Preparation method of nickel material for energy storage structural member

Abstract

The invention relates to a preparation method of a nickel material for an energy storage structural member. The method comprises the following steps: proportioning metal nickel and trace elements; raw material treatment, three-stage vacuumizing smelting, ingot blank annealing, coping and flaw detection repair, and detection and warehousing. The invention belongs to a preparation technology of a pure nickel product in the field of energy storage, and finally achieves the purpose of improving the quality of a nickel material through multi-stage vacuum melting in combination with internal metallurgical defects.

Description

Technical Field

[0001] The invention belongs to the field of energy storage technology, in particular to a pure metal nickel vacuum melting preparation technology, specifically to a method for preparing high-purity metal nickel materials for energy storage structural parts. Background Art

[0002] Compared with traditional smelting, vacuum smelting reduces pollution to the surrounding environment, reduces the labor intensity of operators, and helps to improve the quality stability of products. However, the vacuum smelting method is complicated, and the quality and performance of metal materials prepared by different metal materials, different smelting equipment, and different smelting methods are different. Therefore, the development and innovation of advanced vacuum smelting methods and equipment to further improve the performance of advanced metal materials is the development trend of pure nickel metal preparation in the future energy field.

[0003] Pure nickel has good heat transfer and electrical conductivity, processing ductility and corrosion resistance, and is widely used in electronics, battery energy and other industries. In recent years, the application of pure nickel products has been expanding and the output has been increasing. Due to the gap between the technical level, product quality and cost control compared with foreign countries, my country imports a large amount of metal nickel used in electronics, new energy and other fields. Therefore, it is necessary to improve the quality level of pure nickel products such as ingots, plates, strips, foils, etc. in my country as soon as possible.

[0004] The main preparation processes of nickel metal are electrolytic nickel vacuum melting, pouring ingot casting, ingot forging, etc. Due to the presence of local solidification holes or inclusions in the smelting nickel metal ingot, the subsequent pure nickel products have metallurgical defects such as high inclusion content and large batch performance fluctuations, as well as difficult quality control, which affect the performance of the product. The detection and control of metallurgical defects of nickel metal ingots is the prerequisite for ensuring the quality level of the strip and foil prepared later. The energy battery field has higher and higher requirements for the quality level of nickel metal products, mainly in two aspects: on the one hand, from the perspective of use, the surface of nickel strip products is required to be flat, without bubbles, scars, cracks, scratches, cracks, and inclusions. The above defects will not only damage the appearance of the parts, but also often reduce product performance; on the other hand, it is to meet the internal quality control requirements of product performance. The quality of the internal metallurgical quality of nickel materials has a great impact on the performance and service life of products and components. In addition to requiring uniform grain structure, the internal metallurgical defects of plates and strips include holes, looseness, microcracks, etc. The internal quality of nickel metal materials is closely related to smelting methods.

[0005] Table 1 shows the main control range of pure nickel chemical composition.

[0006] Table 1 Chemical composition of pure nickel (%wt)

[0007]

[0008] In addition to the main element nickel, pure nickel also contains trace elements. The national standard stipulates that the total content of trace impurity elements in pure nickel strips with a grade of N6 is less than or equal to 0.5%, the total impurity content of N4 nickel strips does not exceed 0.1%, and the requirements for N2 nickel strips are higher, and the total impurity content does not exceed 0.02%. Among them, typical harmful impurity elements such as sulfur S and lead Pb are easy to form low-melting point eutectics with nickel, affecting the high-temperature performance of the material. In addition, the elements phosphorus and sulfur have a great affinity with nickel. During solidification and crystallization, NiS2-Ni and Ni3P-Ni are formed and distributed at the grain boundaries, which makes it easy to reduce the weld strength during the welding process of the material; and when the carbon C content in the metal exceeds 0.1%, carbon is easy to precipitate in the nickel in the form of graphite, destroying the intercrystalline bonding force, causing cold brittleness and reducing the mechanical properties of the material.

[0009] Therefore, the metallurgical quality of the material can be improved by optimizing the smelting preparation method to improve the purity of pure metallic nickel.

[0010] At present, the preparation of pure nickel adopts non-vacuum induction melting, vacuum induction melting, vacuum induction melting + protective atmosphere electroslag remelting, vacuum induction melting + vacuum consumable remelting and other methods. Among them, non-vacuum induction melting is prone to increase in oxygen content and other problems; while vacuum induction melting is beneficial to remove gases and inclusions through vacuum degassing, volatilization of low-melting point harmful elements, decomposition and flotation and other physical and chemical reactions during the smelting process, so that the content of harmful gases and impurity elements (such as Pb, Bi, Te, Cd, Sn, etc.) in the alloy is significantly reduced. At present, protective atmosphere electroslag remelting uses electric current slag to resist heat to melt the bottom of the ingot electrode. The alloy droplets with higher density pass through the slag pool floating on the surface of the liquid metal molten pool, and solidify into ingots in a copper water-cooled crystallizer after the cleaning and adsorption of the slag. The electroslag remelting method and vacuum consumable remelting method are complex and costly.

[0011] The present invention mainly adopts a multi-stage vacuum induction short-process smelting method and combines the characteristics of pure metallic nickel to prepare low-cost, high-performance pure metallic nickel. Summary of the invention

[0012] The purpose of the present invention is to propose a method for preparing nickel materials for energy storage structural parts in response to the problem of preparation methods for high-quality pure nickel metal products. The present invention adopts a vacuum induction melting method of three-stage vacuum melting. After vacuum smelting, the metal nickel melt is directly cast into an intermediate billet of the product, eliminating multiple processing links. The method has the advantages of short process, low cost, high production efficiency and no pollution to the environment. It is suitable for the demand for pure nickel products in the field of battery energy and has significant innovation and application prospects.

[0013] The technical solution of the present invention is:

[0014] The present invention provides a method for preparing a nickel material for an energy storage structural component, the method comprising the following steps:

[0015] (1) Material selection: Select metal nickel with a nickel content of ≥99.96% as raw material;

[0016] (2) Raw material processing: removing the oxide scale on the surface of the raw material, placing it in an electric heating furnace for heating, and cooling it down after heating is completed and taking it out of the furnace;

[0017] (3) Three-stage vacuum melting: the processed raw materials are placed into a crucible of a vacuum induction melting furnace and heated for three-stage vacuum melting, including:

[0018] The first stage is evacuated until the vacuum degree reaches 1Pa~20Pa;

[0019] Secondary vacuuming to 0.1Pa~0.8Pa, increasing the power of the power supply, maintaining the time for 10min~15min, and melting the metal nickel in a vacuum environment;

[0020] The third stage is vacuumed to 0.01Pa~0.1Pa, and refined for 15min~20min until the metal nickel is completely melted;

[0021] After complete melting, fill the vacuum induction melting furnace with argon and continue refining for 20min to 30min;

[0022] After refining, the molten metal is poured into a mold in a vacuum chamber to cool, and the ingot is taken out; (4) Ingot annealing: The metal nickel ingot is annealed and then cooled to room temperature.

[0023] Furthermore, in step (1), the trace elements include carbon C, sulfur S, phosphorus P, arsenic As and lead Pb; the preferred ingredients are: nickel Ni content ≥ 99.96%, carbon C content ≤ 0.01%; the total content of impurity elements sulfur S, phosphorus P, arsenic As and lead Pb is less than 0.05%.

[0024] Furthermore, in the step (2), the metal nickel block is ball-milled with pure metal nickel balls to remove oxide scale on the surface of the metal nickel block.

[0025] Furthermore, the purity of the pure metal nickel ball is greater than 99.6%, the particle size range of the nickel ball is 1 mm to 3 mm, and the ball milling time is 30 min to 60 min.

[0026] Furthermore, in the step (2), the heating temperature of the electric heating furnace is 800°C to 900°C, and the insulation time is 2h to 3h; after the heating is completed, the temperature is cooled to 200°C to 300°C and then taken out of the furnace.

[0027] Furthermore, in the step (3), the purity of argon gas in the three-stage vacuum treatment is greater than 99.9%, and the pressure range after filling with argon gas is 1000Pa to 1500Pa.

[0028] Furthermore, in the step (4), the metal nickel ingot is annealed in a trolley-type heat treatment furnace, and the annealing method is heating to 900° C. to 960° C. and keeping the temperature for 2 h to 3 h.

[0029] Furthermore, the method also includes: (5) grinding: performing surface grinding on the annealed metal nickel ingot to remove surface oxide scale and oxide inclusions; (6) flaw detection and repair, and testing before storage.

[0030] Furthermore, in step (6), the flaw detection and repair is specifically: using ultrasonic flaw detection equipment to detect metallurgical defects inside the metal nickel ingot, and if a single display signal exceeding the standard is found, grinding and removing it.

[0031] Furthermore, the flaw detection parameter requirement is that the flat bottom hole diameter is Φ2.0 mm, and the equivalent flat bottom hole diameter of multiple discontinuous indication signals is Φ1.8 mm.

[0032] Beneficial effects of the present invention:

[0033] The present invention aims to solve the problems of high inclusion content and large batch performance fluctuation of domestic pure nickel metal used in the field of energy storage, and improves the metallurgical quality and product performance of nickel metal materials by performing vacuum induction melting through a multi-stage vacuum system.

[0034] The present invention is combined with the traditional smelting method and an innovative triple vacuum system is designed, which not only fully volatilizes harmful elements through the vacuum system, but also suppresses the burning loss of beneficial trace elements in pure metallic nickel, such as Mn, Mg, etc., to achieve micro-alloying, etc.; the raw materials are processed from the front end, avoiding the influence of the introduction of new inclusions on product quality.

[0035] This method has the advantages of short process, low cost, less pollution and low labor intensity.

[0036] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0037] The scheme of the present invention will be described in more detail below with reference to examples. Although the examples show preferred embodiments of the present invention, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0038] In the present invention, % in the ingredients refers to the mass percentage.

[0039] Embodiment 1:

[0040] Selection of metallic nickel raw materials: The nickel content in the metallic nickel (Ni) raw materials is not less than 99.97%, the carbon C content is 0.01%, and the total content of impurity elements sulfur (S), phosphorus (P), arsenic (As), and lead (Pb) is less than 0.02%.

[0041] The metal nickel block is subjected to ball milling to remove oxide scale, and pure metal nickel balls are used for ball milling, the nickel ball particle size is 1mm, and the ball milling time is 30min; after ball milling, the nickel block is placed in an electric heating furnace for heating treatment, and the heating method parameters are: 800℃, and the insulation time is 2h; after heating is completed, the furnace is cooled to 200℃ and then taken out of the furnace, and the metal nickel raw material is loaded into the crucible of the vacuum induction melting furnace for smelting.

[0042] The pure metal nickel smelting equipment adopts a three-stage vacuum system of mechanical pump, maintenance pump and oil booster pump. First, the first-stage mechanical pump is used to evacuate the smelting chamber of the smelting equipment, and the working vacuum degree is 1Pa; then the maintenance pump of the second-stage vacuum system is turned on, and the vacuum degree of the smelting equipment is 0.1Pa, and the holding time is 10min; the third-stage oil booster pump is turned on, and the vacuum degree of the smelting equipment is pumped to 0.01Pa, and maintained for 15min;

[0043] Then, high-purity argon (99.9% wt) was filled into the equipment, the pressure range was 1000 Pa, and the refining time was 20 min.

[0044] After refining, the molten metal is poured into the steel ingot mold in the vacuum chamber to cool. After the metal ingot is completely cooled, the equipment breaks the vacuum and takes out the ingot for subsequent annealing. Annealing of the ingot. The metal nickel ingot is annealed in a trolley-type heat treatment furnace. The annealing method is to heat to 900°C, keep warm for 2 hours, and then cool to room temperature with the furnace. The pure metal nickel ingot is processed by surface grinding machine. The oxide scale and surface oxide inclusions on the surface of the clean ingot are removed.

[0045] Contact ultrasonic flaw detection equipment is used to detect metallurgical defects inside nickel ingots. The flaw detection parameters are flat bottom hole diameter Φ2.0mm, equivalent flat bottom hole diameter of multiple discontinuous indication signals Φ1.8mm, no single display signal exceeding the standard, and the finished product is put into storage. The metallurgical quality and chemical composition of the pure nickel ingot are qualified, and the finished product is put into storage.

[0046] The main components and partial impurity contents of pure metallic nickel prepared in Example 1 are shown in Table 2:

[0047] Table 2

[0048] element Ni Si P O N content(%) 99.97 0.0001 0.0005 0.0003 0.0005

[0049] Embodiment 2:

[0050] The nickel content in the metallic nickel (Ni) raw material is 99.98%, the carbon C content is 0.009%, and the total content of impurity elements sulfur (S), phosphorus (P), arsenic (As), and lead (Pb) is 0.011%.

[0051] The metal nickel plate is ball-milled to remove the oxide scale. Pure metal nickel balls are used for ball milling. The nickel balls have a particle size of 3 mm and the ball milling time is 60 min. After the nickel block is ball-milled, it is placed in an electric heating furnace for heating treatment. The heating method parameters are: 900°C for 3 hours. After the heating is completed, the furnace is cooled to 300°C and then taken out of the furnace. The metal nickel raw material is loaded into the crucible of a vacuum induction melting furnace for smelting.

[0052] The smelting equipment adopts a three-stage vacuum system of mechanical pump, maintenance pump and oil booster pump. First, the mechanical pump is used to evacuate the smelting chamber of the smelting equipment, and the working vacuum degree is 20Pa; then the maintenance pump of the vacuum system is turned on to reduce the vacuum degree of the smelting equipment to 0.8Pa and maintain it for 15 minutes; then the oil booster pump is turned on to reduce the vacuum degree of the smelting equipment to 0.1Pa and maintain it for 20 minutes;

[0053] The pure nickel metal plate is cut into suitable blocks, placed in the crucible of the vacuum induction melting furnace, and slowly heated by electricity; when the vacuum degree of the equipment reaches 0.8Pa, the power of the equipment power supply is increased, and the metal nickel is melted in a vacuum environment. The vacuum degree of the melting equipment is pumped to 0.1Pa, the metal nickel is completely melted, and the refining is 20min. Then, high-purity argon gas 99.9%wt is filled into the equipment, the pressure range is 1500Pa, and the refining is 30min.

[0054] After refining, the molten metal is poured into the steel ingot mold in the vacuum chamber to cool. After the metal ingot is completely cooled, the equipment breaks the vacuum and takes out the ingot for subsequent annealing. Annealing of the ingot. The metal nickel ingot is annealed in a trolley-type heat treatment furnace. The annealing method is to heat to 960°C, keep warm for 3 hours, and then cool to room temperature with the furnace. The pure metal nickel ingot is processed by surface grinding machine. The oxide scale and surface oxide inclusions on the surface of the clean ingot are removed.

[0055] Contact ultrasonic flaw detection equipment is used to detect metallurgical defects inside the nickel ingot. The flaw detection parameter requirement is that the diameter of the flat bottom hole is Φ2.0mm, and no single display signal exceeding the standard is found; the finished product is put into storage. The finished product is put into storage after the internal metallurgical quality and chemical composition of the pure nickel ingot are tested and qualified.

[0056] The main components and partial impurity contents of pure metallic nickel prepared in Example 1 are shown in Table 3:

[0057] Table 3

[0058] element Ni Si P O N content(%) 99.98 0.001 0.0002 0.0003 0.004

[0059] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing nickel material for energy storage structural parts, It is characterized in that The method comprises the following steps: (1) Material selection: Select metal nickel with a nickel content of ≥99.96% as raw material; (2) Raw material processing: removing the oxide scale on the surface of the raw material, placing it in an electric heating furnace for heating, and cooling it down after heating is completed and taking it out of the furnace; (3) Three-stage vacuum melting: the processed raw materials are placed into a crucible of a vacuum induction melting furnace and heated for three-stage vacuum melting, including: The first stage is evacuated until the vacuum degree reaches 1Pa~20Pa; Secondary vacuuming to 0.1Pa~0.8Pa, increasing the power of the power supply, maintaining the time for 10min~15min, and melting the metal nickel in a vacuum environment; The third stage is vacuumed to 0.01Pa~0.1Pa, and refined for 15min~20min until the metal nickel is completely melted; After complete melting, fill the vacuum induction melting furnace with argon and continue refining for 20min to 30min; After refining, the molten metal is poured into a mold in a vacuum chamber to cool, and the ingot is taken out; (4) Ingot annealing: The metal nickel ingot is annealed and then cooled to room temperature.

2. The method for preparing the nickel material for energy storage structural parts according to claim 1, It is characterized in that In the step (1), the trace elements include carbon C, sulfur S, phosphorus P, arsenic As and lead Pb; the preferred ingredients are: nickel Ni content ≥ 99.96%, carbon C content ≤ 0.01%; the total content of impurity elements sulfur S, phosphorus P, arsenic As and lead Pb is less than 0.05%.

3. The method for preparing nickel material for energy storage structural parts according to claim 1, It is characterized in that In the step (2), pure metal nickel balls are used to ball-mill the metal nickel block to remove oxide scale on the surface of the metal nickel block.

4. The method for preparing nickel material for energy storage structural parts according to claim 3, It is characterized in that The purity of the pure metal nickel ball is greater than 99.6%, the particle size range of the nickel ball is 1mm to 3mm, and the ball milling time is 30min to 60min.

5. The method for preparing nickel material for energy storage structural parts according to claim 1, It is characterized in that In the step (2), the heating temperature of the electric heating furnace is 800° C. to 900° C., and the insulation time is 2 h to 3 h. After the heating is completed, the temperature is lowered to 200° C. to 300° C. and then taken out of the furnace.

6. The method for preparing nickel material for energy storage structural parts according to claim 1, It is characterized in that In the step (3), the purity of argon gas in the three-stage vacuum treatment is greater than 99.9%, and the pressure range after filling with argon gas is 1000Pa to 1500Pa.

7. The method for preparing nickel material for energy storage structural parts according to claim 1, It is characterized in that In the step (4), the metal nickel ingot is annealed in a trolley-type heat treatment furnace, and the annealing method is heating to 900° C. to 960° C. and keeping the temperature for 2 h to 3 h.

8. The method for preparing nickel material for energy storage structural parts according to claim 1, It is characterized in that The method further includes: (5) Grinding: The annealed nickel ingot is subjected to surface grinding to remove surface oxide scale and oxide inclusions; (6) NDT repair and inspection before storage.

9. The method for preparing nickel material for energy storage structural parts according to claim 8, It is characterized in that In the step (6), the flaw detection and repair specifically includes: using ultrasonic flaw detection equipment to detect metallurgical defects inside the metal nickel ingot, and if a single display signal exceeding the standard is found, grinding and removing it.

10. The method for preparing nickel material for energy storage structural parts according to claim 9, It is characterized in that The flaw detection parameter requirements are that the flat bottom hole diameter is Φ2.0mm, and the equivalent flat bottom hole diameter of multiple discontinuous indication signals is Φ1.8mm.

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