Metal powder surface treatment method for laser 3D printing

Abstract

The invention discloses a metal powder surface treatment method for laser 3D (three-dimensional) printing, which adopts a salt bath plating method, can realize accurate fine adjustment of metal micro-powder surface elements in the plating process, and generates alloy in situ in the subsequent laser 3D printing process, so that a plating layer and matrix metal are fully fused to form a uniform alloy structure. Compared with a traditional alloy smelting process, the salt bath plating method does not need multiple high-temperature melting and cooling processes, the technological process is greatly simplified, the test cost and time consumption are reduced, meanwhile, higher flexibility is achieved, and the proportion of alloy elements can be rapidly explored and optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy-saving and environmentally friendly alloy material production, and specifically relates to a metal powder surface treatment method for 3D printing. The present invention relates to a salt bath plating method for metal micropowder coating. During the plating process, a chemical bond is formed between the metal coating and the micropowder matrix. The coated metal micropowder sample prepared by the method has a complete and dense coating, which can be directly used for laser 3D printing, or the proportion of its coating components can be used to guide the process and formula improvement of traditional alloy smelting. Background Art

[0002] At present, there are various methods for preparing metal powders used in 3D printing, mainly atomization, reduction, deposition and electrolysis. Among them, the atomization method is to form spherical powder by rapid cooling after high-temperature melting, which is suitable for mass production, but it is difficult to control the particle size; the reduction method reduces metal powder by chemical reaction, which is suitable for preparing high-purity powder, but its process is relatively complicated; the deposition method uses physical or chemical means to deposit metal on the substrate, which can produce high-performance powder, but the output is limited; the electrolysis method can directly extract pure metal particles from metal ions, but its production efficiency is low.

[0003] Since different application scenarios have different requirements for material properties, such as strength, toughness, corrosion resistance, etc., the proportion of alloy elements must be repeatedly adjusted according to specific needs. This repeated debugging process usually relies on alloy smelting technology to continuously optimize the composition and performance of the powder. However, the traditional alloy smelting process requires multiple experimental cycles, and each experiment involves high-temperature melting, cooling and performance testing, which not only consumes a lot of materials and time, but also places high demands on equipment and energy consumption. At the same time, due to the complexity of the process route and the uncertainty of material testing, the cost investment and time consumption in the research process are very high, posing a challenge to the progress and economy of R&D.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a metal powder surface treatment method for laser 3D printing, which solves the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0007] A metal powder surface treatment method for laser 3D printing comprises the following steps:

[0008] Step S1, mixing NaCl and KCl in proportion to obtain salt, and mixing the obtained salt with metal powder and titanium powder in proportion to obtain a mixture after mixing evenly;

[0009] Step S2, placing the mixture in S1 into a calcining boat, evacuating the mixture in a sealed state, and introducing argon gas for protection, repeating the steps twice and placing the calcining boat in a tube furnace for sintering;

[0010] Step S3, cooling the sintered product to room temperature, taking it out, and sequentially performing deionized water immersion cleaning and alcohol rinsing to remove residual salt and impurities;

[0011] Step S4, drying the powder in S3, grinding it after drying, and sieving it with a sieve to obtain titanium-plated metal micropowder with uniform particle size.

[0012] Optionally, the mixing process in step S1 is salt, metal powder and titanium powder in order, and grinding is required after each addition of the material, and the grinding time is not less than 15 minutes.

[0013] Optionally, in step S1, the weight ratio of salt to metal powder is 2:1, and the weight ratio of metal powder to titanium powder is 9:1.

[0014] Optionally, in step S1, the amount of NaCl and KCl substances is 2:1, wherein the concentration of NaCl is 50 g / L, the purity is greater than 99.5%, and the concentration of KCl is 50 g / L.

[0015] Optionally, in step S1, the particle size of the titanium powder is 30-40 μm.

[0016] Optionally, in step S2, when the sintering boat is placed in a tube furnace for sintering, the coating temperature is increased to 900° C. at a heating rate of 10° C. / min, and the holding time is 30 min.

[0017] Optionally, the purity of the argon gas in step S2 is greater than 99.99%.

[0018] Optionally, in step S4, the drying temperature is 60° C., the drying time is 60-120 minutes, and the grinding time is 30 minutes.

[0019] Optionally, the sieve in step S4 is a 300-mesh sieve.

[0020] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below at the same time:

[0021] 1. The present invention adopts the salt bath plating method, which can achieve precise fine-tuning of the surface elements of metal micropowders during the plating process, and in-situ alloy generation during the subsequent laser 3D printing process, so that the coating and the base metal are fully integrated to form a uniform alloy structure. Compared with the traditional alloy smelting process, the salt bath plating method does not require multiple high-temperature melting and cooling processes, greatly simplifies the process flow, reduces the test cost and time consumption, and has higher flexibility, and can quickly explore and optimize the proportion of alloy elements.

[0022] 2. The metal powder prepared by the present invention can generate alloy in situ during the subsequent laser 3D printing process, that is, during the laser melting and cooling process, the coating layer and the base metal are fully fused to form a uniform alloy structure. This in-situ alloying feature avoids the cumbersome steps of adjusting the composition by multiple tests in the traditional alloy smelting process, making the exploration of alloy formulas more efficient and faster.

[0023] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] In the figure:

[0026] Figure 1 This is a schematic diagram of the SEM morphology of titanium metal powder plated in a salt bath;

[0027] Figure 2 The energy spectrum analysis spectra of the original micro powder and the titanium-coated metal micro powder;

[0028] Figure 3 This is the XRD pattern of titanium metal powder plated in salt bath;

[0029] Figure 4 It is a flow chart of titanium metal micro powder plated by salt bath;

[0030] Figure 5 The figure is a comparison of particle size distribution before and after treatment.

[0031] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings.

[0033] See also Figure 1-5As shown, in this embodiment, a metal powder surface treatment method for laser 3D printing is provided, comprising the following steps:

[0034] Step S1, mixing NaCl and KCl in proportion to obtain salt, and mixing the obtained salt with metal powder and titanium powder in proportion to obtain a mixture after mixing evenly;

[0035] Step S2, placing the mixture in S1 into a calcining boat, evacuating the mixture in a sealed state, and introducing argon gas for protection, repeating the steps twice and placing the calcining boat in a tube furnace for sintering;

[0036] Step S3, cooling the sintered product to room temperature, taking it out, and sequentially performing deionized water immersion cleaning and alcohol rinsing to remove residual salt and impurities;

[0037] Step S4, drying the powder in S3, grinding it after drying, and sieving it with a sieve to obtain titanium-plated metal micropowder with uniform particle size.

[0038] In this embodiment, the mixing process in step S1 is salt, metal powder and titanium powder in order, and grinding is required after each addition of the material, and the grinding time is not less than 15 minutes.

[0039] In this embodiment, in step S1, the weight ratio of the salt to the metal powder is 2:1, and the weight ratio of the metal powder to the titanium powder is 9:1.

[0040] In this embodiment, the amount of NaCl and KCl substances in step S1 is 2:1, wherein the concentration of NaCl is 50 g / L, the purity is greater than 99.5%, and the concentration of KCl is 50 g / L.

[0041] In this embodiment, the particle size of the titanium powder in step S1 is 30-40 μm.

[0042] In this embodiment, in step S2, when the sintering boat is placed in a tube furnace for sintering, the coating temperature is increased to 900° C. at a heating rate of 10° C. / min, and the holding time is 30 minutes.

[0043] In this embodiment, the purity of the argon gas in step S2 is greater than 99.99%.

[0044] In this embodiment, the drying temperature in step S4 is 60° C., the drying time is 60-120 minutes, and the grinding time is 30 minutes.

[0045] In this embodiment, the sieve in step S4 is a 300-mesh sieve.

[0046] Embodiment 1: A method for surface treatment of metal powder for laser 3D printing is provided, wherein the ratio of metal micropowder to titanium powder is 3:1, and the method comprises the following steps:

[0047] Mix NaCl and KCl in a ratio of 2:1 to obtain 6g of salt, and then mix it with 3.00g of metal powder and 1.00g of titanium powder in the same proportion. Grind for at least 15 minutes after each addition to ensure that the raw materials are fully mixed and form a uniform powder mixture.

[0048] The mixture obtained in step S1 is placed in a calcining boat and sealed in a vacuum environment. Argon gas is passed through the calcining boat for protection and the process is repeated twice to remove impurities and oxygen and prevent oxidation of the material. The calcining boat is placed in a tube furnace and heated to 900°C at a heating rate of 10°C / min and kept at this temperature for 30 minutes;

[0049] The sintered product is taken out after cooling to room temperature in the furnace and washed with deionized water and alcohol in turn. The washing process not only removes the residual salt;

[0050] The cleaned powder was placed in a drying oven at 100°C for 30 minutes to ensure that the powder was completely dry and free of residual moisture. The dried powder was then ground for 30 minutes and sieved using a 300-mesh screen to ensure uniform powder particle size.

[0051] Embodiment 2: A method for surface treatment of metal powder for laser 3D printing is provided, wherein the ratio of metal micropowder to titanium powder is 6:1, and the method comprises the following steps:

[0052] Mix NaCl and KCl in a ratio of 2:1 to obtain 6g of salt, and then mix it with 3.00g of metal powder and 0.5g of titanium powder in proportion. Grind for at least 15 minutes after each addition to ensure that the raw materials are fully mixed and form a uniform powder mixture.

[0053] The mixture obtained in step S1 is placed in a calcining boat and sealed in a vacuum environment. Argon gas is passed through the calcining boat for protection and the process is repeated twice to remove impurities and oxygen and prevent oxidation of the material. The calcining boat is placed in a tube furnace and heated to 900°C at a heating rate of 10°C / min and kept at this temperature for 30 minutes;

[0054] The sintered product is taken out after cooling to room temperature in the furnace and washed with deionized water and alcohol in turn. The washing process not only removes the residual salt;

[0055] The cleaned powder was placed in a drying oven at 100°C for 30 minutes to ensure that the powder was completely dry and free of residual moisture. The dried powder was then ground for 30 minutes and sieved using a 300-mesh screen to ensure uniform powder particle size.

[0056] Embodiment 3: A method for surface treatment of metal powder for laser 3D printing is provided, wherein the ratio of metal micropowder to titanium powder is 9:1, and the method comprises the following steps:

[0057] Mix NaCl and KCl in a ratio of 2:1 to obtain 6g of salt, and then mix it with 3.00g of metal powder and 0.33g of titanium powder in proportion. Grind for at least 15 minutes after each addition to ensure that the raw materials are fully mixed and form a uniform powder mixture;

[0058] The mixture obtained in step S1 is placed in a calcining boat and sealed in a vacuum environment. Argon gas is passed through the calcining boat for protection and the process is repeated twice to remove impurities and oxygen and prevent oxidation of the material. The calcining boat is placed in a tube furnace and heated to 900°C at a heating rate of 10°C / min and kept at this temperature for 30 minutes;

[0059] The sintered product is taken out after cooling to room temperature in the furnace and washed with deionized water and alcohol in turn. The washing process not only removes the residual salt;

[0060] The cleaned powder was placed in a drying oven at 100°C for 30 minutes to ensure that the powder was completely dry and free of residual moisture. The dried powder was then ground for 30 minutes and sieved using a 300-mesh screen to ensure uniform powder particle size.

[0061] Test Example 1: The powder was evenly spread on the conductive adhesive and mounted on the scanning electron microscope (SEM) sample stage. The powder surface morphology was observed using SEM. Finally, microscopic images of the untreated and titanium-plated powders were obtained to compare the uniformity of the surface coating and the morphological changes of the particles.

[0062] like Figure 1 As shown in the figure, the left picture shows the untreated metal powder, and the right picture shows the metal powder after titanium plating. The surface shows a highly dense and uniform coating, without obvious defective areas or missed plating. This complete coating not only enhances the antioxidant capacity of the powder particle surface and reduces the risk of oxidation of the powder in the air, but also significantly improves the mechanical bonding force, allowing the particles to better fuse with each other during the printing process. This uniformly covered coating ensures that during the laser scanning and melting process, each powder particle can be evenly distributed in the molten pool, reducing the possibility of structural unevenness and avoiding structural defects or cracks caused by weak or discontinuous coatings.

[0063] In addition, the fluidity and dispersibility of the titanium-plated powder have also been significantly improved, making it easier to transport in the powder supply system and spread more evenly on the print bed during printing. The improved fluidity also reduces blockages and powder waste during printing, and improves printing efficiency and stability. Ultimately, the addition of the titanium coating not only optimizes the physical and chemical properties of the powder, but also significantly improves the surface quality, structural strength and long-term corrosion resistance of the printed product.

[0064] Test Example 2: Use energy dispersive X-ray spectroscopy (EDS) equipment in conjunction with SEM to perform testing in high vacuum mode. The electron gun acceleration voltage is 15KV. Collect elemental spectra and surface morphology data of powder samples. Finally, obtain the weight percentage and atomic percentage of the elements and compare the changes of different elements before and after titanium coating.

[0065] Figure 2 The results of elemental composition analysis of metal micropowder samples using energy dispersive X-ray spectroscopy technology, where the upper figure is the energy spectrum of the original sample without titanium plating, and the lower figure is the energy spectrum after titanium plating. Comparing the two figures, it can be seen that the elemental composition of the sample changes before and after titanium plating, especially the appearance of titanium (Ti), and the proportion of other elements also changes.

[0066] Among them, the energy spectrum analysis of the original sample showed that the main elements were carbon (C), iron (Fe), nickel (Ni) and silicon (Si), among which iron had the highest weight percentage of 41.19%, nickel was 32.25%, and the atomic percentage was 41.3% iron and 12.75% carbon, indicating that the sample was mainly composed of iron-based and nickel-based alloys and lacked titanium. After titanium plating, the energy spectrum showed an obvious titanium (Ti) peak near 4.5keV, indicating that titanium was successfully plated on the surface of the metal powder. The weight proportion of titanium reached 9.24%, the atomic percentage was 12.48%, and the proportion of iron and nickel decreased, which proved the uniformity of the coating and the effectiveness of adhesion.

[0067] Test Example 3: Use X-ray diffractometer (XRD) to analyze the elemental composition. Set the scanning angle range to 20° to 90°, the step length to 0.02°, use Cu-Kα as the radiation source to perform full-angle scanning, record the characteristic peaks of each crystal phase, and finally confirm the components in the sample by comparing the characteristic peaks in the spectrum;

[0068] Figure 3 The X-ray diffraction (XRD) spectrum of metal powder after salt bath titanium plating is shown, from which the characteristic peaks of titanium alloy-related components in the sample can be observed. The peak marks at different angles in the spectrum correspond to different crystal structures, including Ni, Ni 2 Ti 4 O, Fe-Cr, TiO 2 These characteristic peaks indicate that the titanium plating process not only forms titanium oxides (such as TiO 2 ), and successfully produced titanium-nickel alloy (NiTi) with good mechanical properties and thermal stability.

[0069] The multiple peaks in the figure indicate that the material has undergone microstructural reorganization during the salt bath plating process, and a variety of alloy phases and oxide phases have been formed, further verifying the uniformity and effectiveness of the coating. In particular, the emergence of NiTi alloys indicates that the phase change ability and shape memory properties of such materials are enhanced, making them suitable for demanding 3D printing applications. In addition, the retention of the Fe-Cr peak indicates that the core structure of the iron-based material has not been destroyed, but has formed a complementary combination with titanium. The formation of this multiphase structure not only improves the strength and wear resistance of the material, but also enhances its stability and oxidation resistance in high temperature environments.

[0070] Test Example 4: When using a laser particle size analyzer for particle size distribution detection, first place the sample in a dispersion medium, then adjust the laser intensity and detection mode of the instrument to ensure that the measurement range covers all particle size segments, then obtain the percentage of powder in different particle size ranges and fit the particle size distribution curve to compare the particle size changes of the powder before and after treatment.

[0071] Figure 5 The comparison of the particle size distribution of metal micropowders before and after titanium plating is shown. The original powder particle size before treatment is mainly concentrated between 75μm and 100μm, and the distribution is relatively concentrated. After titanium plating, the powder particle size increases, and the main distribution range expands to 80μm to 150μm. This is because the titanium plating layer is evenly wrapped on the powder surface, which slightly increases the diameter of each powder.

[0072] From the distribution curve in the figure, it can be seen that the titanium-plated powder is not only more evenly distributed in each particle size range, but also the coating thickness of each particle size segment is consistent, and there is no uneven coating caused by particle size differences. This shows that whether it is small or large particle size metal powder, it can achieve good coating coverage during the titanium plating process, ensuring the surface consistency of the powder.

[0073] In addition, the uniform coating improves the fluidity and dispersibility of the powder, making it smoother and more stable during the laser 3D printing process. This uniform titanium coating not only enhances the bonding force between particles, but also effectively improves the mechanical properties and antioxidant capacity of the printed product.

[0074] Figure 5 The particle size distribution comparison chart before and after processing shows that the coating thickness in each area is uniform. The original metal micropowders of different particle sizes can be evenly coated with titanium powder.

[0075] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A metal powder surface treatment method for laser 3D printing, characterized in that: The following steps are involved: Step S1, mixing the salt obtained by mixing NaCl and KCl in proportion with metal micropowder and titanium powder in proportion, and obtaining a mixture after mixing them evenly; Step S2, placing the mixture in S1 into a calcining boat, evacuating the mixture in a sealed state, and introducing argon gas for protection, repeating the steps twice and placing the calcining boat in a tube furnace for sintering; Step S3, cooling the sintered product to room temperature, taking it out, and sequentially performing deionized water immersion cleaning and alcohol rinsing to remove residual salt and impurities; Step S4, drying the powder in S3, grinding it after drying, and sieving it with a sieve to obtain titanium-plated metal micropowder with uniform particle size.

2. A metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: The mixing process in step S1 is salt, metal powder and titanium powder in order, and grinding is required after each addition of the material, and the grinding time is not less than 15 minutes.

3. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: In step S1, the weight ratio of salt to metal powder is 2:1, and the weight ratio of metal powder to titanium powder is 9:

1.

4. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: In step S1, the amount of NaCl and KCl substances is 2:1, wherein the concentration of NaCl is 50 g / L, the purity is greater than 99.5%, and the concentration of KCl is 50 g / L.

5. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: In step S1, the particle size of the titanium powder is 30-40 μm.

6. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: In step S2, when the sintering boat is placed in a tube furnace for sintering, the coating temperature is increased to 900° C. at a heating rate of 10° C. / min, and the holding time is 30 min.

7. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: The purity of the argon gas in step S2 is greater than 99.99%.

8. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: In step S4, the drying temperature is 60° C., the drying time is 60-120 minutes, and the grinding time is 30 minutes.

9. The metal powder surface treatment method for laser 3D printing according to claim 1, characterized in that: The sieve in step S4 is a 300-mesh sieve.

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