A method for producing high-purity nickel evaporation particles

Abstract

The application discloses a preparation method of high-purity nickel evaporation particles, and comprises the following steps: hot upsetting of round nickel ingot material to obtain a square blank, first polishing, hot rolling to obtain a hot-rolled blank, second polishing, cold rolling to obtain a cold-rolled blank, heat treatment and flattening of the cold-rolled blank, cutting to obtain a strip material, mould pressing, third polishing and rotary swaging of the strip material to obtain a rod material, polishing of the rod material, stamping forming to obtain nickel particles, and finally, pickling, grinding, cleaning and drying of the nickel particles to obtain nickel evaporation material. The preparation method is low in cost, simple and controllable, high in material comprehensive utilization rate, and the prepared high-purity nickel evaporation particles are few in defects, uniform in structure and good in surface smoothness.

Description

Technical Field

[0001] This invention belongs to the field of vacuum coating, specifically relating to a method for preparing high-purity nickel evaporation particles. Background Technology

[0002] Vacuum evaporation deposition technology refers to a process in which a coating material (or film material) is evaporated and vaporized under vacuum conditions using a specific heating and evaporation method. The particles then fly to the surface of a substrate and condense to form a film. This technology is widely used in semiconductor manufacturing processes such as wafer back-gold deposition and encapsulation coating.

[0003] Wafer back-gold deposition is a process that deposits metal on the back of a wafer. Currently, the main metal materials used in back-gold deposition are titanium, nickel, and silver, and the deposition sequence is titanium layer, nickel layer, and silver layer, respectively. The nickel layer is often used as an intermediate bonding layer between the titanium and silver layers. High-purity nickel evaporation particles are an important material in wafer back-gold deposition. The semiconductor industry has extremely stringent requirements for the purity, internal defect control, and cleanliness of nickel evaporation particles; otherwise, it will cause differences in film performance, and in severe cases, it can lead to chip failure and scrap.

[0004] According to GB / T 26032-2010, the effective composition of nickel evaporation materials of grades IC-Ni99.99 and IC-Ni99.995 shall not be less than 99.99% and 99.995%, respectively, and the total impurity content shall be controlled below 100ppm and 50ppm, respectively. Specific requirements are also set for the content of impurity elements such as C, H, O, N, and S. Furthermore, the surface of the nickel evaporation material should be bright, smooth, and clean, free from oil, rust, particulate matter, and other contaminants. Edges and corners should be intact, free from burrs, inclusions, cracks, and other defects.

[0005] The preparation of high-purity nickel evaporation particles typically uses high-purity nickel ingots as raw materials. According to YS / T 1516-2022, high-purity nickel ingots are generally cylindrical with a rounded bottom, and their surfaces should be smooth, clean, and free of cracks, burrs, inclusions, holes, and other contaminants. Processing these cylindrical nickel ingots into nickel particles of specified dimensions mainly involves a series of plastic deformation processes and forming techniques. Ensuring material purity, the absence of internal defects, and the uniformity of nickel particle size are key issues that need to be addressed in the preparation of nickel evaporation materials.

[0006] CN 113664472 B discloses a method for preparing nickel evaporation material, the specific process of which is as follows: the nickel billet is subjected to a first forging and stretching treatment and a second forging and stretching treatment to reduce the transverse dimension of the billet while reducing internal defects; then the material is turned to further reduce the transverse dimension of the material and standardize the material shape to facilitate the next stage of processing; the material is subjected to a third forging and stretching treatment and drawn to a specified size; finally, ultrasonic cleaning, pre-acid pickling treatment, grinding and cleaning, and drying treatment are performed in sequence to finally obtain nickel evaporation material.

[0007] CN 114622167 B discloses a production apparatus for high-purity nickel evaporation material. The apparatus consists of a vacuum system, a furnace cover, a furnace body, and a furnace bottom. The furnace body has a fixed plate for placing a crucible. An induction heating coil is installed around the crucible. A cooling crystallizer and a synchronous displacement crystallizer are sequentially installed at the bottom, and multiple cooling water pipes are installed. A guide rod is provided below the bottom hole of the crucible. A crystallizer transmission mechanism is provided next to the guide rod. A wire positioning wheel is provided below the crystallizer transmission mechanism. A positioner is provided at the lower end of the guide rod. A wire reel is provided next to the positioner for winding the wire prepared by the continuous casting device. After the wire is drawn to the specified size, straightened, and cut, the nickel evaporation material can be obtained.

[0008] The aforementioned existing technologies and equipment for processing nickel evaporation materials suffer from low material utilization and high processing costs. Since nickel evaporation particles are consumables, it is necessary to reduce costs while ensuring their quality. Summary of the Invention

[0009] To address the problems of low material utilization and high processing cost in existing nickel evaporation particles, this invention aims to provide a method for preparing high-purity nickel evaporation particles. This method is low-cost, simple and controllable, has high material utilization, and produces high-purity nickel evaporation particles with fewer defects, uniform structure, and good surface finish.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention discloses a method for preparing high-purity nickel evaporation particles. A round nickel ingot is hot-forged to obtain a square billet. After a first grinding, it is hot-rolled to obtain a hot-rolled billet. After a second grinding, it is cold-rolled to obtain a cold-rolled billet. The cold-rolled billet is then heat-treated, flattened, and subsequently cut into strips. The strips are then sequentially die-pressed, ground a third time, and forged to obtain bars. After polishing, the bars are stamped to obtain nickel particles. Finally, the nickel particles are sequentially acid-washed, ground, cleaned, and dried to obtain the nickel evaporation material.

[0012] The preparation method provided by this invention uses high-purity nickel ingots as raw materials and employs a combination of processes such as hot upsetting, rolling, and rotary forging to reduce internal defects in the material. Furthermore, a grinding process is set between different plastic deformation processes to prevent surface defects from expanding and extending during subsequent plastic deformation, which would further affect the surface quality of the nickel evaporation particles. The plastically processed sheet material is transformed into strip material that is easy to rotary forge by using a cutting method, avoiding the high cost problem caused by a single rotary forging process. Finally, a stamping process is used to obtain nickel evaporation particles of the corresponding specifications. After pickling, grinding, cleaning, and drying, nickel evaporation material with high purity, smooth and defect-free surface, and standardized dimensions can be obtained.

[0013] In a preferred embodiment, the purity of the nickel ingot is above 4N5. In actual operation, it is cut into blanks of a certain thickness according to product specifications for subsequent processing.

[0014] In a preferred embodiment, the hot upsetting process involves holding a round nickel ingot at 800-1000℃, preferably 900℃, for 0.5-2 hours, preferably 1 hour, and then upsetting it into a square shape under a hydraulic press, followed by flattening and air cooling.

[0015] Since rotary forging blanks are rod-shaped materials with an approximately square cross-section, the present invention uses hot upsetting to turn nickel casting round ingots into square billets, which can ensure the dimensional consistency of rotary forging bars and improve material utilization. On the other hand, hot upsetting can effectively break up the coarse columnar structure in the ingot.

[0016] By controlling the hot upsetting temperature within the range of this invention, the final nickel evaporation material has the best performance. If the hot upsetting temperature is too high, it will result in a coarse structure, while if the temperature is too low, the material's resistance to plastic deformation will be too high, which will reduce the efficiency of hot upsetting plastic processing. In addition, by hot upsetting the round billet into a square and then flattening it, wrinkles on the surface of the billet can be avoided in the subsequent hot rolling process.

[0017] In a preferred embodiment, the first polishing process involves using an angle grinder to polish the surface of the square blank until it is smooth and glossy. In actual operation, after the square blank obtained from hot upsetting has cooled, the surface is polished again using an angle grinder to eliminate defects such as surface folds, protrusions, and oxide scale.

[0018] The preferred method is to preheat the temperature to 800-1000℃, preferably 900℃, for 0.5-2 hours, preferably 1 hour, before hot rolling.

[0019] In a preferred embodiment, the single-pass reduction in hot rolling is 5-15%, preferably 10%, and the total deformation is 60-80%, preferably 70%. By controlling the total deformation of hot rolling within the above range, and coordinating with subsequent cold rolling, the rolling dimensions can be effectively controlled, and a material with fine grains can be obtained. If the total deformation of hot rolling is too large, it will lead to excessive grain growth; if the total deformation of hot rolling is too small, it will be necessary to increase the deformation of cold rolling, thereby increasing processing costs.

[0020] In a preferred embodiment, the hot rolling process employs cross rolling, with the material rotating 90° for each rolling pass.

[0021] By employing cross rolling, a single texture along the rolling direction can be avoided, ensuring the anisotropy of the material and ultimately resulting in the best performance of the nickel evaporation material.

[0022] In a preferred embodiment, the second grinding process involves using an angle grinder to grind the surface of the hot-rolled billet until it is smooth and glossy. Grinding the surface of the hot-rolled billet eliminates defects such as surface folds and protrusions, preventing defects such as peeling and cracks from forming on the material surface during subsequent cold rolling.

[0023] In a preferred embodiment, the single-pass reduction in cold rolling is 2-10%, preferably 5%, and the total deformation in cold rolling is 40-60%, preferably 50%.

[0024] In a preferred embodiment, the cold rolling process employs cross rolling, with the material rotating 90° for each rolling pass.

[0025] By employing cross rolling, a single texture along the rolling direction can be avoided, ensuring the anisotropy of the material and ultimately resulting in the best performance of the nickel evaporation material.

[0026] In a preferred embodiment, the cold-rolled billet is heat-treated in a heat treatment furnace at 400-600℃, preferably 500℃, for 0.5-2 hours, preferably 1 hour. Afterward, it is removed from the heat treatment furnace, flattened, air-cooled, and then cut into strips. Heat treatment removes processing stress and regulates the microstructure. Controlling the heat treatment temperature within the aforementioned range yields the material with optimal performance. If the heat treatment temperature is too high, the grains will be coarse; if the temperature is too low, grain growth will be incomplete, resulting in poor grain size uniformity. In actual operation, water jet cutting is used to cut the billet into square-section strips.

[0027] In a preferred embodiment, the molding process involves placing the strip material in a mold and molding the edges of the strip material under a hydraulic press to remove sharp edges.

[0028] In a preferred embodiment, the third grinding process involves grinding the surface of the molded strip material using an angle grinder to remove surface oxide scale and burrs.

[0029] In a preferred embodiment, the total deformation of the rotary forging is 40-60%, preferably 50%, the deformation of the last three passes is 0.5-2%, preferably 1%, and the deformation of the remaining passes is 4-6%, preferably 5%.

[0030] In this invention, the strip material obtained from the third grinding is used to obtain a bar through rotary forging. Through rotary forging, the billet is subjected to compressive stress evenly distributed in the circumferential direction and is compressed and deformed, which can eliminate internal defects such as pores and voids, break up coarse grains, and improve the material microstructure. In the rotary forging process, the last three passes use a smaller amount of deformation, which reduces the deformation resistance on the one hand, and allows for more accurate control of the bar size on the other hand.

[0031] After rotary forging, polishing is performed. In actual operation, the surface is first wiped with anhydrous ethanol to remove oil stains from the surface of the bar, and then the surface is polished with sandpaper to remove burrs. Then, a stamping machine is used to place the front end of the nickel bar into a specific die and stamp it to obtain nickel particles of the specified length.

[0032] In a preferred embodiment, the pickling is performed by immersion in a dilute nitric acid solution for 20-40 minutes, preferably 30 minutes, followed by rinsing with clean water.

[0033] The volume ratio of nitric acid to water in the dilute nitric acid solution is 1:3 to 1:5, preferably 1:4; the volume ratio of the dilute nitric acid solution to nickel particles is 1:1 to 1:1.6, preferably 1:1.3.

[0034] In a preferred embodiment, the grinding is carried out in a grinding mill containing grinding balls and a grinding solution, and the grinding time is 20-40 minutes, preferably 30 minutes.

[0035] The mass ratio of grinding balls to nickel particles is 1:1 to 1:1.5, preferably 1:1.2; the volume-to-mass ratio of grinding solution to nickel particles is 2 to 4 L / kg, preferably 3 L / kg; and the total volume of grinding balls, grinding solution and nickel particles does not exceed 80-95% of the cavity of the grinder, preferably 90%.

[0036] In a preferred embodiment, the cleaning process involves first ultrasonically cleaning in an aqueous solution containing detergent for 20-40 minutes, preferably 30 minutes; then rinsing with clean water; and finally ultrasonically cleaning with anhydrous ethanol for 10-20 minutes, preferably 15 minutes.

[0037] The volume-to-mass ratio of the aqueous solution containing the detergent to the nickel particles is 1-3 L / kg, preferably 2 L / kg;

[0038] The volume-to-mass ratio of anhydrous ethanol to nickel particles is 0.5~2L / kg, preferably 1L / kg.

[0039] After cleaning, the material is dried using one of the following methods: natural air drying, drying oven drying, or hot air drying. Then, it is vacuum-packed to obtain the nickel evaporation material.

[0040] Beneficial effects

[0041] The preparation method provided by this invention uses high-purity nickel ingots as raw materials and employs a combination of processes such as hot upsetting, rolling, and rotary forging to reduce internal defects in the material. A grinding process is set between different plastic deformation processes to prevent surface defects from expanding and extending during subsequent plastic deformation, which would further affect the surface quality of the nickel evaporation particles. The plastically processed sheet material is transformed into strip material that is easy to rotary forge by cutting, avoiding the high cost problem caused by a single rotary forging process. Finally, a stamping process is used to obtain nickel evaporation particles of the corresponding specifications. After pickling, grinding, cleaning, and drying, nickel evaporation material with high purity, smooth and defect-free surface, and standardized dimensions can be obtained.

[0042] The preparation method of the present invention has high material utilization rate, and the obtained nickel evaporation material has high purity, few internal defects, good grain consistency, excellent surface quality, and uniform size, which can realize large-scale production. Attached Figure Description

[0043] Figure 1 A schematic diagram of the specific mold used for molding in this invention.

[0044] Figure 2 The high-purity nickel evaporation material prepared in Example 1 of this invention.

[0045] Figure 3 The microstructure of the high-purity nickel evaporation material prepared in Example 1 of this invention.

[0046] Figure 4 According to the composition detection results of the high-purity nickel evaporation material in Example 1 of the present invention.

[0047] Figure 5 Typical defects of the high-purity nickel evaporation material obtained in Comparative Example 1. Detailed Implementation

[0048] Example 1

[0049] This embodiment provides a method for preparing high-purity nickel evaporation material, the preparation method including the following steps:

[0050] Material preparation: Cut 65mm sections from a high-purity nickel ingot with a purity of 4N5 and a diameter of 190mm to form a billet.

[0051] Hot upsetting: The billet is held in a muffle furnace at 900℃ for 1 hour, and then upsetting is performed using a hydraulic press to form a square hot upsetting billet with a cross section of 168×168mm. The billet is then flattened and air-cooled.

[0052] Grinding: After the hot upsetting blank has cooled, use an angle grinder to grind the surface to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and shiny.

[0053] Hot rolling: The hot upsetting billet is held at 900℃ for 1 hour, then taken out and placed on the rolling mill roller table. The billet is rotated 90° clockwise in each pass, and the reduction in a single pass is 10%, finally obtaining a hot-rolled billet with a thickness of 20mm.

[0054] Grinding: Grind the surface of the hot-rolled billet to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and bright.

[0055] Cold rolling: cross rolling, rotating 90° clockwise in each pass, with a reduction of 5% per pass, finally obtaining a cold-rolled billet with a thickness of 10.5mm, ensuring an effective length of not less than 400mm.

[0056] Heat treatment: Hold at 520℃ for 1 hour, then place under the hydraulic press platform to flatten after being taken out of the furnace and cool in the air.

[0057] Cutting: The cold-rolled billet is cut into square strips with a cross section of 10.5×10.5mm using a waterjet cutting machine.

[0058] Molding: Placing a rectangular strip on a specific tooling (such as...) Figure 1 As shown, during use, the strip material is placed into the die hole. The upper end of the die acts on the strip material under the pressure of the hydraulic press, causing it to undergo plastic deformation, eliminating sharp edges and corners, and preventing damage to the die during subsequent rotary forging.

[0059] Grinding: Using an angle grinder to grind off the oxide scale and burrs on the surface of the material.

[0060] Rotary forging: Nickel bars are forged into Φ6.0mm round bars using a rotary forging machine. The deformation amount is 5% for each of the first three passes and 1% for the last three passes.

[0061] Polishing: To polish the surface of the bar, first wipe the surface with anhydrous ethanol to remove residual oil stains, and then polish the surface with sandpaper to remove burrs.

[0062] Stamping: The front end of the nickel rod is placed into the mold and punched under the pressure of the stamping machine to form nickel evaporation material with specifications of Φ6.0×6.0mm.

[0063] Pickling: The nickel particles are immersed in a dilute nitric acid solution with a volume ratio of 1:4 to water for 30 minutes. The volume ratio of the dilute nitric acid solution to the nickel particles is 1:1.3.

[0064] Grinding: Grinding and polishing are carried out in a grinding mill containing grinding balls and grinding solution. The mass ratio and volume / mass ratio of grinding balls, grinding solution and nickel evaporation material are 1:1.2 and 3L / kg, respectively. The total volume of grinding balls, grinding solution and nickel evaporation particles does not exceed 85% of the grinding chamber. The grinding time is 30 minutes.

[0065] Cleaning: Ultrasonic cleaning in an aqueous solution containing detergent for 20 min, with a volume-to-mass ratio of 2 L / kg for the nickel particles; after rinsing with water, ultrasonic cleaning in anhydrous ethanol for 15 min, with a volume-to-mass ratio of 1 L / kg for the nickel particles.

[0066] Drying: After removal, dry with hot air and vacuum pack.

[0067] Figure 2 The high-purity nickel evaporator prepared in Example 1 of this invention has a smooth and defect-free surface, as can be seen from the figure. The surface roughness is measured to be Ra 0.9. Figure 3 The microstructure of the high-purity nickel evaporation material prepared by the method disclosed in Example 1 of this invention shows that it is uniform in size, fine, and has good grain consistency.

[0068] Figure 4 Based on the composition detection results of the high-purity nickel evaporation material in Example 1 of this invention, from... Figure 4 The test results showed that the effective Ni content reached 99.9994934% (higher than 5N).

[0069] The density of the high-purity nickel evaporation material prepared in Example 1 is 99.3% of the theoretical density.

[0070] It is evident that the high-purity nickel evaporation material prepared in this embodiment can well meet the requirements of evaporation coating.

[0071] Example 2

[0072] Material preparation: Cut 60mm sections from a high-purity nickel ingot with a purity of 4N5 and a diameter of 190mm to form a billet.

[0073] Hot upsetting: The billet is held in a muffle furnace at 1000℃ for 0.5 hours, and then upsetting is performed using a hydraulic press to form a square hot upsetting billet with a cross section of 160×160mm. The billet is then flattened and air-cooled.

[0074] Grinding: After the hot upsetting blank has cooled, use an angle grinder to grind the surface to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and shiny.

[0075] Hot rolling: The hot upsetting billet is held at 800℃ for 2 hours, then taken out and placed on the rolling mill roller table. The billet is rotated 90° clockwise in each pass, and the reduction in a single pass is 15%, finally obtaining a hot-rolled billet with a thickness of 20mm.

[0076] Grinding: Grind the surface of the hot-rolled billet to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and bright.

[0077] Cold rolling: cross rolling, rotating 90° clockwise in each pass, with a reduction of 10% per pass, finally obtaining a cold-rolled billet with a thickness of 12mm, ensuring an effective length of not less than 400mm.

[0078] Heat treatment: Hold at 400℃ for 2 hours, then place under the hydraulic press platform to flatten after being taken out of the furnace and cool in the air.

[0079] Cutting: The cold-rolled billet is cut into square strips with a cross section of 12×12mm using a waterjet cutting machine.

[0080] Molding: A rectangular strip is placed on a specific tooling and its sharp edges are eliminated under a hydraulic press.

[0081] Grinding: Using an angle grinder to grind off the oxide scale and burrs on the surface of the material.

[0082] Rotary forging: Nickel bars are forged into Φ6.0mm round bars using a rotary forging machine. The deformation amount is 6% for each of the first three passes and 2% for the last three passes.

[0083] Polishing: To polish the surface of the bar, first wipe the surface with anhydrous ethanol to remove residual oil stains, and then polish the surface with sandpaper to remove burrs.

[0084] Stamping: The front end of the nickel rod is placed into the mold and punched under the pressure of the stamping machine to form nickel evaporation material with specifications of Φ6.0×6.0mm.

[0085] Pickling: The nickel particles are immersed in a dilute nitric acid solution with a volume ratio of 1:3 to water for 20 minutes. The volume ratio of the dilute nitric acid solution to the nickel particles is 1:1.

[0086] Grinding: Grinding and polishing are carried out in a grinding mill containing grinding balls and grinding solution. The mass ratio and volume / mass ratio of grinding balls, grinding solution and nickel evaporation material are 1:1 and 2L / kg, respectively. The total volume of grinding balls, grinding solution and nickel evaporation particles does not exceed 80% of the grinding chamber. The grinding time is 20 minutes.

[0087] Cleaning: Ultrasonic cleaning in an aqueous solution containing detergent for 40 min, with a volume-to-mass ratio of aqueous solution to nickel particles of 3 L / kg; after rinsing with water, ultrasonic cleaning in anhydrous ethanol for 20 min, with a volume-to-mass ratio of anhydrous ethanol to nickel particles of 2 L / kg.

[0088] Drying: After removal, air dry naturally and then vacuum pack.

[0089] The high-purity nickel evaporation particles obtained in this embodiment have a surface roughness of Ra0.8, a smooth and defect-free surface, a true density of 99.5% of the theoretical density, an effective Ni content of 99.9991547% (higher than 5N), and uniform and fine grain size, meeting the requirements of evaporation coating.

[0090] Example 3

[0091] Material preparation: Cut 70mm sections from a high-purity nickel ingot with a purity of 4N5 and a diameter of 190mm to form a billet.

[0092] Hot upsetting: The billet is held in a muffle furnace for 2 hours at 800℃, and then upsetting is performed using a hydraulic press to form a square hot upsetting billet with a cross section of 160×160mm. The billet is then flattened and air-cooled.

[0093] Grinding: After the hot upsetting blank has cooled, use an angle grinder to grind the surface to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and shiny.

[0094] Hot rolling: The hot upsetting billet is held at 1000℃ for 0.5h, then taken out and placed on the rolling mill roller table. The billet is rotated 90° clockwise in each pass, and the reduction in a single pass is 5%, finally obtaining a hot-rolled billet with a thickness of 20mm.

[0095] Grinding: Grind the surface of the hot-rolled billet to eliminate defects such as surface folds, protrusions, and oxide scale until the surface is smooth and bright.

[0096] Cold rolling: cross rolling, rotating 90° clockwise in each pass, with a reduction of 2% per pass, finally obtaining a cold-rolled billet with a thickness of 12mm, ensuring an effective length of not less than 380mm.

[0097] Heat treatment: Hold at 600℃ for 0.5h, after being taken out of the furnace, place it under the platform of the hydraulic press to flatten it, and cool it in the air.

[0098] Cutting: The cold-rolled billet is cut into square strips with a cross section of 12×12mm using a waterjet cutting machine.

[0099] Molding: A rectangular strip is placed on a specific tooling and its sharp edges are eliminated under a hydraulic press.

[0100] Grinding: Using an angle grinder to grind off the oxide scale and burrs on the surface of the material.

[0101] Rotary forging: Nickel bars are rotary forged into Φ6.35mm round bars using a rotary forging machine. The deformation amount is 4% for each of the first three passes and 0.5% for the last three passes.

[0102] Polishing: To polish the surface of the bar, first wipe the surface with anhydrous ethanol to remove residual oil stains, and then polish the surface with sandpaper to remove burrs.

[0103] Stamping: The front end of the nickel rod is placed into the mold and punched under the pressure of the stamping machine to form nickel evaporation material with specifications of Φ6.35×6.0mm.

[0104] Pickling: The nickel particles are immersed in a dilute nitric acid solution with a volume ratio of 1:5 of dilute nitric acid to water for 40 minutes. The volume ratio of the dilute nitric acid solution to the nickel particles is 1:1.6.

[0105] Grinding: Grinding and polishing are carried out in a grinding mill containing grinding balls and grinding solution. The mass ratio and volume / mass ratio of grinding balls, grinding solution and nickel evaporation material are 1:1.5 and 4L / kg, respectively. The total volume of grinding balls, grinding solution and nickel evaporation particles does not exceed 95% of the grinding chamber. The grinding time is 40min.

[0106] Cleaning: Ultrasonic cleaning in an aqueous solution containing detergent for 20 min, with a volume-to-mass ratio of aqueous solution to nickel particles of 1 L / kg; after rinsing with water, ultrasonic cleaning in anhydrous ethanol for 20 min, with a volume-to-mass ratio of anhydrous ethanol to nickel particles of 0.5 L / kg.

[0107] Drying: After removal, dry in a drying oven and vacuum pack.

[0108] The high-purity nickel evaporation particles obtained in this embodiment have a surface roughness of less than Ra0.9, a smooth and defect-free surface, a true density of 99.2% of the theoretical density, an effective Ni content of 99.9987627% (higher than 4N5), and uniform and fine grain size, meeting the requirements of evaporation coating.

[0109] Comparative Example 1

[0110] Comparative Example 1 is the same as Example 1, except that the polishing step between the plastic deformation processes was omitted. The resulting nickel particles exhibited defects such as cracks and peeling on their surface. Figure 5 .

Claims

1. A method for preparing high-purity nickel evaporation particles, characterized in that: Round nickel ingots are hot-forged to obtain square billets. After the first grinding, they are hot-rolled to obtain hot-rolled billets. After the second grinding, they are cold-rolled to obtain cold-rolled billets. The cold-rolled billets are then heat-treated, flattened, and cut into strips. The strips are then die-pressed, ground a third time, and forged to obtain bars. After the bars are polished, they are stamped to obtain nickel granules. Finally, the nickel granules are pickled, ground, cleaned, and dried to obtain nickel evaporation material. The hot upsetting process involves holding a round nickel ingot at 800-1000℃ for 0.5-2 hours, upsetting it into a square shape under a hydraulic press, then flattening it and air cooling it. The first polishing process is as follows: use an angle grinder to polish the surface of the square blank until the surface is smooth and shiny; Before hot rolling, hold at 800-1000℃ for 0.5-2 hours; The single-pass reduction in hot rolling is 5-15%, and the total deformation is 60-80%. The hot rolling process employs cross rolling, with the material rotating 90° in each rolling pass. The second polishing process is as follows: the surface of the hot-rolled billet is polished with an angle grinder until the surface is smooth and bright. The molding process involves placing the strip material in a mold and molding the edges and corners of the strip material under a hydraulic press to remove sharp edges. The third polishing process is as follows: the surface of the molded strip material is polished with an angle grinder to remove the surface oxide scale and burrs.

2. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: The single-pass reduction in cold rolling is 2-10%, and the total deformation in cold rolling is 40-60%. The cold rolling process employs cross rolling, with the material rotating 90° for each rolling pass.

3. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: The cold-rolled billet is heat-treated in a heat treatment furnace at 400-600℃ for 0.5-2 hours. Then it is taken out of the heat treatment furnace, flattened, air-cooled, and then cut into strips.

4. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: The total deformation of the rotary forging is 40-60%, the deformation of the last three passes is 0.5-2%, and the deformation of the remaining passes is 4-6%.

5. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: The pickling process involves immersing the food in a dilute nitric acid solution for 20-40 minutes, followed by rinsing with water. The volume ratio of nitric acid to water in the dilute nitric acid solution is 1:3 to 1:5, and the volume ratio of the dilute nitric acid solution to nickel particles is 1:1 to 1:1.

6. The grinding is carried out in a grinding mill containing grinding balls and grinding solution, and the grinding time is 20-40 minutes. The mass ratio of grinding balls to nickel particles is 1:1 to 1:1.5, and the volume ratio of grinding solution to nickel particles is 2 to 4 L / kg; and the total volume of grinding balls, grinding solution and nickel particles does not exceed 80-95% of the cavity of the grinder.

6. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: The cleaning process is as follows: first, ultrasonic cleaning in an aqueous solution containing detergent for 20-40 minutes, then rinsing with clean water, and then ultrasonic cleaning with anhydrous ethanol for 10-20 minutes. The volume-to-mass ratio of the aqueous solution containing the cleaning agent to the nickel particles is 1~3 L / kg; The volume-to-mass ratio of anhydrous ethanol to nickel particles is 0.5~2 L / kg.

7. The method for preparing high-purity nickel evaporation particles according to claim 1, characterized in that: After cleaning, the material is dried using one of the following methods: natural air drying, drying oven drying, or hot air drying. Then, it is vacuum-packed to obtain the finished nickel evaporation material.

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