocking layer disposed between the shield and the main pole, at least one non-magnetic layer disposed between the main pole and the shield, the at least one non-magnetic layer being disposed at the MFS, and at least one spin orbit torque (SOT) layer disposed over the at least one non-magnetic layer, the SOT layer being recessed a distance of about 20 nm to about 100 nm from the MFS. A ratio of a length of the SOT layer to a thickness of the SOT layer is greater than 1. The at least one SOT layer comprises BiSb.

The utility model discloses a medium box for fine fraction separation of a vertical ring high-gradient magnetic separator, which belongs to the technical field of magnetic mineral separation equipment and comprises two fixing plates. At least one supporting plate is located between the two fixing plates. The two ends of the multiple reinforcing medium rods are connected with the fixing plate and penetrate through the supporting plate. The multiple reinforcing medium rods are distributed along the edge and form a medium containing cavity with the fixing plate. A plurality of spaced medium rods are positioned in the medium accommodating chamber, and two ends of the spaced medium rods are connected with the fixing plate and penetrate through the supporting plate; the diameter of the spacing medium rod is not greater than that of the reinforcing medium rod; the magnetic medium is embedded in a gap between the adjacent interval medium rods; the reinforcing medium rods and the spacing medium rods penetrate through the supporting plate and are fixedly connected with the fixing plate, so that the structural strength can be improved; the reinforcing medium rods, the spacing medium rods and the magnetic medium are arranged in order, so that a compact mineral separation medium can be formed, and the recovery rate of fine-fraction minerals is increased; and the magnetic medium can be conveniently pulled out and cleaned, so that the cleaning difficulty is reduced.

The invention provides a heat dissipation type magnetic medium sealing device, and relates to the technical field of sealing devices.The heat dissipation type magnetic medium sealing device comprises a shell, a rotating shaft and a magnetic sealing assembly; the rotating shaft is pivotally connected with the cavity, at least one end is located outside the shell, the rotating shaft is provided with a heat exchange channel, and at least part of the heat exchange channel is located outside the shell; the magnetic sealing assembly is matched with the cavity and sleeves the rotating shaft, a sealing gap is defined between the inner circumferential surface of the magnetic sealing assembly and the outer circumferential surface of the rotating shaft, and a magnetic medium is adsorbed in the sealing gap; the heat exchange channel is arranged adjacent to the sealing gap, a phase change medium is arranged in the heat exchange channel, the phase change medium has a first state and a second state, and the phase change medium can be switched between the first state and the second state so as to exchange heat with the magnetic sealing assembly. Magnetic medium sealing heat exchange can be enhanced, the heat dissipation effect is good, and the linear speed and the working temperature of magnetic medium sealing can be improved.

The invention discloses a dredging device for an ore unloading water pipe of a vertical ring high-gradient magnetic separator, which belongs to the technical field of flushing ore unloading equipment, and comprises a separation rotating ring capable of rotating, and a magnetic medium box is arranged on the circumferential surface of the separation rotating ring; a plurality of water spraying holes are formed in the bottom of the ore discharging water pipe; the movable cross beam is arranged in the ore unloading water pipe, a plurality of conducting columns are arranged on the movable cross beam, and a high-pressure air channel is formed in the movable cross beam; an air injection hole communicated with the high-pressure air channel is formed in the conduction column, and a first valve is arranged between the air injection hole and the high-pressure air channel; the movable cross beam can move between a first position and a second position; at the first position, the conducting column is separated from the water spraying hole; at the second position, the conducting column extends into the water spraying hole, and the first valve is in an open state; the conducting column can extend into the water spraying hole to directly eject impurities in the water spraying hole, meanwhile, ore unloading water quickly flows through the gap, high-pressure gas is sprayed out of the gas spraying hole, and the impurities on the inner wall of the water spraying hole are thoroughly removed through the combined action of the two.

The invention discloses an integrated treatment process for heavy metal wastewater. The integrated treatment process comprises the following steps: step 1, pretreatment; 2, biological agent treatment; step 3, air flotation and magnetic separation; step 4, precipitation and separation; step 5, post-processing; step 6, magnetic medium separation and recovery; wherein in the second step, a biological agent adding unit and a hydrolysis reaction unit are included, the biological agent treatment unit comprises a stirrer, an agent adding ring and a guide cylinder, the stirrer comprises a stirring motor and a stirring impeller, the stirring impeller is connected with the stirring motor and inserted into the guide cylinder, and the agent adding ring is connected with the stirring impeller and synchronously rotates with the stirring impeller; the flow guide cylinder is provided with a turbulent flow ring, the turbulent flow ring comprises a ring body and cutting teeth, the ring body is installed in the flow guide cylinder, and the cutting teeth are arranged on the ring body. Compared with the prior art, the purposes of efficient treatment, stable water outlet, land occupation and cost saving and convenience in installation and extension are achieved.

A magnetic medium is described which includes a thin film magnet structure formed of a ferromagnetic alloy or compound. The thin film magnet structure includes one or more ferromagnetic domains and is coupled to one or more optical structures. Each of the one or more ferromagnetic domains have a magnetization that is switchable between two or more states. Each of the one or more optical structures is configured to increase absorbance of light at a target wavelength in the thin film magnet structure, such that in response to illumination of a ferromagnetic domain with continuous-wave light including the target wavelength, that ferromagnetic domain undergoes all-optical magnetic switching.

A lubricant for magnetic media is synthesized using click chemistry. In one aspect the lubricant is according to general formula (I):where Rc is a fluorinated or non-fluorinated divalent linking segment; where each Re1 and Re2 is a click linker moiety that can be triazole or sulfone; n is from 2 to 50; where each Rb1 and Rb2 is an optionally non-fluorinated divalent linking segment optionally comprising at least one least one first anchoring functional group engageable with a protective overcoat of a magnetic recording medium; and where each of Rv1 and Rv2, when present, independently comprises a moiety having at least one second anchoring functional group engageable with the protective overcoat of the magnetic recording medium. The click linker moiety may also functional as an anchoring functional group.

The magnetic separation column comprises an ore feeding hopper, a tailing overflow groove, a separation column body, an electromagnetic system, a concentrate opening and a water feeding pipe, the ore feeding hopper is arranged at the top of the separation column body, the lower portion of the separation column body is communicated with the separation column body, the tailing overflow groove is formed in the upper portion of the separation column body, the concentrate opening is formed in the bottom of the separation column body, and the electromagnetic system is arranged outside the separation column body in a sleeved mode. The water supply pipe is inserted into the lower part of the sorting column; the device is characterized by further comprising a magnetism gathering medium body, the magnetism gathering medium body is fixedly arranged in the separation column, and the top of the magnetism gathering medium body corresponds to the uppermost electromagnetic system. According to the utility model, the phenomenon that fine-particle magnetite moves upwards along with rising water flow and enters tailings to cause black running is effectively avoided, so that the recovery rate of iron ore concentrate is increased, and the grade of the tailings is reduced.

The present invention relates to a piston dry superconducting magnetic separator and a dry magnetic separation and impurity removal method thereof, wherein the piston dry superconducting magnetic separator comprises a piston-magnetic medium structural assembly, a precision tube assembly, and a superconducting magnet; the precision tube assembly passes through the superconducting magnet and is relatively fixed in position; a piston-magnetic medium structural assembly capable of reciprocating along an axial direction is installed in the precision tube assembly; three groups of inlets and outlets are provided on the precision tube; the piston-magnetic medium structural assembly is provided with two separation zones along the axial direction, and the two separation zones are connected together; a separation zone central axis is provided in the separation zone, piston flanges are provided at both ends of the separation zone central axis, and magnetic medium is filled between the two piston flanges; a sliding fit is formed between the outer wall of the piston flange and the inner wall of the precision tube. The dry magnetic separation and impurity removal method, namely, using the above-mentioned piston dry superconducting magnetic separator to dryly remove impurities from high-purity powder, shortens the impurity removal process of the high-purity powder, and improves production efficiency.

A magnetic suction head includes a connecting wire, both ends of the connecting wire are provided with connecting heads, and two sets of the connecting heads are fixedly connected with the connecting wire through insulating layers respectively. Outer walls of two sets of the insulating layers are provided with magnetic sleeves, and the outer walls of the two sets of the insulating layers are magnetically suctioned together. By setting the magnetic sleeves at the two sets of the connecting heads, and the magnetic sleeves are molded by injection molding of a magnetic media and a plastic body. On the one hand, magnetic distribution is uniform, which is convenient for magnetic suction of the two sets of magnetic suction heads. On the other hand, it can reduce a weight and a structural dimension of the magnetic suction head, thereby improving usage experience.

The present invention relates to the field of spintronic technologies, and discloses an optical method for dynamically regulating the propagation direction of spin waves. Based on the excitation of spin waves by an ultrashort laser pulse, a liquid crystal spatial light modulator is used to dynamically shape the excitation light field, modulate the amplitude and phase of the excitation light field, obtain an arbitrarily controllable pulsed excitation light field distribution on the surface of a magnetic medium, and further generate a desired instantaneous spin wave source field, thereby realizing the dynamic regulation of the propagation direction of spin waves. This method can be controlled by a computer and has the advantages of flexibility, real-time performance, programmability, etc.

The invention discloses a dielectric composite electromagnetic interference suppression winding magnetic ring, and relates to the field of electronic components. The device comprises a winding belt, and the winding belt is arranged on the periphery of a suppressed cable in a winding mode to form a winding magnetic ring structure. One of the two modes is as follows: (1) a soft magnetic material-polymer composite belt: an electromagnetic functional material is a soft magnetic material; the winding belt is a magnetic medium composite belt material formed by compounding a soft magnetic material and a high polymer material. And (2) a soft magnetic material / dielectric material / high-molecular double-layer composite belt and a grounding metal layer, wherein the electromagnetic functional material comprises a soft magnetic material and a dielectric material. The winding belt is formed by compounding a soft magnetic material and a dielectric material with a high polymer material, the soft magnetic material and the high polymer material are compounded to form a magnetic dielectric layer, and the dielectric material and the high polymer material are compounded to form a dielectric medium layer; and the magnetic medium layer and the dielectric medium layer are overlapped along the thickness direction to form a double-layer composite winding belt. The resonant frequency and the insertion loss can be flexibly adjusted through the structure size and the material parameters.

The invention discloses a large electromagnetic slurry magnetic separator, and belongs to the technical field of magnetic separation equipment. The magnetic separation assembly comprises a bottom plate and a plurality of nested positioning cylinders, and the space between every two adjacent positioning cylinders is filled with a magnetic medium; a plurality of first through holes are formed in the bottom plate; a plurality of second through holes are formed in the circumferential surface of the positioning cylinder; the pre-magnetization cavity extends into the innermost positioning cylinder and is connected with a feeding pipe and a water inlet pipe, and a plurality of excitation rings are arranged in the pre-magnetization cavity; the driving assembly can drive the magnetic separation assembly to rotate; the magnetic separation assembly is positioned in the material barrel; a discharging pipeline is arranged at the bottom of the material barrel; the magnet exciting coil is arranged around the material barrel; in the magnetic separation stage, ore pulp enters the magnetic separation assembly through the pre-magnetization cavity, the excitation ring can magnetize weakly magnetic particles in the ore pulp, and the magnetized weakly magnetic particles are more easily adsorbed to a magnetic medium; in the iron removal stage, the driving assembly drives the magnetic separation assembly to rotate forwards and backwards, the flushing water can thoroughly clean the magnetic particles adhered to the magnetic medium, and regular disassembly and cleaning are not needed any more.

The present application belongs to the technical field of quartz sand sorting process and equipment, and particularly relates to a medium box dismounting device specially used for a vertical ring high gradient magnetic separator. The dismounting of the medium box of the magnetic separator completely depends on manual operation, which is complicated and inefficient, and the medium box is easily tilted, the nut is wrongly toothed or the mounting thread is damaged due to unstable clamping. The present application provides a medium box dismounting tool, which can tighten or loosen the fixing nut while clamping the medium box, thereby significantly improving the dismounting efficiency and safety. The dismounting device comprises a pair of clamping arms, the lower ends of the clamping arms are provided with clamping portions, and the medium box is arranged between the pair of oppositely arranged clamping portions of the pair of clamping arms to realize fixation. The present application can conveniently grasp, assemble and fix the magnetic medium box of the magnetic separator, reduces the subjective error probability of manual operation, saves time and effort, and is more convenient to take and operate in cooperation with a mechanical arm, can more labor-savingly align the assembly hole position, and more quickly rotates and tightens the nut.

The present disclosure relates to the pretreatment of a magnetic recording head assembly for a magnetic media drive. The magnetic recording head assembly comprises a slider with a media-side surface (MFS), an upper surface opposite the MFS, a trailing-edge surface adjacent to the upper surface, and an optical grating arranged on the trailing-edge surface. A vertical resonator surface-emitting laser device (VCSEL device) is mounted on the trailing-edge surface of the slider. The VCSEL device is aligned with the optical grating. A magnetic recording head, comprising a waveguide and a near-field transducer (NFT) coupled to the waveguide, is arranged on the trailing-edge surface of the slider. The VCSEL device is capable of emitting a plurality of phase-coherent lasers onto the optical grating.The optical grating is capable of directing the emitted laser beams at approximately 90 degrees to the waveguide.

This invention relates to the field of fluid impurity removal detection technology, and discloses an online detection method and system for the impurity removal efficiency of a fluid iron separator. The method includes: measuring the instantaneous content of magnetic impurities at the inlet and outlet in real time using a high-frequency electromagnetic induction sensor; monitoring the change in magnetic flux on the surface of the magnetic medium in real time using a miniature fluxgate sensor array; calculating the apparent impurity removal efficiency based on the impurity content at the inlet and outlet using an edge computing gateway, and simultaneously calculating the magnetic medium adsorption saturation based on the magnetic flux decay curve; weighting the apparent impurity removal efficiency using the magnetic medium adsorption saturation as a weight for adsorption effectiveness; when the magnetic medium adsorption saturation is lower than a preset saturation threshold, attenuation is performed according to the ratio of the apparent impurity removal efficiency multiplied by the magnetic medium adsorption saturation to the preset saturation threshold to obtain the true impurity removal efficiency. This invention solves the problem in existing technologies that cannot distinguish whether impurities are effectively retained or merely pass through the iron separator, achieving accurate detection of the true impurity removal efficiency.

A data storage device comprises a magnetic medium and a head configured to be actuated over the magnetic medium. The head comprises a write element and a write driver configured to generate a write current to be applied to the write element. The write driver comprises a data switch section configured to switchably output low-level signals and high-level signals, and a stationary cascode section configured to receive the low-level signals and high-level signals from the data switch section and to generate a cascode pass through current. The data switch section comprises low voltage CMOS devices and the stationary cascode section comprises high voltage CMOS devices.

The invention discloses a three-dimensional network structure magnetic fiber carrier reinforced micro-plastic magnetic separation removal method, which is characterized in that Fe3O4 nanoparticles are selectively precipitated among sepiolite fiber bundle layers by controlling a coprecipitation process, and a wedging effect is generated to realize controllable stripping of fiber bundles, so that a three-dimensional network structure magnetic carrier is formed; a mechanical interlocking structure is formed on the surface of the flexible fiber and the micro-plastic, and the pH of a water body is self-adaptively regulated and controlled through the amphoteric ionization characteristic of silicon hydroxyl; enabling the magnetic aggregate suspension to sequentially pass through a multi-stage gradient magnetic field consisting of a pre-magnetization field, a main separation field and a fine scavenging field, and controlling the flow rate to enable the aggregate to form a stable filter cake layer on the surface of a magnetism gathering medium, so as to realize efficient separation of the micro-plastic; and the magnetic gathering medium capturing the aggregate is subjected to heat treatment, so that the micro-plastic is thermally decomposed, the magnetic carrier is directly recycled, the magnetic performance is improved, and regeneration reinforcement is realized. The micro-plastic removal rate reaches 99% or above, the performance is stable after multiple cycles, and the method is suitable for treating various micro-plastic-containing water bodies.

The invention discloses a target object control method and device, and belongs to the technical field of computers. The target object control method comprises the following steps: constructing at least one sampling path corresponding to a target to-be-measured point based on the target to-be-measured point in a plurality of to-be-measured points in a target area corresponding to a magnetic medium object; the sampling path comprises at least one sampling point; based on the at least one sampling point included in each sampling path corresponding to the target to-be-measured point, obtaining a magnetic physical quantity corresponding to the target to-be-measured point; and controlling the target object based on the magnetic physical quantity. The target object control method can be suitable for various computer surface geometric discrete formats, accurate, efficient and large-scale magnetic physical quantity solving can be completed in various scenes, and therefore the control precision and accuracy of virtual or entity objects are improved.

The magnetic medium sealing device suitable for the hollow rotating shaft comprises a shell, the hollow rotating shaft and a magnetic sealing assembly, the hollow rotating shaft is arranged in the shell in a penetrating mode, a first permanent magnet surrounds the periphery of the hollow rotating shaft, and a first gap is reserved between the first permanent magnet and the hollow rotating shaft; the second permanent magnet is located on the side, facing the shell, of the hollow rotating shaft, a second gap is reserved between the second permanent magnet and the end of the hollow rotating shaft, the third permanent magnet surrounds the inner circumference of the hollow rotating shaft, a third gap is reserved between the third permanent magnet and the hollow rotating shaft, and the outer circumferential face of the hollow rotating shaft is provided with first pole teeth protruding towards the first gap. The end face of the hollow rotating shaft is provided with second pole teeth protruding towards the second gap, and the peripheral face of the third permanent magnet is provided with third pole teeth protruding towards the third gap. According to the magnetic medium sealing device suitable for the hollow rotating shaft, three-stage sealing is formed on the inner side, the outer side and the end of the hollow rotating shaft, and the requirements for sealing reliability and equipment light weight are met.

A lubricant for magnetic media according to general formula (I):Rv1-Rb1-Re1-Rc-Re2-Rb2-Rv2  (I);where Rc is an optionally non-fluorinated divalent linking segment comprising a first at least one anchoring functional group engageable with a protective overcoat of a magnetic recording medium; where each Re1 and Re2 has a rotational energy barrier that is greater than the rotational energy barrier of CH2; where each Rb1 and Rb2 independently is a chain segment comprising at least one of a fluoroalkyl ether moiety, a fluoroalkenyl ether moiety, a perfluoroalkyl ether moiety, a perfluoroalkenyl ether moiety, or a combination thereof; and where each of Rv1 and Rv2, when present, independently each has a second at least one anchoring functional group engageable with the protective overcoat of a magnetic recording medium. -Re1-Rc-Re2 may have the formula:where RL, if present, is CnM2, wherein M is H, and n is from 1 to 10.