A method of making a porous aluminum alloy, a porous aluminum alloy, and a manufacturing system

Abstract

The embodiment of the application relates to a porous aluminum alloy preparation method, a porous aluminum alloy and a preparation system, the preparation method comprises the following steps: using a CMT welding method, based on an aluminum alloy welding wire, preparing aluminum alloy additive on the surface of a substrate, synchronously applying water at the bottom of a welding bead, and synchronously performing ultrasonic treatment on the aluminum alloy additive, so that the water at the bottom of the droplet forms water vapor, the aluminum melt reacts with the water vapor to obtain hydrogen and aluminum oxide, and after solidification, the porous aluminum alloy with a porous structure in the inside and dispersed distribution of aluminum oxide microparticles is obtained, therefore, the porous aluminum alloy with high precision, good pore structure and flexible size can be prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy preparation, and more particularly to a porous aluminum alloy preparation method, a porous aluminum alloy and a preparation system. BACKGROUND

[0002] The density of aluminum alloy is 2.63-2.85 g / cm 3 , has a higher strength (σ b 110-650 MPa), a specific strength close to high alloy steel, a specific rigidity exceeding steel, good casting performance and plastic processing performance, good electrical conductivity, thermal conductivity, corrosion resistance and weldability, and 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 material has a special structure and combines the characteristics of metal and pores, such as small density, large specific surface area, sound absorption, sound insulation, shock absorption, impact energy absorption, and good electromagnetic shielding performance, and has broad application prospects in the industrial field. Preparing aluminum alloy into porous material can fully exert the advantages of aluminum alloy and porous metal, so that the aluminum alloy has high bending specific rigidity, sound absorption, sound insulation, heat insulation, electromagnetic shielding, vibration damping and other excellent properties, and also has the inherent properties of metal aluminum, such as fireproof, moistureproof, nontoxic, odorless, corrosion resistant, and aging resistant. This will be conducive to the development of aluminum alloy structure and function integration, and further broaden the application field, such as application in ships, tunnels, highway sound barriers, factories, shopping malls, stadiums and other occasions. Moreover, introducing voids into metal materials is the most effective and widely used method of lightweight.

[0004] At present, the preparation of porous aluminum alloy mainly adopts powder foaming method, melt foaming method, direct blowing method, investment casting method, infiltration casting method, etc. The traditional method for preparing porous aluminum alloy material has many defects, such as complex process, poor pore structure (uneven pore size and distribution), etc. To meet the needs of development, the demand for porous aluminum alloy materials with high precision, complex structure, good pore structure and flexible size is increasing. SUMMARY

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

[0006] In a first aspect, the present application provides a method for preparing a porous aluminum alloy, the 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, synchronously applying water to the bottom of the welding bead, and synchronously performing ultrasonic treatment on 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 with a porous structure inside and dispersed distribution of aluminum oxide micro-nanoparticles is obtained.

[0007] In a second aspect, the present application provides a porous aluminum alloy prepared by the method of any one of the embodiments of the present application, wherein the porosity of the porous aluminum alloy is 2% to 25%.

[0008] In a third aspect, the present application provides a system for preparing a porous aluminum alloy, the system comprising a CMT welding machine, a water delivery device, and an ultrasonic device, the CMT welding machine comprising a welding torch, the water delivery device comprising a nozzle, and the ultrasonic device comprising an ultrasonic rod, the nozzle being coaxially arranged at the end of the welding torch, and the ejection direction of the nozzle being opposite to the bottom of the welding bead to synchronously deliver water to the bottom of the welding bead, the bottom of the ultrasonic rod being adjacent to the end of the welding torch, and the bottom of the ultrasonic rod being in contact with the aluminum alloy additive.

[0009] The method for preparing a porous aluminum alloy, the porous aluminum alloy, and the preparation system provided by the embodiments of the present application have the following advantages: the CMT welding method has low heat input, which is suitable for the preparation of a porous aluminum alloy material; the CMT welding method can directly use an aluminum alloy welding wire to obtain an aluminum alloy additive with a porous structure, and after cooling, a porous aluminum alloy is obtained; the method of the present application mainly synchronously applies water to the bottom of the welding bead during the preparation of the aluminum alloy additive, and synchronously performs ultrasonic treatment on the aluminum alloy additive, which can make the aluminum melt react with water vapor, and thus obtain a porous structure; by synchronously performing ultrasonic treatment, the problem of few pores due to the large density and viscosity of the aluminum alloy melt and the weak reactivity with water can be overcome; because the ultrasonic treatment is performed synchronously during the reaction of the molten droplet with water vapor, the number of pores can be increased, and the uniformity of the pores can also be improved. The present application can also prepare aluminum alloy gradient-pore porous structures and porous sandwich aluminum alloy materials by adjusting the water flow rate and the ultrasonic frequency in real time, and thus the method for preparing a porous aluminum alloy provided by the present application can have a wider application. BRIEF DESCRIPTION OF DRAWINGS

[0010] In the drawings, which are not necessarily drawn to scale, like numerals describe similar components throughout the several views. Like numerals having different letter extensions can represent different instances of like components. The drawings illustrate generally, by way of example, various embodiments discussed herein, and are not intended to limit the claimed embodiments to the embodiments depicted. The same or similar reference numerals can be used in different drawings to represent similar or same components. Such embodiments are illustrative, rather than limiting, of the present devices or methods.

[0011] Figure 1 Positional schematic diagram of nozzle, ultrasonic rod and CMT welding gun in additive manufacturing process according to the embodiments of the present application is shown;

[0012] Figure 2 Cross-sectional structure diagram of porous aluminum alloy according to Embodiment 1 of the present application is shown;

[0013] Figure 3 Cross-sectional structure diagram of porous aluminum alloy according to Embodiment 2 of the present application is shown;

[0014] Figure 4 Cross-sectional structure diagram of porous aluminum alloy according to Embodiment 3 of the present application is shown;

[0015] Figure 5 Cross-sectional structure diagram of porous aluminum alloy according to Comparative Example 1 of the present application is shown;

[0016] Figure 6 Cross-sectional structure diagram of porous aluminum alloy according to Comparative Example 2 of the present application is shown. DETAILED DESCRIPTION

[0017] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail below in combination with the drawings and specific embodiments. The embodiments of the present application will be further described in detail below in combination with the drawings and specific embodiments, but are not intended to limit the present application.

[0018] The terms "first", "second", and similar terms used in the present application do not indicate any order, number or importance, but are only used to distinguish. The terms "include" or "contain" and similar terms mean that the elements before the terms cover the elements listed after the terms, and do not exclude the possibility of also covering other elements.

[0019] According to the embodiments of the present application, a preparation method of a porous aluminum alloy is provided, which comprises: using a welding method of CMT (metal transition technology), preparing aluminum alloy additive manufacturing on the surface of a substrate based on an aluminum alloy welding wire, synchronously applying water at the bottom of a welding bead, and synchronously performing ultrasonic treatment of the aluminum alloy additive manufacturing, so that the water at the bottom of the 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 with a porous structure inside and dispersed distribution of aluminum oxide micro-nanoparticles is obtained.

[0020] The welding method of CMT does not need complex preparation steps, and the porous aluminum alloy is prepared based on the synergistic effect of hot droplets and water, so it has the advantages of simple preparation process, fast preparation speed and low cost.

[0021] Under the action of ultrasonic, the thermal effect, cavitation effect and acoustic streaming effect reduce the viscosity of the aluminum alloy, and at the same time, promote the reaction between the water vapor generated by the instantaneous vaporization of the water delivered at the bottom of the droplet during CMT additive manufacturing and the aluminum melt: (l) +H2O (g) →Al2O 3(s) +H 2(g) The hydrogen generated in a short time is dispersed in the molten pool and cannot escape in time, and cooperates with the cooling and solidification of the molten pool to realize the preparation of the porous aluminum alloy.

[0022] The hydrogen formed after the reaction of the aluminum melt and the water vapor is dissolved and dispersed in the melt, and in the process of solidification of the aluminum melt, the bubbles in the melt grow by homogeneous nucleation, heterogeneous nucleation on the inclusion flat interface and heterogeneous nucleation in the conical pit, so that spherical pores are finally formed in the interior of the aluminum melt. The aluminum oxide micro-nanoparticles obtained after the reaction of the aluminum melt and the 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 formula of the bubble nucleation is:

[0023]

[0024]

[0025] wherein, 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 density of the melt; g = 9.8 m / s 2 is the acceleration of gravity; is the depth of the bubble in the melt. But the system needs to overcome different nucleation work under different bubble nucleation modes. The bubble internal pressure P H-C after bubble nucleation (growth driving force) is greater than the bubble external pressure P reWhen the bubble grows to a certain size (long big resistance), the bubble will grow.

[0026] The principle of the preparation method of the present application for the porous aluminum alloy is the reaction of molten droplets and water vapor. Even if the composition of the aluminum alloy welding wire is different, it does not affect the formation of the porous structure, and thus the present application can be applied to the additive preparation of the porous aluminum alloy with any composition of the aluminum alloy welding wire.

[0027] 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. Without the help of foaming agent and tackifier, the porous aluminum alloy can be prepared and continuously produced. The porous aluminum alloy prepared by the present application has a good porous structure, which can overcome the problems of large melt density, large viscosity, difficult pore formation, small number of pores and poor structure of the aluminum alloy.

[0028] In the process of melting the welding wire, the molten aluminum alloy is accumulated to form a high-freedom additive by using the metal transition technology, so as to obtain the required shape and structure of the additive. Therefore, the preparation method has the advantages of size flexibility and size controllability for the porous aluminum alloy. The porous aluminum alloy can also be customized based on the size and structure requirements, and the preparation process can be continuously and quickly carried out.

[0029] In some embodiments, the water flow rate of the water applied synchronously is 10-30 ml / min. The larger the water flow rate of the water applied, the more water at the bottom of the welding bead, and under the same ultrasonic treatment conditions, more pore structures can be obtained. Preferably, the water flow rate is 20-30 ml / min.

[0030] In some embodiments, the frequency of the ultrasonic is 20-22 kHz. In some embodiments, the power of the ultrasonic is 1000-1800 W.

[0031] 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 torch by 10-15 mm. In order to form the aluminum alloy additive better.

[0032] In some embodiments, the diameter of the aluminum alloy welding wire is 1.2-2.0 mm.

[0033] In some embodiments, the welding speed of the CMT welding method in the preparation of the aluminum alloy additive is 50-70 cm / min; and the wire feeding speed is 5.0-6.0 m / min. The wire feeding and the CMT welding are matched to make the welding wire form a more uniform aluminum alloy additive.

[0034] In some embodiments, the CMT welding method has a welding voltage of 10-15 V, a current of 60-100 A, and a heat input of 800-1200 J / cm in the preparation of the aluminum alloy additive.

[0035] In some embodiments, the preparation of the aluminum alloy additive is performed in an atmosphere of protective gas, and the flow rate of the protective gas is 12-18 L / min.

[0036] The embodiments of the present application also provide a porous aluminum alloy prepared by the preparation method of any of the embodiments of the present application, and the porosity of the porous aluminum alloy is 2%-25%. Preferably, the porosity of the aluminum alloy is 8%-25%.

[0037] As shown in Figure 1 The embodiments of the present application also provide a preparation system of a porous aluminum alloy, and the preparation system comprises a CMT welding machine, a water feeding device, and an ultrasonic device. The CMT welding machine comprises a welding torch, the water feeding device comprises a nozzle, and the ultrasonic device comprises an ultrasonic rod. The nozzle is coaxially arranged at the end of the welding torch, and the spraying direction of the nozzle is opposite to the bottom of the welding bead so as to synchronously feed water to the bottom of the welding bead. The bottom of the ultrasonic rod is adjacent to the end of the welding torch, and the bottom of the ultrasonic rod is in contact with the aluminum alloy additive.

[0038] In this way, the ultrasonic rod can directly and synchronously perform ultrasonic treatment on 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 by the nozzle can be applied to the lower side of the droplet to be vaporized instantaneously.

[0039] The CMT welding machine in each of the following embodiments is a Fronius TPS500i CMT type welding machine. The water feeding device comprises a water pump, a water tank, a pressure controller, and a nozzle. The nozzle is coaxially fixed to the front end of the CMT welding torch (as shown in Figure 1 ) to ensure that the water feeding system synchronously feeds water to the bottom of the welding bead during the CMT additive preparation process. The ultrasonic vibration system is composed of an ultrasonic generator, a transducer, and an amplitude rod to synchronously perform ultrasonic treatment during the reaction process of the droplet and water vapor.

[0040] Embodiment 1

[0041] As shown in Figure 1The schematic diagram of the preparation system shows the use of a CMT welding machine and 5A06 aluminum alloy welding wire to prepare aluminum alloy additive material on the surface of a substrate. Water is simultaneously applied to the bottom of the weld bead, and ultrasonic treatment is performed concurrently to obtain a porous aluminum alloy with a porous internal structure. The welding wire diameter is 1.2 mm, welding speed is 60 cm / min, wire feed speed is 6 m / min, welding voltage is 15 V, current is 100 A, heat input is 1200 J / cm, shielding gas flow rate is 15 L / min, and the shielding gas is high-purity argon. The ultrasonic vibration system has a power of 1500 W and an ultrasonic frequency of 20 kHz. Water is simultaneously supplied to the bottom of the weld bead during the CMT additive process at a flow rate of 20 ml / min. The resulting porous aluminum alloy is shown below. Figure 2 As shown, the aluminum alloy has a large number of holes that are relatively uniform, and some of the spherical holes are quite large.

[0042] Example 2

[0043] like Figure 1 The schematic diagram of the preparation system shows the use of a CMT welding machine and 5A06 aluminum alloy welding wire to prepare aluminum alloy additive material on the surface of a substrate. Water is simultaneously applied to the bottom of the weld bead, and ultrasonic treatment is performed concurrently to obtain a porous aluminum alloy with a porous internal structure. The welding wire diameter is 1.2 mm, welding speed is 60 cm / min, wire feed speed is 6 m / min, welding voltage is 15 V, current is 100 A, heat input is 1200 J / cm, shielding gas flow rate is 15 L / min, and the shielding gas is high-purity argon. The ultrasonic vibration system has a power of 1500 W and an ultrasonic frequency of 20 kHz. During the CMT additive process, water is simultaneously applied to the bottom of the weld bead at a flow rate of 30 ml / min. The resulting porous aluminum alloy is shown below. Figure 3 As shown, the aluminum alloy has a large number of holes that are relatively uniform, and most of the spherical holes are relatively large. Compared with Example 1, the water flow rate is larger, resulting in more and larger holes.

[0044] Example 3

[0045] like Figure 1 The schematic diagram of the preparation system shows the use of a CMT welding machine and 5A06 aluminum alloy welding wire to prepare aluminum alloy additive material on the surface of a substrate. Water is simultaneously applied to the bottom of the weld bead, and ultrasonic treatment is performed concurrently to obtain a porous aluminum alloy with a porous internal structure. The welding wire diameter is 1.2 mm, welding speed is 60 cm / min, wire feed speed is 6 m / min, welding voltage is 15 V, current is 100 A, heat input is 1200 J / cm, shielding gas flow rate is 15 L / min, and the shielding gas is high-purity argon. The ultrasonic vibration system has a power of 1500 W and an ultrasonic frequency of 20 kHz. During the CMT additive process, water is simultaneously applied to the bottom of the weld bead at a flow rate of 10 ml / min. The resulting pore structure is shown below.Figure 4 As shown in FIG. 2, it can be seen that, due to the small water flow, fewer holes are obtained, and the porosity is small, and only a small part of the holes are large spherical holes.

[0046] Comparative Example 1

[0047] Compared with Example 2, no ultrasonic treatment is performed, and the obtained aluminum alloy has Figure 5 As shown in FIG. 4, it can be seen that, compared with the porous aluminum alloy of Example 2, the number of holes in the aluminum alloy obtained in Comparative Example 1 is significantly reduced, and most of the holes are small.

[0048] Comparative Example 2

[0049] Compared with Example 1, the frequency of ultrasonic treatment is 18 kHz, and the power of the ultrasonic vibration system is 1500 W. The cross-sectional view of the obtained aluminum alloy is as shown in FIG. 5. Figure 6 As shown in FIG. 5, it can be seen that, due to the low frequency of ultrasonic treatment, although holes are also obtained, the number of holes in the aluminum alloy is significantly reduced, and the holes are small.

[0050] The porosities of the porous aluminum alloys obtained in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1.

[0051] Table 1 Porosities of the porous aluminum alloys of different examples

[0052]

[0053] The porosities of the porous aluminum alloys of Example 1 and Example 2 are high, the porosity of the porous aluminum alloy of Example 3 is small, which indicates that as the water flow of the delivered water increases, the number of hole structures of the porous aluminum alloy gradually increases, the porosity gradually increases, and the hole diameter also has a trend of increasing. The porosity of the porous aluminum alloy of Comparative Example 1 is greatly different from that of the porous aluminum alloy of Example 2, which indicates that not performing ultrasonic treatment will greatly reduce the porosity. The porosity of the porous aluminum alloy of Comparative Example 2 is reduced compared with that of the porous aluminum alloy of Example 1, which indicates that the ultrasonic frequency is small, and cannot effectively play a role in increasing the number of pores of the aluminum melt.

[0054] In addition, although exemplary embodiments have been described herein, the scope of their range includes any and all embodiments based on the present application with equivalent elements, modifications, omissions, combinations (for example, solutions in which various embodiments are crossed), adaptations or variations. The elements in the claims will be broadly interpreted based on the language adopted in the claims, and are not limited to the examples described in the specification or during the implementation of the application, and the examples will be interpreted as non-exclusive. Therefore, the specification and examples are intended to be considered only as examples, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0055] The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used, which will be apparent to those of ordinary skill in the art upon reviewing the above description. Additionally, the various features described above can be grouped together or divided into separate features for the purpose of simplifying the present disclosure. This should not be interpreted as a requirement to practice a claim in any particular embodiment. Rather, the subject matter of the application can be practiced without all of the features of a particular embodiment. Accordingly, the following claims are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment, and it is made expressly clear that what is claimed can be claimed both as alternative embodiments and / or as claims in combination with other embraces. The scope of the application should be determined by reference to the appended claims, and their full scope of equivalents, and should not be limited by the foregoing description.

[0056] The above embodiments are only exemplary embodiments of the present application, not intended to limit the present application, and the protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements should also be considered to fall within the protection scope of the present application.

Claims

1. A method for producing a porous aluminum alloy, characterized by, The preparation method comprises: using a CMT welding method to prepare aluminum alloy additive on the surface of a substrate based on an aluminum alloy welding wire, synchronously applying water to the bottom of a welding bead, and synchronously performing ultrasonic treatment on the aluminum alloy additive, so that the water at the bottom of the 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 with a porous structure and dispersed distribution of aluminum oxide micro-nanoparticles in the interior is obtained. The water flow rate of the synchronously applied water is 10-30 ml / min. The frequency of the ultrasonic treatment is 20-22 kHz.

2. The production method according to claim 1, characterized by, 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 torch by 10-15 mm.

3. The production method according to claim 1, characterized by, The diameter of the aluminum alloy welding wire is 1.2-2.0 mm.

4. The production method according to claim 1, characterized by, In the preparation of the aluminum alloy additive, the welding speed of the CMT welding method is 50-70 cm / min, and the wire feeding speed is 5.0-6.0 m / min.

5. The production method according to claim 1, characterized by, In the preparation of the aluminum alloy additive, the welding voltage of the CMT welding method is 10-15 V, the current is 60-100 A, and the heat input is 800-1200 J / cm.

6. The production method according to claim 1, characterized by, The preparation of the aluminum alloy additive is performed in an atmosphere of protective gas, and the flow rate of the protective gas is 12-18 L / min.

7. The porous aluminum alloy obtained by the preparation method according to any one of claims 1-6, wherein the porosity of the porous aluminum alloy is 2%-25%.

8. A system for producing a porous aluminum alloy, characterized by comprising: The preparation system comprises a CMT welding machine, a water feeding device, and an ultrasonic device, the CMT welding machine comprises a welding torch, the water feeding device comprises a nozzle, and the ultrasonic device comprises an ultrasonic rod, the nozzle is coaxially arranged at the end of the welding torch, and the ejection direction of the nozzle is opposite to the bottom of the welding bead to synchronously feed water to the bottom of the welding bead, the bottom of the ultrasonic rod is adjacent to the end of the welding torch, and the bottom of the ultrasonic rod is in contact with the aluminum alloy additive; the ultrasonic rod can directly and synchronously perform ultrasonic treatment on the newly formed aluminum melt of the welding wire, so that the ultrasonic treatment acts on the reaction process of the aluminum melt and the water vapor; the water ejected from the nozzle can be applied below the droplet to be vaporized instantaneously.

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