A method and system for controlling the morphology of high oil content tin bronze powder

Abstract

The application discloses a morphology control method and system of high-oil-content tin bronze powder, and the method comprises the following steps: electrolytic copper, pure tin and a deoxidizer are put into a medium-frequency induction melting furnace according to a set ratio, and after deslagging treatment, pure tin bronze molten liquid is obtained; the tin bronze molten liquid is broken into small droplets by using a high-pressure water atomization process, and at the same time, an axial rotating magnetic field is applied around a water atomization nozzle, so that ellipsoidal primary powder is obtained after solidification; the ellipsoidal primary powder is placed in a mixed solution containing fatty acid and ethanol for ultrasonic oscillation treatment, and porous activated powder is obtained; the porous activated powder and a graphene dispersion liquid are mixed according to a preset mass ratio, a planetary ball mill is used for low-speed ball milling, and morphology-regulated tin bronze powder with a three-dimensional oil storage structure is obtained. By using the embodiment of the application, the oil content and oil storage stability of the tin bronze powder can be improved, and good powder fluidity and pressing performance are maintained.

Description

Technical Field

[0001] This invention belongs to the field of tin bronze powder technology, and in particular to a method and system for controlling the morphology of tin bronze powder with high oil content. Background Technology

[0002] Tin bronze powder, due to its excellent mechanical properties, corrosion resistance, and self-lubricating potential, is widely used in the manufacture of high-end components such as oil-impregnated bearings, friction materials, and porous filters. Tin bronze powder prepared by traditional gas atomization or water atomization methods is predominantly spherical, with a smooth surface, small specific surface area, and limited grease adhesion, resulting in generally low oil content. To improve the oil content, existing technologies typically perform vacuum oil impregnation on the sintered body after powder forming. However, this method relies on the open-pore structure inside the sintered blank, making it difficult to guarantee pore connectivity, and the oil impregnation efficiency is significantly limited by pore size and distribution uniformity. Furthermore, attempts have been made to modify the powder morphology by adjusting atomization process parameters, but these often struggle to balance particle sphericity and surface oil storage structure; excessive morphology alteration can also affect powder flowability and pressing performance. In recent years, research on graphene modification for improving lubrication performance has gradually progressed, but it has largely focused on the tribological properties of composite materials, and a stable three-dimensional oil storage structure has not yet been constructed specifically for the tin bronze powder itself. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for controlling the morphology of tin bronze powder with high oil content, so as to overcome the shortcomings of the prior art, improve the oil content and oil storage stability of tin bronze powder, and maintain good powder flowability and pressing performance.

[0004] One embodiment of this application provides a method for controlling the morphology of high oil content tin bronze powder, the method comprising: Electrolytic copper, pure tin, and deoxidizer are added to a medium-frequency induction melting furnace according to a set ratio. The furnace is heated under argon protection to form a uniform alloy melt. After slag removal, pure tin bronze melt is obtained. The molten tin bronze is broken into fine droplets by high-pressure water atomization. At the same time, an axial rotating magnetic field is applied around the water atomization nozzle to cause the droplets to spin and deform during flight. After solidification, an ellipsoidal primary powder with surface pits and internal interconnected pores is obtained. The ellipsoidal nascent powder was placed in a mixed solution containing fatty acids and ethanol and subjected to ultrasonic oscillation treatment to selectively etch the tin-rich phase on the powder surface, thereby increasing the pit depth and forming a micron-scale crack network to obtain porous activated powder. The porous activated powder and graphene dispersion are mixed at a preset mass ratio and then ball-milled at low speed using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges, thereby obtaining morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

[0005] Another embodiment of this application provides a morphology control system for high oil content tin bronze powder, the system comprising: The heating module is used to add electrolytic copper, pure tin and deoxidizer into the medium frequency induction melting furnace according to the set ratio, and heat up under argon protection to form a uniform alloy melt. After slag removal treatment, pure tin bronze melt is obtained. An application module is used to break the molten tin bronze into fine droplets using a high-pressure water atomization process. At the same time, an axial rotating magnetic field is applied around the water atomization nozzle to cause the droplets to spin and deform during flight. After solidification, an ellipsoidal primary powder with surface pits and internal interconnected pores is obtained. An oscillation module is used to place the ellipsoidal nascent powder in a mixed solution containing fatty acids and ethanol for ultrasonic oscillation treatment, selectively etching the tin-rich phase on the powder surface, increasing the pit depth and forming a micron-level crack network to obtain porous activated powder. The control module is used to mix the porous activated powder and graphene dispersion at a preset mass ratio, and to perform low-speed ball milling using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges to obtain morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

[0006] Another embodiment of this application provides a storage medium storing a computer program, wherein the computer program is configured to execute the method described in any of the preceding claims when running.

[0007] Another embodiment of this application provides an electronic device including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the method described in any of the preceding claims.

[0008] Compared with the prior art, the morphology control method of high oil content tin bronze powder provided by the present invention can improve the oil content and oil storage stability of tin bronze powder, while maintaining good powder flowability and pressing performance. Attached Figure Description

[0009] Figure 1 Hardware structure block diagram of a computer terminal for a method of controlling the morphology of high oil content tin bronze powder provided in an embodiment of the present invention; Figure 2 A schematic flowchart illustrating a method for controlling the morphology of high oil content tin bronze powder provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the morphology control system for high oil content tin bronze powder provided in an embodiment of the present invention. Detailed Implementation

[0010] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0011] The present invention first provides a method for controlling the morphology of high oil content tin bronze powder, which can be applied to electronic devices, such as computer terminals, specifically ordinary computers.

[0012] The following detailed explanation uses a computer terminal as an example. Figure 1 This is a hardware block diagram of a computer terminal for a method of controlling the morphology of high oil content tin bronze powder provided in an embodiment of the present invention. Figure 1 As shown, the computer device includes a processor, memory, and network interface connected via a system bus, wherein the memory may include non-volatile storage media and internal memory.

[0013] See Figure 2 The present invention provides a method for controlling the morphology of high oil content tin bronze powder, which may include the following steps: S201 involves adding electrolytic copper, pure tin, and deoxidizer into a medium-frequency induction melting furnace according to a set ratio. The furnace is heated under argon protection to form a uniform alloy melt. After slag removal, pure tin bronze melt is obtained. Specifically, electrolytic copper, pure tin, and phosphor bronze deoxidizer can be weighed according to the following proportions: copper 85% to 90% by mass, tin 10% to 15% by mass, and deoxidizer 0.5% to 1% by mass, to generate a precisely proportioned furnace charge. The core of this step is to accurately weigh the three types of smelting raw materials based on the performance requirements of high-oil-content tin bronze powder, lock in the basic chemical composition of the alloy, and avoid defects in powder pore structure and oil retention performance caused by alloy composition deviations from the source. This lays the raw material foundation for obtaining a stable tin bronze melt in subsequent smelting. The specific implementation method is as follows: The three types of raw materials selected for this smelting are electrolytic copper, pure tin, and phosphorus copper deoxidizer. These three types of raw materials play completely different metallurgical roles in the tin bronze alloy system. At the same time, three mass ratio ranges are set to adapt to the powder preparation requirements under different working conditions. Each mass ratio parameter has been verified by powder oil storage performance test and has clear process adaptation significance. The copper content, ranging from 85% to 90% by mass, forms the matrix metal composition. Electrolytic copper, as the main matrix material of tin bronze alloy, determines the overall mechanical strength, thermal conductivity, and powder matrix structure stability of the alloy. A copper content below 85% leads to insufficient hardness in the alloy matrix, resulting in a significant decrease in wear resistance after powder forming. A copper content above 90% reduces the alloy's internal porosity, failing to meet the core requirement of high oil content. The tin content, ranging from 10% to 15% by mass, forms the alloy strengthening and porosity control auxiliary material composition. Pure tin can dissolve into the copper matrix to form a copper-tin solid solution, improving the alloy's self-lubricating properties. Simultaneously, tin will form a tin-rich phase on the powder surface, suitable for subsequent selective etching and hole-forming processes. A tin content below 10% will... Reducing the number of etchable phases on the surface makes it impossible to construct a sufficient amount of fractured oil-retaining structure. A tin content higher than 15% will increase the viscosity of the alloy melt, which is not conducive to subsequent high-pressure water atomization and breakup into uniform fine droplets. The deoxidizer mass ratio is 0.5% to 1% in the melt deoxidation auxiliary material ratio. This time, phosphorus copper deoxidizer was selected as a special deoxidation auxiliary material. Phosphorus can react chemically with oxygen inside the melt to generate a low-density oxide slag phase, eliminating the internal porosity defects caused by the oxidation of copper and tin metals during high-temperature smelting. If the amount of deoxidizer added is less than 0.5%, the deoxidation will be incomplete, the residual oxygen content in the melt will exceed the standard, and the ineffective porosity inside the powder will increase. If the amount of deoxidizer added is higher than 1%, excessive phosphorus impurities will be introduced, reducing the corrosion resistance and conductivity of the tin bronze powder itself.

[0014] The raw material weighing process employs high-precision static weighing equipment, with overall weighing accuracy controlled within ±0.02%. This eliminates alloy composition fluctuations caused by the accumulation of minute deviations in raw material proportions. The total mass of the furnace charge for a single smelting is uniformly set at 100 kg, facilitating intuitive matching of range parameters to complete the material weighing example. In this practical exercise, the optimal parameters in the middle of the range were selected for the proportioning: 87.5 kg of electrolytic copper, corresponding to a copper mass percentage of 87.5%, which is in the middle of the 85% to 90% standard range; 12 kg of pure tin, corresponding to a tin mass percentage of 12%, which is in the middle of the 10% to 15% standard range; and 0.5 kg of phosphorus copper deoxidizer, corresponding to a deoxidizer mass percentage of 0.5%, which is at the lower limit of the 0.5% to 1% standard range. This proportioning is suitable for the preparation of high oil content tin bronze powder under normal working conditions, taking into account both the powder's mechanical properties and oil-retaining pore structure.

[0015] After weighing, the three types of solid raw materials are simply mixed manually to remove dust, moisture and other trace impurities attached to the surface of the raw materials. This prevents foreign impurities from entering the smelting furnace and affecting the purity of the melt. Finally, the mixed quantitative raw materials are integrated into a complete furnace charge set to ensure that all raw materials fed into the smelting furnace are of uniform composition and accurate total amount, without the problem of local accumulation of single raw materials, and to ensure that the metal mutual solubility efficiency remains consistent during the subsequent heating and melting process.

[0016] The furnace charge is fed into the medium-frequency induction melting furnace, the furnace cover is closed and the furnace chamber is evacuated to a negative pressure of 0.08 MPa, then high-purity argon is introduced to atmospheric pressure and the process is repeated 3 times to generate an argon protective atmosphere. The core of this step is to completely remove the air from the furnace chamber of the medium-frequency induction melting furnace through vacuum extraction combined with multiple replacements of inert gas. This isolates oxygen and water vapor in the air from contact with the high-temperature molten metal, preventing oxidation reactions of electrolytic copper and pure tin in the high-temperature molten state. Simultaneously, it avoids the formation of hydrogen pores caused by water vapor decomposition, thus creating a completely oxygen-free and water-vapor-free sealed melting protective atmosphere. The specific implementation method is as follows: First, the prepared furnace charge is carefully and smoothly placed into the crucible cavity inside the medium-frequency induction melting furnace. During the placement process, care is taken to avoid the furnace charge hitting the inner wall of the crucible and causing damage. After placement, the furnace lid is completely closed. The sealing ring on the furnace lid completely seals the internal cavity of the furnace, blocking the gas exchange channel between the furnace and the outside atmosphere, thus providing a sealed space for subsequent vacuum extraction and gas replacement.

[0017] The negative pressure of 0.08 MPa is the core pressure parameter for this vacuum extraction. The standard atmospheric pressure is 0.1 MPa. The negative pressure parameter represents the pressure difference between the internal pressure of the furnace and the external standard atmospheric pressure. A negative pressure of 0.08 MPa means that the absolute pressure inside the furnace is maintained at 0.02 MPa. This vacuum level is the optimal vacuum parameter for copper-tin alloy melting. A vacuum level below 0.08 MPa will prolong the vacuuming time and increase equipment energy consumption. A vacuum level above 0.08 MPa will increase the pressure difference between the inside and outside of the furnace, posing a risk of deformation of the furnace cover sealing structure due to pressure. The vacuuming process uses an industrial-grade vacuum unit to extract air from the furnace at a uniform speed. The vacuuming time is controlled within 4 minutes. The uniform pressure reduction avoids sudden pressure changes that could cause displacement of the furnace charge inside the crucible. The vacuuming process is considered complete when the real-time value detected by the furnace pressure sensor is stably maintained at a negative pressure of 0.08 MPa and there is no pressure rebound.

[0018] Then, high-purity argon gas is introduced into the sealed furnace. The argon gas used in this case has a purity of no less than 99.999%. Argon is a monatomic inert gas that will not chemically react with copper, tin, or phosphorus raw materials under both room temperature and high temperature conditions. It has extremely high chemical stability and is the most suitable protective gas for non-ferrous metal smelting. The gas introduction process continues until the gas pressure inside the furnace rises back to the external standard atmospheric pressure of 0.1 MPa, at which point the argon gas supply is stopped, completing a single gas replacement process.

[0019] This process involves three repeated replacements, forming the core of a gradient deoxygenation process. A single vacuum extraction and argon filling can only remove about 85% of the residual air in the furnace, which is insufficient for high-precision oxygen-free melting. The first replacement primarily removes most of the macroscopic air inside the furnace, the second replacement further dilutes the trace amounts of residual oxygen, and the third replacement controls the residual oxygen content in the furnace to below 10 ppm, completely eliminating the risk of oxidation. Throughout the three replacements, the furnace lid remains completely sealed. After each replacement, the furnace is completely filled with high-purity argon, creating a stable and continuous argon protective atmosphere. The furnace lid does not need to be opened throughout the process, maintaining a sealed melting space and ensuring that subsequent heating and melting processes are free from oxidation interference.

[0020] Turn on the medium-frequency induction heating power supply and heat up to 1200 degrees Celsius at a rate of 15 to 20 degrees Celsius per minute. Hold the temperature for 30 minutes to allow the electrolytic copper and pure tin to completely dissolve and form a uniform alloy melt, generating an initial melt with uniform composition. The core of this step is to employ a heating strategy of gradient uniform heating combined with constant temperature holding. Utilizing the electromagnetic vortex stirring characteristics of medium-frequency induction heating, the solid electrolytic copper and pure tin raw materials are melted in stages. This ensures sufficient diffusion and mutual solubility of copper and tin atoms, completely eliminating melt defects such as layering, segregation, and unmelted metal particles, resulting in an initial copper-tin alloy melt with uniform composition throughout. The specific implementation method is as follows: The medium-frequency induction heating power supply is the core heating equipment for this smelting process. Its working principle is that alternating current passes through the induction coil to generate an alternating magnetic field. The alternating magnetic field penetrates the metal charge inside the crucible and generates induced eddy currents inside the metal raw material. The Joule heat generated by the eddy currents enables the raw material to self-heat and melt. Unlike external heat source heating methods, this heating mode can simultaneously achieve electromagnetic stirring inside the melt, promoting the homogenization of the metal melt without the need for additional mechanical stirring, and is suitable for the smelting requirements of copper-tin alloys.

[0021] The programmed temperature control set a uniform heating rate of 15 to 20 degrees Celsius per minute. This heating rate is the optimal gradient heating parameter set based on the difference in melting points between copper and tin. Pure tin has a melting point of 232 degrees Celsius, while electrolytic copper has a melting point of 1083 degrees Celsius, a significant difference between the two metals. A heating rate below 15 degrees Celsius per minute will significantly prolong the overall melting time, increase the cost of argon protective atmosphere consumption, and slightly exacerbate the volatilization of elements on the melt surface during prolonged high-temperature holding. A heating rate above 20 degrees Celsius per minute will result in uneven heating, with the surface charge melting rapidly while the charge in the center of the crucible remains solid. This prevents the solid copper from contacting and mixing with the liquid tin in time, leading to severe melt composition segregation. In this practical exercise, the midpoint of the range was selected, with a heating rate set at 17 degrees Celsius per minute. The entire process involved linear and uniform heating without any abrupt changes in the heating rate, ensuring that the charge melted synchronously from the outside to the inside.

[0022] 1200 degrees Celsius is the target temperature for isothermal melting of the alloy. This temperature is 117 degrees Celsius higher than the melting point of electrolytic copper, allowing for sufficient overheating. This ensures that large pieces of electrolytic copper melt completely without any solid residue, while preventing large-scale tin volatilization due to excessive temperature. Tin volatilization directly alters the actual alloy composition, affecting the subsequent powder etching and hole-forming effect. During the heating process, a temperature sensor inside the furnace collects the temperature of the melt in real time, once per second, and feeds the temperature data back to the temperature control system. The temperature control system automatically fine-tunes the heating power to ensure a stable and unfluctuating heating rate throughout the process.

[0023] Once the melt temperature reaches 1200 degrees Celsius, it enters a constant-temperature holding stage, with a fixed holding time of 30 minutes. During this holding process, the medium-frequency induction coil continuously generates an alternating magnetic field, driving the internal alloy melt to undergo continuous circular vortex flow. This enhances the bidirectional diffusion of copper and tin atoms, allowing tin to be uniformly dissolved within the copper matrix, completely eliminating the stratification problem of copper enrichment at the bottom and tin enrichment on the surface of the melt. If the holding time is less than 30 minutes, atomic diffusion is insufficient, and local deviations in the melt's microstructure remain; if the holding time is more than 30 minutes, unnecessary energy consumption will occur, and the risk of gas absorption in the melt will increase. After the holding process, all solid raw materials inside the furnace are completely converted into liquid alloy melt, with the overall melt composition deviation controlled within ±0.1%, ultimately obtaining a homogeneous initial melt without unmelted particles or compositional stratification.

[0024] Add slag-forming agent to the initial melt and stir. After standing for 10 minutes, use a graphite slag skimmer to remove the surface slag. Repeat the slag removal operation twice to finally obtain pure tin bronze melt.

[0025] The core of this step is to remove non-metallic inclusions such as metal oxides, deoxidation reaction products, and trace foreign impurities from the initial melt through three continuous processes: slag adsorption, static flotation, and mechanical slag removal. This eliminates microscopic inclusion defects within the melt, preventing large inclusion pores from appearing in the powder prepared by subsequent water atomization, and ensuring that the powder's pore structure is regular and controllable. The specific implementation method is as follows: After the constant temperature holding period, the melt temperature is kept stable at 1200 degrees Celsius. A metallurgical-specific alkaline slagging agent is then added directly and quantitatively into the initial melt. This slagging agent can adsorb and bind with copper oxide, tin oxide, and phosphorus oxides generated from phosphorus deoxidation within the melt, agglomerating the micron-sized fine solid impurities dispersed within the melt into large-volume slag clusters. This increases the density difference between the slag phase and the liquid melt, facilitating rapid flotation and separation of the slag phase. The amount of slagging agent added is 2% of the total furnace charge mass. For this 100kg total furnace charge system, a single addition of 2kg of slagging agent is sufficient to achieve comprehensive impurity adsorption.

[0026] After the slag-forming agent is added, use the built-in electromagnetic stirring function of the medium-frequency induction to continuously stir for 2 minutes. This enhances the contact reaction between the slag-forming agent and the entire melt, ensuring that fine impurities in all areas of the melt are fully adsorbed by the slag-forming agent, avoiding localized impurity residue. After stirring, turn off the stirring function and proceed to the settling process. The settling time is fixed at 10 minutes. The density of liquid tin bronze melt is much greater than the density of the slag generated by the reaction. During the settling process, all slag phases that have adsorbed impurities will spontaneously move upwards due to the density difference, all gathering on the surface of the melt to form a continuous and complete slag layer. A settling time of less than 10 minutes will result in some fine slag phases not completely floating to the surface, while a settling time of more than 10 minutes will not provide additional slag removal benefits and will only waste process time.

[0027] After settling, a high-temperature resistant graphite skimmer is used to remove surface slag. The core reason for choosing graphite is that it does not chemically react with the copper-tin alloy melt at 1200 degrees Celsius, thus preventing the introduction of new impurities into the melt. Graphite is also resistant to high-temperature erosion and has stable structural strength, making it suitable for high-temperature melt skimming conditions. The first skimming completely removes most of the macroscopic slag from the melt surface. After skimming, a very thin layer of secondary slag remains on the melt surface. This slag cannot be completely removed in a single skimming operation; therefore, the process requires repeating the entire slag removal operation twice. The second skimming process is exactly the same as the first: adding a small amount of slag-forming agent, short-term stirring, settling for 10 minutes, and then skimming the surface slag again to completely remove the secondary slag.

[0028] After two complete slag removal processes, the total content of non-metallic inclusions inside the melt is reduced to below 0.03%. There are no visible solid impurities inside the melt and no floating slag residue on the surface. The purity of the melt meets the stringent requirements of the high-pressure water atomization process, and finally a high-purity tin bronze melt without impurities or oxide inclusions is obtained.

[0029] S202, the molten tin bronze is broken into fine droplets by high-pressure water atomization process, and an axial rotating magnetic field is applied around the water atomization nozzle to cause the droplets to spin and deform during flight. After solidification, an ellipsoidal primary powder with surface pits and internal interconnected pores is obtained. Specifically, pure tin bronze molten metal can be transferred to a tundish and heated to 1150 degrees Celsius. The tundish bottom spout is opened to allow the molten metal to flow into the center of the high-pressure water atomizing nozzle at a flow rate of 3 to 5 kilograms per minute, generating a continuous flow of molten metal. The core of this step is to maintain the temperature and quantitatively guide the pure tin bronze molten metal after smelting. This ensures that the temperature of the molten metal entering the atomization zone is constant, the flow rate is stable, and the liquid flow pattern is continuous and regular. This avoids defects such as uneven droplet size and liquid flow breakage caused by fluctuations in molten metal temperature and flow rate. It provides a stable and qualified liquid metal raw material for subsequent high-pressure water atomization and crushing. The specific implementation method is as follows: The tundish is a specialized molten metal transfer and heat preservation device in the water atomization process of powder metallurgy. It receives pure tin bronze molten metal after it exits the smelting furnace. Unlike the smelting furnace, the tundish does not have a high-power smelting and heating function. Its core functions are constant temperature preservation, molten metal static flow stabilization, and quantitative flow guidance. It can isolate the outside air from contact with the high-temperature molten metal, avoid secondary oxidation of tin bronze molten metal during the transfer process, and eliminate residual micro bubbles inside the molten metal, further optimizing the purity of the molten metal and adapting it to the process requirements of subsequent fine atomization forming.

[0030] This step sets the molten metal holding temperature at 1150 degrees Celsius. This temperature parameter is specific to the tin bronze alloy atomization process, exceeding the tin bronze alloy's liquidus temperature by 210 degrees Celsius. This ensures the alloy molten metal remains in a uniform liquid state throughout the process, preventing premature solidification and crust formation that could clog the nozzle. It also avoids excessive superheating of the molten metal, which could lead to prolonged solidification time and excessive oxidation of powder particles during subsequent droplet flight. Superheat refers to the difference between the actual temperature of the molten metal and the alloy's liquidus temperature. A reasonable superheat balances the molten metal's fluidity and the degree of powder oxidation. The chosen constant holding temperature of 1150 degrees Celsius is the optimal temperature parameter for the subsequent high-pressure water atomization and magnetic field spin deformation processes.

[0031] The bottom of the tundish is equipped with a fixed cylindrical nozzle. The inner diameter of the nozzle is designed to match the process, and together with the constant liquid level inside the tundish, it enables the quantitative output of molten liquid by gravity flow, ensuring a stable and controllable flow rate without the need for additional power supply. The process is set to a molten liquid flow rate range of 3 kg / min to 5 kg / min. This flow rate range is a core parameter for matching the coverage of the high-pressure water atomizing ring nozzle. If the flow rate is too low, the molten liquid stream will be too thin, and the high-pressure water flow will easily disperse the liquid flow, failing to form a complete and continuous liquid column. If the flow rate is too high, the molten liquid stream will be too thick, and the high-pressure water flow will not be able to completely break up the molten liquid in one go, producing large-sized incompletely atomized metal particles, reducing the yield of the finished powder. In this process example, the median value of 4 kg / min is selected as the actual production flow rate. The liquid flow rate data is collected in real time through a flow monitoring sensor throughout the process. Once the flow rate deviates from the set range, the liquid level inside the tundish is automatically fine-tuned to achieve closed-loop flow control.

[0032] With the dual protection of constant temperature insulation and constant flow guidance, molten tin bronze flows vertically downward from the nozzle, forming a continuous columnar molten liquid flow with uniform diameter, no interruption, and no turbulence. The molten liquid flow is vertically aligned with the geometric center of the high-pressure water atomizing nozzle below, ensuring that the subsequent high-pressure water flow can impact the surface of the molten liquid flow uniformly from all directions, making the molten liquid crushing process more uniform, completing the preparation of the continuous molten liquid flow in this step, and providing a stable raw material basis for the subsequent atomization crushing process.

[0033] The high-pressure water pump is started to make the atomized water pressure reach 80 to 100 MPa. The high-pressure water flow is sprayed from the annular nozzle at a 30-degree cone angle, breaking the continuous molten flow into droplets with a particle size of 50 to 150 micrometers, generating a diffusely distributed group of molten droplets. The core of this step relies on the mechanical impact kinetic energy of high-pressure, high-speed water flow to physically break the monolithic columnar molten tin bronze flow into micron-sized fine metal droplets. The droplet size distribution is controlled by both water pressure and the jet cone angle, achieving uniform dispersion and breaking up of the molten metal. This avoids the formation of large molten particles or ultrafine powder waste, constructing a group of molten droplets with controllable size and uniform distribution. This provides uniformly sized liquid metal particles for subsequent magnetic field spin deformation. The specific implementation method is as follows: The high-pressure water pump is the core power equipment in this process, responsible for providing high-pressure power to the atomized water flow. The water pressure directly determines the magnitude of the water flow's impact kinetic energy, and thus the degree of fragmentation of the molten metal. The process sets the atomized water pressure range to 80 MPa to 100 MPa. MPa is a unit of pressure measurement; 1 MPa represents 1 million Newtons of force per square meter. The higher the water pressure, the faster the water jet speed, the stronger the impact kinetic energy, and the smaller the average droplet size obtained from the fragmentation. Conversely, the lower the water pressure, the weaker the impact kinetic energy, and the larger the average droplet size. When the water pressure is below 80 MPa, the water kinetic energy is insufficient to fully fragment the columnar molten flow, resulting in a large amount of millimeter-sized large-particle waste powder. When the water pressure is above 100 MPa, the water kinetic energy is excessive, resulting in a large amount of ultrafine powder with a particle size of less than 50 micrometers, significantly increasing powder loss. At the same time, the water flow impact causes molten metal splashing, disrupting the internal process environment of the atomization chamber. In this process example, the median value of 90 MPa was selected as the actual atomizing water pressure. At this pressure, the water outlet jet velocity can reach 280 meters per second, balancing the crushing effect and the powder yield.

[0034] The annular nozzle is an integrated annular spray structure evenly arranged around the molten flow. Unlike single-hole direct-injection nozzles, the annular nozzle can synchronously spray high-pressure water from all directions around the molten flow, achieving 360-degree molten breakage without dead angles. The process setting is a fixed water jet cone angle of 30 degrees. The cone angle refers to the conical angle formed by the convergence of multiple high-pressure water jets after they are ejected from the nozzle. A cone angle of 30 degrees is the optimal matching angle, which allows the high-pressure water jets to accurately converge at the center of the molten flow, maximizing the concentrated impact kinetic energy. If the cone angle is greater than 30 degrees, the water jet convergence point shifts downward, and the upper part of the molten flow cannot be fully broken up. If the cone angle is less than 30 degrees, the water jets converge prematurely, offsetting the impact kinetic energy, and the breaking efficiency drops significantly.

[0035] Under the combined action of constant water pressure and a fixed jet cone angle, the continuous columnar molten liquid flow is instantly torn, sheared, and broken up by the high-speed, high-pressure water flow, forming a large number of discrete liquid metal droplets. The process controls the droplet size range to 50 micrometers to 150 micrometers. A micrometer is a unit of measurement for microscopic size, and 1 micrometer is equivalent to one-thousandth of a millimeter. Droplets within this size range have moderate mass, allowing them to stably spin and deform under the influence of the Lorentz force of the magnetic field during subsequent flight, while also stably forming an internally interconnected pore structure during solidification. Droplets with too small a size are too light, and the magnetic field force will directly change the droplet's flight trajectory, preventing it from falling normally into the cooling water tank. Droplets with too large a size have excessive inertia, making it difficult to complete spin deformation within a short flight time.

[0036] After the final crushing is completed, all the metal droplets are evenly dispersed in the atomization chamber without mutual adhesion or droplet aggregation, forming a diffusely distributed group of molten droplets with uniform spatial distribution, concentrated particle size, and parallel flight trajectory. This completes the morphological transformation of the molten metal from a continuous liquid column to discrete droplets, connecting to the subsequent magnetic field spin control process.

[0037] A Helmholtz coil is installed around the water atomizing nozzle and a direct current is passed through it to generate a rotating magnetic field with an axial magnetic field strength of 0.5 to 1.5 Tesla. This causes the molten droplets in flight to be subjected to the Lorentz force and spin around their own axis, generating ellipsoidal droplets that undergo spin deformation. The core of this step is to superimpose a controllable axially rotating magnetic field along the droplet's flight path. Using the Lorentz force generated by electromagnetic induction, a constant tangential force is applied to the conductive molten metal droplet, driving the spherical primary droplet to autonomously spin at high speed. Centrifugal force alters the droplet's original spherical shape, gradually stretching and deforming the standard spherical droplet into an ellipsoidal droplet. This pre-constructs the foundation for the formation of surface pits and internal pores in the powder from a morphological perspective. The specific implementation method is as follows: The Helmholtz coil is a dedicated magnetic field generator for this process. It consists of two sets of identical, coaxially parallel circular coils, with the distance between the two sets of coils equal to the radius of the coil itself. This structure can generate a highly uniform axial magnetic field in the central region of the coil, parallel to the direction of droplet flight. This effectively avoids the problem of uneven magnetic field strength at the edges generated by ordinary single coils, ensuring that each metal droplet passing through the magnetic field region experiences a completely consistent electromagnetic force, achieving synchronous and uniform spin deformation of all droplets. Molten tin bronze has excellent electrical conductivity. As the liquid metal droplets cut the axial magnetic field lines, they autonomously generate an induced current, which is the fundamental condition for the droplets to spin in response to the magnetic field force.

[0038] A constant direct current is passed through the Helmholtz coil. The magnitude of the current is linearly and positively correlated with the magnetic field strength. By precisely controlling the output of the direct current, the strength of the axial rotating magnetic field can be precisely controlled. The process is set to an axial magnetic field strength range of 0.5 Tesla to 1.5 Tesla. Tesla is a physical unit of measurement for magnetic induction intensity, used to characterize the strength of the magnetic field force. The magnetic field strength directly determines the droplet spin angular velocity. The lower the magnetic field strength, the smaller the Lorentz force, the lower the droplet spin angular velocity, and the less deformable the droplet is. The higher the magnetic field strength, the greater the Lorentz force, the higher the droplet spin angular velocity, the greater the degree of stretching and deformation of the droplet, and the more likely the droplet will break apart. In this process example, the median value of 1.0 Tesla is selected as the actual axial magnetic field strength, and matched with the DC current parameters, ensuring that the droplet spin angular velocity is stably maintained at 1200 revolutions per minute, with a moderate degree of deformation.

[0039] The Lorentz force is the core physical force in this step. It is the magnetic deflection force experienced by charged particles when they move in a magnetic field. During the flight process, the conductive molten metal droplet cuts the magnetic field lines to generate induced charges. The charges move directionally in the axial magnetic field and are then subjected to a tangential Lorentz force perpendicular to the direction of droplet flight and also perpendicular to the direction of magnetic field lines. The continuous tangential force drives the droplet to spin stably and at high speed around its own central axis. There is no deviation in the flight trajectory, only the rotation of the droplet itself.

[0040] The original atomized droplets are standard spherical shapes. Under the centrifugal force generated by high-speed spin, the equatorial position of the droplet is subjected to outward centrifugal stretching force, while the polar positions are subjected to force contraction. The originally symmetrical spherical structure is uniformly stretched, and the spherical droplet gradually transforms into an ellipsoidal droplet with a fixed ratio of major and minor axes. Throughout the process, the droplet remains intact without splitting or breaking. All droplets uniformly complete the morphological deformation, and finally, a batch of ellipsoidal droplets with extremely high morphological consistency and stable spin state are generated, providing the preliminary morphological conditions for the formation of pores and pits during the subsequent flight cooling and solidification process.

[0041] After flying 5 to 8 meters, the ellipsoidal droplets fall into the water tank below and solidify rapidly. Due to the uneven distribution of surface tension caused by spin, pits are formed and internal pores are interconnected, ultimately resulting in ellipsoidal primary powder with surface pits and internal interconnected pores.

[0042] The core of this step is to allow the ellipsoidal droplet to dissipate heat naturally in the air by relying on a set free flight distance, and then achieve rapid solidification through water cooling in a water tank. Utilizing the differential distribution of surface tension caused by the droplet's spin and the solidification shrinkage effect, regular pits are simultaneously generated on the powder surface and interconnected concave cavities are generated inside the powder, ultimately obtaining an ellipsoidal nascent powder that meets the requirements for subsequent etching and activation. The specific implementation method is as follows: After leaving the magnetic field region, the ellipsoidal droplet enters a free-flight phase free from external interference. The process is designed with a free-flight distance of 5 to 8 meters, which is a key parameter for balancing the droplet's natural heat dissipation and liquid retention time. If the flight distance is less than 5 meters, the droplet's natural heat dissipation time is insufficient, the overall molten liquid temperature remains too high, and the solidification rate is too fast upon entering the water bath, preventing the internal molten metal from shrinking and forming interconnected pores. If the flight distance is greater than 8 meters, the droplet's natural heat dissipation is excessive, and a solid shell forms prematurely on the droplet surface. During water cooling, this surface shell restricts molten metal shrinkage, again preventing the formation of complete internal interconnected pores. This process example selects the median value of 6.5 meters as the droplet's free-flight distance. At this distance, the droplet's surface cools slightly while the interior remains in a complete liquid state, providing optimal solidification and shrinkage conditions.

[0043] Throughout the process, the droplet maintains a high-speed spin state. The liquid metal itself possesses a constant surface tension, which helps maintain the spherical shape of the droplet. However, the centrifugal force generated by the spin couples with the surface tension, disrupting the uniform distribution of surface tension. The centrifugal force is greatest at the droplet's equator, significantly reducing surface tension and causing the liquid metal to flow towards the poles. The amount of surface metal at the equator decreases, naturally forming regular surface pits at the equator after the droplet solidifies. Simultaneously, the high-speed spin of the droplet causes stratified flow of the internal liquid metal, creating a pressure gradient distribution within the melt. This further exacerbates the regional differences in surface tension, resulting in uniformly shaped and regular surface pits without random or irregular depressions.

[0044] When an ellipsoidal droplet falls vertically into a room-temperature cooling water tank below, the water and the high-temperature metal droplet undergo intense heat exchange. The droplet rapidly solidifies layer by layer from the outside in. During the solidification process of the molten metal, volume shrinkage occurs. After solidification, a conventional stationary droplet will only produce isolated closed shrinkage cavities inside. However, the internal flow channels of the molten metal in a continuously spinning droplet remain connected. The tiny shrinkage cavities produced by the shrinkage of the molten metal will connect and intersect with each other, eventually forming a three-dimensional interconnected internal pore structure inside the powder, rather than independent closed pores.

[0045] After the droplets completely solidify, the solid powder particles retain the ellipsoidal shape they had during flight and do not bounce back due to water cooling impact. The macroscopic morphology of the powder is a standard ellipsoid, with uniformly distributed micron-level primary pits on the particle surface and three-dimensional interconnected pore channels inside the particles. The powder as a whole is free of cracks, broken particles, and oxidation peeling defects, which fully meets the raw material requirements of the subsequent ultrasonic etching and activation process. Finally, ellipsoidal primary powder with surface pits and internal interconnected pores is produced in batches.

[0046] S203, the ellipsoidal nascent powder is placed in a mixed solution containing fatty acids and ethanol and subjected to ultrasonic oscillation treatment to selectively etch the tin-rich phase on the powder surface, thereby increasing the pit depth and forming a micron-level crack network to obtain porous activated powder. Specifically, stearic acid and anhydrous ethanol can be mixed in a mass ratio of 1:50 to form a mixed solution, which is then heated to 50 degrees Celsius and stirred until the stearic acid is completely dissolved to generate a selective etching solution. The core of this step is to formulate a targeted selective etching medium suitable for the surface modification requirements of tin bronze alloys. Relying on a complex system of organic acids and organic solvents, a mild etching environment is constructed that only corrodes the tin-rich phase without damaging the copper substrate. Simultaneously, temperature control and uniform stirring eliminate problems such as solute agglomeration and liquid phase stratification, ensuring uniform etching activity throughout the etching solution. This prevents subsequent defects such as localized over-etching or under-etching of the powder from the outset, providing a stable and uniformly performing reaction liquid phase for subsequent powder surface morphology control. The specific implementation method is as follows: Stearic acid is the core active solute in this etching process. It is a long-chain saturated monobasic organic acid with a molecular structure of C18H36O2. This material exhibits extremely strong etching selectivity and is the core basis for the precise modification of the powder surface in the entire porous activation process. Stearic acid can only undergo coordination-type chemical corrosion reactions with tin and cannot react chemically with the copper matrix. This allows for precise identification of the tin-rich phase regions formed during the solidification of tin bronze powder, while perfectly preserving the high-strength copper alloy matrix structure, preventing irreversible defects such as collapse of the overall ellipsoidal contour of the powder or damage to matrix pores. Anhydrous ethanol is used as the dispersion solvent in the etching solution. Analytical grade anhydrous ethanol with an internal moisture content of less than 0.1% is selected. This extremely low moisture content prevents oxidation and corrosion of the tin bronze powder during the solution preparation stage. Ethanol also possesses excellent organic dispersion capabilities and low-temperature volatility, which can fully disperse solid stearic acid. Furthermore, it can quickly evaporate without residue during subsequent cleaning processes, meeting the high-purity and impurity-free preparation standards of powder metallurgy.

[0047] In this process, the mass ratio of stearic acid to anhydrous ethanol is set at 1:50. This value represents the mass ratio of solid solute to liquid solvent, meaning that for every 1 part by mass of solid stearic acid, 50 parts by mass of anhydrous ethanol are required. This ratio has been determined to be the optimal ratio through multiple process comparison experiments. If the proportion of stearic acid is higher than this standard, the overall acidity of the etching solution increases, which will break the selective etching boundary, indirectly corrode the copper substrate, and damage the original mechanical structure of the powder. If the proportion of stearic acid is lower than this standard, the liquid phase etching activity is insufficient, and it is impossible to effectively corrode the tin-rich phase on the powder surface, making it difficult to achieve the process goals of pit deepening and crack formation. In the actual process operation example, 510g of standard selective etching solution is prepared at a time, 10g of sheet-like solid stearic acid is accurately weighed, and 500g of anhydrous ethanol is added, strictly adhering to this mass ratio to ensure constant etching activity.

[0048] The process is set to a heating temperature of 50 degrees Celsius, which is the optimal activation temperature for dissolving stearic acid. At room temperature, stearic acid is a dense, white, waxy solid with strong intermolecular van der Waals forces, making it insoluble in anhydrous ethanol. 50 degrees Celsius effectively weakens the intermolecular forces of stearic acid, accelerating crystal dissociation and dissolution. Furthermore, this temperature is far below the atmospheric boiling point of anhydrous ethanol (78.4 degrees Celsius), ensuring that the ethanol evaporation loss rate is controlled to within 1% throughout the process, without altering the original solid-liquid ratio of the etching solution. After heating, a uniform magnetic stirring process is performed at a fixed speed of 200 rpm for 15 minutes. Magnetic stirring achieves full-scale convection in the liquid phase, allowing the dissociated stearic acid molecules to distribute evenly within the ethanol solvent, completely eliminating localized solute accumulation areas. The criteria for determining complete dissolution of stearic acid are that the mixed solution is a clear, colorless, and transparent liquid phase with no white solid particles and no layering. Once this criterion is met, a selective etching solution with uniform composition, stable etching selectivity, and consistent activity can be obtained.

[0049] The ellipsoidal nascent powder was immersed in a selective etching solution with a powder-etching solution mass ratio of 1:10. The solution was kept at a constant temperature water bath to 60 degrees Celsius to generate a powder-etching solution mixture. The core of this step is to achieve sufficient wetting and matching between the solid alloy powder and the liquid etching medium. By fixing the solid-liquid ratio, it is ensured that each powder particle is completely encapsulated by the liquid phase, with no exposed powder areas. At the same time, the reaction temperature of the system is slightly increased to enhance the chemical reactivity of the interface. This constructs a mixed reaction system with constant temperature, sufficient solid-liquid contact, and a closed and stable reaction environment. This eliminates the problems of poor etching uniformity caused by solid-liquid interface temperature difference and insufficient liquid phase, laying a stable pre-reaction foundation for subsequent ultrasonic-assisted etching. The specific implementation method is as follows: The ellipsoidal primary powder used in this process is a semi-finished powder prepared by the high-pressure water atomization and rotating magnetic field process described earlier. The powder particle size is stably controlled between 50 and 150 micrometers, and the overall shape is an irregular ellipsoid. The powder surface has shallow pits formed by spin solidification. During the solidification process of the alloy, tin has a lower melting point and stronger fluidity, which will spontaneously cause element segregation on the powder surface and the inner wall of the pits, forming a continuously distributed tin-rich segregation layer. This segregation layer is the core reaction site for subsequent selective etching. The ellipsoidal shape can avoid the compaction of powder particles, ensuring that each powder particle can independently contact the etching solution, thus improving the overall etching uniformity.

[0050] The process is set with a powder-to-etching solution mass ratio of 1:10. This parameter represents the solid-liquid mass ratio of solid alloy powder to liquid etching solution, meaning that for every 1 part by mass of ellipsoidal nascent powder, 10 parts by mass of selective etching solution are required. This ratio completely submerges all powder particles, ensuring no powder is exposed above the liquid surface, while also reserving sufficient space for liquid flow to prevent powder particles from sticking together and colliding, creating localized etching blind spots. In the actual process demonstration, 50g of dried ellipsoidal nascent powder was added, along with 500g of the prepared selective etching solution. The solid and liquid phases were completely wetted, with sufficient liquid phase remaining to meet the requirement of uniform reaction throughout the entire process.

[0051] The process was set at a constant temperature of 60 degrees Celsius for the water bath, compared to the base temperature of 50 degrees Celsius during the solution preparation stage. This 10-degree Celsius increase in system temperature aimed to enhance the interfacial coordination reaction rate between stearic acid and the tin-rich phase. According to the kinetics of organometallic corrosion reactions, every 10-degree Celsius increase in temperature can increase the directional corrosion reaction rate by 1.8 times, effectively shortening the overall process time for subsequent ultrasonic etching. The constant temperature water bath was maintained with a stable temperature control accuracy of ±0.5 degrees Celsius to prevent temperature fluctuations from causing deviations in the etching degree of powder at different locations. Mechanical stirring was not activated during the entire holding phase; natural heat convection in the water bath was used to achieve temperature synchronization across the entire liquid phase. The holding time was fixed at 20 minutes to ensure complete uniformity between the powder matrix temperature, the temperature inside the surface pits, and the liquid etching solution temperature, eliminating the solid-liquid interface temperature gradient. This resulted in a powder-etching solution mixture with a uniform temperature field, precise solid-liquid ratio, and complete powder wetting without blind spots.

[0052] The powder-etching solution mixture was placed in an ultrasonic cleaner, and the ultrasonic frequency was set to 40 kHz and the power density to 50 W / L. The mixture was continuously oscillated for 60 minutes to allow stearic acid to preferentially react with the tin-rich phase on the powder surface and dissolve tin ions, thereby generating an etched powder suspension. The core of this step is to combine the dual effects of selective chemical corrosion and ultrasonic physical cavitation. Utilizing the micro-jet generated by ultrasonic vibration to impact the inner wall of the original pits in the powder, coupled with the directional chemical corrosion of stearic acid, the surface pits are deepened while simultaneously inducing the formation of interconnected micron-sized cracks on the powder wall. This process avoids the risk of corrosion to the copper matrix throughout, achieving in-situ activation and modification of the powder surface's porous structure, giving the powder a basic oil-retaining pore structure. The specific implementation method is as follows: Ultrasonic cleaning machines are the core equipment in this process. The transducers inside the equipment can convert high-frequency electrical signals into high-frequency mechanical vibrations in the liquid phase, thereby continuously generating a large number of micron-sized cavitation bubbles inside the etching solution. The bubbles will periodically complete the entire process of generation, expansion, and collapse. At the moment of bubble collapse, instantaneous high-pressure micro-jet will be generated, which mechanically impacts the powder surface and the inner wall of the pit, breaking the trace amount of organic tin reaction product film accumulated on the powder surface during the etching reaction. This ensures that the chemical etching reaction can continue to proceed stably, solving the industry pain point of static etching product accumulation blocking the reaction.

[0053] The process is set with an ultrasonic frequency of 40 kHz. Ultrasonic frequency refers to the number of ultrasonic vibration cycles per unit time, measured in kHz. 40 kHz falls within the low-frequency ultrasonic range specifically designed for industrial powder modification. Low-frequency ultrasound generates larger cavitation bubbles, and the mechanical impact energy generated by bubble collapse is stronger, effectively compressing and tearing the inner walls of the original shallow pits in the powder, causing the pits to extend and deepen inward. If the ultrasonic frequency is higher than this value, the cavitation bubble size is too small, resulting in insufficient mechanical impact force and inability to induce crack formation. If the ultrasonic frequency is lower than this value, the uniformity of ultrasonic vibration distribution decreases significantly, and the etching degree varies significantly between the upper and lower regions of the powder. 40 kHz is perfectly suited to the modification needs of tin bronze powder with a particle size of 50 micrometers to 150 micrometers.

[0054] The process power density is set at 50 watts per liter. Power density refers to the effective ultrasonic output power per unit volume of etching solution, expressed in W / L. This parameter directly determines the strength of the ultrasonic cavitation effect. 50 watts per liter is the optimal power density for this process, providing sufficient mechanical impact energy to assist in crack formation without excessively high ultrasonic power that could break through the original interconnected pores inside the powder and damage the integrity of the alloy matrix. When the power density is higher than this value, excessive mechanical impact will directly break the ellipsoidal powder, causing a sharp drop in powder particle size; when the power density is lower than this value, the cavitation effect is too weak, and only static chemical etching can deepen the pits, failing to form an interconnected micron-sized crack network.

[0055] The process was set to a continuous oscillation duration of 60 minutes, which is the optimal duration for the synergistic effect of chemical etching and ultrasonic impact. The entire oscillation process is divided into three reaction stages: the first 20 minutes are the rapid surface etching stage, where stearic acid rapidly erodes the powder surface to expose the tin-rich phase and remove surface tin elements; the middle 20 minutes are the pit deepening stage, where ultrasonic microjets continuously impact the inner wall of the pit, combined with chemical etching, allowing the original shallow pits to continue to extend inward; the last 20 minutes are the crack formation stage, where stress concentration generates fine cracks on the pit wall, and these cracks gradually connect with each other. Insufficient oscillation time will result in insufficient pit depth and inability to connect cracks; excessive oscillation time will lead to etching boundary failure, with the copper substrate beginning to be slightly corroded, damaging the strength of the powder matrix.

[0056] Throughout the reaction, the carboxyl functional groups of stearic acid continuously undergo coordination corrosion with the tin-rich phase on the powder surface. Solid elemental tin is gradually transformed into soluble organotin complexes, which are uniformly dissolved into the ethanol liquid phase. Ultrasonic convection continuously refreshes the fresh etching solution on the powder surface, ensuring that the reaction proceeds uninterruptedly. Finally, all the powders are uniformly dispersed in the liquid phase, forming an etched powder suspension with no agglomeration and a consistent degree of etching.

[0057] The etched powder suspension was vacuum filtered, washed three times with anhydrous ethanol, and then placed in a vacuum drying oven at 80 degrees Celsius for 4 hours to increase the pit depth from the original 1 to 2 micrometers to 5 to 8 micrometers and form an interconnected micrometer-level crack network, finally obtaining porous activated powder.

[0058] The core of this step is to complete the solid-liquid separation, impurity cleaning, and low-temperature drying of the etched powder. This thoroughly removes residual etching solution and organotin byproducts from the powder surface and internal pores. Simultaneously, a vacuum, oxygen-free environment is used to prevent high-temperature oxidation of the powder. Finally, the pore morphology of the powder surface is quantitatively controlled to form a three-dimensional porous oil-retaining structure that is interconnected internally and externally, thus completing the final preparation of the porous activated powder. The specific implementation method is as follows: Vacuum filtration is the first post-processing step, primarily used to rapidly and efficiently separate solid tin bronze powder from the liquid suspension. The process maintains a constant vacuum pressure of 0.07 MPa. This negative pressure environment allows the liquid phase to quickly penetrate the filter membrane, simultaneously trapping all alloy powder particles. Compared to gravity filtration, vacuum filtration shortens the separation time by over 70%, while also reducing the powder's contact time with air and lowering the risk of oxidation. The filtration uses an organic microporous membrane with a pore size of 5 micrometers, which can completely trap all powder particles larger than 50 micrometers. There is no material loss throughout the process. After filtration, residual stearic acid and organotin byproducts still adhere to the micropores, pits, and cracks on the powder surface, requiring further cleaning to remove impurities.

[0059] The subsequent washing process involves three repeated washes using anhydrous ethanol. Anhydrous ethanol, being the same source as the etching solution, is used as the cleaning medium, preventing the introduction of foreign impurities such as water and metal ions. Furthermore, ethanol's low surface tension allows it to penetrate deep into micron-level cracks, flushing away residual reaction byproducts in hidden locations. The standard procedure for a single wash is as follows: Sufficient anhydrous ethanol is added to the filter cake to completely submerge the powder. The mixture is gently stirred at low speed for 30 seconds to ensure the ethanol fully wets all pores of the powder. Then, vacuum filtration is performed again to remove the waste liquid. Each wash takes 2 minutes. Repeating this complete washing process three times thoroughly removes all residual reactants from both inside and outside the powder, preventing residual etching solution from further corroding the powder's pore structure.

[0060] Finally, the washed wet powder is placed in a vacuum drying oven for drying. The vacuum level of the drying environment is maintained at a constant 0.09 MPa, completely isolating it from air and moisture, thus preventing surface oxidation, rusting, and discoloration of the tin bronze powder during heating. The drying temperature is set at 80 degrees Celsius, which is lower than the boiling point of anhydrous ethanol, allowing for the gentle evaporation of residual ethanol solvent inside the powder pores without generating high-temperature thermal stress, preventing the already formed micron-sized cracks from shrinking and closing due to heat. The drying time is fixed at 4 hours to ensure that the ethanol solvent in the surface cracks and deep internal interconnected pores of the powder completely evaporates, achieving thorough drying of the entire powder surface.

[0061] Through a complete set of etching and post-processing techniques, the surface morphology of the powder is precisely and controllably modified: the original ellipsoidal nascent powder surface only has shallow pits formed by spin solidification, with a pit depth ranging from 1 to 2 micrometers. The pore volume is extremely small and cannot store lubricating oil. After processing, the pit depth is increased to 5 to 8 micrometers, and the oil storage cavity volume is significantly increased. At the same time, micron-level cracks with a width of 1 to 3 micrometers are generated on the pit walls. All cracks are interconnected and seamlessly connected with the original interconnected pores inside the powder, constructing a three-dimensional interconnected crack network integrating powder surface cracks, deep surface pits, and internal interconnected pores. This porous structure can significantly improve the powder's lubricating oil adsorption capacity and oil retention stability, complete the powder surface activation modification, and finally obtain a porous activated powder with complete pore structure, no oxidation impurities, and qualified morphological parameters.

[0062] S204, the porous activated powder and graphene dispersion are mixed at a preset mass ratio, and then ball-milled at low speed using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges to obtain morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

[0063] Specifically, graphene powder can be dispersed in anhydrous ethanol at a mass fraction of 0.5%, and ultrasonically dispersed for 30 minutes using a probe to prepare a graphene dispersion, thereby generating a uniform graphene dispersion. The core of this step is to break down the naturally occurring layer agglomeration of dried graphene powder using a high-intensity probe ultrasonic liquid-phase dispersion process. A stable suspension system is built using a chemically inert organic solvent, and the dispersion concentration and duration are precisely controlled to prepare a graphene dispersion with fully exfoliated layers and no agglomeration or precipitation. This ensures the uniformity of the subsequent coating on the tin bronze powder surface from the source, preventing problems such as localized graphene accumulation or incomplete coating. The specific implementation method is as follows: Graphene powder is the core two-dimensional raw material for this powder surface modification. This material possesses an atomically thin, sheet-like structure and exhibits excellent solid self-lubricating properties and surface film-forming capabilities. Furthermore, its flexible sheet structure can conform to the uneven, porous surface of tin bronze powder, meeting the coating requirements of this porous activated powder. However, in its dry state, graphene powder is subject to intermolecular van der Waals forces, leading to spontaneous multilayer aggregation. This aggregation prevents the formation of a uniform film and can clog the oil-retaining pores within the powder. Therefore, liquid-phase ultrasonication is necessary to achieve sheet exfoliation, which is an indispensable core process step.

[0064] Anhydrous ethanol is used as the dedicated liquid dispersion medium. Analytical grade anhydrous ethanol can meet the process requirements. This solvent is completely chemically inert and will not react chemically with the graphene or tin bronze alloy matrix at room temperature or under ultrasonic treatment. It can completely preserve the micron-level cracks and internal interconnected pore structures formed after powder etching. At the same time, anhydrous ethanol has a low surface tension, which provides excellent wetting effect on graphene powder. Moreover, there is no solid residue after drying and evaporation, and it will not contaminate the oil storage channels of the powder. It is the optimal dispersion solvent for this process and does not need to be mixed with water or other polar solvents, thus avoiding the oxidation and corrosion of bronze powder caused by moisture.

[0065] The graphene dispersion mass fraction set in the process is 0.5%, which specifically refers to the proportion of graphene solid powder mass to the total mass of the dispersion. This translates to 0.5 grams of graphene powder and 99.5 grams of anhydrous ethanol solvent per 100 grams of dispersion. This concentration is the optimal process concentration determined through multiple sets of comparative experiments. The concentration directly determines the thickness of the subsequent coating layer: when the mass fraction is higher than 0.5%, the graphene content in the liquid phase is excessive, resulting in a thick layer of graphene accumulation on the powder surface after ball milling, blocking surface cracks and directly reducing the powder's oil storage capacity; when the mass fraction is lower than 0.5%, the effective graphene content in the liquid phase is insufficient, resulting in large exposed areas on the powder surface, preventing the formation of a complete and continuous protective lubricating coating layer, and reducing the overall tribological properties of the composite powder.

[0066] Ultrasonic dispersion using a probe differs from conventional water bath ultrasonic dispersion. It is a direct, high-energy dispersion method where the ultrasonic probe directly inserts into the liquid system to output high-frequency mechanical vibration energy. This energy utilization rate is far higher than that of water bath ultrasonic dispersion, directly disrupting the stacking forces between graphene sheets and enabling the exfoliation of multilayer graphene into fewer-layer graphene. In this study, a fixed ultrasonic dispersion time of 30 minutes was set. This timeframe can exfoliate most agglomerated graphene into 2-5 layers of fewer-layer graphene, satisfying the structural requirements for surface coating without breaking the intact graphene sheets due to excessive ultrasonic time, thus avoiding the generation of tiny graphene fragments that clog the micropores inside the powder. In actual operation, the graphene powder is first slowly added to anhydrous ethanol, and then stirred at low speed for 10 minutes beforehand to eliminate dry powder clumps. The probe is then turned on and ultrasonically operated continuously for 30 minutes. The container is sealed throughout the process to minimize ethanol evaporation. The final result is a graphene dispersion that, after standing for 2 hours, exhibits no stratification, no sedimentation, and a uniform distribution of sheets, ensuring consistent raw material properties in the next mixing process.

[0067] Porous activated powder and graphene dispersion were mixed at a mass ratio of 10:1 and added to the grinding jar of a planetary ball mill. Zirconia grinding balls with a diameter of 3 mm were selected, and the ball-to-material mass ratio was 5:1 to generate a ball-milled mixture. The core of this step is to quantitatively blend solid porous bronze powder and liquid graphene dispersion, match suitable grinding media specifications and ball-to-powder ratios, and build a low-damage, force-controllable ball milling reaction system. This allows the mechanical force generated by the grinding balls to effectively bond graphene and bronze powder without damaging the already formed three-dimensional oil-storing pore structure of the powder. The specific implementation method is as follows: The porous activated powder used in this step is a semi-finished powder prepared in the previous ultrasonic etching process. After selective etching, the surface pit depth of this powder is increased to 5-8 micrometers, and a fully interconnected micrometer-level crack network is formed. The powder retains a complete interconnected constriction structure inside, and has excellent oil storage space. However, the powder surface has no lubrication modification layer, resulting in poor wear resistance under dry friction conditions. In addition, the surface pore openings are too large, and the lubricating oil is prone to rapid loss after storage. Therefore, it is necessary to use graphene sheets for surface coating and pore sealing reinforcement. The ratio of the two materials directly determines the comprehensive performance of the final composite powder.

[0068] The mass ratio of porous activated powder to graphene dispersion is set at 10:1, meaning that for every 10 units of porous activated powder in the system, there is a corresponding 1 unit of graphene dispersion. This ratio precisely balances the proportion of matrix powder and the amount of modified graphene. If the ratio is too large, it means that the amount of dispersion is too small, and the graphene cannot completely cover the outer surface of the powder, resulting in insufficient reinforcement of the pore openings. If the ratio is too small, the amount of dispersion is too large, and the viscosity of the liquid phase system decreases significantly. During ball milling, the graphene is difficult to adhere to the powder surface, and a large amount of graphene remains free in the liquid phase, resulting in material waste and failure of the coating effect.

[0069] Planetary ball mills are the designated gentle ball milling equipment for this process. Unlike traditional drum ball mills, this equipment features a composite planetary motion trajectory of revolution and rotation, capable of outputting controllable micro-shearing, micro-friction, and micro-extrusion forces. It operates in a low-speed ball milling mode throughout the process, avoiding strong impact loads and maximally protecting the internal micropores, surface cracks, and pit structures of the powder from being compressed and collapsed. The accompanying grinding jar is a sealed, pressure-resistant vessel. This sealed structure isolates the tin bronze powder from oxygen during ball milling, preventing secondary oxidation and minimizing the evaporation of anhydrous ethanol solvent, thus ensuring a stable liquid phase concentration throughout the mixture.

[0070] Zirconia grinding balls with a diameter of 3 mm were selected as the grinding media. Zirconia material has extremely high chemical stability, high hardness, and no metal ion precipitation. The entire ball milling process will not generate impurities that contaminate the tin bronze powder, nor will it cause side reactions with ethanol or graphene. The 3 mm diameter of the grinding balls is the optimal size for the gentle coating process. The small diameter grinding balls exert a gentle and uniform force, which can only promote the sliding and adhesion of graphene sheets without impacting and damaging the porous structure of the powder. If the diameter of the grinding balls is too large, the strong impact load will directly close the cracks on the powder surface and completely destroy the oil storage structure. If the diameter of the grinding balls is too small, the mechanical force is insufficient, and the graphene cannot adhere firmly to the powder surface.

[0071] The ball-to-material ratio of 5:1 refers to the ratio of the total mass of all zirconia grinding balls in the jar to the total mass of the porous activated powder raw material. This parameter determines the overall density of mechanical forces within the ball mill chamber. If the ball-to-material ratio is too high, the amount of grinding balls in the jar is too large, compressing the material's movement space and causing excessive powder compression. If the ball-to-material ratio is too low, the number of grinding balls is insufficient, resulting in inadequate effective interaction frequency and a significant reduction in the uniformity of graphene coating. Powder, dispersion, and grinding balls are added sequentially according to this ratio. The ball mill jar is then sealed and allowed to stand for 2 minutes to achieve initial mixing of the materials, ultimately yielding a uniformly composed and precisely proportioned ball-milled mixture, providing a stable material basis for subsequent speed-controlled ball milling processes.

[0072] The planetary ball mill was set to a revolution speed of 150 rpm and a rotation speed of 225 rpm, with a milling time of 2 hours. The rotation direction was changed every 30 minutes to allow the graphene sheets to adhere evenly to the powder surface and partially embed into the crack edges under mechanical force, thus generating a composite powder slurry after ball milling. The core of this step is the dual-dimensional control of the ball mill's motion parameters. Relying on the composite force field formed by the coupling of revolution and rotation, a gradient and gentle mechanical force is output to achieve a triple effect of graphene sheet spreading, surface adhesion, and precise embedding at the crack edges. At the same time, periodic reversal eliminates dead zones in material movement, ensuring consistent coating of the entire batch of powder and preventing damage to the pore structure throughout the process. The specific implementation method is as follows: The planetary ball mill has two independent operating systems: a revolution system and a rotation system. Revolution refers to the overall circular motion of the milling jars around the central axis of the equipment, while rotation refers to the independent rotation of each individual milling jar around its own central axis. Both systems are independently speed-adjustable, precisely matching the requirements for non-destructive coating. Setting the revolution speed to 150 revolutions per minute is within the low-speed range, primarily used to drive all milling jars in synchronous circulation, ensuring all material within the jars forms a unified circulating flow field and preventing localized material accumulation. Excessive revolution speed increases overall kinetic energy, generating destructive impact loads; conversely, insufficient revolution speed leads to ineffective material circulation and extremely poor coating uniformity.

[0073] The rotation speed is set to 225 revolutions per minute, and the rotation speed is always higher than the revolution speed. The rotation speed ratio is fixed at 1:1.5. The stable speed difference can generate continuous and gentle relative shear force and extrusion force. This force is just right to smooth out the natural wrinkles of the graphene sheets, allowing the flexible graphene sheets to completely fit the rough and porous powder surface. At the same time, it can push a small number of graphene sheets to slowly embed into the opening edge of the micron-level cracks, achieving pore sealing and reinforcement, without puncturing the inner wall of the powder pores or compressing the internal oil storage cavity.

[0074] The total ball milling time was fixed at 2 hours, and the graphene composite molding was completed in two stages: In the first hour of ball milling, the free graphene sheets gradually adhered to the outer surface of the powder under the action of friction, completing the initial physical adhesion; in the second hour of ball milling, continuous micro-extrusion pressure pushed the graphene sheets into the edge of the cracks, reducing the size of the pore openings, slowing down the seepage rate of lubricating oil, and at the same time preserving the oil storage cavities inside the cracks. If the ball milling time is less than 2 hours, the bonding force between graphene and powder is weak, and graphene is prone to falling off during subsequent use; if the ball milling time exceeds 2 hours, the continuous mechanical force for a long time will gradually squeeze the microporous structure, causing the oil storage space to shrink, directly reducing the final oil content of the powder.

[0075] The rotation direction is changed every 30 minutes. During the 2-hour ball milling process, the revolution and rotation directions are switched synchronously at 30, 60, and 90 minutes, completing three reversal operations in total. Single-direction ball milling causes the material inside the tank to form a fixed trajectory, creating dead zones where powder cannot contact the grinding balls' force, resulting in blank areas on the surface coating. Periodic reversal disrupts the inherent flow field, eliminates dead zones, and ensures that every particle of tin bronze powder is evenly contacted by the mechanical force, guaranteeing a completely consistent coating effect throughout the entire batch.

[0076] Under the continuous action of the composite mechanical force field, the graphene sheets uniformly cover the entire outer surface of the powder, while an appropriate amount of sheets are stuck at the edge of the cracks, which not only achieves surface self-lubrication modification, but also completes the protection of the pore openings, and finally obtains a ball-milled composite powder slurry with a firm bond between graphene and bronze powder and a complete pore structure.

[0077] After ball milling, the composite powder slurry was taken out, vacuum filtered, washed three times with anhydrous ethanol, and then vacuum dried at 60 degrees Celsius for 6 hours to finally obtain a three-dimensional oil storage structure morphology-controlled tin bronze powder with graphene sheets forming a continuous coating layer and internal cracks retaining oil storage space.

[0078] The core of this step involves three post-processing steps: solid-liquid separation, impurity cleaning, and low-temperature vacuum drying. These steps thoroughly remove residual solvents and ineffective free graphene from the slurry, completing powder drying and molding under conditions of oxidation isolation and no thermal damage. The result is a three-dimensional composite structure with a continuous outer layer of graphene for lubrication and an inner layer of multi-level porous oil storage, meeting the requirements for high-oil-content tin bronze powder. The specific implementation method is as follows: The composite powder slurry removed after ball milling consists of three parts: solid-phase composite bronze powder, anhydrous ethanol solvent, and a small amount of unbonded free graphene fragments. The free graphene fragments cannot participate in surface coating and will enter the micropores of the powder and block the oil storage channels. Therefore, it is necessary to thoroughly remove impurities through solid-liquid separation and cleaning processes.

[0079] Vacuum filtration is the first post-processing step. It relies on a negative pressure vacuum environment to achieve rapid separation of solid powder and liquid ethanol. Under negative pressure, the liquid solvent quickly penetrates the filter membrane and is discharged, while the solid powder is completely retained by the filter membrane. This process does not involve mechanical compression and does not compact the porous structure of the powder. Compared with natural filtration, the efficiency is more than 4 times higher. It can quickly remove most of the free ethanol solvent in the slurry and achieve preliminary solid-liquid separation.

[0080] Subsequently, the filter membrane was washed three times with anhydrous ethanol. In each wash, sufficient anhydrous ethanol was added to completely submerge the powder layer above the filter membrane, gently rinsing away any remaining free graphene fragments and trace powder particles in the crevices of the powder surface. Three washes were set as the optimal number of washes. A single wash is insufficient to remove trace impurities deep within the crevices, and washing more than three times would wash away the firmly adhered graphene coating, disrupting the continuous film structure. Three washes balance the effectiveness of impurity removal with the integrity of the coating.

[0081] Finally, vacuum drying is carried out. The vacuum drying chamber maintains a negative pressure vacuum environment throughout the process to isolate oxygen and water vapor in the air, thereby preventing the tin bronze powder from undergoing surface oxidation during the heating and drying process and preventing the oxide film from reducing the powder's lubrication compatibility. At the same time, the negative pressure environment can lower the boiling point of the ethanol solvent, achieving low-temperature drying and avoiding the damage to the microporous structure caused by high-temperature thermal stress.

[0082] The drying temperature is set at 60 degrees Celsius. This temperature is within the low-temperature constant-temperature drying range, which ensures that the ethanol solvent evaporates quickly and completely without generating thermal stress that would cause the micropores and surface cracks inside the powder to shrink and close, thus preserving the original oil storage space to the greatest extent. If the temperature is too high, the pores will shrink thermally, and the oil content will drop significantly. If the temperature is too low, the solvent will evaporate slowly, and the drying will be incomplete.

[0083] A vacuum drying time of 6 hours is sufficient to completely remove residual ethanol that has penetrated deep into the micropores and cracks of the powder, ensuring that the overall dryness of the powder meets the standards. After drying, a continuous graphene coating without breaks is formed on the outer layer of the powder, which plays a role in reducing friction, lubrication, and protecting the pores. Micron-sized cracks, deep pits, and internal interconnected pores on the powder surface are all completely preserved, without pore blockage or collapse. The final product is a three-dimensional oil-storage structure with an outer layer for lubrication and protection and an inner layer for multi-level oil storage, resulting in tin bronze powder with high oil content and morphology control that meets the process requirements.

[0084] Another embodiment of the present invention provides a morphology control system for high oil content tin bronze powder, see [link to relevant documentation]. Figure 3 The system may include: The heating module 301 is used to put electrolytic copper, pure tin and deoxidizer into the medium frequency induction melting furnace according to the set ratio, and heat up under argon protection to form a uniform alloy melt. After slag removal treatment, pure tin bronze melt is obtained. The application module 302 is used to break the molten tin bronze into fine droplets using a high-pressure water atomization process, while applying an axial rotating magnetic field around the water atomization nozzle to cause the droplets to spin and deform during flight, and obtain an ellipsoidal primary powder with surface pits and internal interconnected holes after solidification. The oscillation module 303 is used to place the ellipsoidal nascent powder in a mixed solution containing fatty acids and ethanol for ultrasonic oscillation treatment, selectively etching the tin-rich phase on the powder surface, increasing the pit depth and forming a micron-level crack network to obtain porous activated powder. The control module 304 is used to mix the porous activated powder and graphene dispersion at a preset mass ratio, and to perform low-speed ball milling using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges to obtain morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

[0085] This invention also provides a storage medium storing a computer program, wherein the computer program is configured to execute the steps in any of the above method embodiments when running.

[0086] This invention also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0087] Specifically, the aforementioned electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the aforementioned processor, and the input / output device is connected to the aforementioned processor.

[0088] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A method for controlling the morphology of high oil content tin bronze powder, characterized in that, The method includes: Electrolytic copper, pure tin, and deoxidizer are added to a medium-frequency induction melting furnace according to a set ratio. The furnace is heated under argon protection to form a uniform alloy melt. After slag removal, pure tin bronze melt is obtained. The molten tin bronze is broken into fine droplets by high-pressure water atomization. At the same time, an axial rotating magnetic field is applied around the water atomization nozzle to cause the droplets to spin and deform during flight. After solidification, an ellipsoidal primary powder with surface pits and internal interconnected pores is obtained. The ellipsoidal nascent powder was placed in a mixed solution containing fatty acids and ethanol and subjected to ultrasonic oscillation treatment to selectively etch the tin-rich phase on the powder surface, thereby increasing the pit depth and forming a micron-scale crack network to obtain porous activated powder. The porous activated powder and graphene dispersion are mixed at a preset mass ratio and then ball-milled at low speed using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges, thereby obtaining morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

2. The method according to claim 1, characterized in that, The process involves adding electrolytic copper, pure tin, and a deoxidizer in a predetermined ratio into a medium-frequency induction melting furnace, heating under argon protection to form a homogeneous alloy melt, and obtaining pure tin bronze molten metal after slag removal. The process includes: Weigh out electrolytic copper, pure tin, and phosphor bronze deoxidizer in a ratio of 85% to 90% copper by mass, 10% to 15% tin by mass, and 0.5% to 1% deoxidizer by mass to generate a precisely proportioned furnace charge. The furnace charge is fed into the medium-frequency induction melting furnace, the furnace cover is closed and the furnace chamber is evacuated to a negative pressure of 0.08 MPa, then high-purity argon is introduced to atmospheric pressure and the process is repeated 3 times to generate an argon protective atmosphere. Turn on the medium-frequency induction heating power supply and heat up to 1200 degrees Celsius at a rate of 15 to 20 degrees Celsius per minute. Hold the temperature for 30 minutes to allow the electrolytic copper and pure tin to completely dissolve and form a uniform alloy melt, generating an initial melt with uniform composition. Add slag-forming agent to the initial melt and stir. After standing for 10 minutes, use a graphite slag skimmer to remove the surface slag. Repeat the slag removal operation twice to finally obtain pure tin bronze melt.

3. The method according to claim 2, characterized in that, The process employs high-pressure water atomization to break the molten tin bronze into fine droplets. Simultaneously, an axial rotating magnetic field is applied around the water atomizing nozzle to cause the droplets to spin and deform during flight. Upon solidification, an ellipsoidal primary powder with surface pits and internally communicating pores is obtained, comprising: The pure molten tin bronze is transferred to a tundish and heated to 1150 degrees Celsius. The spout at the bottom of the tundish is opened to allow the molten liquid to flow into the center of the high-pressure water atomizing nozzle at a flow rate of 3 to 5 kg per minute, generating a continuous flow of molten liquid. The high-pressure water pump is started to make the atomized water pressure reach 80 to 100 MPa. The high-pressure water flow is sprayed from the annular nozzle at a 30-degree cone angle, breaking the continuous molten flow into droplets with a particle size of 50 to 150 micrometers, generating a diffusely distributed group of molten droplets. A Helmholtz coil is installed around the water atomizing nozzle and a direct current is passed through it to generate a rotating magnetic field with an axial magnetic field strength of 0.5 to 1.5 Tesla. This causes the molten droplets in flight to be subjected to the Lorentz force and spin around their own axis, generating ellipsoidal droplets that undergo spin deformation. After flying 5 to 8 meters, the ellipsoidal droplets fall into the water tank below and solidify rapidly. Due to the uneven distribution of surface tension caused by spin, pits are formed and internal pores are interconnected, ultimately resulting in ellipsoidal primary powder with surface pits and internal interconnected pores.

4. The method according to claim 3, characterized in that, The process involves placing the ellipsoidal nascent powder in a mixed solution containing fatty acids and ethanol for ultrasonic oscillation treatment, selectively etching the tin-rich phase on the powder surface to increase the pit depth and form a micron-scale crack network, thereby obtaining porous activated powder, comprising: Stearic acid and anhydrous ethanol were mixed in a mass ratio of 1:50 to prepare a mixed solution. The solution was heated to 50 degrees Celsius and stirred until the stearic acid was completely dissolved to generate a selective etching solution. The ellipsoidal nascent powder was immersed in a selective etching solution with a powder-etching solution mass ratio of 1:

10. The solution was kept at a constant temperature water bath to 60 degrees Celsius to generate a powder-etching solution mixture. The powder-etching solution mixture was placed in an ultrasonic cleaner, and the ultrasonic frequency was set to 40 kHz and the power density to 50 W / L. The mixture was continuously oscillated for 60 minutes to allow stearic acid to preferentially react with the tin-rich phase on the powder surface and dissolve tin ions, thereby generating an etched powder suspension. The etched powder suspension was vacuum filtered, washed three times with anhydrous ethanol, and then placed in a vacuum drying oven at 80 degrees Celsius for 4 hours to increase the pit depth from the original 1 to 2 micrometers to 5 to 8 micrometers and form an interconnected micrometer-level crack network, finally obtaining porous activated powder.

5. The method according to claim 4, characterized in that, The process involves mixing the porous activated powder with a graphene dispersion at a preset mass ratio, and then performing low-speed ball milling using a planetary ball mill. By controlling the diameter of the grinding balls and the milling time, graphene sheets are uniformly coated onto the powder surface and partially fill the edges of cracks, resulting in morphology-controlled tin bronze powder with a three-dimensional oil-retaining structure. Graphene powder was dispersed in anhydrous ethanol at a mass fraction of 0.5%, and ultrasonically dispersed for 30 minutes using a probe to prepare a graphene dispersion, resulting in a uniform graphene dispersion. Porous activated powder and graphene dispersion were mixed at a mass ratio of 10:1 and added to the grinding jar of a planetary ball mill. Zirconia grinding balls with a diameter of 3 mm were selected, and the ball-to-material mass ratio was 5:1 to generate a ball-milled mixture. The planetary ball mill was set to a revolution speed of 150 rpm and a rotation speed of 225 rpm, with a milling time of 2 hours. The rotation direction was changed every 30 minutes to allow the graphene sheets to adhere evenly to the powder surface and partially embed into the crack edges under mechanical force, thus generating a composite powder slurry after ball milling. After ball milling, the composite powder slurry was taken out, vacuum filtered, washed three times with anhydrous ethanol, and then vacuum dried at 60 degrees Celsius for 6 hours to finally obtain a three-dimensional oil storage structure morphology-controlled tin bronze powder with graphene sheets forming a continuous coating layer and internal cracks retaining oil storage space.

6. A morphology control system for high oil content tin bronze powder, characterized in that, The system includes: The heating module is used to add electrolytic copper, pure tin and deoxidizer into the medium frequency induction melting furnace according to the set ratio, and heat up under argon protection to form a uniform alloy melt. After slag removal treatment, pure tin bronze melt is obtained. An application module is used to break the molten tin bronze into fine droplets using a high-pressure water atomization process. At the same time, an axial rotating magnetic field is applied around the water atomization nozzle to cause the droplets to spin and deform during flight. After solidification, an ellipsoidal primary powder with surface pits and internal interconnected pores is obtained. An oscillation module is used to place the ellipsoidal nascent powder in a mixed solution containing fatty acids and ethanol for ultrasonic oscillation treatment, selectively etching the tin-rich phase on the powder surface, increasing the pit depth and forming a micron-level crack network to obtain porous activated powder. The control module is used to mix the porous activated powder and graphene dispersion at a preset mass ratio, and to perform low-speed ball milling using a planetary ball mill. By controlling the diameter of the grinding balls and the ball milling time, the graphene sheets are uniformly coated on the powder surface and fill part of the crack edges to obtain morphology-controlled tin bronze powder with a three-dimensional oil storage structure.

7. The system according to claim 6, characterized in that, The heating module is specifically used for: Weigh out electrolytic copper, pure tin, and phosphor bronze deoxidizer in a ratio of 85% to 90% copper by mass, 10% to 15% tin by mass, and 0.5% to 1% deoxidizer by mass to generate a precisely proportioned furnace charge. The furnace charge is fed into the medium-frequency induction melting furnace, the furnace cover is closed and the furnace chamber is evacuated to a negative pressure of 0.08 MPa, then high-purity argon is introduced to atmospheric pressure and the process is repeated 3 times to generate an argon protective atmosphere. Turn on the medium-frequency induction heating power supply and heat up to 1200 degrees Celsius at a rate of 15 to 20 degrees Celsius per minute. Hold the temperature for 30 minutes to allow the electrolytic copper and pure tin to completely dissolve and form a uniform alloy melt, generating an initial melt with uniform composition. Add slag-forming agent to the initial melt and stir. After standing for 10 minutes, use a graphite slag skimmer to remove the surface slag. Repeat the slag removal operation twice to finally obtain pure tin bronze melt.

8. The system according to claim 7, characterized in that, The application module is specifically used for: The pure molten tin bronze is transferred to a tundish and heated to 1150 degrees Celsius. The spout at the bottom of the tundish is opened to allow the molten liquid to flow into the center of the high-pressure water atomizing nozzle at a flow rate of 3 to 5 kg per minute, generating a continuous flow of molten liquid. The high-pressure water pump is started to make the atomized water pressure reach 80 to 100 MPa. The high-pressure water flow is sprayed from the annular nozzle at a 30-degree cone angle, breaking the continuous molten flow into droplets with a particle size of 50 to 150 micrometers, generating a diffusely distributed group of molten droplets. A Helmholtz coil is installed around the water atomizing nozzle and a direct current is passed through it to generate a rotating magnetic field with an axial magnetic field strength of 0.5 to 1.5 Tesla. This causes the molten droplets in flight to be subjected to the Lorentz force and spin around their own axis, generating ellipsoidal droplets that undergo spin deformation. After flying 5 to 8 meters, the ellipsoidal droplets fall into the water tank below and solidify rapidly. Due to the uneven distribution of surface tension caused by spin, pits are formed and internal pores are interconnected, ultimately resulting in ellipsoidal primary powder with surface pits and internal interconnected pores.

9. A storage medium, characterized in that, The storage medium stores a computer program, wherein the computer program is configured to execute the method of any one of claims 1-5 when it is run.

10. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the method of any one of claims 1-5.

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