Aluminum alloy composite board, heat exchange tube and heat exchanger

Abstract

The invention discloses an aluminum alloy composite board, a heat exchange tube and a heat exchanger, the aluminum alloy composite board comprises a core material layer, a first composite layer and a second composite layer, the first composite layer and the second composite layer are arranged on the two sides of the core material layer in the thickness direction of the core material layer respectively, and the core material layer comprises, by mass, 1.0-2.0% of Mn, 0.1-1.0% of Fe, 0.1-3.0% of Cu, smaller than or equal to 0.10% of Ce, smaller than or equal to 0.3% of Si, smaller than or equal to 0.1% of Mg, smaller than or equal to 0.5% of P, smaller than or equal to 0.5% of S and the balance Al. The core material layer comprises the following components in percentage by weight: less than or equal to 0.5% of Zn, less than or equal to 0.25% of Zr, less than or equal to 0.25% of Cr, less than or equal to 0.25% of Ti and the balance of Al and inevitable impurity elements, and Al-Cu-Ce alloy is formed on the core material layer. According to the aluminum alloy composite board, Ce is introduced into the core material layer, the Ce and Cu have strong interaction, an Al-Cu-Ce alloy is formed, the probability of intergranular corrosion is reduced, and the corrosion resistance of the aluminum alloy composite board is improved.

Description

Technical Field

[0001] This invention relates to the field of microchannel heat exchangers, and more specifically, to an aluminum alloy composite plate, a heat exchange tube, and a heat exchanger. Background Technology

[0002] Currently, heat exchangers are widely used in various air conditioning fields. Heat exchanger tubes, as one of the main materials of heat exchangers, are a key research focus in this field. During use, aluminum alloy heat exchanger tubes exposed to air are prone to corrosion, leading to leaks and affecting the heat exchanger's performance and lifespan. Summary of the Invention

[0003] This invention is based on the inventor's discovery and understanding of the following facts and problems: Currently, the aluminum alloy core material used in heat exchange tubes includes different contents of Cu element. Cu element has a relatively low equilibrium solid solubility in aluminum alloy. Excessive Cu content in aluminum alloy is prone to segregation at grain boundaries to form Al2Cu. Cu element makes the material susceptible to intergranular corrosion, affecting the corrosion resistance of heat exchange tube.

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose an aluminum alloy composite plate, a heat exchange tube, and a heat exchanger. The aluminum alloy composite plate incorporates Ce, which interacts strongly with Cu atoms to form an Al-Cu-Ce alloy, reducing the probability of intergranular corrosion and improving the corrosion resistance of the aluminum alloy composite plate.

[0005] This invention provides an aluminum alloy composite sheet, which includes a core layer, a first composite layer, and a second composite layer. The first composite layer and the second composite layer are respectively disposed on both sides of the core layer along its thickness direction. By mass percentage, the core layer includes: Mn: 1.0-2.0%, Fe: 0.1-1.0%, Cu: 0.1-3.0%, Ce: ≤0.10%, Si: ≤0.3%, Mg: ≤0.1%, Zn: ≤0.5%, Zr: ≤0.25%, Cr: ≤0.25%, Ti: ≤0.25%, with the remainder being Al and unavoidable impurity elements. The core layer forms an Al-Cu-Ce alloy.

[0006] The aluminum alloy composite plate of this invention includes a core layer, a first composite layer, and a second composite layer. By setting the first and second composite layers on both sides of the core layer in the thickness direction, welding is facilitated. Moreover, the multi-layer structure design of the aluminum alloy composite plate creates a potential difference with the core layer, protecting the core layer. The core layer improves its corrosion resistance by adding the rare earth element Ce to improve the composite ratio. The introduction of Ce into the core layer results in a strong interaction between Ce and Cu atoms, forming an Al-Cu-Ce alloy, reducing the segregation of Al2Cu at the grain boundaries and purifying the grain boundaries. At the same time, Al-Cu-Ce is a lamellar eutectic structure with extremely small interlamellar spacing, enhancing the density of the alloy and reducing the probability of intergranular corrosion, thus greatly improving the corrosion resistance of the aluminum alloy composite plate.

[0007] This invention provides a heat exchange tube, which includes at least one heat exchange channel extending along the length of the heat exchange tube. The heat exchange tube also includes a tube wall, and the wall surrounding the heat exchange channel includes at least a portion of the tube wall. The material of the tube wall includes the aluminum alloy composite plate described in this invention.

[0008] In this embodiment of the invention, the heat exchange tube adopts the aluminum alloy composite plate described in this invention. Rare earth element Ce is introduced into the core layer of the aluminum alloy composite plate. There is a strong interaction between Ce and Cu atoms to form an Al-Cu-Ce alloy, which reduces the probability of intergranular corrosion and improves the corrosion resistance of the aluminum alloy composite plate, thereby greatly improving the corrosion resistance of the heat exchange tube.

[0009] This invention provides a heat exchanger, the heat exchanger comprising:

[0010] First pipe and second pipe;

[0011] A heat exchange tube, wherein the heat exchange tube is the heat exchange tube described in the embodiment of the present invention, there are multiple heat exchange tubes, the multiple heat exchange tubes are spaced apart along the length direction of the first tube, the heat exchange tube includes a heat exchange channel extending along its length direction, the multiple heat exchange channels are spaced apart in the width direction of the heat exchange tube, the heat exchange tube is in communication with the first tube, the heat exchange tube is in communication with the second tube, and the first tube and / or the second tube is welded to the heat exchange tube.

[0012] In this embodiment of the invention, the heat exchanger uses the heat exchange tube described in this invention. The heat exchange tube is made of aluminum alloy composite plate. Rare earth element Ce is introduced into the core layer of the aluminum alloy composite plate. There is a strong interaction between Ce and Cu atoms to form an Al-Cu-Ce alloy, which reduces the probability of intergranular corrosion and improves the corrosion resistance of the aluminum alloy composite plate. This greatly improves the corrosion resistance of the heat exchange tube and the heat exchanger, and extends the service life of the heat exchanger. Attached Figure Description

[0013] Figure 1 This is a cross-sectional structural diagram of an aluminum alloy composite plate according to an embodiment of the present invention.

[0014] Figure 2 This is a cross-sectional structural diagram of an aluminum alloy composite plate according to another embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram of the heat exchange tube according to an embodiment of the present invention.

[0016] Figure 4 This is a three-dimensional structural diagram of the heat exchange tube according to an embodiment of the present invention.

[0017] Figure 5 This is a schematic diagram of the heat exchanger according to an embodiment of this application.

[0018] Figure label:

[0019] First composite layer 1, intermediate layer 2, core material layer 3, second composite layer 4, heat exchange tube 5, heat exchange channel 6, tube wall 7, first component 8, first tube 9, second tube 10, fins 11, heat exchanger 12. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, with examples of the embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] The aluminum alloy composite sheet of this invention includes a core layer 3, a first composite layer 1, and a second composite layer 4. The first composite layer 1 and the second composite layer 4 are respectively disposed on both sides of the core layer 3 along the thickness direction of the core layer 3. By mass percentage, the core layer 3 includes: Mn: 1.0-2.0%, Fe: 0.1-1.0%, Cu: 0.1-3.0%, Ce: ≤0.10%, Si: ≤0.3%, Mg: ≤0.1%, Zn: ≤0.5%, Zr: ≤0.25%, Cr: ≤0.25%, Ti: ≤0.25%, with the remainder being Al and unavoidable impurity elements. The core layer forms an Al-Cu-Ce alloy.

[0022] The aluminum alloy composite plate of this invention includes a core layer, a first composite layer, and a second composite layer. By setting the first composite layer and the second composite layer on both sides of the core layer in the thickness direction, welding is facilitated. Moreover, the multi-layer structure design of the aluminum alloy composite plate creates a potential difference with the core layer, protecting the core layer and further improving the corrosion resistance of the aluminum alloy composite plate.

[0023] In this embodiment of the invention, the difference in Cu content in the core layer can easily lead to accelerated intergranular corrosion. Adding the rare earth element Ce to the core layer improves the composite ratio and enhances its corrosion resistance. The Cu content in the core layer is 0.1-3.0%. The role of Cu in the core layer is to create a high potential difference with other layers, thus protecting the core layer. However, excessive Cu can cause Al₂Cu to segregate at grain boundaries, easily leading to intergranular corrosion. Introducing Ce into the core layer creates an Al-Cu-Ce alloy due to the strong interaction between Ce and Cu atoms, reducing Al₂Cu segregation at grain boundaries and purifying them. Simultaneously, Al-Cu-Ce is a lamellar eutectic structure with extremely small interlamellar spacing, enhancing the alloy's density and reducing the probability of intergranular corrosion, thus significantly improving the material's corrosion resistance.

[0024] In this embodiment of the invention, Fe in aluminum alloys often exists as the Al3Fe phase or other iron-rich phases. These iron-rich phases cause anodizing of the aluminum matrix, which is continuously consumed, leading to intergranular corrosion. Introducing Ce into the core layer can also form Ce-Fe compounds such as CeFe5 with Fe, and these compounds precipitate from within the grains, reducing the precipitation of other second iron-rich phases.

[0025] In this embodiment of the invention, when Ce ≤ 0.10%, the subgrain boundaries within the aluminum alloy grains are clear, and the subgrains are very fine and uniformly distributed. When Ce > 0.10%, the subgrains grow, and blocky polygonal rare earth crystalline phases appear within the alloy. As the Ce content increases, the blocky rare earth crystalline phases become larger, and some cracks are distributed on the surface. Some cracks penetrate the entire rare earth crystalline phase, even dividing it into multiple units. The rare earth crystalline phase is a brittle rare earth phase, which will break under stress during welding and heat deformation. Some coarse rare earth phases break significantly, appearing as fragments around the coarse rare earth phases, while most rare earth phases cannot be fully broken, resulting in surface cracks. These cracks severely reduce the mechanical properties of the alloy.

[0026] In this embodiment of the invention, Ce can also stabilize the substructure of the deformable structure in the alloy, hindering dislocation rearrangement and subgrain boundary migration, thereby suppressing crystal recrystallization. Simultaneously, the diffusion rate of Ce in the aluminum alloy core layer is low, and the diffusion rate of elements such as Cu is reduced. During high-temperature brazing, the presence of Ce reduces the activity of Cu, thus decreasing the diffusion rate of Cu to other layers, such as the low-concentration intermediate layer, resulting in a larger potential difference between the intermediate layer and the core layer compared to when Ce is not added. Therefore, the addition of Ce enables the aluminum alloy core layer to achieve a more significant potential difference between different layers, sacrificing the low-potential intermediate layer and protecting the high-potential core layer.

[0027] In this embodiment of the invention, the Mn content is 1.0-2.0%. A higher Mn content can improve the mechanical properties of the alloy, and the presence of Mn can also effectively improve the morphology of the primary Al3Fe phase, while effectively reducing the amount of β-Fe. The Fe content in the core layer is 0.1-1.0%. Fe in aluminum alloys often exists as the Al3Fe phase or other iron-rich phases. These iron-rich phases cause anodizing of the aluminum matrix, leading to continuous consumption and intergranular corrosion. Therefore, to improve the corrosion resistance of the material, the Fe content should not be too high. When Mn / Fe > 0.5, the presence of Mn further promotes the growth of the α-Fe phase. Manganese in aluminum alloys mainly exists as the MnAl6 phase. The MnAl6 phase has an electrode potential similar to that of the aluminum matrix, thereby eliminating some of the influence of strong cathodic iron-rich phases such as AlSi2Fe on the aluminum matrix, thus further improving the corrosion resistance of the material. During the alloy smelting process, due to the high temperature, Fe atoms inevitably integrate into the aluminum alloy. In addition to the positive effect of Mn, the introduction of Ce can also help. Ce has low solid solubility in α-Al, so it can form CeFe5 with Fe and precipitate from the grain, reducing the precipitation of other iron-rich second phases from the grain boundaries, lowering the probability of intergranular corrosion, and enhancing the corrosion resistance of the material.

[0028] In some embodiments, the Si content in the core layer 3 is less than or equal to 0.3%. Since Si diffusion easily leads to intergranular corrosion, the Si content should not be excessive.

[0029] In some embodiments, the Mg content in the core layer 3 is less than or equal to 0.1%. Excessive Mg content in the core layer will cause diffusion during welding, affecting welding performance; excessive Mg can also easily lead to corrosion.

[0030] In some embodiments, the Zn content in the core layer 3 is less than or equal to 0.5%. Zn can lower the potential, and a low potential makes it easier to corrode. In order to improve the corrosion resistance of the core layer, the Zn content in the core layer should not be too high, and can even be 0, thereby increasing the potential difference between the core layer and other layers and improving the corrosion resistance of the core layer.

[0031] In some embodiments, the Zr content in the core layer 3 is less than or equal to 0.25%. The microstructure of aluminum alloys without added Zr mainly consists of an α-Al matrix and other second phases, such as Al3Fe. Adding a small amount of Zr can change the second phase in the ingot structure, control or refine the as-cast structure, and inhibit recrystallization and grain growth during processing and heat treatment, thereby improving corrosion resistance.

[0032] In some embodiments, the Cr content in the core layer 3 is less than or equal to 0.25%. Cr can form intermetallic compounds such as (AlFe)Al7 and CrMnAl12 in aluminum alloys. These compounds can hinder the nucleation and growth process of recrystallization, thereby enhancing the alloy properties to a certain extent. At the same time, the Cr13Al4Cr-Al alloy forms a dense oxide film on the surface of the aluminum alloy, preventing further oxidation of the metal in harsh environments such as strong acids and strong alkalis, and improving corrosion resistance.

[0033] In some embodiments, the Ti content in the core layer 3 is less than or equal to 0.25%. The presence of a certain amount of Ti in the core layer can cause the corrosion of the material to occur in bands, thereby slowing down the corrosion rate and improving corrosion resistance.

[0034] In some embodiments, the core layer 3 also includes other impurity elements, such as Bi, Ni, etc., wherein the content of a single impurity element is ≤0.05% by mass percentage, and the total content of other impurity elements is ≤0.15%.

[0035] In some embodiments, the mass ratio of Ce to Cu (Ce / Cu) is greater than 0.02 and less than 0.08, specifically, for example, 0.021, 0.025, 0.03, 0.04, 0.05, 0.06, 0.07, 0.075, 0.079.

[0036] In this embodiment of the invention, 0.02 < Ce / Cu < 0.08. Due to the addition of Ce, during the alloy solidification process, α-Al precipitates first, followed by the formation of the eutectic Al8Cu4Ce phase, and finally the ternary eutectic reaction occurs to form Al2Cu. When 0.02 < Ce / Cu < 0.08, the eutectic Al8Cu4Ce phase in the alloy continuously increases, while the Al2Cu phase decreases accordingly. Moreover, the size of the eutectic Al8Cu4Ce phase at this time is small, and the Al8Cu4Ce phase can act as a continuously reinforcing phase in the aluminum matrix, enhancing the alloy properties. Because the eutectic Al8Cu4Ce phase is formed, the Al2Cu phase is reduced, thereby reducing the segregation of the Al2Cu phase between grains, reducing intergranular corrosion, and improving corrosion resistance.

[0037] When Ce / Cu < 0.02, the Al8Cu4Ce phase in the alloy is relatively small, with most being Al2Cu phase at the grain boundaries. The Al2Cu phase at the grain boundaries is the biggest culprit for intergranular corrosion in the core material. As the Ce / Cu ratio increases, when Ce / Cu > 0.08, the acicular Al8Cu4Ce phase gradually increases, and the Al2Cu phase adheres and grows at the edges of the Al8Cu4Ce, forming a closed network structure distributed along the grain boundaries. This closed structure composed of brittle intergranular phases compromises the alloy's corrosion resistance.

[0038] In some embodiments, the mass ratio of Ce to Fe (Ce / Fe) is greater than 0.2 and less than 0.5, specifically, for example, 0.21, 0.25, 0.3, 0.35, 0.4, 0.45, 0.49; and / or, the aluminum alloy core material is also formed with a Ce-Fe alloy.

[0039] In this embodiment of the invention, 0.2 < Ce / Fe < 0.5. When 0.2 < Ce / Fe < 0.5, the Ce element introduced into the core material forms Ce-Fe compounds such as CeFe5 with Fe and precipitates from the grain, reducing the precipitation of other iron-rich second phases. At this time, the alloy mainly contains α-Al, Al2Cu, Al8Cu4Ce and a small amount of β-Fe (such as Al7Cu2Fe) phase. The β-Fe (such as Al7Cu2Fe) is smaller in size than other iron-rich second phases and will not have a significant cutting effect on the matrix. While enhancing the strength of the material, it also reduces the Al3Fe phase in the grain boundaries to a greater extent, purifies the grain boundaries, and reduces intergranular corrosion.

[0040] When Ce / Fe < 0.2, the alloy contains coarse β-Fe phase and a small amount of Al3(Cu,Fe) phase. Since the Al3(Cu,Fe) phase is metastable in the alloy, it easily transforms into coarse β-Fe phase at the high temperatures of brazing. The β-Fe phase forms a galvanic cell with the aluminum matrix; in other words, the β-Fe phase has a higher potential relative to the aluminum matrix. In this case, the aluminum matrix acts as the anode, resulting in oxidation, consumption, and corrosion of the aluminum matrix. When the Ce / Fe ratio is greater than 0.5, the alloy is mainly Al-Cu alloy. Al-Cu alloys are relatively brittle, and their mechanical properties deteriorate, making the material prone to deformation during brazing.

[0041] In some embodiments, the Cu content in the core layer 3 is 0.6-1.3% by mass percentage. In this embodiment of the invention, this is beneficial for further improving the corrosion resistance of the aluminum alloy composite sheet. Adding a certain amount of Cu to the aluminum alloy in the core layer can increase the potential of the core layer, thereby forming a higher potential difference with other layers and protecting the core layer. However, if the Cu content is too high, it is easy for Al2Cu to segregate at the grain boundaries, making the material susceptible to intergranular corrosion and affecting its corrosion resistance. In this invention, due to the addition of a certain amount of Ce, the Cu content can be higher. Furthermore, when the Cu content is in the range of 0.6-1.3%, the potential of the core layer can be further increased while reducing intergranular corrosion, thereby better protecting the core layer and improving the overall corrosion resistance of the aluminum alloy composite sheet.

[0042] In some embodiments, the first composite layer 1 comprises an Al-Si alloy; optionally, by mass percentage, the Al-Si alloy comprises: Si: 2.0-11.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.03%, Zn: ≤0.1%, with the remainder being Al and unavoidable impurity elements. In this embodiment of the invention, the Al-Si alloy of the first composite layer is used for brazing. The first composite layer melts at high temperatures and solidifies upon cooling, thus performing the welding function.

[0043] In some embodiments, the first composite layer 1 further includes flux; optionally, in addition to the flux, a certain amount of Si powder is added to the first composite layer 1 to improve solderability, so that the Si content in the first composite layer 1 is 9.0-11.0 wt%, which makes it easier to weld with other components; optionally, the flux and Al-Si alloy are uniformly distributed in the first composite layer 1; optionally, the first composite layer 1 is a brazing layer, which is made by uniformly mixing flux powder and Al-Si alloy powder; optionally, the flux is potassium fluorochlorate powder.

[0044] In some embodiments, the flux concentration is 1.0-2.0 g / m 2 In this embodiment of the invention, the flux concentration is set to 1.0-2.0 g / m³. 2 This facilitates the mixing of the flux into the first composite layer, ensuring brazing quality, and reduces flux usage and costs compared to traditional methods that require additional flux spraying. When the flux concentration is below 1.0 g / m²... 2 If the flux concentration is too low, it will affect the brazing quality and cause poor welding; if the flux concentration is higher than 2.0 g / m³, it will also affect the welding quality. 2 This increases the difficulty of adding flux to the first composite layer and results in high processing costs.

[0045] In this embodiment of the invention, the uniform distribution of flux is a crucial factor in ensuring welding strength. The first composite layer employs pre-embedded flux technology, ensuring uniform flux distribution within the first composite layer. This guarantees welding strength and eliminates the need for drying and assembly processes. During brazing, the first composite layer melts at high temperatures, and the flux melts along with it. After the flux removes the oxide film, the solder cools and solidifies, achieving the welding effect. In related technologies, when welding heat exchange tubes to other components, flux needs to be sprayed onto the surface of the heat exchange tube to achieve brazing. After welding, the flux on the surface of the heat exchange tube also needs to be dried, and uneven spraying may occur. This application, by adding flux to the first composite layer, ensures uniform flux distribution, improves welding strength, and reduces the need for additional flux spraying and drying processes, thus lowering processing costs.

[0046] In some embodiments, the first composite layer 1 further includes other impurity elements, such as Bi, Ni, etc., wherein the content of a single impurity element is ≤0.05% by mass percentage, and the total content of other impurity elements is ≤0.15%.

[0047] In some embodiments, the second composite layer 4 comprises an Al-Si alloy; optionally, by mass percentage, the Al-Si alloy comprises: Si: 2.0-11.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.03%, Zn: ≤0.1%, with the remainder being Al and unavoidable impurity elements. In this embodiment of the invention, the Al-Si alloy of the second composite layer is used for brazing. The second composite layer melts at high temperatures and solidifies upon cooling, thus performing a welding function.

[0048] In some embodiments, the second composite layer 4 further includes flux; optionally, in addition to the flux, a certain amount of Si powder is added to the second composite layer 4 to improve soldering, so that the Si content in the second composite layer 4 is 9.0-11.0 wt%; optionally, the flux and Al-Si alloy are uniformly distributed in the second composite layer 4; optionally, the second composite layer 4 is a brazing layer, which is made by uniformly mixing flux powder and Al-Si alloy powder; optionally, the flux is potassium fluorochlorate powder.

[0049] In some embodiments, the flux concentration is 1.0-2.0 g / m 2 In this embodiment of the invention, the flux concentration is set to 1.0-2.0 g / m³. 2 This facilitates the mixing of the flux into the second composite layer while ensuring brazing quality. Furthermore, compared to the traditional method requiring additional flux spraying, it reduces flux usage and lowers costs. When the flux concentration is below 1.0 g / m²... 2 If the flux concentration is too low, it will affect the brazing quality and cause poor welding; if the flux concentration is higher than 2.0 g / m³, it will also affect the welding quality. 2 This increases the difficulty of adding flux to the second composite layer and results in high processing costs.

[0050] In this embodiment of the invention, the uniform distribution of flux is a crucial factor in ensuring welding strength. The second composite layer employs pre-embedded flux technology, ensuring uniform flux distribution within the second composite layer. This guarantees welding strength and eliminates the need for drying and assembly processes. During brazing, the second composite layer melts at high temperatures, and the flux melts along with it. After the flux removes the oxide film, the solder cools and solidifies, achieving the welding effect. In related technologies, when welding heat exchange tubes to other components, flux needs to be sprayed onto the surface of the heat exchange tube to achieve brazing. After welding, the flux on the surface of the heat exchange tube also needs to be dried, and uneven spraying may occur. This application, by adding flux to the second composite layer, ensures uniform flux distribution, improves welding strength, and reduces the need for additional flux spraying and drying processes, thus lowering processing costs.

[0051] In some embodiments, the second composite layer 4 further includes other impurity elements, such as Bi, Ni, etc., wherein the content of a single impurity element is ≤0.05% by mass percentage, and the total element content of other impurity elements is ≤0.15%.

[0052] In some embodiments, the first composite layer 1 and the second composite layer 4 have the same composition.

[0053] In some embodiments, the aluminum alloy composite sheet further includes an intermediate layer 2, such as... Figure 1 or Figure 2 As shown, the intermediate layer 2 is disposed between the core material layer 3 and the first composite layer 1; and / or, the intermediate layer 2 is disposed between the core material layer 3 and the second composite layer 4, as shown. Figure 2 As shown.

[0054] Optionally, the intermediate layer 2 comprises an Al-Mn alloy; by mass percentage, the intermediate layer 2 comprises: Si: ≤0.3%, Fe: ≤0.8%, Cu: ≤0.5%, Mn: 1.0-2.0%, Mg: ≤0.1%, Zn: 1.0-2.0%, Ti: ≤0.25%, Zr: ≤0.25%, Cr: ≤0.25%, with the remainder being Al and unavoidable impurity elements.

[0055] In this embodiment of the invention, the intermediate layer is an Al-Mn alloy layer with good resistance to intergranular corrosion. By limiting the content of elements such as Si, Fe, and Cu in the intermediate layer, the migration of Cu and Mg elements from the core layer to the composite layer can be effectively prevented, thus preventing local enrichment. It can also block the diffusion of Si from the composite layer to the core layer, thereby playing a blocking role, protecting the core layer, and improving the overall corrosion resistance of the material.

[0056] Specifically, a high Zn content in the intermediate layer can create a significant potential difference with the core layer, acting as a sacrificial anode layer for electrochemical corrosion, thus protecting the core layer during corrosion. However, to avoid excessively rapid corrosion as a sacrificial protective layer, the Zn content should not be too high; therefore, the Zn content in the intermediate layer ranges from 1.0% to 2.0%. Excessive Cu content causes Al₂Cu to agglomerate at grain boundaries, increasing the risk of intergranular corrosion. Therefore, the Cu content in the intermediate layer is low, ≤0.5%, or even 0%, to reduce the probability of intergranular corrosion. A Si content ≤0.3% in the intermediate layer can reduce intergranular corrosion caused by Si diffusion. This intermediate layer, containing Zn, Si, and Cu, also provides good resistance to intergranular corrosion and acts as a barrier. During welding, it prevents Si from diffusing from the composite layer into the core layer, improving the corrosion resistance of the core layer. It also prevents Cu, Mg, and other elements from diffusing from the core layer into the composite layer, thus protecting the core layer and improving the overall corrosion resistance of the material.

[0057] In this embodiment of the invention, the Cu element in the core layer serves to create a higher potential difference with the intermediate layer, thus protecting the core layer. Simultaneously, the presence of Ce in the aluminum alloy core layer reduces the diffusion rate of elements such as Cu. During high-temperature brazing, the presence of Ce in the core layer reduces the activity of Cu, thereby decreasing the diffusion rate of Cu to the low-concentration intermediate layer. This results in a larger potential difference between the intermediate layer and the core layer compared to when Ce is not added. Therefore, the addition of Ce creates a more significant potential difference between different layers in the aluminum alloy composite sheet, sacrificing the low-potential intermediate layer and protecting the high-potential core layer. The Zn element content in the core layer should not be too high, thereby increasing the potential difference between the core layer and the intermediate layer and improving the corrosion resistance of the core layer. The intermediate layer can block the diffusion of Cu. Through the combined advantages of the material composition design and multi-layer structure design of the aluminum alloy composite sheet, a potential difference is formed between the composite layer, the intermediate layer, and the core layer. This preferentially corrodes the low-potential intermediate layer, protecting the core layer as the cathode, and significantly improving the material's corrosion resistance.

[0058] In some embodiments, the Ce content in the core layer 3 is 0.02-0.08% by mass percentage, and the potential difference between the core layer 3 and the intermediate layer 2 is increased by at least 10mV relative to the potential difference between the core layer 3 and the intermediate layer 2 without Ce.

[0059] In this embodiment of the invention, the amount of Ce added in the core material layer is in the range of 0.02-0.08 wt%, which can significantly increase the potential difference between the intermediate layer and the core material layer, and preferentially corrode the intermediate layer, thus protecting the core material layer. Moreover, this potential difference prevents the potential gradient from changing too quickly, and the corrosion occurs slowly layer by layer with the potential gradient, which prolongs the corrosion time and further protects the core material layer from rapid corrosion, thereby protecting the heat exchange tube from being penetrated and improving the corrosion resistance of the heat exchange tube.

[0060] In some embodiments, the intermediate layer 2 further includes Ce, wherein Ce ≤ 0.10% by mass percentage.

[0061] In this embodiment of the invention, after adding Ce to the intermediate layer, Ce ≤ 0.10% can, on the one hand, purify the grain boundaries of the intermediate layer, reduce the segregation of Al2Cu in the grain boundaries, reduce the probability of grain boundary corrosion in the intermediate layer, and improve the corrosion resistance of the material; on the other hand, although the intermediate layer contains a low content of Cu, Cu in the core layer may diffuse into the intermediate layer during the brazing process. Adding a certain amount of Ce to the intermediate layer can reduce the activity of Cu, reduce the diffusion rate of Cu, and further improve the corrosion resistance of the material.

[0062] In some embodiments, the intermediate layer 2 also includes other impurity elements, such as Bi, Ni, etc., wherein the content of a single impurity element is ≤0.05% by mass percentage, and the total content of other impurity elements is ≤0.15%.

[0063] In some embodiments, the thickness of the first composite layer 1 is 10-15% of the thickness of the aluminum alloy composite sheet, specifically, for example, 10%, 11%, 12%, 13%, 14%, 15%; and / or, the thickness of the second composite layer 4 is 10-15% of the thickness of the aluminum alloy composite sheet, specifically, for example, 10%, 11%, 12%, 13%, 14%, 15%; and / or, the thickness of the intermediate layer 2 is 10-20% of the thickness of the aluminum alloy composite sheet, specifically, for example, 10%, 11%, 12%, 13%, 14%, 15%, 18%, 20%; and / or, the thickness of the core layer 3 is 60-65% of the thickness of the aluminum alloy composite sheet, specifically, for example, 60%, 61%, 62%, 63%, 64%, 65%.

[0064] In this embodiment of the invention, the thickness of the first composite layer and the second composite layer is 10-15% of the overall thickness of the aluminum alloy composite sheet. The thickness of the first and second composite layers should be sufficient to fill the solder required for welding with other components, while avoiding excessive solder ratios that could lead to erosion of the aluminum alloy composite sheet and reduced material strength. The thickness of the first and second composite layers is set within the range of 10%-15%, and the thicknesses of the first and second composite layers can be the same or different. The thickness of the intermediate layer is 10-20% of the thickness of the aluminum alloy composite sheet. The thickness of the intermediate layer should be sufficient to form a low-potential corrosion protection layer for the outer material after welding, and also sufficient to form a corrosion potential gradient that gradually increases from the outer layer to the inner layer.

[0065] This invention discloses an application of an aluminum alloy composite plate for heat exchange. In this embodiment, the aluminum alloy composite plate exhibits excellent corrosion resistance, making it suitable for heat exchange applications.

[0066] like Figure 3 or Figure 4 As shown, an embodiment of the present invention provides a heat exchange tube 5, which includes at least one heat exchange channel 6 extending along the length of the heat exchange tube 5. The heat exchange tube 5 also includes a tube wall 7, the wall surrounding the heat exchange channel 6 comprising at least a portion of the tube wall 7, and the material of the tube wall 7 comprising the aluminum alloy composite plate of the present invention. Optionally, the heat exchange tube 5 is formed by folding the aluminum alloy composite plate, and the heat exchange tube 5 can be welded to other components through a first composite layer 1 and / or a second composite layer 4.

[0067] Optionally, the heat exchange tube 5 can be a microchannel flat tube, such as... Figure 3 The flat structure shown in Figure 4 can also be an elliptical or circular heat exchange tube, or other shapes, which are not limited here.

[0068] In this embodiment of the invention, the heat exchange tube adopts the aluminum alloy composite plate of the present invention. Rare earth element Ce is introduced into the core layer of the aluminum alloy composite plate. There is a strong interaction between Ce and Cu atoms to form an Al-Cu-Ce alloy, which reduces the probability of intergranular corrosion and improves the corrosion resistance of the aluminum alloy composite plate, thereby greatly improving the corrosion resistance of the heat exchange tube.

[0069] In some embodiments, the aluminum alloy composite plate further includes an intermediate layer 2. In this embodiment of the invention, by limiting the content of elements such as Si, Fe, and Cu in the intermediate layer, the migration of Cu and Mg elements from the core layer to the composite layer can be effectively prevented, thus preventing local enrichment. It can also block the diffusion of Si from the composite layer to the core layer, thereby playing a blocking role, protecting the core layer, improving the overall corrosion resistance of the aluminum alloy composite plate, and further improving the corrosion resistance of the heat exchange tube.

[0070] In some embodiments, the aluminum alloy composite plate further includes a first composite layer 1 and a second composite layer 4, wherein the first composite layer 1 and the second composite layer 4 contain a certain amount of Si, which facilitates the welding of the heat exchange tube 5 to other components.

[0071] In some embodiments, the first composite layer 1 and / or the second composite layer 4 include flux. In these embodiments, by adding flux to the first composite layer and / or the second composite layer, on the one hand, the uniformity of flux distribution can be ensured, improving the welding strength between the heat exchange tube and other components; on the other hand, it reduces the need for additional flux spraying and drying processes when welding the heat exchange tube to other components, thus lowering processing costs and improving processing efficiency.

[0072] In some embodiments, the heat exchange tube 5 further includes a first piece 8, which is located inside the heat exchange tube 5. The wall surrounding the heat exchange channel 6 includes at least a portion of the first piece 8. The first piece 8 and the tube wall 7 are an integral structure or a separate structure. The material of the first piece 8 includes the aluminum alloy composite plate of the embodiments of the present invention.

[0073] In some embodiments, the first element 8 is located inside the heat exchange tube 5. In this embodiment of the invention, the first element can enhance the turbulence of the heat exchange medium inside the heat exchange tube, thereby improving the heat exchange performance of the heat exchange tube.

[0074] In some embodiments, the wall surrounding the heat exchange channel 6 includes at least a portion of the first piece 8, or the wall surrounding the heat exchange channel 6 includes at least a portion of the first piece 8 and the tube wall 7. Optionally, the first piece 8 and the tube wall 7 can be an integral structure, that is, a heat exchange tube 5 is formed by bending a single piece of aluminum alloy composite sheet, the heat exchange tube 5 including the first piece 8 and the tube wall 7, the first piece 8 and the tube wall 7 being formed by bending the same piece of aluminum alloy composite sheet; the first piece 8 and the tube wall 7 can also be separate structures, the heat exchange tube 5 can also be formed by bending two or more pieces of aluminum alloy composite sheet.

[0075] In some embodiments, the material of the first piece 8 includes the aluminum alloy composite plate of the present invention, and the first piece 8 can be welded to the pipe wall 7 through the first composite layer 1 and / or the second composite layer 4 of the aluminum alloy composite plate.

[0076] The heat exchanger 12 of this embodiment of the invention, such as Figure 5As shown, the heat exchanger 12 includes: a first tube 9 and a second tube 10; heat exchange tubes 5, which are heat exchange tubes 5 according to the embodiments of the present invention, and there are multiple heat exchange tubes 5. The multiple heat exchange tubes 5 are spaced apart along the length direction of the first tube 9. Each heat exchange tube 5 includes a heat exchange channel 6 extending along its length direction. The multiple heat exchange channels 6 are spaced apart along the width direction of the heat exchange tube 5. The heat exchange tubes 5 are connected to the first tube 9. Optionally, the heat exchange tubes 5 and the first tube 9 are directly or indirectly connected. The heat exchange tubes 5 are connected to the second tube 10. Optionally, the heat exchange tubes 5 and the second tube 10 are directly or indirectly connected. Optionally, the first tube 9 and / or the second tube 10 are connected to the heat exchange tubes 5 by welding.

[0077] In this embodiment of the invention, the heat exchanger uses the heat exchange tube of the present invention, which is made of aluminum alloy composite plate. Rare earth element Ce is introduced into the core layer of the aluminum alloy composite plate. There is a strong interaction between Ce and Cu atoms to form an Al-Cu-Ce alloy, which reduces the probability of intergranular corrosion and improves the corrosion resistance of the aluminum alloy composite plate. This greatly improves the corrosion resistance of the heat exchange tube and the heat exchanger, and extends the service life of the heat exchanger.

[0078] In some embodiments, such as Figure 5 As shown, the heat exchanger 12 also includes fins 11, with at least some fins 11 disposed between adjacent heat exchange tubes 5. Since the heat exchange tubes 5 have a first composite layer 1 or a second composite layer 4 on their outer side, the fins 11 can be single-layer fins. The fins 11 and the heat exchange tubes 5 are welded together through the first composite layer 1 and / or the second composite layer 4 of the heat exchange tubes 5. In this embodiment of the invention, the fins and heat exchange tubes are welded together, which reduces the gap between the heat exchange tubes and the fins, lowers the thermal resistance of the heat exchanger, and improves the heat exchange efficiency of the heat exchanger.

[0079] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0080] Example 1

[0081] like Figure 1 As shown, an aluminum alloy composite sheet includes a first composite layer 1, an intermediate layer 2, a core layer 3, and a second composite layer 4, with the intermediate layer 2 disposed between the core layer 3 and the first composite layer 1. The elemental composition of the alloys in each layer is shown in Table 1. The thickness percentages of the first composite layer 1, intermediate layer 2, core layer 3, and second composite layer 4 are 10%, 15%, 65%, and 10%, respectively.

[0082] Table 1

[0083] Chemical composition / wt% Si Fe Cu Mn Mg Zn Ti Zr Cr Ce Al First composite layer 1 10.4 0.18 0.02 0.02 0.02 0.01 / / / / RES Intermediate layer 2 0.08 0.15 0.01 1.57 0.01 1.92 0.15 0.15 0.15 / RES Core layer 3 0.08 0.27 1.23 1.50 0.05 0.08 0.04 0.15 0.11 0.06 RES Second composite layer 4 10.4 0.18 0.02 0.02 0.02 0.01 / / / / RES

[0084] The aluminum alloy composite plate is folded to form the heat exchange tube 5, and the heat exchange tube 5 is connected with other components to form the heat exchanger 12.

[0085] Examples 2-8

[0086] Similar to the aluminum alloy composite plate and heat exchanger 12 in Example 1, the difference is that the contents of Fe, Cu and Ce in the core layer 3 of the aluminum alloy composite plates in Examples 2 to 8 are shown in Tables 2 and 3.

[0087] Examples 9-12

[0088] Similar to the aluminum alloy composite plate and heat exchanger 12 in Example 1, the difference is that the Ce content of the core layer 3 of the aluminum alloy composite plates in Examples 9 to 12 is shown in Table 4.

[0089] Comparative Examples 1-6

[0090] Similar to the aluminum alloy composite plate and heat exchanger 12 in Example 1, the difference is that the contents of Fe, Cu, and Ce in the core layer 3 of the aluminum alloy composite plates in Comparative Examples 1-6 are shown in Tables 2 and 3.

[0091] Comparative Example 7

[0092] Similar to the aluminum alloy composite plate and heat exchanger 12 in Example 1, the difference is that the Ce content of the core layer 3 of the aluminum alloy composite plate in Comparative Example 7 is shown in Table 4.

[0093] Corrosion resistance refers to the resistance of aluminum alloy composite sheets to general corrosion and intergranular corrosion in the corrosive environment specified in the ASTM G85-A3 SWAAT TEST standard. Specifically, the test environment is as follows: the salt solution is simulated synthetic seawater with a concentration of 42 g / L, the pH value of the solution is 2.8-3.0, and the temperature inside the chamber is set at 49°C; the test cycle is 30 minutes of spraying + 90 minutes of immersion in moisture at 98% RH or higher.

[0094] Resistance to overall corrosion refers to the durability of the aluminum alloy composite sheet against overall corrosion, in other words, its durability against leakage failure. Resistance to intergranular corrosion refers to the maximum depth of intergranular corrosion occurring in the aluminum alloy composite sheet. In this invention, it is a comparison of the maximum intergranular corrosion depth under the same SWAAT test time. Under the same time, the greater the maximum depth of intergranular corrosion, the weaker the resistance to intergranular corrosion; conversely, the stronger the resistance.

[0095] The heat exchangers 12 tested in the embodiments are identical except for the chemical elements of the aluminum alloy composite plate; the manifolds, fins 11, and other components are the same.

[0096] The corrosion resistance of the aluminum alloy composite plate and the heat exchanger 12 in the embodiments and comparative examples of the present invention are compared, as shown in Tables 2 and 3. Corrosion performance evaluation methods were used to evaluate the resistance to general corrosion and intergranular corrosion of the aluminum alloy composite plate and the heat exchanger 12, respectively. For the aluminum alloy composite plate: Before testing, aluminum alloy composite materials of the same size were sealed near the surface of the second composite layer 4 and the edge of the aluminum alloy composite plate, and placed in the SWAAT test chamber at a vertical angle of 15°. For the heat exchanger 12: Before testing, heat exchanger 12 samples of the same model were placed near the finless area of ​​the first tube 9 or the second tube 10, and placed in the SWAAT test chamber at a vertical angle of 15°.

[0097] Table 2

[0098]

[0099]

[0100] During the testing process, aluminum alloy composite plates were subjected to SWAAT testing for 500 and 700 hours, respectively. The maximum depth of intergranular corrosion in the aluminum alloy composite plates was measured using metallographic methods. By comparing the maximum corrosion depth at different times, the corrosion resistance of the materials in different embodiments or comparative examples was determined. The smaller the maximum corrosion depth, the stronger the corrosion resistance. "SWAAT 500h" indicates the maximum depth of intergranular corrosion observed under a metallographic microscope after 500 hours in the SWAAT test chamber. "SWAAT 700h" indicates the maximum depth of intergranular corrosion after 700 hours of SWAAT testing.

[0101] During SWAAT 1500h, the aluminum alloy composite panel was simply cleaned with alcohol, placed in complete darkness, and a beam of light was emitted directly onto it to measure its light transmittance. The light transmittance of the aluminum alloy composite panel is calculated as: (Area of ​​transmitted beam) / (Original area of ​​the aluminum alloy composite panel). Light transmittance also indicates that the aluminum alloy composite panel has been corroded through; the larger the area penetrated, the higher the light transmittance. The more areas of penetration, the worse the corrosion resistance of the aluminum alloy composite panel.

[0102] In Examples 1-5, when the Ce / Fe content of the core layer 3 is within the range of 0.2-0.5, the advantages of the material composition design and multi-layer structure design of the aluminum alloy composite plate are combined to form a potential difference between the composite layer, the intermediate layer 2, and the core layer 3, protecting the core layer 3 as the cathode, and significantly improving the corrosion resistance of the aluminum alloy. For example, in the core layer 3 of the aluminum alloy composite plate in Example 1, Fe is 0.27wt%, Ce is 0.06%, the Ce / Fe ratio is 0.22, the Ce / Fe ratio is within the range of 0.2-0.5, the transmittance is 52.2μm after "SWAAT 500h", 60.5μm after "SWAAT 700h", and the transmittance is 9% after SWAAT 1500h. The Ce / Fe ratio of Comparative Example 1 was 0.12, and that of Comparative Example 2 was 0.77. Neither of these Ce / Fe ratios falls within the range of 0.2-0.5. Comparing the maximum intergranular corrosion depth and light transmittance after 1500 hours of comparison between Example 1, Comparative Example 1, and Comparative Example 2, the maximum intergranular corrosion depth and light transmittance of Example 1 were significantly reduced. This indicates that the corrosion resistance of aluminum alloy composite plates with a Ce / Fe ratio of core layer 3 within the range of 0.2-0.5 is significantly better than that of aluminum alloy composite plates with a Ce / Fe ratio of core layer 3 outside the range of 0.2-0.5.

[0103] In Examples 6-8, when the Ce / Cu content of the core layer 3 is within the range of 0.02-0.08, the advantages of the material composition design and multi-layer structure design of the aluminum alloy composite plate are combined to form a potential difference between the composite layer, the intermediate layer 2, and the core layer 3, protecting the core layer 3 as the cathode, and significantly improving the corrosion resistance of the aluminum alloy. For example, in the core layer 3 of the aluminum alloy composite plate in Example 8, Cu is 1.53wt%, Ce is 0.09wt%, the Ce / Cu ratio is 0.06, the Ce / Cu is within the range of 0.02-0.08, the transmittance is 57.4μm after "SWAAT 500h", the transmittance is 59.3μm after "SWAAT 700h", and the transmittance is 10% after SWAAT 1500h. The Ce / Cu ratio of Comparative Example 3 was 0.01, and that of Comparative Example 4 was 0.11. Neither of these Ce / Cu ratios falls within the range of 0.02-0.08. Comparing the maximum intergranular corrosion depth and light transmittance after 1500 hours of comparison with Example 8, Comparative Example 3, and Comparative Example 4, the maximum intergranular corrosion depth and light transmittance of Example 8 were significantly reduced. This indicates that the corrosion resistance of aluminum alloy composite plates with a Ce / Cu ratio of core layer 3 within the range of 0.02-0.08 is significantly better than that of aluminum alloy composite plates with a Ce / Cu ratio of core layer 3 outside the range of 0.02-0.08.

[0104] Comparative Example 5 is an aluminum alloy composite plate with core layer 3 without the addition of rare earth element Ce. As can be seen from Table 2, the maximum depth of intergranular corrosion of the aluminum alloy composite plate is greater than that with the addition of rare earth element Ce. The light transmittance of Comparative Example 5 is as high as 36%, and the corrosion resistance of the aluminum alloy composite plate is relatively poor.

[0105] Comparative Example 6 is an aluminum alloy composite plate with 0.27 wt% Ce added to the core layer 3. Comparing the maximum intergranular corrosion depth and the light transmittance after 1500 hours of SWAAT between Example 1 and Comparative Example 6, it can be seen that when the amount of Ce added to the core layer 3 of the aluminum alloy composite plate is higher than 0.1 wt%, the corrosion resistance is poor, and when the amount of Ce added is less than 0.1 wt%, the corrosion resistance is good.

[0106] Table 3

[0107]

[0108]

[0109] In Table 3, for the heat exchanger 12 sample examples, during the testing process, heat exchanger 12 samples from different embodiments or comparative examples were taken out of the SWAAT test chamber at 2000h and 3000h respectively. The average corrosion depth of the heat exchange tube 5 in the finned area was measured by metallography, and the corrosion resistance of the heat exchange tube 5 in different embodiments or comparative examples was determined by comparing the corrosion depth at different times. The smaller the average corrosion depth of the heat exchange tube 5, the stronger the corrosion resistance of the heat exchanger 12 sample. "SWAAT 2000h" indicates the average corrosion depth after 2000h in the SWAAT test chamber. "SWAAT 3000h" indicates the average corrosion depth after 3000h in the SWAAT test chamber.

[0110] Meanwhile, the corrosion resistance of heat exchanger 12 can also be determined by the leakage time of the heat exchanger 12 sample. The longer the duration in the SWAAT test chamber, the stronger the corrosion resistance. The leakage time of heat exchanger 12 is the time it takes for the heat exchanger tube 5 of the heat exchanger 12 sample to corrode and leak during the salt spray test.

[0111] As can be seen from Examples 1-5, when the Ce / Fe content of the core material layer 3 is within the range of 0.2-0.5, the corrosion resistance of the heat exchanger 12 is significantly improved. For example, the heat exchanger 12 of Example 1 has a Ce / Fe ratio of 22.3 μm for "SWAAT 2000h" and 44.8 μm for "SWAAT 3000h", and a leakage time of 4224 hours. The Ce / Fe ratio of Comparative Example 1 is 0.12, and that of Comparative Example 2 is 0.77. Neither of these Ce / Fe ratios falls within the range of 0.2-0.5. Comparing the average corrosion depth and leakage time of Examples 1, Comparative Example 1, and Comparative Example 2, the average corrosion depth of Example 1 is lower, while the leakage time is significantly higher. Therefore, it can be concluded that the corrosion resistance of the heat exchanger 12 with a Ce / Fe ratio of core material layer 3 within the range of 0.2-0.5 is significantly better than that of the heat exchanger 12 with a Ce / Fe ratio outside the range of 0.2-0.5.

[0112] As can be seen from Examples 6-8, when the Ce / Cu content of the core material layer 3 is in the range of 0.02-0.08, the corrosion resistance of the heat exchanger 12 is significantly improved. For example, the heat exchanger 12 of Example 6 has a corrosion depth of 20.4 μm after SWAAT 2000h, a corrosion depth of 43.1 μm after SWAAT 3000h, and a leakage time of 4478 hours. The Ce / Cu ratio of Comparative Example 3 was 0.01, and that of Comparative Example 4 was 0.11. Neither of these Ce / Cu ratios falls within the range of 0.02-0.08. Comparing the average corrosion depth and leakage time of Example 6, Comparative Example 3, and Comparative Example 4, the average corrosion depth of Example 6 was reduced, while the leakage time was significantly increased. It can be concluded that the corrosion resistance of heat exchanger 12 with a Ce / Cu ratio of core material layer 3 within the range of 0.02-0.08 is significantly better than that of heat exchanger 12 with a Ce / Cu ratio of core material layer 3 outside the range of 0.02-0.08.

[0113] By comparing Tables 2 and 3, it can be seen that the samples with rare earth element Ce added to the core material layer 3 in the embodiments of the present invention, whether aluminum alloy composite plates or heat exchanger 12 samples, have better corrosion resistance than the samples without Ce added to the core material layer 3. Moreover, the corrosion resistance is best when the Ce content of the core material layer 3 is less than 0.1 wt%.

[0114] The corrosion resistance evaluation method used in Table 4 is as follows: Before testing, one side of the aluminum alloy composite plate was sealed with electroplated adhesive and further sealed with 3M electrical adhesive. It was then placed alternately at a 15° vertical angle and tested in a SWAAT chamber for 21, 42, and 50 days. During the test, "O" indicates that the aluminum alloy composite plate was not penetrated, and "×" indicates that the aluminum alloy composite plate was corroded through. The test results are shown in Table 4. "SWAAT 21d" represents the result after 21 days of SWAAT testing; "SWAAT 42d" represents the result after 42 days of SWAAT testing; and "SWAAT 50d" represents the result after 50 days of SWAAT testing.

[0115] Table 4

[0116]

[0117] In aluminum alloy composite plates, the corrosion potential of a single layer of multi-layer material changes in a gradient. The slower the potential gradient changes, the more obvious the gradient corrosion of the material, resulting in a slower overall corrosion rate and better corrosion resistance.

[0118] This embodiment achieves superior corrosion resistance in aluminum alloy heat exchanger tube 5 by adding a designed amount of Ce to the core layer 3 of the aluminum alloy composite plate. The Ce addition in the core layer 3 is within the range of 0.02-0.08 wt%, increasing the potential difference between the intermediate layer 2 and the core layer 3. This preferentially corrodes the intermediate layer 2, protecting the core layer 3. Furthermore, the potential gradient between the intermediate layer 2 and the core layer 3 does not change too rapidly; the corrosion of the intermediate layer 2 occurs in a stepwise manner with the potential gradient, prolonging the corrosion time and further protecting the core layer 3 from rapid corrosion. This, in turn, protects the heat exchanger tube 5 from penetration, improving its corrosion resistance.

[0119] In Example 9, the Ce element content of the core layer 3 of the aluminum alloy composite sheet is 0.02 wt%, the potential of the intermediate layer 2 is -768 mV, and the potential of the core layer 3 is -668 mV. The absolute value of the potential difference is the absolute value of the difference between the potentials of the intermediate layer 2 and the core layer 3, which is 100 mV. The aluminum alloy composite sheet in Example 9 showed no penetration after 21 days, 42 days, and 50 days, demonstrating excellent corrosion resistance.

[0120] Comparative Example 5 is an aluminum alloy composite plate without Ce added to the core layer 3. The potential of the intermediate layer 2 is -765mV, and the potential of the core layer is -680mV, with a potential difference of 85mV. The aluminum alloy composite plate in Comparative Example 5 was not penetrated after 21 days and 42 days. However, it was penetrated after 50 days. This is because the core layer 3 did not contain the rare earth element Ce.

[0121] Within the range of 0 < Ce < 0.1 wt%, the potential difference between the intermediate layer 2 and the core layer 3 increases due to the presence of Ce. Furthermore, when the Ce content is in the range of 0.02-0.08 wt%, the potential between the intermediate layer 2 and the core layer 3 can be significantly increased by at least 10 mV. As can be seen from Table 4, the potential difference between the intermediate layer 2 and the core layer 3 changes significantly with the addition of only 0.02 wt% Ce. The aluminum alloy composite plate was not penetrated after 50 days, exhibiting excellent corrosion resistance and improving the service life of the aluminum alloy composite plate, thereby improving the service life of the heat exchanger 12.

[0122] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0123] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. An aluminum alloy composite sheet, characterized in that, The aluminum alloy composite sheet comprises a core layer, a first composite layer, and a second composite layer. The first composite layer and the second composite layer are respectively disposed on both sides of the core layer along its thickness direction. By mass percentage, the core layer comprises: Mn: 1.0-2.0%, Fe: 0.1-1.0%, Cu: 0.1-3.0%, Ce: ≤0.10%, Si: ≤0.3%, Mg: ≤0.1%, Zn: ≤0.5%, Zr: ≤0.25%, Cr: ≤0.25%, Ti: ≤0.25%, with the remainder being Al and unavoidable impurity elements. The core layer forms an Al-Cu-Ce alloy.

2. The aluminum alloy composite sheet according to claim 1, characterized in that, The mass ratio of Ce to Cu is greater than 0.02 and less than 0.08, and / or the mass ratio of Ce to Fe is greater than 0.2 and less than 0.

5.

3. The aluminum alloy composite sheet according to claim 1 or 2, characterized in that, The Cu content in the core layer is 0.6-1.3% by weight.

4. The aluminum alloy composite sheet according to claim 1, characterized in that, By mass percentage, the first composite layer Includes: Si: 2.0-11.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.03%, Zn: ≤0.1%, with the remainder being Al and unavoidable impurity elements; And / or, by mass percentage, the second composite layer Includes: Si: 2.0-11.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.03%, Zn: ≤0.1%, with the remainder being Al and unavoidable impurity elements.

5. The aluminum alloy composite sheet according to claim 1 or 4, characterized in that, At least one of the first composite layer and the second composite layer includes flux, the concentration of which is 1.0-2.0 g / m³. 2 .

6. The aluminum alloy composite sheet according to claim 1, characterized in that, The aluminum alloy composite sheet further includes an intermediate layer, which is disposed between the core material layer and the first composite layer, and / or, the intermediate layer is disposed between the core material layer and the second composite layer; The intermediate layer comprises, by mass percentage: Si: ≤0.3%, Fe: ≤0.8%, Cu: ≤0.5%, Mn: 1.0-2.0%, Mg: ≤0.1%, Zn: 1.0-2.0%, Ti: ≤0.25%, Zr: ≤0.25%, Cr: ≤0.25%, with the remainder being Al and unavoidable impurity elements.

7. The aluminum alloy composite plate according to claim 6, characterized in that, The core layer contains 0.02-0.08% Ce by mass percentage, and the potential difference between the core layer and the intermediate layer is increased by at least 10mV compared to the potential difference between the core layer and the intermediate layer without Ce.

8. The aluminum alloy composite sheet according to claim 6 or 7, characterized in that, The intermediate layer also includes Ce, which is ≤0.10% by mass percentage.

9. The aluminum alloy composite sheet according to claim 6, characterized in that, The aluminum alloy composite sheet has at least one of the following characteristics: A. The thickness of the first composite layer is 10-15% of the thickness of the aluminum alloy composite plate; B. The thickness of the second composite layer is 10-15% of the thickness of the aluminum alloy composite plate; C. The thickness of the intermediate layer is 10-20% of the thickness of the aluminum alloy composite plate; D. The thickness of the core material layer is 60-65% of the thickness of the aluminum alloy composite plate.

10. A heat exchange tube, characterized in that, The heat exchange tube includes at least one heat exchange channel extending along the length of the heat exchange tube. The heat exchange tube also includes a tube wall, and the wall surrounding the heat exchange channel includes at least a portion of the tube wall. The material of the tube wall includes the aluminum alloy composite plate according to any one of claims 1 to 9.

11. The heat exchange tube according to claim 10, characterized in that, The heat exchange tube further includes a first component located inside the heat exchange tube. The wall surrounding the heat exchange channel includes at least a portion of the first component. The first component and the tube wall are an integral structure or a separate structure. The material of the first component includes the aluminum alloy composite plate according to any one of claims 1 to 9.

12. A heat exchanger, characterized in that, The heat exchanger includes: First pipe and second pipe; A heat exchange tube, wherein the heat exchange tube is the heat exchange tube according to claim 10 or 11, wherein there are multiple heat exchange tubes, the multiple heat exchange tubes are spaced apart along the length direction of the first tube, the heat exchange tube includes heat exchange channels extending along its length direction, the multiple heat exchange channels are spaced apart in the width direction of the heat exchange tube, the heat exchange tube is in communication with the first tube, the heat exchange tube is in communication with the second tube, and the first tube and / or the second tube is welded to the heat exchange tube.

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