Method for preparing high-strength sub-microcrystalline phosphor copper balls through three-pass multidirectional upsetting and drawing assisted by electromagnetic-ultrasonic composite field

Abstract

The invention discloses a method for preparing high-strength sub-microcrystalline phosphor copper balls through three-pass multidirectional upsetting and drawing assisted by an electromagnetic-ultrasonic composite field, and relates to the field of metal material machining. By sequentially introducing electromagnetic pulse, ultrasonic vibration and superimposed field assistance, deformation is conducted in the three-pass staggered direction, annealing treatment is matched, crystal grains are remarkably refined, meanwhile, the yield strength, the tensile strength and the hardness are remarkably improved, and good plasticity is achieved. And the surface quality and the structure uniformity of the workpiece are guaranteed through the composite field synergistic effect. The process has high efficiency and industrial adaptability, and is suitable for large-scale preparation of high-performance phosphor copper components.

Description

Technical Field

[0001] This invention relates to the field of metal material processing, and in particular to a method for preparing high-strength submicrocrystalline phosphor bronze spheres by three-pass multi-directional upsetting and drawing assisted by electromagnetic-ultrasonic composite field. Background Technology

[0002] In the field of metal forming, especially in the plastic deformation and grain refinement of copper, traditional processes include multi-directional upsetting / drawing, ultrasonic-assisted forming, and electromagnetic forming. However, these processes typically suffer from problems such as numerous processing steps, low efficiency, and poor microstructure uniformity. Current technologies have not effectively combined electromagnetic field and ultrasonic vibration techniques in the three-pass multi-directional upsetting process of copper alloys, thus failing to balance efficiency and the preparation of submicrocrystalline structures.

[0003] For example, regarding the multi-directional upsetting and drawing technology for manufacturing TC18 titanium alloy, Chinese patent CN117415262A discloses a process of "three-stage upsetting and drawing → three-directional reversing upsetting and drawing → multi-stage forging". This process adopts a large deformation die forging scheme with multiple passes and cyclic reversing to improve the problems of coarse grains and uneven structure in the core, which helps to improve the ultrasonic flaw detection level. However, it requires as many as 7-12 forging stages, which significantly increases the production cycle and cost.

[0004] Ultrasonic-assisted machining can significantly reduce surface friction and internal flow stress in materials, thereby improving the uniformity of deformation. For example, Chinese invention patent CN102756067A describes an ultrasonic-assisted interference riveting process, in which ultrasonic excitation is continuously applied during the upsetting, riveting, and pressure holding stages. This can reduce additional friction within the range of 20–100kHz and 300–3000W, allowing the rivet material to flow uniformly along the axial direction and achieving uniform upsetting.

[0005] In addition, a molecular dynamics research paper revealed the interfacial friction mechanism of ultrasonic vibration in the upsetting process of single-crystal copper: ultrasonic vibration significantly improves surface friction behavior by reducing the interfacial energy barrier and lattice structure mismatch, which is of great significance for understanding its microscopic plasticity mechanism.

[0006] In recent years, some studies have attempted to combine electrical pulses (such as electromagnetic or electroplastic) with ultrasonic vibrations for strengthening processes of metallic materials. For example, patent CN202310215785.3 proposes a device for "electrical pulse-assisted ultrasonic large-scale continuous impact on metallic materials," which combines an ultrasonic shot peening system with X, Y, and Z triaxial drive components and an electrical pulse system to achieve auxiliary strengthening treatment of the workpiece. This composite approach has initially explored the possibility of coupling ultrasonic and electrical pulse fields, but it has not yet been applied to upsetting or copper-based subcrystalline material preparation processes.

[0007] In summary, while existing technologies have made some progress in multi-directional upsetting, efficient deformation, and ultrasonic-assisted machining, they still have significant limitations:

[0008] Multi-directional upsetting processes (such as TC18 alloy) are inefficient and involve cumbersome steps; ultrasonic assistance is mostly used for riveting or turning and has not yet been integrated into complex three-pass upsetting processes; although there have been preliminary explorations of the coupling of electromagnetic or electrical pulses with ultrasound, there is a lack of systematic methods for the fine processing of copper materials; especially for phosphor bronze materials, there is currently no published literature or patent report on achieving sub-micron grain refinement in multi-directional multi-pass upsetting through electromagnetic-ultrasound composite fields. Summary of the Invention

[0009] Based on the problems mentioned in the background technology, this invention proposes a method for preparing high-strength submicrocrystalline phosphor bronze spheres by three-pass multi-directional upsetting assisted by electromagnetic-ultrasonic composite field. It deeply integrates the composite assistance of electromagnetic pulse and ultrasonic vibration, and by rationally setting parameters and deformation paths during the three-pass multi-directional upsetting process, it innovatively achieves efficient processing and preparation of submicrocrystalline phosphor bronze spheres, solving the problem of balancing processing efficiency and structural uniformity in the prior art.

[0010] The technical solution is as follows:

[0011] A method for preparing high-strength submicrocrystalline copper phosphorus spheres by three-pass multi-directional upsetting and drawing assisted by electromagnetic-ultrasonic composite field includes the following steps:

[0012] (1) Raw material preparation: Prepare 100 parts by weight of phosphorus-containing copper masterbatch into cylindrical blanks with a phosphorus content of 0.05–0.2 parts and the remainder being high-purity copper;

[0013] (2) First upsetting: X-direction electromagnetic pulse;

[0014] (3) First intermediate annealing;

[0015] (4) Second upsetting: ultrasonic vibration in the Y direction;

[0016] (5) Second intermediate annealing;

[0017] (6) Spraying of loaded additives: Spraying loaded additives onto the surface of the blank;

[0018] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field:

[0019] (8) Final processing: Naturally cool or water cool to room temperature, mechanically trim and polish into balls.

[0020] In this invention, the parameters for the first upsetting and drawing pass are as follows:

[0021] The electromagnetic pulse energy is set to 3–8 kJ;

[0022] The upsetting deformation ratio is 20–30 parts.

[0023] The strain rate is 102 -10 4 s -1 ;

[0024] The auxiliary lubricant is 1–3 parts of phospholipid-based oil.

[0025] In this invention, the parameters for the first intermediate annealing and the second intermediate annealing are as follows:

[0026] The annealing temperature is 350–450℃;

[0027] The heat preservation time is 0.5–2 hours;

[0028] Nitrogen atmosphere;

[0029] The cooling method is air cooling or water cooling rapid cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0030] In this invention, the parameters for the second upsetting and drawing pass are:

[0031] The ultrasonic frequency is set to 15–25 kHz;

[0032] The ultrasonic power is 0.5–2 kW;

[0033] The upsetting deformation ratio is 20–30 parts;

[0034] The vibration duration is the entire deformation process.

[0035] In this invention, the thickness of the loaded additive coating is 8-16 μm.

[0036] The preparation method of the supported adjuvant in this invention is as follows:

[0037] 70-90 parts by weight of aluminum borate whiskers were dispersed in 600-800 parts by weight of butanone, and 5-7 parts by weight of 3-isopropyltriethoxysilane were added. The mixture was reacted at 60-70°C for 80-100 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was then mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 80-90°C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0038] The preparation method of the borate ester-polyurethane additive in this invention is as follows:

[0039] Add 30-50 parts of trimethyl borate, 40-60 parts of pentaerythritol, and 3-6 parts of melamine polyphosphate to 80-120 parts of butanone, stir until dissolved, and perform a condensation reaction at 60-80℃ for 2-3 hours to generate a borate intermediate; add 20-30 parts of hexamethylene diisocyanate and 2-5 parts of stannous octoate catalyst, and heat to 70-90℃ for an addition reaction for 3-4 hours to introduce polyurethane segments and melamine ring structures to obtain a borate-polyurethane additive.

[0040] In this invention, the parameters for the third upsetting and drawing process are as follows:

[0041] The electromagnetic energy is 3–8 kJ;

[0042] The ultrasonic frequency and power are the same as the second pass;

[0043] The upsetting deformation ratio is 15–25 parts;

[0044] An axial compressive force of 1–5 kN is added as an auxiliary load.

[0045] In this invention, the diameter of the ball in the final processing is 0.8–0.9 times the original blank diameter.

[0046] Reaction mechanism

[0047] Synthesis mechanism of additives: Trimethyl borate undergoes a condensation reaction with the hydroxyl groups of pentaerythritol to form a borate ester cross-linked structure; the -NCO group of hexamethylene diisocyanate undergoes an addition reaction with the remaining hydroxyl groups to form polyurethane segments; the phosphate ester group of melamine polyphosphate coordinates with the borate ester group, introducing the melamine ring into the system and enhancing its resistance to thermal cracking.

[0048] Loading mechanism: The isopropyl groups on the surface of aluminum borate whiskers form van der Waals forces with the polyurethane segments in the additives, while the borate ester groups react with the Al groups in the whiskers. 3+ Coordination ensures that the additives do not fall off during high-temperature continuous casting; the high strength properties of aluminum borate can enhance the grain boundary bonding of the ingot.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] 1) Electromagnetic pulse forming is a high-speed, non-contact cold working technology that can generate strong magnetic force within microseconds to drive the plastic flow of deformable bodies, thereby improving the formability of metal materials, reducing friction, reducing lubrication requirements, and improving forming accuracy and surface quality.

[0051] 2) Ultrasonic vibration can generate localized high-frequency impacts and micro-vibrations on the metal surface, activating dislocation motion, alleviating stress concentration, reducing flow stress during plastic processing, and improving material fluidity, which is conducive to grain recrystallization and refinement. The second and third passes utilize a superposition of ultrasonic and electromagnetic fields, effectively promoting submicrocrystalline structure.

[0052] 3) Three-pass multi-directional upsetting and drawing combined with intermediate annealing, applying staggered deformation paths in different axes, is beneficial for promoting dynamic recrystallization, avoiding non-uniform grain growth, and significantly refining grains to the submicron scale. This multi-pass, staggered deformation path strategy is far superior to traditional unidirectional or multiple unidirectional deformation methods.

[0053] 4) Borate ester groups chelate with impurities in magnesium alloys, reducing their harmful effects and improving melt fluidity; the rigid structure of melamine rings enhances the grain boundary strength of ingots and inhibits the generation of hot cracks under the stress of three-way continuous casting; the stirring effect of electromagnetic-ultrasonic field and the dispersion effect of additives work together to promote uniform distribution of components. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the spirit of the contents disclosed in the present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0055] The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0056] Example 1

[0057] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by three-pass multi-directional upsetting and drawing assisted by an electromagnetic-ultrasonic composite field. The specific steps are as follows:

[0058] (1) Raw material preparation

[0059] Cylindrical blanks containing phosphorus copper masterbatch are prepared according to a mass of 100 kg, wherein the phosphorus content is 0.05 kg and the remainder is high-purity copper.

[0060] (2) First upsetting: X-direction electromagnetic pulse

[0061] The electromagnetic pulse energy is set to 3 kJ; the upsetting deformation ratio is 20 kg; and the strain rate is 10. 2 s -1 Add 1 kg of phospholipid-based oil as an auxiliary lubricant.

[0062] (3) First intermediate annealing

[0063] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0064] (4) Second upsetting: Y-direction ultrasonic vibration

[0065] The ultrasonic frequency was set to 15kHz; the ultrasonic power was 0.5kW; the upsetting deformation ratio was 20kg; and the vibration duration was the entire deformation process.

[0066] (5) Second intermediate annealing

[0067] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0068] (6) Spraying of load-bearing additives

[0069] A loaded additive is sprayed onto the surface of the blank, with a coating thickness of 8 μm.

[0070] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0071] The electromagnetic energy is 3kJ; the ultrasonic frequency is 15kHz; the ultrasonic power is 0.5kW; the upsetting deformation ratio is 15kg; and an axial compressive force of 1kN is added as an auxiliary load.

[0072] (8) Final processing

[0073] The material is naturally cooled to room temperature, then mechanically trimmed and polished into spheres with a diameter 0.8 times that of the original blank.

[0074] Among them, the preparation method of supported additives

[0075] 70 kg of aluminum borate whiskers were dispersed in 600 kg of butanone, and 5 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 60 °C for 80 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 80 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0076] Preparation method of borate ester-polyurethane additives

[0077] 30 kg of trimethyl borate, 40 kg of pentaerythritol, and 3 kg of melamine polyphosphate were added to 80 kg of butanone and stirred until dissolved. The mixture underwent a condensation reaction at 60 °C for 2 hours to generate a borate intermediate. 20 kg of hexamethylene diisocyanate and 2 kg of stannous octoate catalyst were added, and the mixture was heated to 70 °C for an addition reaction for 3 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate-polyurethane additive.

[0078] Example 2

[0079] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by electromagnetic-ultrasonic composite field-assisted three-pass multi-directional upsetting and drawing. The specific steps are as follows:

[0080] (1) Raw material preparation

[0081] Cylindrical blanks containing phosphorus copper masterbatch are prepared at a mass of 100 kg, wherein the phosphorus content is 0.1 kg and the remainder is high-purity copper.

[0082] (2) First upsetting: X-direction electromagnetic pulse

[0083] The electromagnetic pulse energy was set to 4.5 kJ; the upsetting deformation ratio was 23 kg; and the strain rate was 3 × 10⁻⁶. 3 s -1 Add 1.5 kg of phospholipid-based oil as an auxiliary lubricant.

[0084] (3) First intermediate annealing

[0085] The annealing temperature is 380℃; the holding time is 1 hour; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling rapid cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0086] (4) Second upsetting: Y-direction ultrasonic vibration

[0087] The ultrasonic frequency was set to 18kHz; the ultrasonic power was 1kW; the upsetting deformation ratio was 23kg; and the vibration duration was the entire deformation process.

[0088] (5) Second intermediate annealing

[0089] The annealing temperature is 380℃; the holding time is 1 hour; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling rapid cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0090] (6) Spraying of load-bearing additives

[0091] A loaded additive is sprayed onto the surface of the blank, with a coating thickness of 10 μm.

[0092] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0093] The electromagnetic energy is 4.5 kJ; the ultrasonic frequency is 18 kHz; the ultrasonic power is 1 kW; the upsetting deformation ratio is 18 kg; and an axial compressive force of 2.5 kN is added as an auxiliary load.

[0094] (8) Final processing

[0095] The material is cooled to room temperature by water, and then mechanically trimmed and polished into spheres with a diameter of 0.83 times that of the original blank.

[0096] Among them, the preparation method of supported additives

[0097] 75 kg of aluminum borate whiskers were dispersed in 650 kg of butanone, and 5.5 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 63 °C for 85 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 83 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0098] Preparation method of borate ester-polyurethane additives

[0099] 35 kg of trimethyl borate, 45 kg of pentaerythritol, and 4 kg of melamine polyphosphate were added to 90 kg of butanone and stirred until dissolved. The mixture was then subjected to a condensation reaction at 65 °C for 2.3 hours to generate a borate ester intermediate. 23 kg of hexamethylene diisocyanate and 3 kg of stannous octoate catalyst were added, and the mixture was heated to 75 °C for an addition reaction for 3.3 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate ester-polyurethane additive.

[0100] Example 3

[0101] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by electromagnetic-ultrasonic composite field-assisted three-pass multi-directional upsetting and drawing. The specific steps are as follows:

[0102] (1) Raw material preparation

[0103] Cylindrical blanks containing phosphorus copper masterbatch are prepared according to a mass of 100 kg, wherein the phosphorus content is 0.15 kg and the remainder is high-purity copper.

[0104] (2) First upsetting: X-direction electromagnetic pulse

[0105] The electromagnetic pulse energy was set to 6 kJ; the upsetting deformation ratio was 27 kg; and the strain rate was 7 × 10⁻⁶. 3 s -1 Add 2.5 kg of phospholipid-based oil as an auxiliary lubricant.

[0106] (3) First intermediate annealing

[0107] The annealing temperature is 420℃; the holding time is 1.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling rapid cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0108] (4) Second upsetting: Y-direction ultrasonic vibration

[0109] The ultrasonic frequency was set to 22kHz; the ultrasonic power was 1.5kW; the upsetting deformation ratio was 27kg; and the vibration duration was the entire deformation process.

[0110] (5) Second intermediate annealing

[0111] The annealing temperature is 420℃; the holding time is 1.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling rapid cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0112] (6) Spraying of load-bearing additives

[0113] A loaded additive was sprayed onto the surface of the blank, with a coating thickness of 14 μm.

[0114] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0115] The electromagnetic energy is 6kJ; the ultrasonic frequency is 22kHz; the ultrasonic power is 1.5kW; the upsetting deformation ratio is 22kg; and an axial compressive force of 4kN is added as an auxiliary load.

[0116] (8) Final processing

[0117] The material is cooled to room temperature by water, and then mechanically trimmed and polished into spheres with a diameter of 0.87 times that of the original blank.

[0118] Among them, the preparation method of supported additives

[0119] 85 kg of aluminum borate whiskers were dispersed in 750 kg of butanone, and 6.5 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 67 °C for 95 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 87 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0120] Preparation method of borate ester-polyurethane additives

[0121] 45 kg of trimethyl borate, 55 kg of pentaerythritol, and 5 kg of melamine polyphosphate were added to 110 kg of butanone and stirred until dissolved. The mixture was then subjected to a condensation reaction at 75 °C for 2.7 hours to generate a borate intermediate. 27 kg of hexamethylene diisocyanate and 4 kg of stannous octoate catalyst were added, and the mixture was heated to 85 °C for an addition reaction for 3.7 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate-polyurethane additive.

[0122] Example 4

[0123] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by electromagnetic-ultrasonic composite field-assisted three-pass multi-directional upsetting and drawing. The specific steps are as follows:

[0124] (1) Raw material preparation

[0125] Cylindrical blanks containing phosphorus copper masterbatch are prepared at a mass of 100 kg, wherein the phosphorus content is 0.2 kg and the remainder is high-purity copper.

[0126] (2) First upsetting: X-direction electromagnetic pulse

[0127] The electromagnetic pulse energy is set to 8 kJ; the upsetting deformation ratio is 30 kg; and the strain rate is 10. 4 s -1 Add 3 kg of phospholipid-based oil as an auxiliary lubricant.

[0128] (3) First intermediate annealing

[0129] The annealing temperature is 450℃; the holding time is 2 hours; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling with a cooling rate not exceeding 50℃ / min.

[0130] (4) Second upsetting: Y-direction ultrasonic vibration

[0131] The ultrasonic frequency was set to 25kHz; the ultrasonic power was 2kW; the upsetting deformation ratio was 30kg; and the vibration duration was the entire deformation process.

[0132] (5) Second intermediate annealing

[0133] The annealing temperature is 450℃; the holding time is 2 hours; the annealing is carried out in a nitrogen atmosphere; the cooling method is water cooling with a cooling rate not exceeding 50℃ / min.

[0134] (6) Spraying of load-bearing additives

[0135] A loaded additive was sprayed onto the surface of the blank, with a coating thickness of 16 μm.

[0136] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0137] The electromagnetic energy is 8kJ; the ultrasonic frequency is 25kHz; the ultrasonic power is 2kW; the upsetting deformation ratio is 25kg; and an axial compressive force of 5kN is added as an auxiliary load.

[0138] (8) Final processing

[0139] The material is cooled to room temperature by water, and then mechanically trimmed and polished into spheres with a diameter of 0.9 times that of the original blank.

[0140] Among them, the preparation method of supported additives

[0141] 90 kg of aluminum borate whiskers were dispersed in 800 kg of butanone, and 7 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 70 °C for 100 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 90 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0142] Preparation method of borate ester-polyurethane additives

[0143] 50 kg of trimethyl borate, 60 kg of pentaerythritol, and 6 kg of melamine polyphosphate were added to 120 kg of butanone and stirred until dissolved. The mixture underwent a condensation reaction at 80 °C for 3 hours to generate a borate intermediate. 30 kg of hexamethylene diisocyanate and 5 kg of stannous octoate catalyst were added, and the mixture was heated to 90 °C for an addition reaction for 4 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate-polyurethane additive.

[0144] Comparative Example 1

[0145] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by three-pass multi-directional upsetting and drawing assisted by an electromagnetic-ultrasonic composite field. The specific steps are as follows:

[0146] (1) Raw material preparation

[0147] Cylindrical blanks containing phosphorus copper masterbatch are prepared according to a mass of 100 kg, wherein the phosphorus content is 0.05 kg and the remainder is high-purity copper.

[0148] (2) First upsetting: X-direction electromagnetic pulse

[0149] The electromagnetic pulse energy is set to 3 kJ; the upsetting deformation ratio is 20 kg; and the strain rate is 10. 2 s -1 Add 1 kg of phospholipid-based oil as an auxiliary lubricant.

[0150] (3) First intermediate annealing

[0151] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0152] (4) Second upsetting: Y-direction ultrasonic vibration

[0153] The ultrasonic frequency was set to 15kHz; the ultrasonic power was 0.5kW; the upsetting deformation ratio was 20kg; and the vibration duration was the entire deformation process.

[0154] (5) Second intermediate annealing

[0155] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0156] (6) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0157] The electromagnetic energy is 3kJ; the ultrasonic frequency is 15kHz; the ultrasonic power is 0.5kW; the upsetting deformation ratio is 15kg; and an axial compressive force of 1kN is added as an auxiliary load.

[0158] (7) Final processing

[0159] The material is naturally cooled to room temperature, then mechanically trimmed and polished into spheres with a diameter 0.8 times that of the original blank.

[0160] Comparative Example 2

[0161] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by three-pass multi-directional upsetting and drawing assisted by an electromagnetic-ultrasonic composite field. The specific steps are as follows:

[0162] (1) Raw material preparation

[0163] Cylindrical blanks containing phosphorus copper masterbatch are prepared according to a mass of 100 kg, wherein the phosphorus content is 0.05 kg and the remainder is high-purity copper.

[0164] (2) First upsetting: X-direction electromagnetic pulse

[0165] The electromagnetic pulse energy is set to 3 kJ; the upsetting deformation ratio is 20 kg; and the strain rate is 10. 2 s -1 Add 1 kg of phospholipid-based oil as an auxiliary lubricant.

[0166] (3) First intermediate annealing

[0167] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0168] (4) Second upsetting: Y-direction ultrasonic vibration

[0169] The ultrasonic frequency was set to 15kHz; the ultrasonic power was 0.5kW; the upsetting deformation ratio was 20kg; and the vibration duration was the entire deformation process.

[0170] (5) Second intermediate annealing

[0171] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0172] (6) Spraying of load-bearing additives

[0173] A loaded additive is sprayed onto the surface of the blank, with a coating thickness of 8 μm.

[0174] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0175] The electromagnetic energy is 3kJ; the ultrasonic frequency is 15kHz; the ultrasonic power is 0.5kW; the upsetting deformation ratio is 15kg; and an axial compressive force of 1kN is added as an auxiliary load.

[0176] (8) Final processing

[0177] The material is naturally cooled to room temperature, then mechanically trimmed and polished into spheres with a diameter 0.8 times that of the original blank.

[0178] Among them, the preparation method of supported additives

[0179] 70 kg of aluminum borate whiskers were dispersed in 600 kg of butanone, and 5 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 60 °C for 80 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 80 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0180] Preparation method of borate ester-polyurethane additives

[0181] 40 kg of pentaerythritol and 3 kg of melamine polyphosphate were added to 80 kg of butanone and stirred until dissolved. The mixture was then subjected to a condensation reaction at 60 °C for 2 hours to generate a borate ester intermediate. 20 kg of hexamethylene diisocyanate and 2 kg of stannous octoate catalyst were added, and the mixture was heated to 70 °C for an addition reaction for 3 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate ester-polyurethane additive.

[0182] Comparative Example 3

[0183] This embodiment relates to a method for preparing high-strength submicrocrystalline copper phosphorus spheres by three-pass multi-directional upsetting and drawing assisted by an electromagnetic-ultrasonic composite field. The specific steps are as follows:

[0184] (1) Raw material preparation

[0185] Cylindrical blanks containing phosphorus copper masterbatch are prepared according to a mass of 100 kg, wherein the phosphorus content is 0.05 kg and the remainder is high-purity copper.

[0186] (2) First upsetting: X-direction electromagnetic pulse

[0187] The electromagnetic pulse energy is set to 3 kJ; the upsetting deformation ratio is 20 kg; and the strain rate is 10. 2 s -1 Add 1 kg of phospholipid-based oil as an auxiliary lubricant.

[0188] (3) First intermediate annealing

[0189] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0190] (4) Second upsetting: Y-direction ultrasonic vibration

[0191] The ultrasonic frequency was set to 15kHz; the ultrasonic power was 0.5kW; the upsetting deformation ratio was 20kg; and the vibration duration was the entire deformation process.

[0192] (5) Second intermediate annealing

[0193] The annealing temperature is 350℃; the holding time is 0.5h; the annealing is carried out in a nitrogen atmosphere; the cooling method is air cooling, and the rapid cooling rate does not exceed 50℃ / min.

[0194] (6) Spraying of load-bearing additives

[0195] A loaded additive is sprayed onto the surface of the blank, with a coating thickness of 8 μm.

[0196] (7) Third upsetting: Z-direction electromagnetic-ultrasonic composite field

[0197] The electromagnetic energy is 3kJ; the ultrasonic frequency is 15kHz; the ultrasonic power is 0.5kW; the upsetting deformation ratio is 15kg; and an axial compressive force of 1kN is added as an auxiliary load.

[0198] (8) Final processing

[0199] The material is naturally cooled to room temperature, then mechanically trimmed and polished into spheres with a diameter 0.8 times that of the original blank.

[0200] Among them, the preparation method of supported additives

[0201] 70 kg of aluminum borate whiskers were dispersed in 600 kg of butanone, and 5 kg of 3-isopropyltriethoxysilane was added. The mixture was reacted at 60 °C for 80 minutes to obtain an aluminum borate support with isopropyl surface modification. The support was mixed with a borate ester-polyurethane additive at a mass ratio of 12:1 and reacted at 80 °C for 3 hours. Loading was achieved through hydrogen bonding and coordination. After drying, the supported additive was obtained.

[0202] Preparation method of borate ester-polyurethane additives

[0203] 30 kg of trimethyl borate, 40 kg of pentaerythritol, and 3 kg of melamine polyphosphate were added to 80 kg of butanone and stirred until dissolved. The mixture underwent a condensation reaction at 60 °C for 2 hours to generate a borate intermediate. 2 kg of stannous octoate catalyst was added, and the mixture was heated to 70 °C for an addition reaction for 3 hours to introduce polyurethane segments and melamine ring structures, thus obtaining a borate-polyurethane additive.

[0204] Test method:

[0205] 1) Grain size (average grain diameter / ASTM E112)

[0206] Sample preparation: The sample is cut, inlaid, and ground to 1200# sandpaper according to conventional methods. Then it is polished with 0.05μm diamond immersion polishing (SiO2 or alumina paste). Finally, it is electrolytically polished or ion polished to obtain a mirror-finished sample.

[0207] Optical metrology (ASTM E112 interception method): Under an optical microscope at 100×, 200×, and 500× magnification, the number of interceptions in multiple fields of view is counted according to the ASTM E112 interception method, and the average grain diameter is calculated. The main reference is to the ASTM E112 method steps and formulas.

[0208] 2) Vickers microhardness (ASTM E92 / E384)

[0209] Sample preparation: Polish to mirror finish, ensuring surface roughness Ra≤0.05μm.

[0210] Test conditions: Use a micro Vickers hardness tester, load 500 gf (4.9 N), indentation holding time 10–15 s, take at least 10 indentations (at different locations) for each specimen, take the average value and report the standard deviation. Test and calibration shall be performed in accordance with ASTM E92 / E384 (machine calibration, calibration block verification).

[0211] 3) Tensile properties (ASTM E8)

[0212] Specimen preparation: Micro tensile strips are macroscopically cut from a sphere or specimen (if a sphere cannot be directly used for specimen preparation, small flat plates or round bars prepared in the same batch can be used as tensile sheets); prepare according to the classic miniature style or sub-size sample of ASTM E8 (refer to the corresponding fixtures and gauge lengths).

[0213] Test conditions: room temperature (20±5℃), loading rate according to ASTM E8 recommendations (strain rate 0.001–0.01s). -1 (Corresponding to the engineering strain rate), provide the yield strength (0.2% offset), tensile strength, and elongation (elongation at gauge length after fracture). Perform at least 3 repeated tests, take the average, and report the standard deviation.

[0214] Table 1 Test Results

[0215]

[0216] The electromagnetic-ultrasonic composite field-assisted three-pass multi-directional upsetting and drawing process described in this invention can achieve submicrocrystalization of phosphor bronze materials within industrially feasible parameter ranges, significantly improving hardness and strength while maintaining good plasticity and superior surface quality and residual stress distribution. This invention achieves a better comprehensive balance among strength, plasticity, and surface quality, verifying the reliability and practicality of the technical effect.

[0217] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-strength sub-microcrystalline phosphor copper ball by electromagnetic-ultrasonic compound field assisted three-pass multi-direction upsetting and drawing, characterized in that, It comprises the following steps: (1) raw material preparation: 100 parts by mass of phosphorus-containing copper master batch is prepared into a cylindrical blank, the phosphorus content is 0.05-0.2 parts, and the rest is high-purity copper; (2) first pass upsetting: X-direction electromagnetic pulse; (3) first intermediate annealing; (4) second pass upsetting: Y-direction ultrasonic vibration; (5) second intermediate annealing; (6) load additive spraying: spraying load additive on the surface of the billet; (7) third pass upsetting: Z-direction electromagnetic-ultrasonic composite field: (8) final processing: natural cooling or water cooling to room temperature, mechanical finishing and polishing into balls; The load additive is prepared by reacting aluminum borate whiskers, 3-isopropyl triethoxysilane and borate-containing polyurethane additive; The borate-containing polyurethane additive is prepared by reacting trimethyl borate, pentaerythritol, melamine polyphosphate, hexamethylene diisocyanate and stannous octoate catalyst.

2. The method of claim 1, wherein the method is characterized in that: The first pass upsetting parameters are: The electromagnetic pulse energy is set to 3-8 kJ; The upsetting deformation ratio is 20-30 parts, Strain rate is 10 2 -10 4 s -1 ; The auxiliary lubricant is phospholipid-based oil 1-3 parts.

3. The method of claim 1, wherein the method is characterized in that: The first intermediate annealing and second intermediate annealing parameters are: The annealing temperature is 350-450℃; The holding time is 0.5-2h; The nitrogen atmosphere; The cooling method is air cooling or water cooling, and the quenching rate is not more than 50℃ / min.

4. The method of claim 1, wherein the method is characterized in that: The second pass upsetting parameters are: The ultrasonic frequency is set to 15-25 kHz; The ultrasonic power is 0.5-2 kW; The upsetting deformation ratio is 20-30 parts; The vibration duration is the entire deformation process.

5. The method of claim 1, wherein the method is characterized in that: The spraying thickness of the load additive is 8-16μm.

6. The method of claim 1, wherein the method is characterized in that: The preparation method of the load additive is: Disperse 70-90 parts by mass of aluminum borate whiskers in 600-800 parts by mass of butanone, add 5-7 parts by mass of 3-isopropyl triethoxysilane, and react at 60-70℃ for 80-100 minutes to obtain aluminum borate carrier with isopropyl modification on the surface; mix the carrier with borate-containing polyurethane additive at a mass ratio of 12:1, and react at 80-90℃ for 3 hours to realize loading through hydrogen bonding and coordination; and dry to obtain the load additive.

7. The method of claim 6, wherein the method is characterized in that: The preparation method of the borate-containing polyurethane additive is: Add 30-50 parts of trimethyl borate, 40-60 parts of pentaerythritol and 3-6 parts of melamine polyphosphate to 80-120 parts of butanone, stir until dissolved, and condense at 60-80℃ for 2-3 hours to generate a borate intermediate; add 20-30 parts of hexamethylene diisocyanate and 2-5 parts of stannous octoate catalyst, and heat to 70-90℃ for addition reaction for 3-4 hours to introduce polyurethane segments and melamine ring structures to obtain the borate-containing polyurethane additive.

8. The method for preparing high-strength submicrocrystalline copper phosphorus spheres by electromagnetic-ultrasonic composite field assisted three-pass multi-directional upsetting and drawing according to claim 1, characterized in that: The third pass upsetting parameters are: The electromagnetic energy is 3-8 kJ; The ultrasonic frequency and power are the same as the second pass; The upsetting deformation ratio is 15-25 parts; An axial compression force of 1-5 kN is added as an auxiliary load.

9. The method for preparing high-strength submicrocrystalline copper phosphorus spheres by electromagnetic-ultrasonic composite field assisted three-pass multi-directional upsetting and drawing according to claim 1, characterized in that: The ball diameter in the final processing is 0.8-0.9 times the diameter of the original blank.

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