A method and apparatus for resistive heat additive manufacturing of large size nanonickel components

Abstract

The application discloses a resistance heat additive manufacturing method and device for large-size nanometer nickel components and belongs to the technical field of nanometer material preparation. The manufacturing method comprises the following steps: nanometer nickel powder is laid on the surface of a substrate to form a nanometer nickel powder layer or the nanometer nickel powder is pressed to form a nanometer nickel powder plate which is placed on the surface of the substrate; the nanometer nickel powder layer or the nanometer nickel powder plate is subjected to resistance heat additive manufacturing, the gap of the nanometer nickel powder and the contact area between the nanometer nickel powder and the substrate are selectively melted by using the resistance heat effect to form metallurgical bonding, and meanwhile, the nanometer structure inside the nanometer nickel powder is reserved, so that a single-layer nanometer nickel component is obtained; and the single-layer nanometer nickel component is subjected to multi-layer resistance heat additive manufacturing, so that the large-size nanometer nickel component is prepared. The application fundamentally solves the problem that the traditional laser / arc melting additive manufacturing technology destroys the nanometer structure and causes the performance of the prepared component to be significantly reduced, and can prepare the centimeter / meter-level nanometer nickel component at a low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanometer material preparation, and particularly relates to a resistance heat additive manufacturing method and device for large-size nanometer nickel components. BACKGROUND

[0002] Nanometer nickel refers to nickel particles or structures with a diameter in the range of 1-100 nanometers. This size of nickel material has completely different physical and chemical properties from traditional macro-scale nickel. Due to a substantial increase in the proportion of surface atoms, nanometer nickel exhibits higher reactivity, lower melting point, stronger magnetism and electrical conductivity, etc. Nanometer nickel components are structures with specific functions processed by specific preparation processes with nanometer-scale nickel material as the core. They have excellent advantages in the fields of wear resistance improvement, efficient catalysis of batteries, efficient electron transmission of electronic devices, high-performance corrosion-resistant materials, etc.

[0003] Nanometer powder production and preparation are relatively mature, and the production cost is relatively low. However, it is extremely difficult to convert nanometer powder into large-size nanometer material components with nanocrystalline structure. Traditional powder laying (powder feeding) printing or powder laying (powder feeding) additive technology has been widely used in the field of additive manufacturing. Through powder feeding, powder laying and cooperation with heat sources such as electric arc and laser, the powder can be melted, solidified and metallurgically combined. However, this technology generally needs to melt the powder to form a molten pool and then solidify it again. The powder used is of micron-level structure size. Even if nanometer powder is used, the nanometer structure (10-100 nm) will be destroyed, and the solidified structure size will grow to micron-level size (1-500 μm). Compared with nanocrystalline materials, the tensile strength is reduced from 1-30 GPa to 0.1-0.8 GPa, and the plasticity and toughness are also significantly reduced. Therefore, the performance of the components prepared by using nanometer powder or micron-level powder generally does not have significant differences, and the advantages of nanometer powder cannot be fully utilized. That is, the existing electric arc and laser powder feeding / laying additive manufacturing technology will melt the nanometer powder and destroy its nanocrystalline structure, resulting in a significant reduction in material strength and other properties, and it is impossible to prepare nanocrystalline components based on nanometer powder.

[0004] At present, physical vapor deposition (PVD) and chemical vapor deposition (CVD) are the main technologies for preparing nanometer materials, but PVD and CVD are thin film preparation processes. However, they can only prepare thin film nanocrystalline nickel components with a thickness of several microns or tens of microns, and the preparation cost is relatively high, which greatly limits the wide industrial application of nanometer materials. At present, there is no report on the use of nanometer nickel powder and resistance heat additive technology to prepare centimeter or decimeter large-size nanometer nickel components. This technology has a significant advantage in the low-cost preparation of large-size nanometer nickel components. Therefore, the application urgently needs to provide a resistance heat additive manufacturing method and device for large-size nanometer nickel components to solve the above problems. SUMMARY

[0005] To solve the technical problems proposed in the background art, the main purpose of the present application is to provide a large-size nano-nickel component resistance heat additive manufacturing method and device, which uses resistance heat effect to form metallurgical bonding between powder and powder gap and between powder and substrate, while retaining the nano structure inside the nano-nickel powder. Compared with the prior art, the grain size of the prepared metal component is reduced to the nano level, the tensile strength can be increased by 3-15 times, and the toughness is improved by more than 20%.

[0006] To achieve the above-mentioned purpose, one aspect of the present application provides a large-size nano-nickel component resistance heat additive manufacturing method, comprising the following steps:

[0007] Step S1, providing nano-nickel powder;

[0008] Step S2, laying the nano-nickel powder on the surface of the substrate to form a nano-nickel powder layer or pressing the nano-nickel powder into a nano-nickel powder plate and placing it on the surface of the substrate;

[0009] Step S3, resistance heat additive of the nano-nickel powder layer or the nano-nickel powder plate, using resistance heat effect to selectively melt the gap of nano-nickel powder and the contact area between nano-nickel powder and substrate to form metallurgical bonding, while retaining the nano structure inside the nano-nickel powder, obtaining a single-layer nano-nickel component;

[0010] Step S4, recycling the single-layer nano-nickel component as a new substrate to repeat steps S2 and S3 for multi-layer resistance heat additive until the desired large-size nano-nickel component is obtained.

[0011] Further, in step S2, the laying into a nano-nickel powder layer adopts electrostatic powder laying process, specifically including the following steps: quantitative delivery of nano-nickel powder through a powder feeding hopper, distribution of the nano-nickel powder to the surface of the substrate through a powder feeding roller, and then oscillation, flattening and preliminary compaction of the nano-nickel powder using a non-contact powder laying electrode, finally further compaction using a multi-stage roller to obtain the nano-nickel powder layer.

[0012] Further, in step S2, the nano-nickel powder is pressed into a nano-nickel powder plate under a pressure of 0.1-3 GPa.

[0013] Further, in step S3, the nano-nickel powder layer is subjected to resistance heat additive, specifically including:

[0014] The upper surface of the nanometer nickel powder layer is applied with a rolling type pressure structure electrically conductive electrode for electrically conductive pressure, the lower surface of the substrate is used as another side electrically conductive electrode to form a current loop with the electrically conductive electrode on the upper surface, and the electric resistance heat effect generated in the current loop is used to selectively melt the gaps of the nanometer nickel powder and the contact area between the nanometer nickel powder and the substrate to form a metallurgical bond, while the nanometer structure inside the nanometer nickel powder is reserved, so that a single-layer nanometer nickel component is obtained.

[0015] Further, the parameter conditions of the electrically conductive pressure include that the voltage parameter is 5-10 V, the current parameter is 2000-7000 A, the load is 1-100 MPa, the single rolling width is 1-20 mm, and the rolling speed is 2-6 mm / s.

[0016] Further, in step S3, the nanometer nickel powder plate is subjected to resistance heat addition, specifically including:

[0017] The upper and lower surfaces of the nanometer nickel powder plate are applied with a flat plate type electrically conductive electrode for electrical conduction operation, the electrically conductive electrode on the lower surface forms a current loop with the electrically conductive electrode on the upper surface, and the electric resistance heat effect generated in the current loop is used to selectively melt the gaps of the nanometer nickel powder and the contact area between the nanometer nickel powder and the substrate to form a metallurgical bond, while the nanometer structure inside the nanometer nickel powder is reserved, so that a single-layer nanometer nickel component is obtained.

[0018] Further, the voltage parameter of the electrically conductive operation is 2-10 V, the current parameter is 2000-7000 A, and the load is 0-100 MPa.

[0019] Further, in step S1, the particle size of the nanometer nickel powder is 10-50 nm.

[0020] Further, in step S1, the nanometer nickel powder is prepared by the following steps: the micron-sized nickel powder is subjected to ball milling, the ball-to-material ratio is set to 15-20:1, the ball milling rotation speed is set to 500-800 rpm, and the ball milling time is 6-15 h, and the nanometer nickel powder is obtained after the ball milling is completed.

[0021] Another aspect of the present application provides a large-size nanometer nickel component prepared by the resistance heat addition manufacturing method.

[0022] Still another aspect of the present application also provides a resistance heat addition manufacturing device for a large-size nanometer nickel component, which is used to implement the resistance heat addition manufacturing method, and the addition manufacturing device includes an electrostatic powder laying unit, a powder compaction unit, and an electrically conductive pressure unit.

[0023] The electrostatic powder laying unit comprises an insulating support, a powder feeding hopper, a powder feeding roller, an insulator and a non-contact powder laying electrode arranged on the insulating support, the insulator is located in front of the non-contact powder laying electrode and is bonded with the non-contact powder laying electrode;

[0024] The powder compacting unit comprises a multi-stage roller arranged on the insulating support, and the multi-stage roller is located behind the non-contact powder laying electrode.

[0025] The power supply and pressure unit comprises a power supply electrode arranged in a roller type pressure structure, and the power supply electrode is arranged behind the multi-stage roller.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The present application uses the resistance heating effect to additively manufacture a nano nickel component, only selectively melts the areas with larger resistance such as the gaps and contact points between nano powders, realizes the metallurgical bonding between the powders and the base material, and perfectly retains the nano crystal structure inside the nano powder, fundamentally solves the problem that the traditional laser / arc melting additive manufacturing technology destroys the nano structure and causes the performance of the prepared component to be significantly reduced. Compared with the PVD and CVD processes, the problem that large-size nano-crystalline nickel components cannot be prepared by the above processes and the preparation cost is high is solved.

[0028] 2. The microstructure of the nickel component is nano-sized, the nano-crystals are metallurgically bonded, the tensile strength is GPa, and the component size is centimeter / meter, which is significantly improved in component size and comprehensive performance compared with the prior art.

[0029] 3. In view of the problem that the existing arc heat additive preparation equipment for large-size low-cost nano nickel components cannot realize integrated, continuous and efficient operation in the powder feeding, powder laying and forming processes, the present application provides a resistance heat additive manufacturing device for large-size nano nickel components, which integrates the power supply electrode with the roller type pressure structure behind the non-contact electrostatic powder laying equipment, realizes online powder feeding, powder laying, powder leveling, multi-stage compaction and continuous additive manufacturing, successfully solves the problem that the resistance heat additive process for nano nickel powder cannot be flexibly and continuously operated, and realizes the preparation of large-size nano nickel components with low cost and high efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The technical principle diagram of the resistance heat additive manufacturing method for large-size nano nickel components of the present application is shown;

[0031] Figure 2 The technical principle diagram of the existing laser / arc additive manufacturing method is shown;

[0032] Figure 3A structural schematic diagram of a resistance heat additive manufacturing device for large-size nanometer nickel components of the present application is shown.

[0033] Figure 4 A flowchart of a process combining powder pressing and flat plate resistance heat additive manufacturing of Example 2 in the present application is shown. DETAILED DESCRIPTION

[0034] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the range and any other stated value or intermediate value in the range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range. The present application will be described in detail below with reference to the embodiments.

[0035] To achieve the above-mentioned purpose, a first aspect of an embodiment of the present application provides a resistance heat additive manufacturing method for large-size nanometer nickel components, comprising the following steps:

[0036] Step S1, providing nanometer nickel powder;

[0037] Step S2, laying the nanometer nickel powder into a nanometer nickel powder layer on a substrate surface or pressing the nanometer nickel powder into a nanometer nickel powder plate and placing it on the substrate surface;

[0038] Step S3, resistance heat additive manufacturing of the nanometer nickel powder layer or the nanometer nickel powder plate, selectively melting the gaps between the nanometer nickel powders and the contact areas between the nanometer nickel powders and the substrate by resistance heat effect to form metallurgical bonding, while retaining the nanometer structure inside the nanometer nickel powders, to obtain a single-layer nanometer nickel component;

[0039] Step S4, recycling the single-layer nanometer nickel component as a new substrate to repeat the steps S2 and S3 for multi-layer resistance heat additive manufacturing until the required large-size nanometer nickel component is obtained.

[0040] The present application innovatively proposes a preparation process for large-size, low-cost and high-performance nanometer nickel components. The process performs power-on pressurization or power-on on the nanometer nickel powder, only causes the gap positions and the contact positions of the nanometer powder to melt due to the large resistance heat, forms metallurgical bonding between the powders and between the powders and the substrate, and retains the nanometer structure inside the nanometer powder without grain growth, so as to realize the microstructure of the nanometer nickel powder without being damaged, and further prepare a large-size nanometer nickel component through multi-layer resistance heat additive manufacturing of the nanometer powder. The size of the nanometer nickel component can be increased to centimeter or decimeter size.

[0041] The specific principles of the present application are referred toFigure 1 Specifically, in the process of power supply, the gap between the powders and the position where the powders contact the substrate have large resistance, and the resistance heat generated thereby can rapidly melt the materials in the part, and once the materials in the part are melted, metallurgical bonding is formed, the resistance rapidly decreases, and the resistance heat generated thereby decreases. The powders inside the powders originally become metallurgical bonding, have small resistance, and have small resistance heat under the same current, so the nanometer powders inside the powders are not melted and still maintain the nano structure, and therefore, the large-size nanocrystalline component can be prepared by the resistance heat additive method.

[0042] The principle of the existing electric arc / laser additive method for preparing a metal component is referred to Figure 2 The powder used in the electric arc / laser additive method is a micron powder, rather than a nanometer powder, and specifically, the technology uses an arc (electric arc), laser or other physical field as a heat source, and the core thereof needs to melt the whole powder, form a molten pool and then solidify to form metallurgical bonding to obtain a metal component, which will destroy the structure of the original powder and cannot retain the performance characteristics of the original powder, and thus the high performance characteristics of the nanometer powder cannot be exerted, and thus a low-cost micron powder is generally used. Even if a nanometer powder structure is used, a nanometer metal component cannot be obtained, because the whole powder is melted and then solidified again, and the size of the structure is increased to the micron size (for example, the initial 1-50 nm can be increased to 1-500 mu m), and thus the tensile strength of the nanocrystalline structure material is reduced from 1-30 GPa to 0.1-0.8 GPa, and the toughness is also worse.

[0043] In summary, the preparation process of the present application solves the problems that the above-mentioned processes cannot prepare large-size nanocrystalline nickel components and have high preparation cost, and the preparation size of nanometer nickel is expanded from micron to centimeter and decimeter. Compared with the existing electric arc / laser additive method, the above-mentioned technology melts the nanometer powder and destroys the nano structure, which leads to a significant decrease in the performance of the prepared component, and the grain size of the metal component is reduced to the nanometer level, the tensile strength is increased by 3-15 times, and the toughness is increased by more than 20% compared with the prior art.

[0044] In a preferred embodiment of the present application, the electrostatic powder laying process and the rolling resistance heat additive process are used to prepare large-size nano-nickel components. The electrostatic powder laying process specifically includes the following steps: quantitatively delivering nano-nickel powder through a powder feeding hopper, distributing it to the surface of the substrate through a powder feeding roller, and then using a non-contact powder laying electrode to oscillate, level and initially compact the nano-nickel powder. Finally, a multi-stage roller is used for further compaction to obtain the nano-nickel powder layer. By the above method, the powder can be fed, laid and compacted in line, which has the advantages of continuous integration, can obtain a high-density nano-nickel powder layer, and is convenient for subsequent resistance heat additive, which is finally conducive to the preparation of large-size nano-nickel components with high performance. Preferably, the powder travel speed in the electrostatic powder laying process is 0.05-5 m / min, more preferably 0.1-2 m / min, and the working voltage is 5-70 Kv, more preferably 0.5-1 m / min.

[0045] In a preferred embodiment of the present application, in step S3, the rolling resistance heat additive process is used to additively manufacture the nano-nickel powder layer, which specifically includes: applying a rolling pressure structure to the upper surface of the nano-nickel powder layer to form a current electrode, and the lower surface of the substrate as another current electrode forms a current loop with the upper surface current electrode, and the resistance heat effect generated in the current loop is used to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while the nano structure inside the nano-nickel powder is retained, to obtain a single-layer nano-nickel component. The application of the current electrode with a rolling pressure structure can ensure the flatness and density of the powder layer, and realize high strength of the nano-nickel component.

[0046] Further, the parameter conditions of the current pressure include: the voltage parameter is 5-10 V, the current parameter is 2000-7000 A, preferably 3000-500 A, the load is 1-100 MPa, preferably 20-80 MPa, the single rolling width is 1-20 mm, and the rolling speed is 2-6 mm / s. By precisely controlling the voltage and current parameters of the current pressure under the above conditions, appropriate resistance heat can be ensured, which can selectively melt the gaps between the nano-nickel powder and the contact area with the current electrode, form a metallurgical bond, and ensure the nano structure inside the nano-nickel powder. By precisely controlling the load, rolling width and rolling speed of the current pressure under the above conditions, the powder can be fully compacted, a large amount of Joule heat I 2 R can be quickly generated to quickly melt the nano-powder, and the nano-crystalline structure of the final component is considered.

[0047] In an alternative embodiment of the present application, the current-carrying electrode of the roll-type pressurizing structure of the present application may, for example, adopt a modified roll welding device, and the roll surface of the roll welding device is modified into a roll-type current-carrying pressurizing structure as a current-carrying electrode to perform current-carrying pressurizing operation. The flat plate-type current-carrying electrode may, for example, adopt a flat graphite electrode as a current-carrying electrode.

[0048] It is considered that, in order to prepare a nano nickel component by resistance heating additive manufacturing of a nano nickel powder layer, contact pressurization and contact current-carrying must be performed, but the contact will cause displacement of the powder laid in the early stage, resulting in problems of uneven forming, insufficient density or inability to form. In a preferred embodiment of the present application, the nano nickel powder can be pre-pressed into a nano nickel powder plate for flat plate-type resistance heating additive manufacturing, specifically comprising:

[0049] The nano nickel powder is first pressed into a nano nickel powder plate by a mold under a pressure of 0.1-3 GPa, the pressed nano nickel powder plate is placed on the surface of the substrate, and then the nano nickel powder plate on the substrate is placed between the flat plate-type current-carrying electrodes for current-carrying operation. The voltage parameter of the current-carrying operation is 2-10 V, and the current parameter is 2000-7000 A (preferably 3000-5000 A). The resistance heating effect generated in the current loop formed by the lower current-carrying electrode and the upper current-carrying electrode selectively melts the gaps between the nano nickel powder and the contact area between the nano nickel powder and the substrate to form a metallurgical bond, while retaining the nano structure inside the nano nickel powder, thereby obtaining a single-layer nano nickel component. The resistance heating additive manufacturing of the nano nickel powder plate by using current-carrying electrodes with similar shapes can print larger components in a single pass and the final component has better density.

[0050] In a preferred embodiment of the present application, in step S1, the particle size of the nano nickel powder is 10-50 nm. Nano powder generally refers to powder with a particle size of less than 100 nm. The selection of a powder with a particle size of 10-50 nm can ensure relatively uniform particle size of the nano powder, excellent comprehensive mechanical properties of the nano-crystalline structure component prepared from the powder, and better balance between economic cost and quality. Further, a planetary ball mill can be used to ball mill micron-grade nickel powder to obtain nano nickel powder. The specific preparation method comprises: ball milling micron-grade nickel powder, setting the ball-to-material ratio to 15-20:1, setting the ball milling speed to 500-800 rpm, and setting the ball milling time to 6-15 h. After the ball milling is completed, the nano nickel powder is obtained. Optionally, the micron-grade nickel powder has a particle size distribution of 45-106 μm.

[0051] In an alternative embodiment of the present application, the nano nickel powder can be selected from nano pure nickel powder or nano nickel-based powder.

[0052] In a second aspect, the application provides a large-size nanometer nickel component, which is prepared by the large-size nanometer nickel component resistance heat additive manufacturing method.

[0053] Based on the above reasons, the large-size nanometer nickel component has nanometer size (20-80 nm), metallurgical bonding between nanocrystals, tensile strength of GPa level (1-30 GPa), and component size of centimeter / meter level, which has significant improvement in component size and comprehensive performance compared with the prior art.

[0054] In a third aspect, the application provides a large-size nanometer nickel component resistance heat additive manufacturing device, which has the structure as shown in Figure 3 , and is used to realize the preparation method of the large-size nanometer nickel component by using the electrostatic powder laying process and the rolling resistance heat additive process, and the resistance heat additive manufacturing device comprises an electrostatic powder laying unit, a powder compacting unit, and an electrification and pressurization unit.

[0055] The electrostatic powder laying unit comprises an insulating support, a powder feeding hopper, a powder feeding roller, an insulator, and a non-contact powder laying electrode arranged on the insulating support, the insulator is located in front of the non-contact powder laying electrode and is bonded with the non-contact powder laying electrode.

[0056] The powder compacting unit comprises a multi-stage roller arranged on the insulating support, and the multi-stage roller is located behind the non-contact powder laying electrode.

[0057] The electrification and pressurization unit comprises an electrification electrode arranged in a roller type pressurization structure, and the electrification electrode is arranged behind the multi-stage roller.

[0058] The arc heat additive manufacturing device for large-size low-cost nanometer nickel components has difficulty in realizing integrated, continuous and efficient operation in powder feeding, powder laying and forming processes. The resistance heat additive manufacturing device provided by the application realizes the integration of the feeding funnel of the non-contact electrostatic powder laying device and the feeding roller by integrating the electrified electrode of the roller pressing structure behind the non-contact electrostatic powder laying device (the electrostatic powder laying unit and the powder compaction unit), and the feeding funnel is used to contain the nanometer nickel powder and the feeding roller is used to lay the nanometer nickel powder on the substrate in a rough and quantitative manner, wherein a gap exists between the insulating support and the feeding funnel to ensure the rotation of the roller. The non-contact powder laying electrode is arranged behind the feeding roller (insulation), the powder laying electrode completes powder leveling and compaction through electrostatic force, oscillation and compaction, and the multi-stage roller (insulation on the outer surface) is integrated into the insulating support of the non-contact electrostatic powder laying device and arranged behind the powder laying electrode to further compact the nanometer nickel powder and obtain a nanometer nickel powder layer, so that the subsequent formed component can have higher density. Finally, the nanometer nickel powder layer is subjected to resistance heat additive manufacturing through the electrified electrode of the roller pressing structure. Compared with other types of electrified electrodes, the electrified electrode of the roller pressing structure can cooperate with the electrostatic powder laying unit and the powder compaction unit to realize integrated operation of powder feeding, powder laying, compaction and electrified pressing forming, and can adapt to planar, cylindrical curved surface and other structures and can work efficiently on the above structures.

[0059] In summary, the resistance heat additive manufacturing device for large-size nanometer nickel components can realize online powder feeding, powder laying, powder leveling, multi-stage compaction and continuous additive manufacturing. After the resistance heat additive manufacturing process of nanometer nickel powder is proposed, the problem that the resistance heat additive manufacturing process of nanometer nickel powder cannot be flexibly and continuously integrated is solved, and large-size nanometer nickel components are prepared in a low-cost and efficient manner.

[0060] The application will be further described in detail below in combination with specific embodiments, and these embodiments cannot be understood as limiting the scope of the application.

[0061] Embodiment 1

[0062] A resistance heat additive manufacturing method for large-size nanometer nickel components, which combines electrostatic powder laying and rolling resistance heat additive manufacturing to prepare large-size nanometer nickel components, and is specifically implemented according to the following steps:

[0063] Step S1, preparing nanometer nickel powder: preparing nanometer nickel powder with a particle size distribution of 10-50 nm from micron-sized nickel powder by a planetary ball mill, including:

[0064] Step 1.1, selecting In625 nickel-based alloy powder as the initial material, the powder model is GH3625, the powder particle size is 45-106 μm, and the GH3625 powder is put into the grinding tank of the planetary ball mill according to the ball-to-powder ratio of 20:1 for grinding;

[0065] Step 1.2, set the rotation speed of the planetary ball mill to 700 rpm, and the grinding time to 12 h, with a 30-minute pause for cooling every hour to avoid high-temperature oxidation;

[0066] Step 1.3, after 12 h of grinding, the GH3625 powder with a particle size of 45-106 μm is prepared into nano-GH3625 powder with a structure of 10-50 nm, and a small amount of powder is taken out for characterization under TEM to ensure that the microstructure of the prepared powder is 10-50 nm.

[0067] Step S2, a large-size nano-nickel component is prepared by combining the electrostatic powder laying and rolling resistance heat additive process, which is realized by using the additive manufacturing device described above (the device structure is referred to Figure 3 ).

[0068] Step 2.1, the nano-nickel powder is quantitatively delivered through the powder feeding hopper, distributed to the surface of the substrate (30CrMo steel) through the powder feeding roller, and then oscillated, leveled and preliminarily compacted by using the non-contact powder laying electrode, and finally further compacted by using the multi-stage roller to obtain a nano-nickel powder layer;

[0069] Step 2.2, the upper surface of the nano-nickel powder layer is subjected to energization and pressure by using the energized electrode of the roller type pressure structure, and the lower surface of the substrate serves as the energized electrode to form a current loop with the energized electrode on the upper surface, and the resistance heat effect generated in the current loop selectively melts the gaps between the nano-nickel powder and the contact areas between the nano-nickel powder and the substrate to form a metallurgical bond, while the nanostructure inside the nano-nickel powder is retained, thereby obtaining a single-layer nano-nickel component, wherein the parameter conditions for energization and pressure are as follows: the voltage is 7.0 V, the current is 5000 A, the load is 20 MPa, the single rolling width is 10 mm, and the rolling speed is 3 mm / s;

[0070] Step 2.3, the single-layer nano-nickel component is used as a new substrate, and the nano-nickel powder layer is laid on the single-layer nano-nickel component by using the method of step 2.1, and then the laid nano-nickel powder layer is subjected to resistance heat additive by using step 2.2, and the multi-layer resistance heat additive is repeated for 4 times by repeating steps 2.1 and 2.2, thereby forming a metallurgical bond between the layers, and obtaining a nano-crystalline nickel component (5 layers) with a size of 1000 mm x 20 mm x 8 mm.

[0071] Example 2

[0072] A resistance heat additive manufacturing method for a large-size nano-nickel component, which combines powder pressing and flat plate resistance heat additive to prepare a large-size nano-nickel component, and is implemented according to the following steps:

[0073] Step S1, preparation of nano nickel powder: micron-sized nickel powder is prepared into nano nickel powder with a particle size distribution of 10-50 nm by a planetary ball mill, including:

[0074] Step 1.1, select In625 nickel-based alloy powder as the initial material, powder model GH3625, powder particle size is 45-106 μm, according to the ball-to-material ratio of 20:1, put GH3625 powder into the grinding tank of the planetary ball mill for grinding;

[0075] Step 1.2, set the rotation speed of the planetary ball mill to 700 rpm, and the grinding time to 12 h, pause and cool every 30 minutes to avoid high temperature oxidation;

[0076] Step 1.3, after 12h grinding, the GH3625 powder with a particle size of 45-106 μm is prepared into nano GH3625 powder with a structure of 10-50 nm, and a small amount of powder is taken out for characterization under TEM to ensure that the microstructure of the prepared powder is 10-50 nm.

[0077] Step S2, the process of powder pressing and forming combined with flat plate resistance heat additive is used to prepare large-size nano nickel components, and the process is referred to Figure 4 :

[0078] Step 2.1, use powder pressing tool to press the above GH3625 nano powder into a 180mm×210mm×2mm dense nano nickel powder plate at 500MPa, and then place the pressed nano nickel powder plate on the substrate (30CrMo steel);

[0079] Step 2.2, place the GH3625 nano nickel powder plate with a size of 180mm×210mm×2mm on the substrate between the graphite electrodes with a size of 180mm×210mm×2mm for power operation, the power parameters are current 4000A, voltage 6.5V, and load 1MPa, the resistance heat effect generated in the current loop by the lower surface graphite electrode and the upper surface graphite electrode is used to selectively melt the gap of nano nickel powder and the contact area between nano nickel powder and substrate to form metallurgical bonding, while retaining the nano structure inside the nano nickel powder, to obtain a single-layer nano nickel component;

[0080] Step 2.3, taking the single-layer nano-nickel component as a new substrate, placing the pre-pressed nano-nickel powder plate on the single-layer nano-nickel component in the manner of step 2.1, and then performing resistance heat addition on the nano-nickel powder plate placed on the single-layer nano-nickel component in step 2.2, repeating steps 2.1 and 2.2 for 3 times to perform multi-layer resistance heat addition, and realizing metallurgical bonding between layers to obtain a large-size nano-nickel component (180 mm x 210 mm x 6 mm, 4 layers).

[0081] Example 3

[0082] A resistance heat additive manufacturing method of a large-size nano-nickel component, which is different from example 1 only in that the parameter conditions of power supply and pressure are different, and the specific conditions are as follows: the voltage parameter is 5V, the current parameter is 2000A, the load is 1MPa, the single rolling width is 1mm, and the rolling speed is 2mm / s.

[0083] Example 4

[0084] A resistance heat additive manufacturing method of a large-size nano-nickel component, which is different from example 1 only in that the parameter conditions of power supply and pressure are different, and the specific conditions are as follows: the voltage parameter is 10V, the current parameter is 7000A, the load is 100MPa, the single rolling width is 20mm, and the rolling speed is 6mm / s.

[0085] Example 5

[0086] A resistance heat additive manufacturing method of a large-size nano-nickel component, which is different from example 2 only in that the parameter conditions of power supply are different, and the voltage parameter is 2V and the current parameter is 2000A.

[0087] Example 6

[0088] A resistance heat additive manufacturing method of a large-size nano-nickel component, which is different from example 2 only in that the parameter conditions of power supply are different, and the voltage parameter is 10V and the current parameter is 7000A.

[0089] Comparative Example 1

[0090] A micro-sized metal nickel component is prepared by taking a traditional laser coaxial powder feeding addition as an example, and the preparation process of the micro-sized metal nickel component specifically includes the following steps:

[0091] Step 1, selecting 30CrMo steel as a substrate, and selecting In625 nickel-based alloy powder as an initial material, the powder type is GH3625, and the powder particle size is 45-106μm;

[0092] Step 2, laser coaxial powder feeding additive printing is performed. The laser power is 8000 W, the walking speed is 20 mm / s, the track spacing is 1.2 mm, the powder feeding speed is 1.8 g / min, the preset layer height is 1.5 mm, the protective gas flow is 0.8 L / min, the powder feeding mode is coaxial ring, the protective gas is 100% argon, the additive layer overlap rate of each pass is 45%, and the light plate diameter is 4 mm.

[0093] Step 3, step 2 is repeated to perform 30 layers of 120 passes of additive printing to prepare a nickel-based alloy additive component with a height of 60 mm, a length of 100 mm, and a width of 150 mm.

[0094] Performance test:

[0095] The tensile strength of the metal nickel components of the above examples and comparative examples is tested by the indentation method, and the execution standard is GB / T 39635-2020; the elongation test (plastic performance) of the metal nickel components of the above examples and comparative examples is tested by the micro-column compression method (a micro-column is prepared from bulk material by a focused ion beam (FIB), usually with a diameter of 200 nanometers and a height of 800 nanometers of the diameter, the micro-column is placed under the compression equipment, and the axial load is slowly applied, the load-displacement curve is recorded, and the elongation is calculated by the strength change of the load-displacement curve). The test results are shown in Table 1.

[0096] Table 1

[0097]

[0098] From the above Table 1, it can be found that the mechanical properties of the metal nickel components prepared by the embodiments of the present application are greatly increased compared with the metal nickel components prepared by the prior art laser coaxial powder feeding additive, the tensile strength is increased by about 10 times, and the elongation is also significantly improved, and the increase is about 1.2-1.5 times. The present application fundamentally solves the problem that the traditional laser / electric arc melting additive manufacturing technology destroys the nano structure, resulting in a significant decrease in the performance of the prepared component. In addition, the component size of the present application can reach centimeter / decimeter level, which is significantly improved compared with the prior art in terms of component size and comprehensive performance.

[0099] The above-described embodiments only represent the embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the present application, and the present application can also be implemented in other specific ways or other specific forms without deviating from the spirit or essential characteristics of the present application. Therefore, the described embodiments should be regarded as illustrative rather than limiting in any aspect. The scope of the present application should be illustrated by the appended claims, and any changes equivalent to the intent and scope of the claims should also be included in the scope of the present application.

Claims

1. A method for resistive thermal additive manufacturing of large-size nano-nickel components, characterized in that, Includes the following steps: Step S1, providing nano-nickel powder; Step S2: The nano-nickel powder is deposited on the substrate surface to form a nano-nickel powder layer or the nano-nickel powder is pressed into a nano-nickel powder plate and placed on the substrate surface. Step S3: Perform resistance thermal additive manufacturing on the nano-nickel powder layer or the nano-nickel powder plate to obtain a single-layer nano-nickel component; The process of applying resistance heat to the nano-nickel powder layer specifically includes: applying an energized electrode with a roller-type pressure structure to the upper surface of the nano-nickel powder layer for energization and pressure application; the substrate on the lower surface serves as the other energized electrode, forming a current loop with the energized electrode on the upper surface; utilizing the resistance heat effect generated in the current loop to selectively melt the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while preserving the nanostructure inside the nano-nickel powder, resulting in a single-layer nano-nickel component; the parameters for energization and pressure application include: voltage of 5~10V, current of 2000~7000A, load of 1~100MPa, single rolling width of 1~20mm, and rolling speed of 2~6mm / s; The process of resistive thermal additive manufacturing of a nano-nickel powder plate specifically includes: applying flat plate-type energized electrodes to the upper and lower surfaces of the nano-nickel powder plate and performing an energizing operation. The energized electrodes on the lower and upper surfaces form a current loop. The resistive thermal effect generated in the current loop selectively melts the gaps between the nano-nickel powder and the contact area between the nano-nickel powder and the substrate to form a metallurgical bond, while retaining the nanostructure inside the nano-nickel powder, resulting in a single-layer nano-nickel component. The voltage parameters of the energizing operation are 2~10V, the current parameters are 2000~7000A, and the load is 0~100MPa. Step S4: Using the single-layer nickel nanostructure obtained in step S3 as a new substrate, repeat steps S2 and S3 to perform multilayer resistance thermal additive manufacturing until the desired large-size nickel nanostructure is obtained.

2. The resistance thermal additive manufacturing method according to claim 1, characterized in that, In step S2, the nano-nickel powder layer is laid using an electrostatic powder laying process, which specifically includes the following steps: nano-nickel powder is quantitatively conveyed through a powder feeding funnel, distributed to the substrate surface by a powder feeding roller, and then the nano-nickel powder is vibrated, leveled and initially compacted using a non-contact powder laying electrode. Finally, multi-stage rollers are used for further compaction to obtain the nano-nickel powder layer.

3. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S2, the nano-nickel powder is pressed into a nano-nickel powder plate under a pressure of 0.1~3 GPa.

4. The resistance thermoforming additive manufacturing method according to claim 1, characterized in that, In step S1, the particle size of the nano-nickel powder is 10~50nm.

5. The resistance thermoforming additive manufacturing method according to claim 1 or 4, characterized in that, In step S1, the nano-nickel powder is prepared by the following steps: micron-sized nickel powder is ball-milled with a ball-to-material ratio of 15-20:1, a ball milling speed of 500-800 rpm, and a ball milling time of 6-15 h. The nano-nickel powder is obtained after the ball milling is completed.

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