High-loading-capacity nickel-based nano ink for jet bonding forming, preparation method and part preparation

Abstract

The invention relates to the field of jet bonding forming, and provides high-loading-capacity nickel-based nano ink for jet bonding forming, a preparation method of the high-loading-capacity nickel-based nano ink and part preparation.The preparation method of the ink comprises the steps that a nickel precursor and nickel nano particles are dissolved in a rapid-volatilization solvent, then a dispersing agent is added to regulate and control the rheological property of the ink, and the high-loading-capacity nickel-based nano ink is obtained; finally, uniform and stable ink is formed through stirring and / or ultrasonic treatment. According to the ink, the precursor is added, the stability of the nano particles in a solution is adjusted, the loading capacity of the nano particles of the ink can reach 40-70 wt.%, meanwhile, the formula of the quick-drying solvent and the stable dispersing agent is optimized, and quick curing and stability maintaining after ink jetting are achieved. In the subsequent sintering process, the nickel precursor is heated and self-decomposed into nickel nanoparticles, the nickel nanoparticles are matched with the previously added nickel nanoparticles, so that gradient density distribution is formed between the nanoparticles with different sizes and the base powder to promote sintering, and meanwhile, the nanoparticles with different sizes are filled in gaps of the base powder to improve the sintering performance. And the sintering shrinkage rate is remarkably reduced while material densification is promoted, and finally, high-density and low-shrinkage-rate parts are manufactured.

Description

Technical Field

[0001] The present invention relates to the field of jet bonding molding, and in particular to a high-load nickel-based nano-ink for jet bonding molding, a preparation method and parts preparation. Background Art

[0002] Binder Jetting technology is an advanced 3D printing method that forms parts by spraying a binder onto powdered materials and stacking them layer by layer. It has the potential to manufacture parts with complex geometries. In binder jetting technology, the binder is the core material for achieving bonding of powder particles, and its performance directly affects the strength of the green body, sintering behavior, and the quality of the final part. At present, the binders commonly used in metal jetting bonding technology are mainly polymer binders (such as polyvinyl alcohol (PVA), polyacrylic acid (PAA), etc.). These binders will completely decompose during high-temperature sintering, resulting in pores inside the parts, making it difficult to fully densify during sintering. At the same time, the decomposition and volatilization of the binder at high temperatures further aggravate the volume shrinkage.

[0003] Despite its significant advantages, spray bonding technology currently has significant shortcomings in terms of binder performance, sintered density, and shrinkage control. Existing binders lack sufficient sintered density, limiting part performance. Furthermore, high sintering shrinkage affects dimensional accuracy and manufacturing efficiency. These issues urgently need to be addressed to promote the widespread application of spray bonding technology in high-performance, high-precision applications. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a high-load nickel-based nano-ink, preparation method and part preparation for jet bonding molding, so as to solve the problems of low sintering density and high shrinkage rate of existing binders in jet bonding technology. By filling the gaps in the blank with high-content nickel nanoparticles, the density of the parts is improved and the shrinkage rate is reduced, thereby realizing high-performance and high-precision additive manufacturing.

[0005] The present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a method for preparing a high-load nickel-based nano-ink for jet bonding molding, comprising: dissolving a nickel precursor and nickel nanoparticles in a fast-evaporating solvent, adding a dispersant to regulate the rheological properties of the ink, and finally forming a uniform and stable ink through stirring and / or ultrasonic treatment.

[0007] Any possible implementation as described above, further provides an implementation, wherein the nickel precursor is a nickel salt, and the nickel salt is a combination of any one or more of nickel formate, nickel acetate, nickel sulfate, nickel nitrate, nickel acetylacetonate, and nickel chloride; and the particle size of the nickel nanoparticles is 1-300 nm.

[0008] Any possible implementation as described above further provides an implementation, wherein the fast evaporating solvent is any one or more combinations of methanol, ethanol, and ethylene glycol.

[0009] According to any of the possible implementations described above, there is further provided an implementation in which the amount of the nickel precursor added is 10-20 wt.%, and the amount of the nickel nanoparticles added is 40-60 wt.%.

[0010] Any possible implementation as described above further provides an implementation, wherein the dispersant is a combination of any one or more of surfactants, polymer dispersants, and small molecule organic compound dispersants.

[0011] Any possible implementation as described above, further provides an implementation, wherein the surfactant dispersant is any one or a combination of two of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB); the polymer dispersant is any one or more of PVP, PAA, PEG, and CMC-Na; and the small molecule organic compound dispersant is selected from any one or more of citric acid, oleic acid, and tartaric acid.

[0012] In any of the possible implementations described above, a further implementation is provided, wherein the dispersant used to control the rheological properties is one or a combination of the above-mentioned dispersants, added in an amount of 3-10 wt.%, and the rheological behavior of the ink is improved by adsorbing on the surface of the nanoparticles to reduce the attraction between the particles.

[0013] Any possible implementation as described above further provides an implementation, wherein the stirring is mechanical stirring, the mechanical stirring speed is 500-1000 rpm, and the stirring time is 1-2 hours; the frequency of the ultrasonic treatment is 20-40 kHz, and the treatment time is 20-40 minutes.

[0014] On the other hand, the present invention also provides a high-load nickel-based nano-ink for jet bonding molding, wherein the ink is obtained using the above-mentioned preparation method, and the solid content of nickel nanoparticles in the ink is 40-70wt.%.

[0015] On the other hand, the present invention also provides a method for preparing high-precision nickel-containing metal parts, using the above-mentioned high-load nickel-based nano-ink, specifically comprising:

[0016] S1, loading the high-load nickel-based nanoparticle ink into an ink cartridge of a high-precision inkjet printing device;

[0017] S2. Evenly spread the nickel-based powder on the printing platform to form a powder layer;

[0018] S3, according to the preset 3D model, control the inkjet device to spray ink onto the powder layer along a predetermined path, and the ink quickly solidifies to bond the powder particles into shape;

[0019] S4, repeat steps S2 and S3, printing layer by layer until the entire blank is printed;

[0020] S5. Place the printed blank in a sintering furnace for sintering to obtain the final part.

[0021] Any possible implementation as described above, further provides an implementation, in step S2, the particle size of the nickel-based powder is 10-50 μm, and the thickness of each layer of nickel-based powder is 50-100 μm; in step S5, the sintering conditions are: protective atmosphere, temperature 900-1100°C, and holding time 1-3 hours.

[0022] The beneficial effects of the present invention are:

[0023] 1. High nanoparticle loading: One of the core advantages of the present invention is that the introduction of precursors significantly increases the loading of nanoparticles in the ink. Traditional methods for preparing nanoparticle inks are limited by dispersibility and stability, and the solid content is usually difficult to reach 40wt.%. The present invention innovatively introduces nickel-based precursors to generate nickel-based nanoparticles in situ in the ink system through thermal decomposition. This method not only avoids the agglomeration problem that may be caused by the direct addition of nanoparticles, but also can accurately control the generation process and particle size distribution (10-100nm) of nanoparticles. At the same time, the addition of the precursor further optimizes the stability and fluidity of the suspension. The coupling of the two enables the nanoparticle loading to reach 40-70wt.%, and even approaches the maximum loading under optimal conditions.

[0024] 2. High sintering density: The present invention significantly improves the densification degree of parts through the unique advantages of nanoparticles. The density of traditional spray bonding technology is usually only 90%-95%, while the present invention utilizes the high activity of nickel-based nanoparticles in sintering, which can effectively fill the tiny pores between powder particles, promote grain growth and material fusion, and the final part density can reach more than 97%-98%, which is close to the level of traditional powder metallurgy. This high density is due to the low sintering temperature characteristics of nanoparticles, which makes the sintering process more efficient and reduces the pore defects caused by the decomposition of the binder. The parts thus obtained exhibit excellent mechanical properties (such as high strength and hardness) and physical properties (such as thermal conductivity and corrosion resistance), meeting the stringent requirements of aerospace, automotive and other fields.

[0025] 3. Low sintering shrinkage: The present invention utilizes the gradient density distribution of nanoparticles and green body powder to significantly reduce the high shrinkage of 15%-20% commonly seen in traditional spray bonding technology. The particle size of the nanoparticles (10-100nm) gives them a high specific surface area, which can more tightly fill the gaps between the powder particles after the ink solidifies, forming a green body with a higher initial density. During sintering, the nanoparticles promote material diffusion and pore closure, the volume change is greatly reduced, and the shrinkage can be controlled below 5%. This low shrinkage not only improves the dimensional accuracy of the parts and reduces the complexity of design compensation and post-processing, but also reduces the risk of deformation or cracking due to uneven shrinkage, making the technology more suitable for the manufacture of parts with complex geometries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure shows a flow chart of a method for preparing high-precision nickel-containing metal parts according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will describe in detail specific embodiments of the present invention with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0028] An embodiment of the present invention provides a method for preparing a high-load nickel-based nano-ink for jet bonding molding, comprising: dissolving a nickel precursor and nickel nanoparticles in a fast-evaporating solvent, adding a dispersant to control the rheological properties of the ink, and finally forming a uniform and stable ink through stirring and / or ultrasonic treatment.

[0029] In a specific embodiment, the nickel precursor is a nickel salt, and the nickel salt is any one or more of nickel formate, nickel acetate, nickel sulfate, nickel nitrate, nickel acetylacetonate, and nickel chloride; the particle size of the nickel nanoparticles is 1-300 nm.

[0030] In a specific embodiment, the fast evaporating solvent is any one or more of methanol, ethanol, and ethylene glycol.

[0031] In a specific embodiment, the amount of the nickel precursor added is 10-20 wt.%, and the amount of the nickel nanoparticles added is 40-60 wt.%.

[0032] In a specific embodiment, the dispersant is a combination of any one or more of surfactants, polymer dispersants, and small molecule organic compound dispersants.

[0033] In a specific embodiment, the surfactant dispersant is any one or a combination of two of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB); the polymer dispersant is any one or more of PVP, PAA, PEG, and CMC-Na; and the small molecule organic compound dispersant is selected from any one or more of citric acid, oleic acid, and tartaric acid.

[0034] In a specific embodiment, the dispersant used to control the rheological properties is one or a combination of the above-mentioned dispersants, and the addition amount is 3-10 wt.%. By adsorbing on the surface of the nanoparticles, the attraction between the particles is reduced, thereby improving the rheological behavior of the ink.

[0035] In a specific embodiment, the stirring is mechanical stirring, the rotation speed of the mechanical stirring is 500-1000 rpm, and the stirring time is 1-2 hours; the frequency of the ultrasonic treatment is 20-40 kHz, and the treatment time is 20-40 minutes.

[0036] An embodiment of the present invention provides a high-load nickel-based nano-ink for jet bonding molding. The ink is obtained using the above-mentioned preparation method, and the solid content of nickel nanoparticles in the ink is 40-70 wt.%.

[0037] like Figure 1 As shown, a method for preparing a high-precision nickel-containing metal part according to an embodiment of the present invention uses the above-mentioned high-load nickel-based nano-ink, specifically comprising:

[0038] S1, loading the high-load nickel-based nanoparticle ink into an ink cartridge of a high-precision inkjet printing device;

[0039] S2. Evenly spread the nickel-based powder on the printing platform to form a powder layer with a thickness of 50-100 μm;

[0040] S3, according to the preset 3D model, control the inkjet device to spray ink onto the powder layer along a predetermined path, and the ink quickly solidifies to bond the powder particles into shape;

[0041] S4, repeat steps S2 and S3, printing layer by layer until the entire blank is printed;

[0042] S5. Place the printed blank in a sintering furnace for sintering to obtain the final part.

[0043] In a specific embodiment, in step S2, the particle size of the nickel-based powder is 10-50 μm, and the thickness of each layer of nickel-based powder is 50-100 μm.

[0044] In a specific embodiment, in step S5, the sintering conditions are: protective atmosphere, temperature 900-1100° C., and holding time 1-3 hours.

[0045] The possible working mechanism of the present invention is as follows: During the sintering stage, the small-scale nanoparticles generated by the thermal decomposition and reduction of the nickel precursor rapidly initiate surface diffusion and form neck connections due to their high surface energy. They preferentially establish connections at the contact points or pores of the matrix powder particles, forming a large number of nanoscale interfaces with the matrix powder. These interfaces act as efficient material transfer channels, significantly promoting the diffusion process of larger-scale nanoparticles introduced into the suspension. The synergistic effect of grain boundary diffusion and the high-activity sintering effect of nanoparticles greatly improves the densification efficiency. At the same time, the interaction of multi-scale interfaces further promotes grain refinement, interface strengthening, and reduction of shrinkage.

[0046] Example 1

[0047] A high-solid content nickel nanoparticle fast-drying ink for jet bonding printing of 316L, the specific preparation process is as follows:

[0048] (1) 10 wt.% nickel formate, 40 wt.% nano-nickel particles (particle size 50-200 nm) and a methanol-ethanol mixture were mixed to form a base solution;

[0049] (2) 5 wt.% PVP (molecular weight approximately 40,000) was added to adjust the rheological properties of the ink, and a uniform and stable ink was obtained by ultrasonic dispersion (frequency 20-40 kHz, time 20-40 minutes) and mechanical stirring (speed 500-1000 rpm, time 1-2 hours), making it suitable for inkjet printing.

[0050] The process steps for 3D printing metal parts:

[0051] (1) loading a high-load nickel-based nanoparticle ink into an ink cartridge of a high-precision inkjet printing device;

[0052] (2) 316L powder (particle size 10-50 μm) was evenly spread on the printing platform to form a powder bed with a thickness of 50-100 μm;

[0053] (3) According to the preset 3D model, the inkjet device is controlled to spray ink layer by layer onto the powder bed along a predetermined path. The ink is quickly solidified and the powder particles are bonded into shape;

[0054] (4) Repeat steps 2 and 3 until the entire blank is printed;

[0055] (5) The printed blank is placed in a sintering furnace and sintered under optimized sintering conditions (e.g., temperature 1000-1450°C, nitrogen protective atmosphere, and holding time 1-3 hours) to obtain the final part. The measured density is 98.2%, and the sintering shrinkage is controlled at ~11.5%.

[0056] Example 2

[0057] A high-solid content nickel nanoparticle quick-drying ink for inkjet bonding printing of 18Ni300, the specific preparation process is as follows:

[0058] (1) 10 wt.% nickel formate, 40 wt.% nano-nickel particles (particle size 50-200 nm) and a methanol-ethanol mixture were mixed to form a base solution;

[0059] (2) 5 wt.% hexadecyltrimethylammonium bromide (CTAB) and 1 wt.% PEG (molecular weight 400) were added to adjust the rheological properties of the ink, and then a uniform and stable ink was obtained by ultrasonic dispersion (frequency 20-40 kHz, time 20-40 minutes) and mechanical stirring (speed 500-1000 rpm, time 1-2 hours), making it suitable for inkjet printing.

[0060] The process steps for 3D printing metal parts:

[0061] (1) loading a high-load nickel-based nanoparticle ink into an ink cartridge of a high-precision inkjet printing device;

[0062] (2) 18Ni300 powder (particle size 20-55 μm) is evenly spread on the printing platform to form a powder bed with a thickness of 40-100 μm;

[0063] (3) According to the preset 3D model, the inkjet device is controlled to spray ink layer by layer onto the powder bed along a predetermined path. The ink is quickly solidified and the powder particles are bonded into shape;

[0064] (4) Repeat steps 2 and 3 until the entire blank is printed;

[0065] (5) The printed blank is placed in a sintering furnace and sintered under optimized sintering conditions (e.g., temperature 1100-1500°C, argon protective atmosphere, and holding time 2-4 hours) to obtain the final part. The measured density is 97.8%, and the sintering shrinkage is controlled at ~10.9%.

[0066] The present invention regulates the stability of the nanoparticle suspension binder by introducing precursor dissolution to achieve maximum nanoparticle loading in the suspension, thereby overcoming the bottleneck of sintering and densification of the spray adhesive green body and achieving fully dense and low-shrinkage production of parts. The method of the present invention utilizes the high sintering activity of nanoparticles and the fact that they continue to fill the gaps in the green body after sintering, thereby increasing the density of the parts while reducing the shrinkage rate. The greater the loading amount of nanoparticles, the more obvious the effect of increasing density and reducing shrinkage rate. The method of the present invention has conducted systematic research and innovation on maximizing the loading amount of nanoparticles, and the use of this binder in the field of spray bonding molding technology meets the demand for high-performance and high-precision parts.

[0067] Although several embodiments of the present invention have been described herein, those skilled in the art will appreciate that modifications may be made to the embodiments herein without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as limitations on the scope of the present invention.

Claims

1. A method for preparing a high-load nickel-based nano-ink for jet bonding molding, characterized in that: The preparation method of the high-load nickel-based nano-ink comprises: dissolving a nickel precursor and nickel nanoparticles in a fast-evaporating solvent, adding a dispersant to control the rheological properties of the ink, and finally forming a uniform and stable ink through stirring and / or ultrasonic treatment.

2. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 1, wherein: The nickel precursor is a nickel salt, which is any one or more combinations of nickel formate, nickel acetate, nickel sulfate, nickel nitrate, nickel acetylacetonate, and nickel chloride; and the particle size of the nickel nanoparticles is 1-300 nm.

3. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 1, wherein: The fast evaporating solvent is any one or more combinations of methanol, ethanol, and ethylene glycol.

4. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 1, wherein: The amount of the nickel precursor added is 10-20 wt.%, and the amount of the nickel nanoparticles added is 40-60 wt.%.

5. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 1, wherein: The dispersant is any one or more combinations of surfactants, polymer dispersants, and small molecule organic compound dispersants, and the added amount of the dispersant is 3-10 wt.%.

6. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 5, wherein: The surfactant dispersant is any one or a combination of two of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB); the polymer dispersant is any one or more of PVP, PAA, PEG, and CMC-Na; and the small molecule organic compound dispersant is any one or more of citric acid, oleic acid, and tartaric acid.

7. The method for preparing a high-load nickel-based nano-ink for jet bonding molding according to claim 1, wherein: The stirring is mechanical stirring with a rotation speed of 500-1000 rpm and a stirring time of 1-2 hours; the frequency of ultrasonic treatment is 20-40 kHz and the treatment time is 20-40 minutes.

8. A high-load nickel-based nano-ink for jet bonding molding, characterized in that: The ink is obtained by the preparation method according to any one of claims 1 to 7, and the solid content of nickel nanoparticles in the ink is 40-70 wt.%.

9. A method for preparing high-precision nickel-containing metal parts, characterized in that: The method for preparing the metal part uses the high-load nickel-based nano-ink as claimed in claim 8, and specifically comprises: S1, loading the high-load nickel-based nanoparticle ink into an ink cartridge of a high-precision inkjet printing device; S2. Evenly spread the nickel-based powder on the printing platform to form a powder layer with a thickness of 50-100 μm; S3, according to the preset 3D model, control the inkjet device to spray ink onto the powder layer along a predetermined path, and the ink quickly solidifies to bond the powder particles into shape; S4, repeat steps S2 and S3, printing layer by layer until the entire blank is printed; S5. Place the printed blank in a sintering furnace for sintering to obtain the final part.

10. The method for preparing high-precision nickel-containing metal parts according to claim 9, characterized in that: In step S2, the particle size of the nickel-based powder is 10-50 μm, and the thickness of each layer of nickel-based powder is 50-100 μm; In step S5, the sintering conditions are: protective atmosphere, temperature 900-1100° C., and holding time 1-3 hours.

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