79results about How to "Does not affect contact" patented technology

The invention provides a titanium dioxide / metal core-shell structure composite nano-particle and a preparing method thereof. The method comprises the steps that a water solution of titanium dioxide hollow nano-particles with inner surfaces modified with amino is provided and is scattered in a chloroauric acid water solution, and ultrasound reaction is carried out after light shielding stirring is carried out for the first time; water bath heating is carried out, centrifugal separation is carried out after light shielding stirring is carried out for the second time, and Au@TiO2 composite nano-particles are obtained after drying; the Au@TiO2 composite nano-particles are annealed at the high temperature to obtain the titanium dioxide / metal core-shell structure composite nano-particle. The preparing method is simple, easy to operate and high in repeatability. The size of the prepared material is even. The specific surface area is improved through a hollow structure, and light catalysis is facilitated; a shell layer is thin, the scattering difficulty of electrons and cavities is lowered, and the shell can easily arrive at the surface of the material to be involved in the catalytic reaction; the material is good in dispersity in water, the purpose of further separating the electrons and the cavities is achieved through the titanium dioxide / metal core-shell structure, and the photocatalytic activity is improved.

The invention discloses a rolling brush structure with spiral blades. The rolling brush structure comprises a rolling brush body, hairs spirally arranged on the rolling brush body, a left connecting part and a right connecting part, wherein the left connecting part and the right connecting part are arranged at the two ends of the rolling brush body and connected with a suction chassis; the spiral blades are arranged on the rolling brush body; and the external ends of the blades are higher than the external ends of the hairs. The rolling brush structure has the advantages and positive effects that the spiral blades are respectively arranged between every two adjacent rows of hairs on the rolling brush structure, and when the rolling brush body rotates, the blades are rotated together, thus, certain axial flowing is brought to airflow when the spiral blades rotate, dust is blown toward the direction of a suction inlet, and the dust collecting efficiency of a dust collector is improved. Simultaneously, the external ends of the blades are higher than the external ends of the hairs, so that the hairs can be in contact with the ground or a carpet and can clean the ground or the carpet without being influenced, and the resistance occurred along with the rotating of the rolling brush body cannot be increased.

The invention relates to an ecological retaining wall, in particular relates to an ecological retaining wall with a segmented separation type baffling wall. The ecological retaining wall is divided into an upper water level region, a water level changing region and a lower water level region; the ecological retaining wall further comprises a segmented separation type baffling wall; and the segmented separation type baffling wall is arranged at the outer side of the lower water level region of the ecological retaining wall. The ecological retaining wall with the segmented separation type baffling wall, disclosed by the invention, prevents waves and reduces the brushing on a bank side. The baffling wall can be used for abutting against the brushing of main water surface waves of the outer side to a lake bank; meanwhile, a stable water surface is formed between the baffling wall and the common ecological retaining wall, so as to be good for aquatic plant growing, plant landscape plants including lotuses, water lilies, calamus and the like, and common ecological plants including reeds, scirpus tabernaemontani and zizania caduciflora, and purify water bodies; and the ecological retaining wall is far away from the bank to reduce the influence on landscapes, so as to form a waterfront landscape space which is separated from a main water surface. With the adoption of an offshore type structure, a distance of 3-5 m is reserved between the ecological retaining wall and a land region and the plants in the water are matched so as to weaken the landscape effects which are sudden with the baffling wall visually.

The invention relates to an electric connector combination, which at least comprises an insulating body, complex first terminals, complex second terminals and a flexible flat cable, wherein the insulating body is provided with complex terminal slots, and the first terminals and the second terminals are simultaneously assembled in the terminal slots and extended along the inner surfaces at two sides of the terminal slots respectively so that upper contact points of the first terminals and lower contact points of the second terminals are opposite vertically; and double surfaces of the flexible flat cable are provided with conductive contact points which can form electrically conductive connections with the upper contact points of the first terminals and the lower contact points of the second terminals respectively.

The invention belongs to the technical field of surface electroplating, and particularly relates to an electroplating brush device. The electroplating brush device comprises a brush application tank,a workpiece fixing device, a brush application device, a drive device, a brush application liquid conveying device and an infrared distance measuring sensor. A controller is used for automatically controlling the workpiece fixing device, the brush application device, the drive device, the brush application liquid conveying device and the infrared distance measuring sensor. A cam is arranged in a center hole of a friction wheel, an extrusion plate is arranged in a sliding groove of the friction wheel in a sliding manner, two air bags are symmetrically arranged on the left side and the right side below the friction wheel, the lower ends of the air bags are connected with second one-way valves, the second one-way valves communicate with water spraying discs, the water spraying discs are fixedly connected to the middle portions of hair bundles, electroplating liquid is evenly sprayed to the upper ends of the hair bundles, and accordingly the uniformity of a workpiece surface clad layer isguaranteed; and when the friction wheel drives the extrusion plate to the upper half part of the cam, the extrusion plate contracts into the friction wheel under the action of elasticity of springs, and accordingly contact between the friction wheel and the workpiece surface cannot be influenced.

The invention discloses a self-tightening sealing structure for a single detector. The self-tightening sealing structure comprises the detector, a tube base and a tubular connecting piece, wherein the tube base is provided with a fluid cavity and a detector introducing passage communicated with the fluid cavity; the lower end of the tubular connecting piece is arranged inside the detector introducing passage and connected with the tube base; the lower end of the detector is arranged inside the fluid cavity after passing through an inner bore of the tubular connecting piece and the detector introducing passage. An annular supporting platform is formed on the inner wall of the detector introducing passage; the detector is connected with a separation ring which is positioned below the tubular connecting piece and arranged on the annular supporting platform; a filling sealing member is arranged in an area between the tubular connecting piece and the separation ring. The self-tightening sealing structure is simple integrally, is convenient to install and disassemble, and has a reliable self-tightening sealing function to ensure a good sealing effect and improve the safety of the detector.

A preparation method of a UV viscosity reducing protective film comprises the following steps: S1, respectively extruding a copolyester layer raw material and a PET base layer raw material by two extruders and then co-extruding to form a base film; S2, performing longitudinal stretching and transverse stretching on the base film to form a stretch film; S3, pressing a plurality of rectangular pyramids distributed in a rectangular shape on the copolyester layer by using a heated mould pressing roller with patterns; S4, carrying out an addition surface treatment on the surface of the base film; and S5, filling the space between the rectangular pyramids with an ultraviolet viscosity reducing layer, and then attaching a release film to the ultraviolet viscosity reducing layer. Compared with a common UV viscosity reducing film, the contact area between the ultraviolet viscosity reducing layer and the base film is much larger, the peeling strength is large; the base film does not influence the contact between the ultraviolet viscosity reducing layer and a bonded object, the peeling strength is not influenced, after UV irradiation, the ultraviolet viscosity reducing layer is further crosslinked, part of the base film is exposed from the ultraviolet viscosity reducing layer and forms a fulcrum on the surface of the bonded object, and the peeling strength is further reduced.

This invention relates to a shield isolation breaker including static contactors and a dynamic contactor, in which, an isolation device is set between the two static contactors at both sides containing a shell, a flex board and a flat-push board, the shell is fixed on the base, the flex board makes up of a moving pair with a flex leading groove on the surface, a flexible leading inclined plane inserted into the leading groove is set on the flat push board, the groove is matched with the narrow end of the plane corresponding to the contact position of the static and dynamic contactors and the contractive position to the shell, the groove is matched with the wide end of the plane against the off-contact position of the contactors and the extending position to the shell, which can either isolate the cavity between two sides of contactors or shield the arc between dynamic and static contactors in the process of arc suppression.

The invention discloses a lithium battery anode and a preparation method, a lithium battery and a preparation method and an application. The lithium battery anode comprises a current collector, a cathode material layer combined on the surface of the current collector, and a protection layer combined on the cathode material layer surface and a cathode material layer aperture wall. The lithium battery anode can inhibit the generation of betatopic oxidation reaction of an electrolyte solvent when the high voltage is used, and the antioxidation capability of the electrolyte is increased. The lithium battery contains the lithium battery anode, and its electrochemistry performance is excellent. The preparation method of the lithium battery anode and the lithium battery has the advantages of simple technology, easy condition control and high efficiency, and is adapted to industrial production.

The invention relates to an adjustable auto-transformer capable of automatically locking a carbon brush arm length. The adjustable auto-transformer comprises a shell, an annular iron core, a winding and a carbon brush arm and is characterized in that the shell is hollow and cylindrical, the center of the lower end face of the shell is provided with a lower through hole, the upper edge of the lowerthrough hole is provided with an inner threaded cylinder, the lateral wall of the inner threaded cylinder is longitudinally provided with an outer routing hole, the upper end of the shell is providedwith an opening and detachably connected with an annular upper cover, and the inner end face of the lateral wall of the shell is provided with a pawl and an unlocking protruding head; the carbon brush arm comprises a hollow circular tube, a carbon brush support, a lead device, a drive handle and a drive swing arm. The adjustable auto-transformer has the advantages that the radial length from thecontact part of a carbon brush body and the winding to the axis of the hollow circular tube can be adjusted precisely; a rotary mandrel can be locked through a locking ejector pin to finally fix the position of the carbon brush body, and radial deviation of the carbon brush body when the carbon brush body operates along with the drive swing arm is avoided.

The invention provides an improved spiral case structure at the outdoor side of a window air conditioner, which comprises a spiral case arranged at the outdoor side of a box body of the window air conditioner, wherein the inside of the spiral case is used for arranging a fan, two outside wall surfaces of the spiral case are positioned between inlet and outlet pipe bodies of a condenser at the outdoor side of the box body and a water ring of the fan. The improvement of the spiral case structure lies in that two outside wall surfaces, which are close to the side wall of the outdoor side of the box body of the spiral case are provided with an arc-shaped body respectively which is convex towards the side wall of the box body, which increases a clearance between the outside wall surfaces of the spiral case and the water ring of the fan, can not affect the contact to the pipe bodies, avoids the problem that the water ring of the fan and the inlet and outlet pipe bodies of the condenser interfere with each other, realizes the maximization of the size of the fan, assures the heat needed by heat exchange of the outdoor side, and ensures that the water ring of an axial-flow fan can contact condensed water to achieve efficacies of effectively utilizing the condensed water, improving condensing effect, reducing condensing temperature and input power, reducing work noise, improving the energy efficiency ratio (EER) of the air conditioner, and optimizing working environment.

The invention belongs to the technical field of metal surface repair, in particular to a metal shell surface repair process. A surface film plating device in the process comprises a brushing tank, a workpiece fixing device, a brushing device, a driving device, a brushing liquid conveying device and an infrared distance measuring sensor; the workpiece fixing device, the brushing device, the drivingdevice, the brushing liquid conveying device and the infrared distance measuring sensor are automatically controlled through a controller; a cam is arranged in a center hole of a friction wheel; an extrusion plate is slidingly mounted in a chute of the friction wheel; two airbags are symmetrically arranged on the left and right sides under the friction wheel; the lower ends of the airbags communicate through a second one-way valve water spraying disc to realize uniform spraying of electroplating liquid to the upper ends of pieces so as to guarantee the surface plating layer uniformity of workpieces; and when the friction wheel drives the extrusion plate to rotate to the upper half part of the cam, the extrusion plate shrinks into the friction wheel under the effect of elastic force of a spring without influencing the contact of the friction wheel and the surfaces of the workpieces.

The invention relates to a biomass nanocellulose / nano transition metal oxide porous material, and a preparation method and application thereof. Nano transition metal oxide is loaded on the surface of biomass nanocellulose through non-covalent interaction. The biomass nano cellulose / nano transition metal oxide porous material has both adsorption and catalysis functions, and can be used as a recyclable adsorption and degradation material; when being used as an adsorption catalytic degradation material, the porous material has the advantages of high adsorption catalytic degradation efficiency, environment friendliness, excellent regeneration capacity, easiness in separation, recyclability and no repeated pollution, and has a considerable application prospect.

The invention relates to a lithium ion battery for an automobile. At present, no lithium ion battery with reasonable structural design and stable performance for the automobile exists. The lithium ion battery comprises a battery core, an upper cover, an anode terminal, a cathode terminal and a shell, and is characterized by further comprising an anode conductive metal plate, a cathode conductive metal plate, an anode cover plate, a cathode cover plate, a temperature detection guard plate and a metal isolation groove, wherein the anode terminal comprises an anode terminal body, an anode boss and an anode temperature measuring head; the anode conductive metal plate is fixed on the battery core anode plug of the battery core; the anode terminal body is fixed on the anode conductive metal plate; the cathode terminal comprises a cathode terminal body, a cathode boss and a cathode temperature measuring head; tThe cathode conductive metal plate is fixed on the battery core cathode lug of the battery core; the cathode terminal body is fixed on the cathode conductive metal plate; the wall faces of the shell are provided with multiple rows of heat-dissipating holes; and the inner walls of the wall faces, provided with the heat-dissipating holes, of the shell are provided with multiple heat-conducting grooves. The lithium ion battery for the automobile has the advantages of reasonable structural design, good heat dissipation and stable performance.

The invention relates to the technical field of water treatment, in particular to circular super-effect shallow air flotation filter treatment equipment and a treatment process thereof. The circular super-efficiency shallow air floatation filter treatment equipment comprises a filter pressing device and an air floatation biological filter for further purifying water filtered by the filter pressing device, wherein the filter pressing device comprises filter plates, a push plate assembly, a connecting rod assembly and a transmission assembly; there are even number of filter plates which are stacked and arranged in the left-right direction, and rollers are arranged on the front side and the rear side of the middle of each filter plate; the push plate assembly is used for pushing the filter plates to open; every two filter plates form a group in sequence from left to right, and each group of filter plates comprises a first filter plate positioned on the left side and a second filter plate positioned on the right side; the connecting rod assembly is configured to enable the second filter plate to be lifted upwards within a preset distance of rightward movement of the second filter plate; the transmission assembly enables the inner ends of the rollers of the first filter plate to move rightwards along with the second filter plate when the second filter plate is lifted upwards so that the rollers of the first filter plate are inclined, and the first filter plate is prevented from sliding rightwards along with the second filter plate under the adhesion of a filter cake.

The invention discloses a storage battery positive pole plate and a manufacturing method thereof. The storage battery positive pole plate comprises a plate body and the upper and lower surfaces of the plate body are provided with glass fiber mat layers. Each one of the glass fiber mat layer has thickness of 0.2+ / -0.03mm. The manufacturing method comprises 1, filling a continuously produced grid band with lead paste to obtain a pole plate band main body, 2, pasting glass fiber mats to upper and lower surfaces of the pole plate band main body to obtain a pole plate band, 3, compressing the film-coated pole plate band so that the glass fiber mats are fully bonded to the pole plate band main body, 4, cutting the pole plate band to obtain pole plates, 5, stacking the cut pole plates, 6, putting the stacked pole plates in a curing chamber and carrying out curing and drying and 7, carrying out natural cooling. The surface of the positive pole plate is provided with the netted porous glass fiber mat layer so that contact between an electrolyte and an active substance is not influenced, the glass fiber mat layer effectively prevents plate active substances on the plate body from falling off, positive and negative pole plate short circuit caused by the fallen active substances is avoided and a lead acid battery service life is effectively prolonged.

The invention discloses a sampling pipe used for chemical technology process monitoring. The sampling pipe used for chemical technology process monitoring comprises a sampling outer pipe fixed to theside wall of a reaction container in a penetrating mode and a sampling inner pipe which is installed in the sampling outer pipe coaxially and rotatably in a sealed and matched mode, wherein multiple first sampling inlets are formed in the side, facing the material movement direction, of the sampling outer pipe, the interior of the sampling inner pipe is a sampling cavity used for receiving material which falls in through second sampling inlets from the first sampling inlets, the side, outside the reaction container, of the sampling cavity is communicated with the outside, an air cavity used for introducing compressed air into the sampling cavity is formed in the sampling outer pipe, and the air cavity is connected with a compressed air source through an air source pipeline. According to the sampling pipe, by means of an internal backflushing design, contact between the reaction container and the sampling pipe is not affected, and detection is accurate; by means of the air cavity air supply design, a blocking problem can be solved without taking out the sampling pipe, so that use is convenient; by means of the inner and outer pipe design, switching is flexibly carried out between sampling and backflushing.

The invention relates to an adjustment method of an adjustable auto-transformer capable of automatically locking length of a carbon brush arm, and the adjustable auto-transformer capable of automatically locking length of the carbon brush arm is adopted for adjustment; the adjustable auto-transformer capable of automatically locking length of the carbon brush arm comprises a shell, annular iron cores, windings and a carbon brush arm; the adjustment method comprises the steps of 1, rotating a driving handle; 2, maintaining the position of a carbon brush body; and 3, performing reciprocating extension and retraction of the carbon brush body. By adoption of the adjustment method of the adjustable auto-transformer capable of automatically locking length of the carbon brush arm, the radial length from the contact part, between the carbon brush body and the winding, to a hollow circular tube axis can be adjusted; accurate adjustment can be realized, and the radial length of the winding can be utilized effectively; and a rotational core shaft can be locked by a locking top rod, and the position of the carbon brush body can be fixed finally, so that radial offset of the carbon brush body in transfer process of a driving swing arm can be avoided.

The invention discloses a slot board with a high sealing performance, and relates to the technical field of line concentration cable arrangement equipment. When a cable is aligned, a fastener is turned and moves towards a cover plate until the fastener is embedded into a clamp slot, and a pushing strip is driven to slide by sliding of the fastener, so that a limited post on the pushing strip slides. As the limited post penetrates a sliding slot and the sliding slot is inclined to a vertical plane, the limited post pushes a guide post and a whole upper sealing element to slide downwards when sliding. Owing to elastic restoring force of a compression spring, the upper sealing element constantly slides downwards until the upper sealing element is abutted to a lower sealing element, an upper cable slot is arranged on the upper side of the cable in a fitted manner, and dust more difficultly enters a threading slot.

The invention relates to the technical field of household appliance equipment, in particular to a safe automatic wire connecting double-side socket. In order to overcome the defects of difficult wire connection, no safety, high cost and poor contact, the safe automatic wire connecting double-side socket comprises power copper plates, cams, switch shifting forks, a gum cover and a lock ring. The double-side socket is characterized in that one side of each of three copper plates is respectively provided with a cam, while the other side is provided with a cam for a switch; two holes of the switch cam are matched with switch shifting forks; axial holes of three wire connecting cams are diagonally provided with a return spring hole; and a small ring tows the return spring hole to make the cams deflected and pressed against the copper plates. One end of the gum cover is jointed with a silk bushing at the wire connecting part, while the other end is provided with the lock ring which is screwed with the silk bushing; grounding copper plates, the power copper plates, and the like are fixed by shuttering rests and elastic foam rubber blocks; the cams are designed into a cylinder shape; the four cams have the same size; and the back side of the socket is also provided with power jacks and common earthing jacks with the same number. The double-side socket has the characteristics of automatic wire connection, safety, low cost and capability of being inserted on two sides.

The invention relates to an autotransformer with adjustable telescopic damping of a carbon brush body. The autotransformer comprises a shell, annular iron cores, windings and a carbon brush arm. The invention further relates to an adjusting method of the autotransformer with the adjustable telescopic damping of the carbon brush body. The method comprises the following steps of step 1, rotating a rifled tube; step 2, carrying out reciprocated telescoping of the carbon brush body; and step 3, adjusting the telescopic damping of the carbon brush body. According to the adjusting method, the radiallength from a contact part of the carbon brush body and the windings to the axis of a hollow round tube can be adjusted; accurate adjustment can be realized, and the radial length of the windings canbe effectively used; the telescopic damping of the carbon brush body can be adjusted, and the uncontrollable telescoping caused by unsmooth winding surface shapes when a telescopic flat plate and thecarbon brush body slide on the windings is avoided; the damping adjustment of the telescopic flat plate and the carbon brush body in two different contact forms can be realized.

The invention discloses a method for manufacturing a low-temperature silicon carbide ohmic contact, comprising the following steps of S1, preparing an N-type or P-type silicon carbide substrate, and preparing a region where an ohmic contact is required to be manufactured; S2, depositing layers of metal on the ohmic contact region to form a metal layer, wherein the metal layer includes, in order from bottom to top, a nickel thin film layer formed by evaporation, an amorphous silicon thin film layer formed by sputtering, and a titanium thin film layer formed by evaporation or sputtering, and wherein an atomic ratio of silicon in the nickel thin film layer to nickel in the amorphous silicon thin film layer is greater than 0.25 but less than or equal to 0.50; and S3, annealing the metal layerat an annealing temperature of 600 to 780 degrees centigrade to prepare the ohmic contact structure. The method not only reduces the ohmic contact annealing temperature, but also prevents carbon deposition.

The invention relates to the technical field of hydrogel, and provides a preparation method of a hydrogel flexible strain sensor with resistance-capacitance dual modes and the sensor. The sensor is formed by laminating and compounding hydrogel and a flexible grid electrode, according to different wiring modes, the sensor has a resistive working mode and a capacitive working mode, resistive sensing is achieved through the flexible grid electrode with strain response capacity, capacitive sensing is achieved through a double-electric-layer capacitor at the interface of the hydrogel and the flexible grid electrode, and thesensor can be used for detecting tensile strain; and the whole flexible device designed by the invention has good stretchability, high sensitivity and wide detection range, can realize real-time monitoring of tiny and violent human motion, and can be applied to the fields of wearable equipment, flexible robots, electronic skin and the like.

The invention discloses a method for dispersing carbon paste on pins PIN and a carbon paste dispersing system. The method includes the following steps of firstly, placing a sheet PIN roll on a transmission device, stretching one end of the sheet PIN roll and fixing the end into a second disc, and making bayonets of all the pins PIN in the sheet PIN roll face downwards; secondly, placing a carbon paste box containing the carbon paste between a first disc and the second disc; thirdly, starting the transmission device so that all the pins PIN can pass through the carbon paste box, and winding all the pins PIN in the second disc in rolls after coating the bayonets of all the pins PIN with the carbon paste in the carbon paste box. On the premise of not influencing contact performance, the carbon paste dispersing efficiency is improved, a solution is provided for production automation, the full contact between the pins PIN and an LCD electrode is ensured, and contact resistance is reduced.

The invention discloses an adjustable stern shaft rubber sealing device which comprises a stern shaft, a front end cover, a rear end cover, a sealing assembly, and an adjusting mechanism. The adjusting mechanism is additionally arranged; a driving screw rod is rotated to drive an adjusting block to transversely move, so that the adjusting block abuts against the inner end of an abutting elastic body; and when the adjusting block extrudes the abutting elastic body towards the outer end, the abutting elastic body extrudes a driving ring towards the outer side due to the force transmissibility, so that the abutting sealing ring abuts against the rear end cover more tightly, and therefore the abutting degree can be adjusted.

The invention relates to a display device, an array substrate, a thin film transistor and a manufacturing method thereof, and relates to the technical field of display. The thin film transistor comprises an active layer, a gate insulating layer, a gate electrode, a dielectric layer, a source electrode and a drain electrode. The active layer is provided with a channel region, doped regions located on the two sides of the channel region and buffer regions separated between the doped regions and the channel region, and the doping concentration of the buffer regions is smaller than that of the doped regions. The gate insulating layer is arranged on one side of the active layer, covers the channel region and the buffer region, and exposes the doped region. The grid electrode is arranged on the surface, away from the active layer, of the grid insulating layer, and the projection of the grid electrode on the active layer coincides with the channel region. The dielectric layer covers the grid electrode, the grid insulating layer and the active layer; the source electrode and the drain electrode are arranged on the surface, away from the active layer, of the dielectric layer, located on the two sides of the channel region and connected to the different doped regions.

The invention discloses an automatic compression expansion type wastebin comprising a bin cover, an inner bin body and an outer bin body. A vertical groove and a liquid storage cavity are symmetrically formed in the side wall of the outer bin body, a circular groove is formed in the bottom wall of the outer bin body, a sliding groove is formed in the side wall of the outer bin body and located below the vertical groove, and a pedal is installed in the sliding groove in a sliding mode. A trigger piece is arranged on the groove wall of the sliding groove, a first gear and a first toothed plate which are meshed with each other are installed in the vertical groove, the lower end of the first toothed plate penetrates through the vertical groove and is fixedly connected with the pedal, the firstgear is fixedly connected with a winding pipe, and a second gear and a second toothed plate which are meshed with each other are installed in the circular groove. A second pull rope is fixedly connected between the second toothed plate and the winding pipe, and a magnetic plate is coaxially supported by the second gear. By means of the automatic compression expansion type wastebin, waste paper inthe wastebin can be automatically compressed and softened, the space occupied by the paper is further reduced, and therefore the capacity of the wastebin is relatively increased.

The invention provides a high-load graphitized carbon layer coated transition metal nanoparticle catalyst and a preparation method of the transition metal nanoparticle catalyst. The graphitized carbon layer coated transition metal nanoparticle catalyst is composed of core-shell structure nanoparticles anchored by porous carbon networks distributed on a carbon substrate, wherein the core is transition metal nanoparticles, the shell is a graphitized carbon layer, the transition metal nanoparticles are coated with the graphitized carbon layer, and the core-shell structure of the metal nanoparticles is fixed on the carbon substrate by the porous carbon network. The catalyst is obtained by using a carbon-substrate supported metal hydroxide as a metal source, coating a high-molecular polymer on the outer layer of a transition metal hydroxide through a polymerization reaction and then carrying out heat treatment. The graphitized carbon layer coated transition metal nanoparticle catalyst prepared in the invention has the advantages of high metal loading capacity, small particle size and uniform distribution. The catalyst is excellent in oxygen reduction and oxygen evolution reaction catalytic performance, and has huge potential application value in many industrial catalysts or other scientific fields.