Preparation method of porous aluminum alloy, porous aluminum alloy and preparation system

Abstract

The embodiment of the invention relates to a preparation method of a porous aluminum alloy, the porous aluminum alloy and a preparation system.The preparation method comprises the steps that a CMT welding method is utilized, aluminum alloy additive preparation is carried out on the surface of a base plate based on an aluminum alloy welding wire, water is synchronously applied to the bottom of a welding bead, and ultrasonic treatment of the aluminum alloy additive is synchronously carried out; water at the bottom of molten drops forms water vapor, the aluminum melt reacts with the water vapor to obtain hydrogen and aluminum oxide, the porous aluminum alloy with a porous structure inside and aluminum oxide micro-nano particles distributed in a dispersed mode is obtained after solidification, and therefore the porous aluminum alloy high in precision, good in pore structure and flexible in size can be prepared.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum alloy preparation, and more specifically, to a method for preparing a porous aluminum alloy, a porous aluminum alloy and a preparation system. Background Art

[0002] The density of aluminum alloy is 2.63~2.85g / cm 3 , has a higher strength (σ b 110~650MPa), its specific strength is close to that of high alloy steel, and its specific stiffness exceeds that of steel. It has good casting performance and plastic processing performance, good electrical and thermal conductivity, good corrosion resistance and weldability. It can be used as a structural material and is widely used in aerospace, aviation, transportation, construction, electromechanical, light chemical and daily necessities.

[0003] Porous metal or foam metal materials have a special structure, and have the characteristics of both metal and pores, such as low density, large specific surface area, good sound absorption, sound insulation, shock absorption, impact energy absorption, and electromagnetic shielding performance, and have broad application prospects in the industrial field. The preparation of aluminum alloy into porous materials can give full play to the advantages of aluminum alloy and porous metal, so that aluminum alloy has many excellent properties such as high bending specific stiffness, sound absorption, sound insulation, heat insulation, electromagnetic shielding, vibration reduction and buffering, and at the same time has the inherent fireproof, moisture-proof, non-toxic, odorless, corrosion-resistant, and aging-resistant properties of metal aluminum. This will be conducive to the integrated development of aluminum alloy structure and function, and further broaden the application field, such as in ships, tunnels, highway sound barriers, factories, shopping malls, stadiums and other occasions. Moreover, the introduction of voids into metal materials is the most effective and widely applicable lightweight method.

[0004] At present, the preparation of porous aluminum alloys mainly adopts powder foaming method, melt foaming method, direct blowing method, investment casting method, infiltration casting method, etc. There are many defects in the preparation of porous aluminum alloy materials by traditional methods, such as complex process, poor pore structure (uneven pore size and distribution), etc. In order to meet the needs of development, the demand for porous aluminum alloy materials with higher precision, complex structure, good porosity and flexible size is increasing rapidly. Summary of the invention

[0005] The present application is provided to solve the above defects in the prior art. A method for preparing a porous aluminum alloy, a porous aluminum alloy and a preparation system are needed to prepare a porous aluminum alloy with high precision, good pore structure and flexible size.

[0006] In a first aspect of the present application, a method for preparing a porous aluminum alloy is provided, the preparation method comprising: using a CMT welding method to prepare an aluminum alloy additive on the surface of a substrate based on an aluminum alloy welding wire, simultaneously applying water to the bottom of the weld, and simultaneously performing ultrasonic treatment of the aluminum alloy additive, so that the water at the bottom of the molten droplet forms water vapor, the aluminum melt reacts with the water vapor to obtain hydrogen and aluminum oxide, and after solidification, a porous aluminum alloy having a porous structure inside and dispersed aluminum oxide micro-nano particles is obtained.

[0007] In a second aspect of the present application, a porous aluminum alloy obtained by the preparation method described in any embodiment of the present application is provided, wherein the porosity of the porous aluminum alloy is 2% to 25%.

[0008] According to a third aspect of the present application, a system for preparing a porous aluminum alloy is provided, the system comprising a CMT welding machine, a water supply device and an ultrasonic device, the CMT welding machine comprising a welding gun, the water supply device comprising a nozzle, the ultrasonic device comprising an ultrasonic rod, the nozzle being coaxially arranged with the end of the welding gun, and the spraying direction of the nozzle being opposite to the bottom of the weld bead so as to synchronously deliver water to the bottom of the weld bead, the bottom of the ultrasonic rod being adjacent to the end of the welding gun, and the bottom of the ultrasonic rod being in contact with the aluminum alloy additive.

[0009] The preparation method, porous aluminum alloy and preparation system provided by each embodiment of the present application, the CMT welding method has low heat input and is suitable for the preparation of porous aluminum alloy materials. By using the CMT welding method, the aluminum alloy additive with a porous structure can be directly obtained by using the aluminum alloy welding wire, and the porous aluminum alloy can be obtained after cooling; the method of the present application mainly applies water to the bottom of the weld during the preparation of the aluminum alloy additive, and simultaneously performs ultrasonic treatment of the aluminum alloy additive, so that the aluminum droplet reacts with water vapor to obtain a porous structure; by performing ultrasonic treatment simultaneously, the problem that the aluminum alloy melt has a large density and viscosity, is not highly reactive with water, and has a very small number of pores can be overcome, because in the process of the reaction of the molten droplet with the water vapor, under the condition of simultaneous ultrasonic treatment, the number of pores can be increased, and the uniformity of the pores can also be improved. The present application can also realize the preparation of the aluminum alloy gradient pore porous structure and the porous interlayer aluminum alloy material by adjusting the water flow rate and the ultrasonic frequency in real time, so the preparation method of the porous aluminum alloy provided by the present application can have a wider application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the embodiments applied for. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0011] Figure 1 A schematic diagram showing the positions of a nozzle, an ultrasonic rod and a CMT welding gun in an additive manufacturing process according to an embodiment of the present application; Figure 2 A cross-sectional structure diagram of a porous aluminum alloy according to Example 1 of the present application is shown; Figure 3 A cross-sectional structure diagram of a porous aluminum alloy according to Example 2 of the present application is shown; Figure 4 A cross-sectional structure diagram of a porous aluminum alloy according to Example 3 of the present application is shown; Figure 5 A cross-sectional structure diagram of a porous aluminum alloy according to Comparative Example 1 of the present application is shown; Figure 6 A cross-sectional structural diagram of a porous aluminum alloy according to Comparative Example 2 of the present application is shown. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific implementation examples. The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific implementation examples, but are not intended to limit the present application.

[0013] The words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0014] According to an embodiment of the present application, a method for preparing a porous aluminum alloy is provided, and the preparation method includes: using a CMT (metal transition technology) welding method to prepare an aluminum alloy additive on the surface of a substrate based on an aluminum alloy welding wire, simultaneously applying water to the bottom of the weld, and simultaneously performing ultrasonic treatment of the aluminum alloy additive, so that the water at the bottom of the molten droplet forms water vapor, and the aluminum melt reacts with the water vapor to obtain hydrogen and aluminum oxide, and after solidification, a porous aluminum alloy with a porous structure inside and dispersed distribution of aluminum oxide micro-nano particles is obtained.

[0015] The CMT welding method does not require complicated preparation steps. It is based on the synergistic effect of hot molten droplets and water to prepare porous aluminum alloy. Therefore, it has the advantages of simple preparation process, fast preparation speed and low cost. The thermal effect, cavitation effect and acoustic streaming effect under the action of ultrasound reduce the viscosity of aluminum alloy, and promote the instantaneous vaporization of water at the bottom of the molten droplet during CMT addition to generate water vapor that reacts with the aluminum melt: Al (l) +H2O (g) →Al2O 3(s) +H 2(g) The hydrogen generated in a short time is dispersed in the molten pool and has no time to escape, and cooperates with the cooling and solidification of the molten pool to achieve the preparation of porous aluminum alloy.

[0016] The hydrogen formed by the reaction of aluminum melt and water vapor dissolves and disperses in the melt. During the solidification of aluminum melt, bubbles form in the melt through homogeneous nucleation, heterogeneous nucleation at the inclusion plane interface, and heterogeneous nucleation and growth in conical pits, so that spherical pores are finally formed inside the aluminum melt. The alumina micro-nanoparticles obtained by the reaction of aluminum melt and water vapor are dispersed in the porous aluminum alloy, which can improve the strength of the porous aluminum alloy. Under the three nucleation modes, the critical radius formulas of bubble nucleation are: in, R is the critical nucleation radius of the bubble; is the liquid / gas interface energy; is the gas pressure above the melt; is the static pressure of the melt at the bubble; is the melt density; g = 9.8m / s 2 is the acceleration due to gravity; is the depth of the bubble in the melt. However, the nucleation work required by the system to overcome is different under different bubble nucleation modes. The pressure inside the bubble after bubble nucleation P H-C (Growth force) greater than the pressure outside the bubble P re (growth resistance), the bubbles will grow. Since the principle of obtaining porous aluminum alloy by the preparation method of the present application is the reaction between molten droplets and water vapor, even if the composition of the aluminum alloy welding wire is different, it will not affect the formation of pores. Therefore, it can be applied to aluminum alloy welding wires of any composition for the additive preparation of porous aluminum alloys.

[0017] Therefore, compared with the existing melt foaming method, infiltration casting method, investment casting method, powder metallurgy method, etc., the preparation method of the porous aluminum alloy of the present application is simpler, the process is easier to control, and the preparation cost is lower. The preparation of porous aluminum alloy and its continuous production can be achieved without the help of foaming agent and viscosity enhancer. The porous aluminum alloy prepared by the present application has a good porous structure, which can overcome the problems of high density and viscosity of aluminum alloy melt, difficulty in pore formation, small number of pores and poor structure.

[0018] The present application utilizes metal transition technology to accumulate molten aluminum alloy to form high-freedom additives during the process of melting the welding wire, so as to obtain the required shape and structure of the additive. Therefore, the preparation method has the advantages of flexible and controllable size for the porous aluminum alloy, and can also perform customized preparation of the porous aluminum alloy based on size and structural requirements, and the preparation process can be carried out continuously and quickly.

[0019] In some embodiments, the water flow rate of the synchronously applied water is 10-30 ml / min. A greater water flow rate of the applied water results in more water at the bottom of the weld bead, and more pore structures can be obtained under the same ultrasonic treatment conditions. Preferably, the water flow rate is 20-30 ml / min.

[0020] In some embodiments, the frequency of ultrasound is 20-22 kHz. In some embodiments, the power of ultrasound is 1000-1800W.

[0021] In some embodiments, the tail end of the welding wire is 2-5 mm away from the highest point of the additive plane, and the welding wire extends out of the welding gun by 10-15 mm, so that the welding wire can better form the aluminum alloy additive.

[0022] In some embodiments, the aluminum alloy welding wire has a diameter of 1.2 to 2.0 mm.

[0023] In some embodiments, the welding speed of the CMT welding method in the preparation of the aluminum alloy additive is 50-70 cm / min; the wire feeding speed is 5.0-6.0 m / min. Wire feeding and CMT welding are coordinated to make the welding wire form a more uniform aluminum alloy additive.

[0024] In some embodiments, the welding voltage of the CMT welding method in the preparation of aluminum alloy additives is 10-15V; the current is 60-100A; and the heat input is 800-1200J / cm. The CMT welding method has the characteristics of low heat input and is more suitable for the preparation of porous aluminum alloys.

[0025] In some embodiments, the preparation of aluminum alloy additive is carried out under a protective gas atmosphere, and the flow rate of the protective gas is 12-18 L / min.

[0026] The embodiment of the present application also provides a porous aluminum alloy obtained by the preparation method described in any embodiment of the present application, wherein the porosity of the porous aluminum alloy is 2% to 25%. Preferably, the porosity of the aluminum alloy is 8% to 25%.

[0027] like Figure 1 As shown, an embodiment of the present application also provides a preparation system for a porous aluminum alloy, the preparation system comprising a CMT welder, a water supply device and an ultrasonic device, the CMT welder comprising a welding gun, the water supply device comprising a nozzle, the ultrasonic device comprising an ultrasonic rod, the nozzle being coaxially arranged with the end of the welding gun, and the spraying direction of the nozzle being opposite to the bottom of the weld bead so as to synchronously deliver water to the bottom of the weld bead, the bottom of the ultrasonic rod being adjacent to the end of the welding gun, and the bottom of the ultrasonic rod being in contact with the aluminum alloy additive.

[0028] In this way, the ultrasonic rod can directly and synchronously ultrasonically treat the newly formed aluminum melt of the welding wire so that the ultrasonic treatment acts on the reaction process of the aluminum melt and water vapor. The water sprayed from the nozzle can be applied to the bottom of the molten droplet to be vaporized instantly.

[0029] The CMT welding machine in the following embodiments is a Fronius TPS500i CMT welding machine. The water supply device includes a water pump, a water tank, a pressure controller and a nozzle, and the nozzle is coaxially fixed to the front end of the CMT welding gun (such as Figure 1 As shown in the figure, the water supply system can synchronously supply water to the bottom of the weld during the CMT additive manufacturing process. The ultrasonic vibration system consists of an ultrasonic generator, a transducer, and a horn to synchronously perform ultrasonic treatment during the reaction between the molten droplet and the water vapor.

[0030] Example 1 like Figure 1 The schematic diagram of the preparation system shown in the figure uses a CMT welding machine and a 5A06 aluminum alloy welding wire to prepare aluminum alloy additives on the surface of a substrate, and simultaneously applies water to the bottom of the weld, and simultaneously performs ultrasonic treatment of the aluminum alloy additives to obtain a porous aluminum alloy with a porous structure inside. Among them, the diameter of the welding wire is 1.2mm, the welding speed is 60cm / min, the wire feeding speed is 6m / min, the welding voltage is 15V, the current is 100A, the heat input is 1200J / cm, the shielding gas flow rate is 15L / min, and the shielding gas is high-purity argon. The power of the ultrasonic vibration system is 1500W, and the ultrasonic frequency is 20kHz. During the CMT additive process, the water flow rate of the synchronous water supply at the bottom of the weld is 20ml / min. The porous aluminum alloy obtained is as follows Figure 2 As shown, it can be seen that there are a large number of pores inside the aluminum alloy, which are relatively uniform, and some of the spherical pores are relatively large.

[0031] Example 2 like Figure 1The schematic diagram of the preparation system shown in the figure uses a CMT welding machine and a 5A06 aluminum alloy welding wire to prepare aluminum alloy additives on the surface of a substrate, and simultaneously applies water to the bottom of the weld, and simultaneously performs ultrasonic treatment of the aluminum alloy additives to obtain a porous aluminum alloy with a porous structure inside. Among them, the diameter of the welding wire is 1.2mm, the welding speed is 60cm / min, the wire feeding speed is 6m / min, the welding voltage is 15V, the current is 100A, the heat input is 1200J / cm, the shielding gas flow rate is 15L / min, and the shielding gas is high-purity argon. The power of the ultrasonic vibration system is 1500W, and the ultrasonic frequency is 20kHz. During the CMT additive process, the water flow rate of the synchronous water supply at the bottom of the weld is 30ml / min. The porous aluminum alloy obtained is as follows Figure 3 As shown, it can be seen that the number of pores inside the aluminum alloy is large and relatively uniform, and most of the spherical pores are relatively large. Compared with Example 1, the water flow rate is larger, and the obtained pores are more and larger.

[0032] Example 3 like Figure 1 The schematic diagram of the preparation system shown in the figure uses a CMT welder and a 5A06 aluminum alloy welding wire to prepare aluminum alloy additives on the surface of a substrate, and simultaneously applies water to the bottom of the weld, and simultaneously performs ultrasonic treatment of the aluminum alloy additives to obtain a porous aluminum alloy with a porous structure inside. Among them, the diameter of the welding wire is 1.2mm, the welding speed is 60cm / min, the wire feeding speed is 6m / min, the welding voltage is 15V, the current is 100A, the heat input is 1200J / cm, the shielding gas flow rate is 15L / min, and the shielding gas is high-purity argon. The power of the ultrasonic vibration system is 1500W, and the ultrasonic frequency is 20kHz. During the CMT additive process, the water flow rate at the bottom of the weld is 10ml / min. The obtained pore structure is as follows Figure 4 As shown, it can be seen that due to the smaller water flow rate, fewer pores are obtained, the porosity is smaller, and there are only a few large spherical pores.

[0033] Comparative Example 1 Compared with Example 2, without simultaneous ultrasonic treatment, the obtained aluminum alloy is as follows Figure 5 As shown, it can be seen that compared with the porous aluminum alloy of Example 2, the number of pores inside the aluminum alloy obtained in Comparative Example 1 is significantly reduced, and most of the pores are relatively small.

[0034] Comparative Example 2 Compared with Example 1, the frequency of ultrasonic treatment is 18kHz, and the power of ultrasonic vibration system is 1500W. The cross-sectional view of the interior of the aluminum alloy obtained is as follows: Figure 6 As shown, it can be seen that the frequency of ultrasonic treatment is lower, although holes are also obtained, the number of holes inside the aluminum alloy is significantly reduced and the holes are smaller.

[0035] The porosity of the porous aluminum alloys obtained in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 is shown in Table 1.

[0036] Table 1 Porosity of porous aluminum alloys in different embodiments The porosity of the porous aluminum alloys of Examples 1 and 2 is relatively high, while the porosity of the porous aluminum alloy of Example 3 is relatively low, indicating that as the water flow rate of the transported water increases, the number of pores in the pore structure of the porous aluminum alloy gradually increases, the porosity gradually increases, and the pore size also has a tendency to increase. The porosity of the porous aluminum alloy of Comparative Example 1 is quite different from that of the porous aluminum alloy of Example 2, indicating that the porosity will be greatly reduced if ultrasonic treatment is not performed. The porosity of the porous aluminum alloy of Comparative Example 2 is lower than that of the porous aluminum alloy of Example 1, indicating that the ultrasonic frequency is relatively low and cannot effectively play the role of increasing the number of pores in the aluminum melt.

[0037] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present application with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims are to be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the practice of this application, and the examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0038] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more schemes thereof) may be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features may be grouped together to simplify the present application. This should not be interpreted as an intention that a feature of an application that does not require protection is necessary for any claim. On the contrary, the subject matter of the present application may be less than all the features of an embodiment of a particular application. Thus, the following claims are incorporated herein in the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments may be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalent forms granted by these claims.

[0039] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for preparing a porous aluminum alloy, characterized in that: The preparation method comprises: using a CMT welding method to prepare an aluminum alloy additive on the surface of a substrate based on an aluminum alloy welding wire, simultaneously applying water to the bottom of the weld, and simultaneously performing ultrasonic treatment on the aluminum alloy additive, so that the water at the bottom of the molten droplet forms water vapor, and the aluminum melt reacts with the water vapor to obtain hydrogen and aluminum oxide, and after solidification, a porous aluminum alloy with a porous structure inside and dispersed distribution of aluminum oxide micro-nano particles is obtained.

2. The preparation method according to claim 1, characterized in that: The water flow rate of the synchronously applied water is 10~30ml / min.

3. The preparation method according to claim 1, characterized in that: The frequency of ultrasound is 20~22kHz.

4. The preparation method according to claim 1, characterized in that: The tail end of the welding wire is 2~5mm away from the highest point of the additive plane, and the welding wire extends out of the welding gun by 10~15mm.

5. The preparation method according to claim 1, characterized in that: The aluminum alloy welding wire has a diameter of 1.2-2.0 mm.

6. The preparation method according to claim 1, characterized in that: The welding speed of the CMT welding method described in the preparation of aluminum alloy additives is 50~70cm / min; the wire feeding speed is 5.0~6.0m / min.

7. The preparation method according to claim 1, characterized in that: The welding voltage of the CMT welding method described in the preparation of aluminum alloy additives is 10~15V; the current is 60~100A; and the heat input is 800~1200J / cm.

8. The preparation method according to claim 1, characterized in that: Aluminum alloy additive manufacturing is carried out under a protective gas atmosphere with a flow rate of 12~18L / min.

9. The porous aluminum alloy obtained by the preparation method according to any one of claims 1 to 8, wherein the porosity of the porous aluminum alloy is 2% to 25%.

10. A system for preparing a porous aluminum alloy, characterized in that: The preparation system includes a CMT welder, a water supply device and an ultrasonic device. The CMT welder includes a welding gun. The water supply device includes a nozzle. The ultrasonic device includes an ultrasonic rod. The nozzle is coaxially arranged with the end of the welding gun, and the spraying direction of the nozzle is opposite to the bottom of the weld bead so as to synchronously deliver water to the bottom of the weld bead. The bottom of the ultrasonic rod is adjacent to the end of the welding gun, and the bottom of the ultrasonic rod is in contact with the aluminum alloy additive.

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