Preparation method of iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material

Abstract

The present invention discloses a method for preparing an iron-based multicellular filled circular tube thin-walled structure composite aluminum-based material, which belongs to the technical field of metal composite material preparation. The method of the present invention is: placing the iron-based multicellular filled circular tube thin-walled structure obtained by additive manufacturing or extrusion casting in a suitable graphite mold, adding an appropriate amount of aluminum-based metal powder therein, using an oscillator to evenly fill the powder into the spatial structure, and after pre-pressing, placing it in a spark plasma sintering furnace for sintering, cooling to room temperature, and removing the mold to obtain the iron-based multicellular filled circular tube thin-walled structure composite aluminum-based material. The method of the present invention for preparing the iron-based multicellular filled circular tube thin-walled structure composite aluminum-based material can effectively avoid the problem that the aluminum liquid cannot infiltrate and fill the iron-based small-sized spatial structure due to high surface tension and the oxide layer is easily generated between the Al / Fe alloy. The interface of the obtained composite material is completely fused without obvious boundaries. The method is simple, efficient, and has low energy consumption.

Description

Technical Field

[0001] The invention discloses a method for preparing an iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material, belonging to the technical field of metal composite material preparation. Background Art

[0002] Aluminum-iron composites have attracted widespread attention due to their excellent properties of both aluminum and iron-based materials, including high electrical and thermal conductivity, heat resistance, wear resistance, and corrosion resistance. They have broad application prospects, especially in the fields of aerospace, automobiles, transportation, and mining machinery, where lightweighting of parts, improving part performance, and reducing energy consumption are crucial. Traditionally, aluminum-iron composites are prepared primarily through casting, but this process still presents numerous challenges. These challenges include the inability to form an effective metallurgical bond, the difficulty in forming cracks between the Al / Fe bond due to differences in thermal expansion coefficient and solidification shrinkage, the tendency for a thick oxide layer to form at the interface of the aluminum-iron composite, and the formation of a hard and brittle Al-Fe interphase, which in turn leads to low interfacial bonding strength and poor mechanical properties. Furthermore, due to the properties of aluminum and iron, the casting process is only suitable for composite preparation of simple components, such as aluminum-clad iron conductors. Furthermore, the casting process often requires subsequent heat treatment to enhance the bonding between the aluminum and iron, resulting in a lengthy process that significantly limits the preparation and application of aluminum-iron composites.

[0003] 3D-structured reinforcements have the characteristics of complete structure and continuous spatial distribution, superior and controllable performance, favorable bonding with the matrix, and strong designability. In recent years, they have gained widespread attention in the field of composite materials. The aperture size of the filling cells of the iron-based multi-cellular filled circular tube thin-walled structure is usually small. Conventional casting methods cannot complete the filling and compounding of aluminum-based materials. After aluminum and its alloys are melted, due to surface tension, it is difficult to fill them into small spaces without external forces. The die-casting preparation process requires the design of a relatively complex proprietary mold and requires protective gas protection. Otherwise, a severe black oxide layer will be generated at the aluminum-iron interface. The obtained aluminum-iron composite material is mechanically bonded, and the aluminum and iron do not form an integral structure. The mechanical properties are poor, and the aluminum and iron are easy to separate. In addition, the presence of the loose oxide layer hinders heat conduction, reducing the thermal conductivity of the composite material. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the existing iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based materials, and to provide a preparation method of iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based materials. This method can quickly and efficiently prepare aluminum-based composite iron-based multi-cellular filled circular tube thin-walled structure materials with fine and uniform grains, which can be used as low-density and high-strength materials in the fields of aerospace, rail transportation, automobile industry, construction, etc.

[0005] The technical solution of the present invention is: a method for preparing an iron-based multi-cell filled circular tube thin-walled structure filled with an aluminum-based material, the method comprising the following steps:

[0006] (1) Calculate the mass of metal powder required based on the volume of the filled pores and the density of the aluminum-based solid material, and weigh the metal powder at 1.3 to 1.75 times the calculated amount.

[0007] (2) The iron-based multi-cell filled circular tube thin-wall structure is placed in a graphite mold, aluminum-based metal powder is added to the mold, vibrated by an oscillator, and placed in a spark plasma sintering furnace after pre-pressing.

[0008] (3) Axial pressure is applied by punches at both ends of the graphite mold, and the sintering furnace is evacuated and sintered. The sintering is heated and sintered in a two-stage heating method, kept warm, and then cooled to room temperature with the furnace. The mold is removed to obtain an iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material.

[0009] Furthermore, the aluminum-based metal powder may be pure aluminum spherical powder, aluminum alloy spherical powder, or aluminum-based spherical metal powder added with a certain proportion of other metal or non-metal powder.

[0010] Furthermore, the particle size of the spherical metal material powder is 1-120 μm.

[0011] Furthermore, in step (2), the pre-pressing pressure is 5~100MPa; the graphite mold is selected according to the size of the thin-walled structure, and the mass of the metal powder to be filled is roughly calculated according to the volume of the pores to be filled in the thin-walled structure and the solid density of the filling material. The mass of the spherical metal powder loaded each time is 1.3~1.75 times the calculated mass.

[0012] Furthermore, the spherical powder filled in step (2) overflows to the outside of the spatial structure. Through vibration and pre-compression by an oscillator, the spherical powder can be more fully filled into the entire iron-based multi-cellular filled circular tube thin-wall structure.

[0013] Furthermore, in step (3), the graphite die punch applies an axial pressure of 5 to 40 MPa, and the vacuum degree in the sintering furnace is evacuated to below 10 Pa before sintering. The temperature is first raised to 500 ° C at a rate of 50 to 120 ° C / min, and then raised to the target sintering temperature at a rate of 10 to 50 ° C / min; the sintering temperature is maintained for 0 to 20 min, and then cooled to room temperature with the furnace, and the mold is removed to obtain an iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material. The present invention uses a graphite die punch for pressurization to ensure that sufficient powder is filled into the spatial structure during the sintering process to improve the density of the composite material, and to ensure that the spatial structure is not compressed and deformed during the pressurized sintering process.

[0014] The method described in the present invention prepares an iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material; the material has both the good mechanical properties of iron-based honeycomb structure materials and the lightweight, high thermal and electrical conductivity properties of aluminum-based materials; and the addition of powders of different components expands the application field and potential of the composite material.

[0015] In the second aspect of the present invention, the iron-based multicellular filled circular tube thin-walled structure composite aluminum-based material can meet the requirements of lightweight, high-load-bearing capacity, and high heat dissipation requirements of mechanical parts; through the composite of the iron-based multicellular filled circular tube thin-walled structure and the aluminum-based material and the addition of a small amount of lubricating / friction components, the composite material of the present invention can be used as a friction material for vehicles.

[0016] The present invention adopts spherical metal powder with good fluidity to fill the iron-based multi-cellular filled circular tube thin-wall structure. Vacuum sintering effectively prevents the formation of oxide layer, and the resulting sintered material has uniform grains, high density and good mechanical properties. In addition to the Joule heat of hot pressing sintering and the plastic deformation caused by pressurization to promote the sintering process, the sintering process also generates a DC pulse voltage between the powder particles and effectively utilizes the surface activation and self-heating generated by the discharge between the powder particles. Therefore, the sintering time is short, the energy consumption is low, and it is more green and environmentally friendly.

[0017] Compared with the prior art, the advantages of the present invention are:

[0018] (1) There is no need to design and customize complex casting molds, and the surface tension of aluminum liquid is overcome, which makes it impossible to fill into a small space. The samples prepared by the present invention have good metallurgical interface bonding between Al / Fe.

[0019] (2) Spherical aluminum-based powder has good fluidity and can fully fill the iron-based multi-cellular filled tube thin-wall structure. Compared with the traditional casting process, it can reduce material loss and improve the utilization rate of the filling matrix material.

[0020] (3) The sintering speed is fast, the time consumption is short, and the energy consumption is low. Vacuum sintering effectively prevents the formation of the oxide layer. The sintered body obtained by sintering has uniform grains, high density and good mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 These are longitudinal and transverse cross-sectional views of the placement of the iron-based multi-cellular filled circular tube thin-wall structure used in the present invention in a graphite mold.

[0022] Figure 2 This is a macroscopic morphology of the iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material after sintering in an embodiment of the present invention.

[0023] Figure 3This is a metallographic diagram of the composite aluminum-based material with an iron-based multi-cellular filled circular tube thin-wall structure after sintering in an embodiment of the present invention.

[0024] Figure 4 This is the EDS spectrum of the iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material in an embodiment of the present invention. Implementation Method

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0026] The following examples use a graphite mold with an inner diameter of 1 cm, and the iron-based multi-cell filled circular tube thin-walled structure inside the mold is placed as follows: Figure 1 shown. Example

[0027] The process steps of the method for preparing 316L multi-cell filled circular tube thin-walled composite aluminum-based material by pulsed discharge plasma sintering in this embodiment are as follows:

[0028] (1) Design size of preform: the outer diameter of the filled circular tube is 10 mm (the actual size is slightly smaller than the design size), the side length of the filled cell is 3 mm, the wall thickness is 0.4 mm, and the height is 15 mm; the 316L multi-cell filled circular tube thin-walled structure preform is made according to Figure 1 The graphite mold is placed as shown, and 1.5 times the mass of the space to be filled (about 3.38 g) is added to the graphite mold (density is 2.7 g / cm 3 75μm spherical aluminum powder (Al≥99.9%).

[0029] (2) An oscillator is used to vibrate the added aluminum powder so that it is evenly filled into the interior of the 316L multi-cell filled tube thin-wall structure. After assembling the graphite mold, a press is used to pre-press the powder under an axial pressure of 10 MPa, and then the graphite mold containing the preform and aluminum powder is placed in a sintering furnace.

[0030] (3) The graphite die punch was axially pressurized to 40 MPa, and the sintering furnace was evacuated to below 10 Pa to start sintering. The sintering program was set as follows: heating to 500 °C at 100 °C / min, then heating to 580 °C at 40 °C / min, and keeping warm for 10 min. After sintering, the furnace was cooled to room temperature, and the composite material was obtained after demolding. Figure 2 .

[0031] The density of aluminum filled in the 316L multi-cellular thin-walled circular tube structure before sintering and the composite aluminum-based material of the thin-walled structure after sintering were calculated using the Archimedes principle, and the filling density was 99.3%. Figure 3The metallographic images show that there is no obvious oxide layer at the Al-Fe interface, and the 316L preform and pure aluminum interface are well bonded. A line scan analysis of the aluminum and 316L elemental composition was performed along the direction perpendicular to the interface at the aluminum-iron bonding position of the composite material. The results are as follows: Figure 4 As shown in the figure, the EDS energy spectrum shows that the diffusion of Al element into the iron matrix is more obvious, and the diffusion of Mo and Ni elements in 316L into the Al matrix is more significant, followed by Fe and Cr. The transition region is Al-Fe intermetallic compound. Therefore, the bonding mode of Al / Fe interface of the obtained 316L multi-cell filled circular tube thin-walled structure composite aluminum-based material is metallurgical bonding. Example

[0032] The process steps of the method for preparing 18Ni300 multi-cell filled circular tube thin-walled structure composite aluminum-based material by pulsed discharge plasma sintering in this embodiment are as follows:

[0033] (1) Design size of preform: the outer diameter of the filled circular tube is 10 mm (the actual size is slightly smaller than the design size), the side length of the filled cell is 2 mm, the wall thickness is 0.1 mm, and the height is 15 mm; the 18Ni300 multi-cell filled circular tube thin-walled structure preform is made according to Figure 1 The graphite mold is placed as shown, and 1.7 times the mass of the space to be filled, about 6.76 g (density of pure aluminum 2.7 g / cm 3 Spherical aluminum powder with a size of 15~53μm (Al≥99.9%).

[0034] (2) An oscillator is used to vibrate the added aluminum powder so that it is evenly filled into the interior of the 316L multi-cell filled circular tube thin-wall structure. After assembling the graphite mold, a press is used to pre-press the powder under an axial pressure of 5 MPa, and then the graphite mold containing the preform and aluminum powder is placed in a sintering furnace.

[0035] (3) The graphite die punch was axially pressurized to 20 MPa, and the sintering furnace was evacuated to below 10 Pa to start sintering. The sintering program was set as follows: heating to 500 °C at 50 °C / min, and then heating to 590 °C at 40 °C / min without insulation. After sintering, the material was cooled to room temperature in the furnace and the composite material was obtained after demolding.

[0036] The density of aluminum filled in the 18Ni300 multi-cellular thin-walled circular tube structure before sintering and the thin-walled composite aluminum-based material after sintering in this embodiment was calculated using the Archimedes principle, and the filling density was 97.3%; its metallographic image showed that there was no obvious oxide layer generated at the Al-Fe bonding interface, and the 18Ni300 preform and the pure aluminum interface were well bonded; a line scanning analysis of the aluminum and 18Ni300 elemental composition of the aluminum-iron bonding position of the composite material was performed along the direction perpendicular to the interface, and the transition region was an Al-Fe intermetallic compound. Therefore, the bonding mode of the Al / Fe interface of the obtained 18Ni300 multi-cellular thin-walled circular tube composite aluminum-based material is metallurgical bonding. Example

[0037] The process steps of the method for preparing 316L multi-cell filled circular tube thin-walled composite aluminum-based material by die casting in this embodiment are as follows:

[0038] (1) The 316L multi-cell filled round tube thin-walled structure is fixed in the casting mold, and the mold is placed on the die-casting machine platform and heated to 100°C and kept warm.

[0039] (2) A medium frequency induction furnace was used to melt the A356 aluminum alloy ingot into liquid form. The temperature during casting was controlled at 700 °C. Immediately after casting, the die-casting machine ram was pressed down to press the aluminum cast in the mold into the 316L multi-cell filled round tube thin-wall structure. The ram pressure was 20 tons and the ram pressing time was 15 minutes.

[0040] (3) Remove the mold and the die-cast sample from the die-casting machine, smash the mold with a hammer, and take out the die-cast sample.

[0041] (4) The die-cast sample is cut out from the aluminum matrix by wire cutting to obtain the composite material.

[0042] Comparative analysis shows that the aluminum-iron interface of the 18Ni300 multi-cell filled circular tube thin-walled composite aluminum-based material prepared by pulsed discharge plasma sintering is relatively tight, and due to the high SPS sintering speed, the preparation of the composite material takes only about 6 minutes at the fastest, so the aluminum-based grains of the obtained composite material are small and uniform. However, the aluminum alloy phase of the 316L multi-cell filled circular tube thin-walled composite aluminum-based material prepared by die-casting has coarser and more uneven grains, and a clear black oxide layer at the aluminum-iron interface. Due to the different filling structures, the size distribution of the aluminum alloy grains filled therein is uneven, and the entire preparation process of the die-cast composite material is long and cumbersome.

Claims

1. A method for preparing an iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material, characterized in that: The filling matrix material is an aluminum-based spherical metal powder material, which specifically includes the following steps: (1) Calculate the mass of the required metal powder based on the volume of the filled pores and the density of the aluminum-based solid material, and weigh the metal powder at 1.3 to 1.75 times the calculated amount; (2) The iron-based multi-cell filled circular tube thin-wall structure is placed in a graphite mold, aluminum-based spherical metal powder is added to the mold, vibrated by an oscillator, pre-pressed and placed in a spark plasma sintering furnace; (3) Axial pressure is applied by punches at both ends of the graphite mold, and the sintering furnace is vacuumed and sintered. The sintering is heated and sintered in a two-stage heating method, kept warm, and then cooled to room temperature with the furnace. The mold is removed to obtain an iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material; Step (3) The graphite die punch applies an axial pressure of 5 to 40 MPa, and the vacuum degree in the sintering furnace is evacuated to below 10 Pa before sintering. The temperature is first raised to 500 °C at a rate of 50 to 120 °C / min, and then raised to the target sintering temperature at a rate of 10 to 50 °C / min; the sintering temperature is maintained for 0 to 20 min, and then cooled to room temperature with the furnace, and the die is removed to obtain an iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material; The aluminum-based spherical metal powder material filled in step (2) overflows to the outside of the spatial structure, and is vibrated and pre-pressed by an oscillator to fully fill the aluminum-based spherical metal powder into the entire iron-based multi-cellular filled circular tube thin-wall structure.

2. The method for preparing the iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material according to claim 1, characterized in that: The aluminum-based spherical metal powder is pure aluminum spherical metal powder or aluminum alloy spherical metal powder, or the aluminum-based spherical metal powder is a mixed aluminum-based spherical metal powder added with other metal or non-metal powders.

3. The method for preparing the iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material according to claim 2, characterized in that: The aluminum-based spherical metal powder has a particle size of 1 to 120 μm.

4. The method for preparing the iron-based multi-cell filled circular tube thin-walled structure composite aluminum-based material according to claim 2, characterized in that: In step (2), the pre-pressing pressure is 5-100 MPa.

5. An iron-based multi-cellular filled circular tube thin-walled structure composite aluminum-based material obtained by the preparation method according to any one of claims 1 to 4.

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