A method of post-processing a composite addition

Abstract

The application discloses a composite additive post-processing method, comprising the following steps: dispersing metal powder A in a hot-melt organic material to obtain a paste; drying the paste to obtain a powder; using the powder as raw material and adopting a three-dimensional printing method to build an additive with a cavity, the volume of the cavity accounting for 70-90% of the volume of the additive; performing a debinding treatment on the additive, and then performing a treatment on the additive by an electric arc cladding technology to form an outer coating, the material of the coating being C; filling a semi-solid slurry B into the cavity, and obtaining the composite additive after the additive is cooled.

Description

Technical Field

[0001] This invention relates to the field of semi-solid alloy materials technology, specifically a post-processing method for composite additive manufacturing. Background Technology

[0002] Additive manufacturing technology, also known as 3D printing technology, can be used to manufacture personalized and miniaturized parts, reducing material consumption and improving production efficiency. Additive printing technology has achieved great success in plastic additive manufacturing; however, its application in metal additive manufacturing faces significant challenges. Metal additive manufacturing methods include selective arc cladding, electron beam melting, and laser powder deposition, but these methods produce metal additives with numerous physical defects such as cracks, and they also suffer from significant disadvantages in terms of cost and efficiency.

[0003] GB2519134A discloses a method for manufacturing three-dimensional articles, including forming an object with cavities using 3D printing, and then filling the cavities with a filler to increase the object's rigidity, thereby forming a three-dimensional article. This method uses thermosetting materials as the outer shell material and high-strength solid materials or thermosetting resins as filler materials to improve the rigidity of the three-dimensional object. Applying this technology to the field of metal additive manufacturing can help reduce costs and improve efficiency. However, the outer shell material and inner layer material are formed in two stages, making it difficult to form a good interfacial bond between the inner and outer layers. Furthermore, it is difficult to treat the inner surface of the outer shell material to improve the interfacial bond. Especially when the coefficients of thermal expansion of the outer shell material and the inner layer material are large, heat treatment can easily lead to a further reduction in the interfacial bond, resulting in the mechanical properties of the produced three-dimensional article failing to meet requirements.

[0004] Therefore, it is necessary to provide a post-processing method for composite additive manufacturing. Summary of the Invention

[0005] To address the issue of poor composite effects in composite additive manufacturing, it is necessary to provide a post-processing method for composite additive manufacturing.

[0006] A post-processing method for composite additive manufacturing includes the following steps:

[0007] Metal powder A is dispersed in a hot-melt organic material to obtain a paste;

[0008] The paste is dried to obtain a powder;

[0009] Using the powder as raw material, an additive material with cavities is constructed by 3D printing, wherein the volume of the cavities accounts for 70-90% of the volume of the additive material.

[0010] The additive is degreased and then processed by arc cladding technology to form an outer coating, wherein the material of the coating is C;

[0011] The cavity is filled with semi-solid slurry B. After the additive material cools, the composite additive material is obtained. The coefficient of thermal expansion of A is greater than that of B and C.

[0012] This solution utilizes additive manufacturing technology to create a cavity-containing shell. An arc cladding process is then used to post-process the outer surface of the additive material to form a coating. Under the action of arc cladding, the residual hot-melt organic material in the shell further decomposes, creating pores. Meanwhile, the coating material C melts under the action of arc cladding, filling the pores and preventing the shell from shrinking after cooling. Simultaneously, under the action of arc cladding, the metal particles A of the shell fuse with material C, forming a shell with higher mechanical strength. Therefore, even with a large cavity volume ratio, the shell will not deform during the pouring process. During pouring, the liquid phase component in the semi-solid metal melt B can diffuse into the pores of the shell, further improving the interfacial bonding between the shell and the inner layer material. Furthermore, the inner layer material, the composite layer of the inner layer material and the shell, and the composite layer formed by the shell and material C avoid sudden changes in the coefficient of thermal expansion, thus preventing cracking during subsequent heat treatment or high-temperature environments, which would otherwise reduce the mechanical properties of the composite additive material.

[0013] Furthermore, the volume of the cavity accounts for 80-90% of the volume of the additive manufacturing process. The post-processing method of composite additive manufacturing can give the shell material higher mechanical properties, thereby allowing for cavities with a higher volume ratio, reducing the workload of 3D printing steps, lowering costs, and improving production efficiency.

[0014] Furthermore, the solid fraction of the semi-solid slurry B is 50-60%. Semi-solid slurries with this solid fraction exhibit better fluidity and are less prone to shrinkage cavities after cooling, resulting in composite additives with better mechanical properties.

[0015] Furthermore, the coefficient of thermal expansion of A is 1.05-1.1 times that of B, and the coefficient of thermal expansion of C is 0.95-1.05 times that of B. Thus, the three layers of material—the inner layer (B), the composite layer of the inner layer and the outer shell (A+B), and the composite layer of the outer shell and material C (A+C)—can create a gradient increase in the coefficient of thermal expansion, further preventing cracking during heat treatment.

[0016] Furthermore, the coefficient of thermal expansion of A is 22 × 10⁻⁶. -6 / ℃-23.6×10 -6 / ℃, the coefficient of thermal expansion of B is 20×10⁻⁶. -6 / ℃-22.5×10 -6 / ℃, the coefficient of thermal expansion of C is 19×10⁻⁶. -6 / ℃-23.6×10 -6 / ℃. In this application, the coefficient of thermal expansion refers to the data for the material at 20-100℃.

[0017] Furthermore, material A is 6013, material B is A356.2, and material C is 4032.

[0018] Furthermore, the parameters of the arc cladding technology are: current 80-120A, voltage 10-12V, and argon atmosphere.

[0019] Furthermore, ultrasonic treatment is applied to the additive during post-processing. By applying ultrasonic treatment to the additive, the diffusion of material C in the pores of the shell is promoted, thereby forming a better bonding effect.

[0020] Furthermore, the parameters of the ultrasonic action are 1000-2000W and 10-35kHz.

[0021] Furthermore, the catalyst for the degreasing treatment is HNO3. Attached Figure Description

[0022] Figure 1 The figures show the tensile stress test results of Example 1 and Comparative Examples 1-3. Detailed Implementation

[0023] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0027] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0028] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0029] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0030] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument.

[0031] The term "particle" as used in this application, or a substance with a defined particle size distribution, is not necessarily spherical in shape; it may be irregular and can be either primary or secondary particles. The particle size of irregular particles is calculated as the average of their maximum and minimum diameters.

[0032] The following is the composition of the metal powder in A356.2 (coefficient of thermal expansion 21.4 × 10⁻⁶). -6 The composition ( / ℃) is as follows: by weight fraction, silicon 6.5%, magnesium 0.4%, titanium 0.1%, iron 0.08%, copper 0.05%, manganese 0.02%, zinc 0.04%, with the balance being aluminum.

[0033] The following is the composition of 6061 aluminum alloy (coefficient of thermal expansion 23.4 × 10⁻⁶). -6The composition ( / ℃) is as follows: by weight fraction, magnesium 1%, silicon 0.6%, copper 0.25%, titanium 0.15%, zinc 0.25%, with the balance being aluminum.

[0034] The following is the composition of 4032 aluminum alloy (coefficient of thermal expansion 19.4 × 10⁻⁶). -6 The composition ( / ℃) is as follows: by weight fraction, silicon 12.5%, copper 1%, magnesium 1.3%, zinc 0.2%, chromium 0.05%, nickel 1%, with the balance being aluminum.

[0035] The following is the composition of 6101 aluminum alloy (coefficient of thermal expansion is 23 × 10⁻⁶). -6 The composition ( / ℃) is: silicon 0.5%, iron 0.3%, copper 0.1%, magnesium 0.5%, zinc 0.08%, and the balance aluminum.

[0036] Example 1: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0037] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0038] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0039] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0040] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0041] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is A356.2.

[0042] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0043] Example 2: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0044] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0045] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0046] Using powder as raw material, a 3D printer prints parts with cavities of a preset shape, with the cavity volume accounting for 70% of the part volume;

[0047] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0048] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is A356.2.

[0049] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 60% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0050] Example 3: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0051] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 75% of the weight and the average particle size of the metal powder was 20μm.

[0052] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0053] Using powder as raw material, a 3D printer prints a pre-designed part with a cavity, the cavity volume accounting for 80% of the part volume;

[0054] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0055] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is A356.2.

[0056] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0057] Example 4: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0058] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0059] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0060] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0061] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0062] The surface of the part is post-treated by electric arc cladding technology to form an outer coating with a thickness of 1 mm and a coating material of 4032.

[0063] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0064] Example 5: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0065] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0066] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0067] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0068] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0069] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is A356.2. At the same time as the post-treatment, ultrasonic treatment is applied to the part with ultrasonic parameters of 2000W and 10kHz.

[0070] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0071] Example 6: This example provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0072] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0073] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0074] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0075] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0076] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 2 mm and the coating material is A356.2. At the same time as the post-treatment, the part is subjected to ultrasonic treatment with the parameters of 1000W and 35kHz.

[0077] A semi-solid 6101 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0078] Comparative Example 1: This embodiment provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0079] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0080] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0081] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0082] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0083] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared and injected into the cavity of the part. During the casting process, the additive manufacturing process underwent significant deformation.

[0084] Comparative Example 2: This embodiment provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0085] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0086] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0087] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0088] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0089] The surface of the part is post-treated by electric arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is 6013.

[0090] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 50% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0091] Comparative Example 3: This embodiment provides a post-processing method for composite additive manufacturing, comprising the following steps:

[0092] After drying 6013 aluminum alloy particles, they were mixed with PLA and kneaded for 2 hours to obtain a paste. The metal particles accounted for 85% of the weight and the average particle size of the metal powder was 20μm.

[0093] After the paste is cooled, the dried cake is crushed to obtain powder, which consists of metal particles with PLA on the surface.

[0094] Using powder as raw material, a 3D printer prints parts with pre-defined shapes and cavities, with the cavity volume accounting for 90% of the part volume;

[0095] The parts with cavities are placed in a degreasing furnace for degreasing, and catalytic gas HNO3 is introduced and heated at 110°C for 3 hours to complete the degreasing process.

[0096] The surface of the part is post-treated by arc cladding technology to form an outer coating with a thickness of 1 mm and the coating material is A356.2.

[0097] A semi-solid A356.2 aluminum alloy melt with a solid fraction of 20% was prepared, and the melt was injected into the cavity of the post-processed part. After cooling, the composite additive was obtained.

[0098] Mechanical property testing

[0099] The mechanical properties of the additives in each example and comparative example at room temperature were tested in accordance with the standard GB / T 228.1-2010 "Metallic materials - Tensile testing - Part 1: Test method at room temperature".

[0100] Table 1. Additive yield strength and tensile strength of each embodiment and comparative example.

[0101]

[0102] As shown in Table 1, the mechanical properties of Examples 1-6 are significantly higher than those of Comparative Examples 2-3. Furthermore, the outer shell of Comparative Example 1 deformed during casting. This is because the present invention uses additive manufacturing technology to form an outer shell with cavities, and then uses arc cladding technology to post-process the outer surface of the additive material to form a coating. Under the action of arc cladding, the residual hot-melt organic material in the outer shell further decomposes to generate pores, while the coating material C forms a melt under the action of arc cladding, thus filling the pores to prevent the outer shell from shrinking after cooling. Simultaneously, under the action of arc cladding, the metal particles in the outer shell... Material A fuses with material C to form a shell with higher mechanical strength. Therefore, even with a large cavity volume, the shell will not deform during casting. During casting, the liquid phase component in the semi-solid molten metal B can diffuse into the pores of the shell, further improving the interfacial bonding between the shell and the inner layer material. Furthermore, the composite layer formed by the inner layer material, the inner layer material and the shell, and the shell and material C avoids sudden changes in the coefficient of thermal expansion, thus preventing cracking during subsequent heat treatment or high-temperature environments, which would otherwise reduce the mechanical properties of the composite additive manufacturing. Comparative Example 1, without post-treatment, has a shell with low mechanical strength after degreasing, and a large cavity volume, making it prone to deformation during casting and failing to meet precision manufacturing requirements. Comparative Example 2 uses materials A and C with the same coefficient of thermal expansion, but the difference in coefficients of thermal expansion between the inner and outer layers is significant, making them prone to fracture after heat treatment, resulting in reduced mechanical properties. Comparative Example 3 used a semi-solid slurry B with a low solid content. During the casting process, the liquid components were prone to seeping out from the pores of the shell, and shrinkage cavities were easily generated during the cooling process, resulting in a decrease in its mechanical properties.

[0103] Example 4 uses 4032 material, whose coefficient of thermal expansion differs significantly from that of materials A and B. This better balances the difference in thermal expansion coefficients between materials A and B. The three layers—inner material (B), the composite layer of inner material and outer shell (A+B), and the composite layer of outer shell and material C (A+C)—create a gradient increase in the coefficient of thermal expansion, further preventing cracking during heat treatment. Example 5 uses ultrasonic treatment, which promotes the diffusion of material C within the pores of material A, resulting in better bonding.

[0104] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A post-processing method for composite additive manufacturing, characterized in that, Includes the following steps: Metal powder A is dispersed in a hot-melt organic material to obtain a paste; The paste is dried to obtain a powder; Using the powder as raw material, an additive material with cavities is constructed by 3D printing, wherein the volume of the cavities accounts for 70-90% of the volume of the additive material. The additive is degreased, and then post-processed by arc cladding technology to form an outer coating, wherein the material of the outer coating is C; The cavity is filled with a semi-solid slurry B, the solid fraction of which is 50-60%. After the additive process cools, the composite additive is obtained. The coefficient of thermal expansion of A is greater than that of B and C. The coefficient of thermal expansion of A is 1.05-1.1 times that of B, and the coefficient of thermal expansion of C is 0.95-1.05 times that of B.

2. The post-processing method according to claim 1, characterized in that, The volume of the cavity accounts for 80-90% of the volume of the additive manufacturing process.

3. The post-processing method according to claim 1, characterized in that, The coefficient of thermal expansion of A is 22 × 10⁻⁶. -6 / ℃-23.4×10 -6 / ℃, the coefficient of thermal expansion of B is 20×10⁻⁶. -6 / ℃-22.5×10 -6 / ℃, the coefficient of thermal expansion of C is 19×10⁻⁶. -6 / ℃-23.4×10 -6 / ℃.

4. The post-processing method according to claim 1, characterized in that, The parameters of the arc cladding technology are: current 80-120A, voltage 10-12V, and argon atmosphere.

5. The post-processing method according to claim 1, characterized in that, Ultrasonic effects are applied to the additive material during post-processing.

6. The post-processing method according to claim 5, characterized in that, The parameters of the ultrasound action are 1000-2000W and 10-35kHz.

7. The post-processing method according to claim 1, characterized in that, The catalyst for the degreasing treatment is HNO3.

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