43 results about "Hard chromium" patented technology

The invention belongs to the technical field of metal surface treatment, and discloses an electroplating additive suitable for a steel and alloy surface bright wear-resistant corrosion-resistant hexavalent chromium coating, which is characterized by comprising an organic compound, an inorganic acid, a metal inorganic compound and water, the organic compound comprises a mixture of a fluorine-free compound and a fluorine-containing compound. The method can be widely applied to decorative chromium plating and functional hard chromium plating, the electroplating temperature is 40-70 DEG C, the electroplating time of the decorative chromium plating is 1-10 min, the electroplating time of the hard chromium plating is 20 min or above, the hardness can reach 900 HV or above, the glossiness of the surface of a workpiece can be kept through the decorative plating and the hard chromium plating, the current efficiency can reach about 23%, and the service life of the workpiece is prolonged. The current use requirements of high efficiency, stability and environmental protection are met, and the market prospect is good.

The utility model provides a liquid expansion mandrel fixing device for processing a hard chromium plated ball, which belongs to the technical field of hard chromium plated ball processing, and comprises a mandrel main body, and the inner part of the mandrel main body is divided into cavities and is used for realizing uniform expansion; a filling hole is formed in one side of the core shaft main body and is used for filling a hydraulic medium into the core shaft main body; a sealing screw is arranged at an opening of the filling hole; an expansion chamber and a compression chamber are arranged in an inner cavity of the mandrel body, the compression chamber is arranged on one side of a center shaft of the mandrel body, and a linkage structure is arranged in the compression chamber and used for clamping a ball. The utility model provides a liquid expansion mandrel fixing device for processing a hard chromium plated ball, which can solve the problems that the clamping force is concentrated on a local area and a plating layer is easy to crush due to the single-cavity design of the existing liquid expansion mandrel.

The utility model discloses a highway pavement flatness detection device, and belongs to the technical field of highway pavement detection.The detection device comprises a pavement flatness detector vehicle body and an assembly frame installed on the pavement flatness detector vehicle body, and walking wheels are distributed at the lower end of the pavement flatness detector vehicle body at equal intervals; a wheel carrier is rotationally connected to the assembly frame, a measuring wheel is arranged at one end of the wheel carrier, a magnetic block is arranged at the other end of the wheel carrier, and a sensor corresponding to the magnetic block is arranged on the road surface flatness detector vehicle body; transverse movement of the clamping plates is achieved through rotation of the lead screw, the collection control box located between the two clamping plates is clamped or loosened, the surface of the positioning rod is plated with hard chromium, the positioning rod is matched with a linear bearing of the arm plate, it is ensured that the clamping plates move stably, and finally the two clamping plates get close to each other and clamp and fix the collection control box. If the acquisition control box needs to be taken down in the later period, the screw rod only needs to be manually and reversely rotated.

The application belongs to the technical field of alloy materials, and relates to a Cr-Fe alloy layer for prolonging the service life of a barrel and a preparation method thereof. The Cr-Fe alloy layer comprises Cr: 45-85wt%, Fe: 14-54wt%, C: 0-1.2wt%, and O content is less than or equal to 0.3wt%; the Cr-Fe alloy layer is prepared by laser processing, the microstructure is mainly BCC phase, and 3-8% of Cr 23 strengthening phase is uniformly precipitated; the Cr-Fe alloy layer is metallurgically combined with the barrel substrate, the surface Vickers hardness is 400-600HV, and the mass loss is less than or equal to 0.01g in 500 high-temperature erosion wear cycle tests. The Cr-Fe alloy layer with specific components is formed by optimizing laser processing parameters, microcracks of the hard chromium plating layer are effectively repaired, the high-temperature erosion wear loss rate is reduced, and the service life of the barrel is prolonged.

The utility model relates to the technical field of hard chromium plating, in particular to an automatic production device for hard chromium plating, which comprises a frame and a base, a barrel is fixedly connected to the middle of the lower end of a cover, two sides of the barrel are in threaded connection with bolts, rubber layers are fixedly connected to the tail ends of the bolts, and an electroplating box is fixedly connected to the right side of the upper end of the base. And a discharging opening is formed in the lower side of the right end of the electroplating box. According to the automatic production device for hard chromium plating, through cooperation of the moving mechanism and the frame, the first motor drives the connecting rod to rotate clockwise, the first motor is closed after the bent plate moves leftwards to be reset, in this way, the bent plate pushes a box on the conveying belt to the platform, then workers do not need to frequently carry steel pipes, the labor force of the workers is reduced, and the production efficiency is improved. Through the cooperation of the vibration mechanism and the cover body, the steel pipe plated with hard chromium is knocked and vibrated, so that a solution containing plating metal cations on the steel pipe is reduced, workers can pick up the steel pipe conveniently, and the practicability is improved.

The invention discloses an aluminum alloy surface anti-corrosion composition and a preparation method and application thereof.In the surface anti-corrosion composition, a WC hard phase provides the framework hardness of a coating, a Co-Cr metal phase endows the coating with good toughness, and the WC hard phase and the Co-Cr metal phase act synergistically, so that the obtained coating has excellent hardness, wear resistance and corrosion resistance; according to the surface anti-corrosion composition, rare earth powder is introduced to serve as an auxiliary, grains can be refined, grain boundaries can be purified in the coating, formation of a denser coating is promoted, an optimized Co-Cr metal phase is combined, and the corrosion resistance of the surface anti-corrosion composition is greatly improved. The long-acting corrosion resistance of the coating in severe environments such as salt mist and damp and hot environments is remarkably improved through synergism, bubbling and stripping of the coating and corrosion of a base body are effectively inhibited, and the remarkable corrosion resistance effect is achieved on the whole.

The utility model discloses a shock absorber working cylinder which comprises a working cylinder body, the inner surface of the working cylinder body sequentially comprises a uniform rough surface layer formed through preliminary honing, a hard chromium plating layer covering the uniform rough surface layer and a fine honing chromium plating layer located on the surface of the hard chromium plating layer, and the hardness of the fine honing chromium plating layer is larger than or equal to 800 HV. The surface roughness Ra is 0.1-0.4 micrometer, the roundness tolerance is smaller than or equal to 0.01 mm, and the straightness tolerance is smaller than or equal to 0.015 mm / 100 mm. Through the multi-layer structural design, the hardness, the surface smoothness and the geometric accuracy of the inner wall of the working cylinder are remarkably improved, friction force and abrasion are reduced, the service life is prolonged, and the durability of the working cylinder of the shock absorber is improved.

The present application discloses a hardware surface treatment process, which first cleans the hardware surface and forms a 0.01 to 0.05 micron thick pre-plating layer; then the pre-plating layer is subjected to microcrystallization treatment and annealed in a protective atmosphere to release internal stress; then a hard chromium layer is electroplated on the annealed hardware, the current density is controlled not to exceed 200 amperes per square meter to ensure uniform deposition; after electroplating, the hard chromium layer is subjected to polishing treatment, and a nanoscale oxide coating is applied to enhance the bonding force with the substrate; then the surface of the hard chromium layer is treated with ultrasonic vibration of 20 to 50 kHz frequency for 5 minutes to eliminate interface stress; finally, a silicone resin protective film is coated on the surface of the hardware, and is cured at 100 to 150 degrees Celsius for at least 1 hour to provide additional stress buffering effect. The present application effectively controls the internal stress between the substrate and the hard chromium plating layer through the above steps, reduces the occurrence of cracks, at the same time enhances the wear resistance and corrosion resistance of the plating layer, prolongs the service life of the hardware.

The utility model relates to the technical field of knurled bolts, in particular to a high-toughness wear-resistant knurled bolt for a heavy-duty car. The high-toughness wear-resistant knurled bolt for the heavy-duty car comprises a knurled bolt, and a conical anti-skid sleeve is sleeved on the outer ring of a screw rod of the knurled bolt; according to the knurled bolt, due to the good tensile strength and toughness of the alloy steel and the good wear resistance of the hard chromium, the whole knurled bolt can have high toughness and wear resistance, and when the knurled bolt penetrates through the bolt counter bore in the wheel to be in threaded connection with the threaded hole in the vehicle body, the conical anti-skid sleeve can be tightly attached to the bolt counter bore in the wheel, so that the anti-skid effect is good. And the anti-skid knurls at the bottom of the pressing ring can be tightly attached to the bottom of the inner side wall of the bolt counter bore in the wheel, so that the connection stability between the knurled bolt and the wheel can be effectively improved, the stress change range of the knurled bolt under the action of alternating loads can be reduced, the fatigue life is prolonged, and then the effect of reducing abrasion is achieved.

The invention relates to the technical field of intermediate film embossing, in particular to a continuous embossing method and device for a laminated glass intermediate film, the device comprises guide rollers, a cooling roller, a first embossing mechanism and a second embossing mechanism, and the intermediate film sequentially bypasses the first embossing mechanism, the cooling roller and the second embossing mechanism through a plurality of guide rollers. The first embossing mechanism and the second embossing mechanism are used for respectively embossing the two surfaces of the middle film; each of the first embossing mechanism and the second embossing mechanism comprises a pattern roller and a rubber roller; the rubber roller is rotationally mounted on the main frame and is driven by a motor to rotate; the pattern roller is rotationally installed on the sliding frame through a bearing seat, the sliding frame is fixedly installed on the main frame through a fixing frame, and the pattern roller is driven by a driving motor to rotate. Patterns on the surface of the patterned roller can be specifically protected, a hard chromium plated / Teflon coating on the surface of the patterned roller is prevented from being damaged, the equipment maintenance cost is reduced, and the downtime is shortened.

The invention relates to the technical field of resin-based composite material forming, in particular to a high-finish-degree high-pressure-resistant carbon fiber tube preparation process which comprises the following steps: step 1, tool preparation: preparing a core mold blank from stainless steel, hardening and polishing the surface of the core mold blank, and electroplating hard chromium, so as to obtain a high-finish-degree high-pressure-resistant carbon fiber tube; a core mold with high surface hardness and smoothness is obtained, and then the surface of a core mold blank is coated with a release agent for standby application; step 2, material preparation: selecting T700-grade carbon fibers with the diameter of 0.15 mm; 3, winding, wherein the carbon fiber yarn is led out of the creel and soaked in the resin system. By means of the winding angle design optimized in the annular and oblique alternating mode, the pipe has high strength and rigidity in the axial direction and the annular direction, and internal high pressure and external side pressure can be effectively resisted. Tests show that the sample tube (such as the specification of phi 25mm) prepared by the process can be kept for more than 45 seconds under the internal pressure of 45MPa without cracking or obvious plastic deformation, and the radial deformation is less than or equal to 0.05 mm.

The utility model discloses a power distribution equipment valve mechanism which comprises two guide rods which are symmetrically arranged, an upper valve and a lower valve which are movably arranged on the two guide rods, hard chromium layers are plated on the surfaces of the guide rods, connecting grooves are formed in the two sides of the upper valve and the two sides of the lower valve, connecting sleeves are arranged in the connecting grooves, and the upper valve and the lower valve are connected through the connecting sleeves. The connecting sleeve is connected with the two guide rods in a sleeved mode, a plurality of oil storage cavities are formed in the inner wall of the connecting sleeve in the radial direction and filled with lubricating oil, a wear-resisting ring is arranged between every two adjacent oil storage cavities, and sealing rings are arranged at the positions, close to the outlets, of the two ends of the inner wall of the connecting sleeve. The connecting sleeves are arranged on the two sides of the upper valve and the two sides of the lower valve, so that the upper valve and the lower valve are prevented from making direct contact with the guide rod, the effect of reducing friction is achieved, sliding of the valves is smoother, the clamping stagnation phenomenon is avoided, abrasion is reduced, and the service life is prolonged; and large noise generated when the upper valve and the lower valve slide is avoided.

According to the surface treatment method, the advantages of milky white chromium and hard chromium are combined, milky white chromium is electroplated on the inner surface of a cylinder barrel firstly, then hard chromium is electroplated on the inner surface, and finally a composite protective coating which can improve the corrosion resistance of the inner surface and the wear resistance of the inner surface and is excellent in binding force is obtained. The technical problems that the inner surface of an existing cylinder barrel is prone to rusting, abrasion, scratching and the like due to the fact that no effective protective coating exists on the inner surface of the cylinder barrel are solved, the method is reasonable, feasible and ingenious in design, the corrosion resistance of the inner wall of the jack cylinder barrel can be improved, the abrasion resistance of the inner wall of the cylinder barrel can be improved, and the protective coating is excellent in binding force. And the service life of the jack is prolonged.

Sleeves that can be disposed on either end of a bushing to improve the wear characteristics and usable lifetime of the bushing is disclosed. During the use of the bushing, such as when a machine including the bushing is operated, the sleeves may be in primary contact with abrasive elements (e.g., other parts of the machine, dirt, rock, etc.) and wear, while the underlying bushing is protected, at least in part, from wear and tear. The sleeves may include a bulk material, such as steel, with a hard coating thereon, such as hard chromium, tungsten carbide, or the like. The hard coating may be formed by any variety of processes, such as electroplating, plasma deposition, thermal deposition, or the like. In some cases, the sleeves, after being worn from use, may be replaced or refurbished to further extend the lifetime of the bushing.

The invention relates to the technical field of alloy materials, in particular to a Cr-Fe functional alloy material for prolonging the service life of a gun barrel and a preparation method thereof.The alloy comprises, by mass, 74%-78% of Cr, 22%-56% of Fe and 0.5%-1.2% of C. The microstructure is mainly composed of a BCC phase (larger than or equal to 85%), and Cr23C6 strengthening phases (3%-8% and 0.2-3.0 microns) are evenly separated out. During preparation, laser remelting is conducted on a pre-plated hard chromium base body under nitrogen protection, the laser power density is 4.95 * 10 < 4 >-9.20 * 10 < 4 > W / cm < 2 >, the scanning speed is 5-80 mm / s, preheating is conducted to 400 DEG C, and gradient cooling is conducted; the integrated visual system regulates and controls parameters in real time, the depth-to-width ratio of a molten pool is guaranteed to be 1: 1.5-1: 2.5, and the Cr / Fe distribution standard deviation is smaller than or equal to 5%. The interface dislocation density of the alloy is larger than or equal to 1 * 10 < 14 > m <-2 >, the high-temperature abrasion mass loss is smaller than or equal to 0.01 g, the abrasion resistance is three times that of original hard chromium, and the service life of a gun barrel is remarkably prolonged.

The invention discloses a feeding valve capable of resisting abrasion and swinging. The feeding valve comprises a feeding valve body, a valve element and a swinging structure. A material channel is arranged in the feeding valve main body, the valve core is movably arranged in the material channel and is used for controlling the material flow, a rotating shaft is arranged on the swinging structure, the swinging structure is connected with the valve core through the rotating shaft, and the power device is connected with the rotating shaft and is used for driving the rotating shaft to drive the valve core to swing. Compared with the prior art, the wear resistance is improved, and the service life of the valve is remarkably prolonged through the multi-layer composite coating (hard alloy and hard chromium plating) on the valve element and the silicon nitride inner wall coating of the material channel. And the double-hinge assembly is combined with the buffer spring, so that impact wear can be reduced, and high-pressure working conditions can be adapted. And intelligent maintenance: a wear sensor is linked with a control system, so that predictive maintenance can be realized. And rapid replacement is achieved, the valve element can be rapidly replaced through the modular valve element design, and therefore the downtime is shortened.

The utility model discloses a high-strength wear-resistant change gear set, and belongs to the technical field of gears. The gear set comprises a multi-stage speed change gear, a gear set center shaft and a speed regulation gear ring which are all made of carburized and quenched alloy steel. The gear tooth middle section of the change gear is provided with an oil passing groove to improve lubrication, tooth surface bevel angles are machined at the two ends of the tooth crest to reduce meshing impact, and a tooth bottom groove is plated with a hard chromium wear-resistant layer to improve wear resistance; shaft hole oblique angles are arranged on two sides of the central shaft hole and are matched with transition oblique angles of the central shaft to reduce assembly friction; and the contact area of the adjacent gears is reduced by the annular tooth surface grooves at the spokes. Through structural optimization and surface strengthening, the wear resistance and the contact strength of the gear are remarkably improved, the service life of a change gear set is prolonged, and the gear set is suitable for a high-load gearbox system.

The invention belongs to metal material surface treatment, and particularly discloses a CT bulb tube electroplating method and an electroplating tool, and the method comprises the following steps: carrying out insulation shielding on a CT bulb tube; hanging the CT bulb tube after insulation shielding; and immersing the hung CT bulb tube in an electroplating solution for electroplating to obtain the CT bulb tube with an electroplated layer. The hard chromium-black chromium composite coating which is uniform, high in binding force and high in radiation efficiency can be prepared on the surface of the CT bulb tube, so that the performance of the CT bulb tube is improved, and the service life of the CT bulb tube is prolonged.

The invention relates to the technical field of remanufacturing and surface engineering of key parts of a helicopter transmission system, in particular to a partition repairing method for corrosion of an inner spherical shell of a speed reducer. Comprising the following steps: dividing a to-be-repaired inner spherical shell of the speed reducer into an inner spherical area and a cylindrical surface and end surface area; the corrosion layer of the inner spherical surface area is removed, the inner spherical surface area with the corrosion layer removed is obtained on the inner spherical surface shell of the speed reducer, a hard chromium layer is prepared on the inner spherical surface area with the corrosion layer removed through electroplating, and the electroplated inner spherical surface area is obtained on the inner spherical surface shell of the speed reducer after accurate grinding; the method comprises the steps that a cylindrical surface and an end face area are obtained, a corrosion layer on the cylindrical surface and the end face area is removed, the cylindrical surface and the end face area with the corrosion layer removed are obtained, a copper-aluminum layer is prepared on the cylindrical surface and the end face area with the corrosion layer removed through plasma spraying, and an inner spherical area obtained after plasma spraying is obtained on the inner spherical shell of the speed reducer after accurate grinding. The problem of part missing caused by corrosion of the inner spherical shell is solved.

The application discloses a carbide modified abrasion-resistant alloy steel and a preparation method and application thereof, and relates to the technical field of wear-resistant steel. By adding a higher Cr element and combining with the addition of a proper amount of C element, the solid solution strengthening effect of the steel and the precipitation of hard chromium-containing carbides are ensured, which is beneficial to the improvement of the wear resistance of the steel. In addition, by controlling the addition amount of the C element, after the precipitation of the carbides, part of the carbon still exists in the matrix, which promotes the final formation of hard and tough lath martensite and avoids the generation of high-carbon brittle acicular martensite. Moreover, by adding the higher Cr element and proper amounts of Ni and Mo elements, the steel can still maintain a passivation state in a weak acid corrosive environment, so that the corrosion resistance of the steel is increased. Furthermore, V, Zr and Re in the steel can also react with C to precipitate carbides in the matrix, which can effectively control the size of the carbides, so that the wear resistance of the steel is ensured while the toughness and corrosion resistance of the steel are not damaged.

The utility model discloses a tool for electroplating hard chromium on a star-shaped dial wheel, which comprises a hanging frame, an upper positioning plate and a lower positioning plate are arranged in the middle of the hanging frame, the upper positioning plate is connected with the lower positioning plate through a connecting screw rod, two pictographic workpieces are arranged between the upper positioning plate and the lower positioning plate, and the pictographic workpieces are connected with the hanging frame. The elephant-shaped workpiece is connected with the upper positioning plate and the lower positioning plate through the connecting screws, a plurality of auxiliary anode bars are vertically arranged on one side of the upper positioning plate and one side of the lower positioning plate, the electro-deposition thickness of the electroplated surface of the tool is evenly distributed, and control over the product machining size and the subsequent polishing process is facilitated.

The application discloses a tee type flange connecting electrode for pure water and a forming method thereof, and belongs to the technical field of CNC machining and material welding forming. The electrode comprises a tee main body and a flange welded to the interface end of the tee main body; the tee main body is integrally forged and formed through CNC precision machining, and the wall thickness error is controlled within mm. The flange and the tee main body are seamlessly welded, and the welding protrusions overflowing from the inside and outside of the welding position are removed, so that the welding seam is smooth and free of sand holes and pores. The inner flow channel surface of the tee electrode is polished and treated by electroplating hard chromium or plating platinum, so that the inner surface smoothness reaches Ra The application significantly improves the pressure bearing capacity and service life of the electrode through the integrally forged and seamless welding process, enhances the corrosion resistance by using the high smoothness plating layer, reduces the fouling problem caused by ionization discharge, and has the advantages of scientific structure, convenient connection, low cost and installation convenience.

The present invention discloses a method for preparing a gradient composite material with an in-situ synthesized stainless steel layer on a porous nickel surface, comprising the following steps: 1. loading stainless steel powder and nickel powder into a pressing mold; 2. extracting a tubular foil from the powder-loaded pressing mold; 3. pressing the stainless steel powder and nickel powder; 4. sintering the composite green body in a hydrogen furnace; 5. pre-densifying the outer surface of the composite sintered body; 6. electrodepositing a hard chromium layer on the surface to obtain a porous nickel / stainless steel gradient composite material. The present invention pre-places a tubular foil intermediate layer for powder loading and pressing, thereby obtaining a composite porous material compact with dual gradients in composition and pore size, achieving one-time pressing and forming of the gradient porous composite material. Simultaneously, the outer layer of the workpiece is completely densified by combining the outer surface pre-densification and subsequent electrodeposition of a dense hard chromium layer, thereby proposing a new densification method suitable for porous materials, which ensures both the processing accuracy of the composite material and its functionality and lightweight.

The utility model relates to a kind of anti-loosening MPO buckles, belong to MPO buckle technical field.The anti-loosening MPO buckle includes: adapter, plug, sleeve, limit frame, hinge and limit frame, two the side of the limit frame mutually close side along the two side surfaces of the plug slide and embed the two side interiors of the plug;Sleeve inner wall annular anti-skid line, and with the initial pre-tightening force formed to plug surface, the V-shaped guide slot of limit frame along the two sides of plug slide, limit frame is embedded plug with interference fit, form first level mechanical lock, hinge drives limit frame reverse rotation, terminal insertion limit frame, by stainless steel interference fit realizes secondary interlock, the annular inner wall of limit frame is wrapped plug outer wall, surface plating hard chromium layer reduces plug abrasion, form three levels of wrapping constraint, the design is through material stiffness optimization, three levels of locking structure and self-adapting gap compensation, realize not easy to loosen under wide temperature environment, applicable to base station high frequency plug-in scene.

The invention relates to the technical field of extrusion dies, in particular to a method for improving hardness and wear resistance of a photovoltaic aluminum frame extrusion die. The method comprises the steps that firstly, a photovoltaic aluminum frame extrusion die made of steel is placed in a heating furnace, heating and austenitizing are conducted in a staged heating mode, and then quenching is conducted; tempering the quenched mold for 2-3 times, and air-cooling the mold to room temperature after tempering each time; then plasma nitriding is conducted on the working face of the photovoltaic aluminum frame extrusion die, and strengthening treatment is conducted on the surface of the working face; and after surface strengthening treatment, a ceramic oxide layer is formed on the surface by adopting a micro-arc oxidation process, or hard chromium plating treatment is carried out. After heat treatment and surface treatment, the surface hardness of the extrusion die can reach 1000 HV or above, the wear resistance can reach 4.0 mg / ten thousand times or below, and the extrusion die should adapt to the strict service working condition faced by the photovoltaic aluminum frame extrusion die.

The utility model relates to the technical field of electroplating, and particularly discloses a rotary clamping device for hard chromium electroplating, which comprises a bottom frame and a top frame positioned above the bottom frame, a plurality of clamping structures are mounted on the upper end surface of the bottom frame, and each clamping structure comprises a first fixing cylinder fixedly connected with the bottom frame, a first fixing cylinder is arranged on the upper portion of the bottom frame, a second fixing cylinder is arranged above the first fixing cylinder, lining plates are arranged on the outer wall of the first fixing cylinder and the outer wall of the second fixing cylinder, spring assemblies fixedly connected with the lining plates are installed on the outer wall of the first fixing cylinder and the outer wall of the second fixing cylinder, and the distance between the bottom frame and the top frame is adjusted according to the height of the electroplating pipe. And secondly, an inner rod and a second fixing barrel are unfolded, a to-be-electroplated pipe is connected to the outer wall of a clamping structure in a sleeving mode, the to-be-electroplated pipe is limited from the inner wall of the electroplated pipe, and tubular workpieces with different pipe diameters can be limited and fixed, so that the applicability of the equipment is improved.

The invention belongs to the technical field of alloy materials, and relates to a Cr-Fe alloy layer for prolonging the service life of a barrel and a preparation method of the Cr-Fe alloy layer. The Cr-Fe alloy layer comprises 45 wt%-85 wt% of Cr, 14 wt%-54 wt% of Fe, 0 wt%-1.2 wt% of C, and the content of O is smaller than or equal to 0.3 wt%. The Cr-Fe alloy layer is manufactured through laser machining, the microstructure is mainly composed of a BCC phase, and a Cr23C6 strengthening phase with the mass fraction being 3-8% is evenly separated out. The Cr-Fe alloy layer is metallurgically bonded with the barrel base body, the surface Vickers hardness is 400-600 HV, and the mass loss is smaller than or equal to 0.01 g in 500 times of high-temperature erosion wear cycle tests. By optimizing laser processing parameters, the Cr-Fe alloy layer with specific components is formed, microcracks of the hard chromium plating layer are effectively repaired, the high-temperature erosion wear loss rate is reduced, and the service life of the barrel is prolonged.

A piston ring includes a base body having an inner circumferential surface, first and second flank surfaces and an outer circumferential surface, wherein a first hard chromium layer with a crack network is applied to the outer circumferential surface and has a crack density of 10-250 cracks per mm and solid particles having an average particle size of 0.01-10 μm embedded in cracks of the first hard chromium layer, a second hard chromium layer having a crack network applied to the first hard chromium layer and having a crack density of the crack network of 10-250 cracks per mm, no solid particles being embedded in the cracks thereof, where the cracks have an average width of 1-15 μm, the cracks are electrolytically expanded and the surface proportion of the cracks are 3-25% based on a total surface of the second hard chromium layer.

The invention relates to the technical field of electroplating additives, in particular to an environment-friendly high-wear-resistance hard chromium electroplating additive and a preparation method and application thereof. The additive is prepared by mixing a core function liquid and an auxiliary dispersion liquid, the core function liquid is prepared by mixing sodium benzenesulfinate, sodium thiosulfate, benzenesulfonic acid, tartaric acid, nano composite particles and deionized water, and the auxiliary dispersion liquid is prepared by mixing alkylphenol ethoxylates, polyethylene glycol 400 and a 50vol% ethanol solution. The coating does not contain fluorine components, and is environment-friendly and easy to treat; and the current efficiency reaches 22-27%, the deposition speed is 1 micron / min, the plating hardness is 1000-1100 HV, the wear resistance and the deep plating capacity are excellent, the additive is suitable for surface strengthening of precision parts such as molds and piston rods, and the problems that an existing additive is poor in environmental protection property and insufficient in performance are solved.

The invention belongs to the technical field of titanium alloy surface treatment, and particularly relates to a preparation method of a high-corrosion-resistance gradient coating on the surface of a titanium alloy shaft body, which comprises the following steps of: pretreating the surface of the titanium alloy shaft body, performing two-step activation treatment, plating a compact chromium layer, performing vacuum heat treatment, and plating a hard chromium layer. According to the method, the two-step activation process is combined with the vacuum low-temperature and high-temperature heat treatment process, so that the binding force of the plating layer is improved, and the corrosion resistance of the titanium alloy shaft body is improved through the specific technological process and parameter control. The composite coating with continuous gradient change of components, structures and performance, high bonding strength, high density and excellent corrosion resistance is prepared on the surface of the titanium alloy shaft body, the problems of weak interface bonding and performance mutation are effectively solved, and the chromium plating effect of the titanium alloy shaft body is remarkably improved.