Aluminum alloy composite board and corrosion-resistant aluminum alloy composite board

Abstract

The invention belongs to the technical field of composite aluminum alloy, and discloses an aluminum alloy composite board and a corrosion-resistant aluminum alloy composite board. The aluminum alloy composite board is of a double-layer structure which comprises a core layer and a corrosion-resistant layer; the core layer comprises a Si element, a Fe element, a Cu element, a Mn element and a Mg element, and the anti-corrosion layer comprises a Zn element, the Si element and the Fe element; the corrosion-resistant aluminum alloy composite board is obtained by carrying out zinc impregnation treatment on the aluminum alloy composite board. And after zinc impregnation treatment, the difference value between the potential of a Zn-element-free diffusion area of the anti-corrosion layer and the potential of the innermost layer of the core layer is smaller than or equal to 150 mV. The corrosion-resistant aluminum alloy composite board shows excellent layered corrosion in a corrosion environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite aluminum alloy, and relates to an aluminum alloy composite plate and a corrosion-resistant aluminum alloy composite plate. BACKGROUND

[0002] Heat exchangers are the core components in air conditioning refrigeration systems, and their performance directly determines the energy efficiency, cost and reliability of the entire machine. For a long time, in the field of non-brazing processing and metal pipe materials for heat exchangers, copper and copper alloys have been considered as the preferred materials for manufacturing heat exchangers (including evaporators and condensers) due to their excellent thermal conductivity, outstanding processing performance (such as easy bending and tube expansion) and excellent corrosion resistance.

[0003] However, with the fluctuations in the global commodity market, the continuous improvement of air conditioner energy efficiency standards and the urgent demand for lightweight and sustainable development in the industry, the application of copper materials is facing severe challenges. Aluminum materials have significant advantages such as low density (about 2.7 g / cm³, only 30% of copper), relatively stable and low price, and abundant resources. In theory, manufacturing heat exchangers with aluminum materials can effectively reduce system weight and material cost, and meet the industry direction of energy saving and environmental protection.

[0004] For the brazing field, Zn element can achieve ideal diffusion reordering during brazing process (with high temperature and molten filler material forming a special diffusion environment), while the development of aluminum alloy composite pipe materials for heat exchangers in the non-brazing processing field has always been a difficulty in corrosion effect. However, the large-scale application of aluminum materials in high-performance air conditioner heat exchangers in the prior art still has a series of technical bottlenecks to be solved, especially the corrosion resistance of the heat exchange pipe directly affects the service life of the product.

[0005] To solve the above problems, the prior art usually needs to spray a corrosion-resistant coating on such micro-channel heat exchange pipe materials. For example, the heat exchange pipes in the patents with publication numbers CN222210731U and CN203837551U need to be treated with a corrosion-resistant coating, which can be a zinc layer, a plastic spraying layer, an electrophoretic layer or a TCP layer. However, the corrosion-resistant coating is not only expensive and not environmentally friendly, but also has a relatively thin thickness (a few microns) and uneven thickness, so the corrosion resistance is limited. The example in CN203837551U only shows that the material can meet the 1000-hour salt spray test without leakage.

[0006] If no corrosion-resistant coating is sprayed, it cannot meet the corrosion resistance requirements of high-performance heat exchangers. For example, the pipe material in the patent application with publication number CN104264005A only mentions that it can pass the A3 method 720-hour test in ASTM G85.

[0007] Therefore, there is a need for an aluminum alloy composite sheet and a corrosion-resistant aluminum alloy composite sheet to solve the above problems, which is of great significance. Summary of the Invention

[0008] The purpose of this invention is to solve the problems existing in the prior art and to provide an aluminum alloy composite sheet and a corrosion-resistant aluminum alloy composite sheet.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] An aluminum alloy composite sheet has a double-layer structure, consisting of a core layer and an anti-corrosion layer.

[0011] By weight percentage, the core layer includes no more than 1.3% Si, no more than 0.7% Fe, no less than 0.3% Cu, 1%-1.82% Mn, and no less than 1% Mg.

[0012] As is known, the maximum solubility of Si in aluminum alloys is 1.65%. Si can play a good role in solid solution strengthening and improving the strength of aluminum alloys. However, from the perspective of corrosion resistance, if the content of Si exceeds 1.3%, it may lead to the incomplete solid solution of Si and also result in a decrease in its own corrosion resistance.

[0013] As a known technique, Fe can refine grains and improve the casting performance of materials. However, if the Fe content exceeds 0.7%, it will form coarse, needle-like compounds, reducing the strength and corrosion resistance of the material.

[0014] As a known technique, Cu can play a good role in solid solution strengthening and can increase the corrosion potential of materials. However, if the Cu content is less than 0.3%, the corrosion potential of the core layer will be too low.

[0015] As a known technology, Mn element has the effect of solid solution strengthening and increasing the corrosion potential of materials. If the content of Mn element is less than 1%, it will lead to a decrease in material strength and an excessively low corrosion potential. The limiting solid solubility of Mn element is 1.82%. If the content of Mn element is higher than 1.82%, it will not increase strength and potential, but will generate coarse compounds, leading to a decrease in material strength and corrosion performance.

[0016] This invention introduces Mg element into the core layer. The Mg element in the core layer and the Mg element diffusing into the anti-corrosion layer affect the solid solution of Zn element, thereby forming an unexpected potential difference gradient. This makes the material exhibit excellent layered corrosion in a corrosive environment. If the content of Mg element is less than 1%, it cannot react sufficiently with the Zn element diffusing into the anti-corrosion layer, resulting in insufficient potential difference between the anti-corrosion layer and the core layer.

[0017] By weight percentage, the anti-corrosion layer includes 2%-3% Zn, Si, and Fe elements, wherein the total content of Si and Fe elements does not exceed 0.7%, and the content of Mg elements does not exceed 0.05%.

[0018] Zn can reduce the corrosion potential of the anti-corrosion layer. If the Zn content is less than 2%, the anti-corrosion layer cannot effectively protect the core layer. If the Zn content is greater than 3%, the potential of the anti-corrosion layer will be too low, which will accelerate the self-corrosion rate and cause the anti-corrosion layer to be consumed prematurely.

[0019] The addition of Si and Fe elements to the anti-corrosion layer helps casting performance, but micro-cell corrosion can occur between the compounds formed by Si and Fe elements and the aluminum matrix. Excessive Si and Fe elements can lead to a decrease in the self-corrosion performance of the anti-corrosion layer.

[0020] The inventors discovered that Mg affects the solid solution of Zn. Therefore, the anti-corrosion layer should be controlled to contain virtually no Mg, that is, the Mg content should not exceed 0.05%.

[0021] As a preferred technical solution:

[0022] As described above, in an aluminum alloy composite sheet, the content of Cu in the core layer does not exceed 1% by weight, and the content of Mg does not exceed 2%.

[0023] As described above, the composite ratio of the anti-corrosion layer in the aluminum alloy composite sheet (i.e., the proportion of the anti-corrosion layer to the thickness of the aluminum alloy composite sheet) is 15%-20%.

[0024] The aluminum alloy composite sheet described above has a finished thickness of 0.4-0.8 mm.

[0025] The aluminum alloy composite sheet described above is prepared by hot rolling a first sheet and a second sheet together, followed by cold rolling (cold rolling is rolling at room temperature) to the target thickness, and then annealing to the H2x or O state to suit subsequent processing into heat exchange tubes, thus obtaining the aluminum alloy composite sheet. The material of the first sheet is the same as the core layer, and the material of the second sheet is the same as the anti-corrosion layer. For example, the preheating temperature of the hot rolling is controlled at 480-520℃, and the annealing temperature is 200-400℃.

[0026] The present invention also provides a corrosion-resistant aluminum alloy composite sheet, which is obtained by zinc diffusion treatment of an aluminum alloy composite sheet as described above;

[0027] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer is 200-350mV;

[0028] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is ≥50mV. This characteristic is related to the zinc diffusion treatment process, the amount of elements that initially affect the potential, and the solid solution of Zn (affected by the content of Mg). If the difference is too small, the ability to sacrifice corrosion will be lost.

[0029] After zinc diffusion treatment, the potential difference between the non-Zn diffusion region of the anti-corrosion layer and the potential of the innermost layer of the core layer is ≤150mV. This characteristic is related to the zinc diffusion treatment process and the amount of elements that initially affect the potential. If the difference is too large, it will lead to an accelerated rate of salvage of the anti-corrosion layer.

[0030] As a preferred technical solution:

[0031] As described above, in a corrosion-resistant aluminum alloy composite sheet, after zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 100-300μm, and this characteristic is related to the zinc diffusion treatment process.

[0032] The corrosion-resistant aluminum alloy composite plate described above undergoes zinc diffusion treatment at a temperature of 450-500℃ for 3-7 hours. The zinc diffusion treatment process involves static treatment under high temperature and normal pressure to regulate the diffusion of Zn elements.

[0033] The corrosion-resistant aluminum alloy composite plate described above has a corrosion resistance performance that meets the ASTM G85 A3 standard for more than 3000 hours.

[0034] Invention principle:

[0035] Normally, zinc diffusion treatment alone is insufficient to meet the ASTM G85 A3 test requirements of 5000 / 3000 hours or more. In the absence of magnesium, to ensure that the potential of the outermost layer of the zinc-diffused coating exceeds that of the outermost layer of the core layer by at least 50mV, the zinc diffusion treatment temperature or time needs to be reduced to ensure a high concentration of Zn and a low potential in the coating. However, this results in a lower Zn diffusion depth. Once the diffusion area is completely corroded, the core layer, lacking protection, is rapidly corroded through.

[0036] To ensure sufficient diffusion depth of Zn, adequate temperature and time for zinc diffusion treatment are necessary. However, this leads to a significant reduction in Zn content in the anti-corrosion layer, with the Zn content in the outermost layer of the core layer approaching that of the anti-corrosion layer. Insufficient corrosion potential difference results in the anti-corrosion layer failing to adequately protect the core layer.

[0037] This invention employs sufficient temperature and time for zinc diffusion treatment to ensure the diffusion depth of Zn. Simultaneously, to prevent a decrease in the potential difference between the two layers due to a significant reduction in Zn content in the anti-corrosion layer and a significant increase in its content in the core layer (which would cause the anti-corrosion layer to lose its sacrificial corrosion resistance and fail to protect the core layer), this invention introduces Mg into the core layer. The Mg in the core layer, as well as the Mg diffusing into the anti-corrosion layer, affects the solid solution of Zn. Even if Zn diffuses from the anti-corrosion layer to the core layer, the high Mg content in the core layer reduces the solid solution of Zn, thereby increasing the corrosion potential of the core layer and thus increasing the potential difference between the two layers. Therefore, after zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is ≥50mV.

[0038] Beneficial effects:

[0039] (1) In this invention, Mg element is introduced into the core layer. The solid solution of Zn element is affected by the Mg element in the core layer and the Mg element diffused into the anti-corrosion layer, thereby forming an unexpected potential gradient, which makes the material exhibit excellent layered corrosion in the corrosion environment.

[0040] (2) The corrosion-resistant aluminum alloy composite plate of the present invention does not require additional anti-corrosion coating. The thickness of the anti-corrosion coating is more than 60μm and the thickness is uniform, which has higher corrosion resistance. Detailed Implementation

[0041] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0042] Explanation of terms: The numerical values ​​of alloying elements in the text should be understood as referring to the weight content of the element. The measured values ​​of the element composition are retained to one decimal place. For example, the measured value of Mn is 1.81136%, so the measured value is recorded as 1.8%.

[0043] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0044] Potential Measurement: The aluminum alloy composite plates prepared in each embodiment and comparative example were used as samples. The corrosion potential of the samples at the target thickness location was tested using a Metrohm electrochemical workstation according to ASTM G69 standard to obtain the potential values ​​of different layers. During the potential measurement process, the raw material is corroded layer by layer in the electrolyte over a long period, continuously exposing new surfaces until the corrosion-resistant side surface of the material reaches the core layer surface.

[0045] The diffusion depth of Zn into the core layer: The aluminum alloy composite plates prepared in each embodiment and each comparative example were used as samples. Then, the Zn element in the longitudinal section of the sample was quantitatively scanned and analyzed using a Shimadzu electron probe microanalysis device (model EPMA-1720) to determine the change in Zn element content at different positions in the longitudinal section of the plate, thereby determining the diffusion depth of Zn element.

[0046] Corrosion resistance: The aluminum alloy composite plates prepared in each embodiment and each comparative example were used as samples, and the corrosion resistance of the samples was tested using method A3 in ASTM G85 standard.

[0047] Example 1

[0048] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0049] (1) Preparation of raw materials;

[0050] First plate: by weight percentage, it consists of 1% Si, 0.3% Fe, 0.3% Cu, 1% Mn, 1% Mg, balance Al and unavoidable impurities;

[0051] Second plate: by weight percentage, it consists of 2% Zn, 0.3% Si, 0.4% Fe, the balance Al, and unavoidable impurities;

[0052] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 480℃;

[0053] (3) After the composite material that has reached the target thickness is annealed to the H24 state, the aluminum alloy composite plate is obtained; wherein the annealing temperature is 200℃.

[0054] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0055] The finished aluminum alloy composite sheet has a thickness of 0.4 mm, with a 15% composite rate for the anti-corrosion layer.

[0056] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 450℃ and the time is 7h.

[0057] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 253mV;

[0058] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 51mV.

[0059] After zinc diffusion treatment, the potential difference between the Zn-free diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 114mV.

[0060] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 152μm;

[0061] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 in ASTM G85 standard for 30-45 hours.

[0062] Comparative Example 1

[0063] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that the content of Mg in the first sheet is 0.8% by weight.

[0064] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the aluminum alloy composite plate used is the one prepared in this comparative example.

[0065] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 41mV.

[0066] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 for 2849 hours at most.

[0067] Comparing Comparative Example 1 and Example 1, it can be seen that the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer obtained in this comparative example is too small, which leads to a decrease in corrosion resistance. This is because the Mg element in the core layer and the Mg element diffusing into the anti-corrosion layer affect the solid solution of the Zn element, thereby forming an unexpected potential gradient, which makes the material exhibit excellent layered corrosion in the corrosive environment. Compared with Example 1, the Mg element in the core layer of Comparative Example 1 is too low, which cannot react sufficiently with the Zn diffusing into the anti-corrosion layer, resulting in insufficient potential difference between the anti-corrosion layer and the core material, which in turn leads to a decrease in corrosion resistance.

[0068] Comparative Example 2

[0069] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that the Zn content in the second sheet is 1.8% by weight.

[0070] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the aluminum alloy composite plate used is the one prepared in this comparative example.

[0071] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 43mV.

[0072] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 for 2037 hours at most.

[0073] Comparing Comparative Example 2 and Example 1, it can be seen that the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer obtained in this comparative example is too small, which leads to a decrease in corrosion resistance. This is because Zn can reduce the corrosion potential of the anti-corrosion layer, while the Zn content of the second plate in Comparative Example 2 is too low, which makes the anti-corrosion layer unable to play a good role in protecting the core layer, thus leading to a decrease in corrosion resistance.

[0074] Comparative Example 3

[0075] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that the Zn content in the second sheet is 3.2% by weight.

[0076] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the aluminum alloy composite plate used is the one prepared in this comparative example.

[0077] After zinc diffusion treatment, the potential difference between the Zn-free diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 159mV.

[0078] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 for 2812 hours at most.

[0079] Comparing Comparative Example 3 and Example 1, it can be seen that the difference between the potential of the non-Zn diffusion region of the anti-corrosion layer and the potential of the innermost layer of the core layer in the corrosion-resistant aluminum alloy composite plate prepared in this comparative example is too large, which leads to a decrease in corrosion resistance. This is because Zn can reduce the corrosion potential of the anti-corrosion layer. However, the Zn content of the second plate in Comparative Example 3 is too high, which makes the potential of the anti-corrosion layer too low, which will accelerate the self-corrosion rate and cause the anti-corrosion layer to be consumed prematurely, thus leading to a decrease in corrosion resistance.

[0080] Comparative Example 4

[0081] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that: by weight percentage, the content of Si element in the first sheet is 1.5% and the content of Fe element is 0.8%.

[0082] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the aluminum alloy composite plate used is the one prepared in this comparative example.

[0083] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 for 2906 hours at most.

[0084] Comparing Comparative Example 4 with Example 1, it can be seen that the corrosion resistance of the corrosion-resistant aluminum alloy composite plate prepared in this comparative example is reduced. This is because although Si can play a good role in solid solution strengthening and improving the strength of aluminum alloy, from the perspective of corrosion resistance, the excessive Si content used in this comparative example may lead to incomplete solid solution of Si, and also result in poor corrosion resistance. At the same time, although Fe can refine grains and improve the casting performance of the material, the excessive Fe content used in this comparative example will also lead to the formation of coarse, needle-like compounds, thereby reducing the strength and corrosion resistance of the material.

[0085] Comparative Example 5

[0086] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that: by weight percentage, the content of Si element in the second sheet is 0.5%, and the total amount of Si and Fe is 0.9%.

[0087] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the aluminum alloy composite plate used is the one prepared in this comparative example.

[0088] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 for 2684 hours at most.

[0089] Comparing Comparative Example 5 with Example 1, it can be seen that the corrosion resistance of the corrosion-resistant aluminum alloy composite plate prepared in this comparative example is reduced. This is because adding appropriate amounts of Si and Fe elements to the anti-corrosion layer can help casting performance, but micro-cell corrosion will occur between the compound formed by Si and Fe elements and the aluminum matrix. The amount of Si and Fe elements added in this comparative example is too high, which also leads to a decrease in the self-corrosion performance of the anti-corrosion layer.

[0090] Comparative Example 6

[0091] A method for preparing an aluminum alloy composite sheet is the same as in Example 1.

[0092] A method for preparing an aluminum alloy composite sheet is basically the same as in Example 1, except that the zinc diffusion treatment time is 2 hours.

[0093] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 47mV.

[0094] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 93μm;

[0095] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 standard for 2104 hours.

[0096] Comparing Comparative Example 6 and Example 1, it can be seen that the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer in the corrosion-resistant aluminum alloy composite plate prepared in this comparative example is too small, and the diffusion depth of Zn element into the core layer is too low. This is because the zinc diffusion treatment time affects the diffusion depth of Zn element. If the zinc diffusion treatment time is too short, it will lead to the diffusion depth of Zn element into the core layer being too low, which in turn leads to the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer being too small, resulting in reduced corrosion resistance.

[0097] Comparative Example 7

[0098] A method for preparing an aluminum alloy composite sheet is the same as in Example 1.

[0099] A method for preparing a corrosion-resistant aluminum alloy composite plate is basically the same as in Example 1, except that the zinc diffusion treatment temperature is 400℃.

[0100] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 44mV.

[0101] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 84μm;

[0102] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can only pass the A3 method of ASTM G85 standard for 2056 hours.

[0103] Comparing Comparative Example 7 and Example 1, it can be seen that the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer in the corrosion-resistant aluminum alloy composite plate prepared in this comparative example is too small, and the diffusion depth of Zn element into the core layer is too low. This is because the temperature of zinc diffusion treatment affects the diffusion depth of Zn element. If the temperature of zinc diffusion treatment is too low, it will lead to the diffusion depth of Zn element into the core layer being too low, which in turn leads to the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer being too small, resulting in reduced corrosion resistance.

[0104] Example 2

[0105] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0106] (1) Preparation of raw materials;

[0107] First plate: by weight percentage, it consists of 0.8% Si, 0.7% Fe, 0.7% Cu, 1.5% Mn, 1.5% Mg, the balance being Al and unavoidable impurities;

[0108] Second plate: by weight percentage, it consists of 2.5% Zn, 0.2% Si, 0.1% Fe, the balance Al, and unavoidable impurities;

[0109] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 500℃;

[0110] (3) After the composite material that has reached the target thickness is annealed to the H22 state, the aluminum alloy composite plate is obtained; wherein, the annealing temperature is 300℃.

[0111] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0112] The finished aluminum alloy composite sheet has a thickness of 0.6mm, with the anti-corrosion layer having a composite rate of 18%.

[0113] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 480℃ and the time is 5h.

[0114] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 310mV;

[0115] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 62mV.

[0116] After zinc diffusion treatment, the potential difference between the non-Zn diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 128mV.

[0117] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 194μm;

[0118] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 in ASTM G85 standard for 3749 hours.

[0119] Example 3

[0120] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0121] (1) Preparation of raw materials;

[0122] First plate: by weight percentage, it consists of 1.3% Si, 0.5% Fe, 1% Cu, 1.8% Mn, 2% Mg, balance Al and unavoidable impurities;

[0123] Second plate: by weight percentage, it consists of 3% Zn, 0.3% Si, 0.25% Fe, the balance Al, and unavoidable impurities;

[0124] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 520℃;

[0125] (3) After the composite material that has reached the target thickness is annealed to the 0 state, the aluminum alloy composite plate is obtained; wherein, the annealing temperature is 400℃.

[0126] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0127] The finished aluminum alloy composite sheet has a thickness of 0.8mm, with the anti-corrosion layer having a composite rate of 20%.

[0128] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 500℃ and the time is 3h.

[0129] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 350mV;

[0130] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 67mV.

[0131] After zinc diffusion treatment, the potential difference between the Zn-free diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 143mV.

[0132] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 237μm;

[0133] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 in ASTM G85 standard for 3939 hours.

[0134] Example 4

[0135] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0136] (1) Preparation of raw materials;

[0137] First plate: by weight percentage, it consists of 0.7% Si, 0.4% Fe, 1% Cu, 1.2% Mn, 1% Mg, balance Al and unavoidable impurities;

[0138] Second plate: by weight percentage, it consists of 2.3% Zn, 0.1% Si, 0.2% Fe, the balance Al, and unavoidable impurities;

[0139] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 480℃;

[0140] (3) After the composite material that has reached the target thickness is annealed to the O state, the aluminum alloy composite plate is obtained; wherein the annealing temperature is 360℃.

[0141] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0142] The finished aluminum alloy composite sheet has a thickness of 0.5mm, with a composite rate of 16% for the anti-corrosion layer.

[0143] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 450℃ and the time is 7h.

[0144] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 284mV;

[0145] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 54mV.

[0146] After zinc diffusion treatment, the potential difference between the non-Zn diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 129mV.

[0147] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 259μm;

[0148] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 of ASTM G85 standard for 4130 hours.

[0149] Example 5

[0150] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0151] (1) Preparation of raw materials;

[0152] First plate: By weight percentage, it consists of 1.2% Si, 0.6% Fe, 0.6% Cu, 1.8% Mn, 1.2% Mg, the balance being Al and unavoidable impurities;

[0153] Second plate: by weight percentage, it consists of 2.6% Zn, 0.3% Si, 0.15% Fe, the balance Al, and unavoidable impurities;

[0154] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 500℃;

[0155] (3) After the composite material that has reached the target thickness is annealed to the H24 state, the aluminum alloy composite plate is obtained; wherein, the annealing temperature is 250℃.

[0156] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0157] The finished aluminum alloy composite sheet has a thickness of 0.45mm, with the anti-corrosion layer having a composite rate of 18%.

[0158] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 500℃ and the time is 3h.

[0159] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 302mV;

[0160] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 59mV.

[0161] After zinc diffusion treatment, the potential difference between the Zn-free diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 124mV.

[0162] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 167μm;

[0163] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 of ASTM G85 standard for 3268 hours.

[0164] Example 6

[0165] A method for preparing an aluminum alloy composite sheet, comprising the following steps:

[0166] (1) Preparation of raw materials;

[0167] First plate: by weight percentage, it consists of 1.3% Si, 0.7% Fe, 0.5% Cu, 1.6% Mn, 1.6% Mg, balance Al and unavoidable impurities;

[0168] Second plate: by weight percentage, it consists of 2.8% Zn, 0.2% Si, 0.3% Fe, the balance Al, and unavoidable impurities;

[0169] (2) The first plate and the second plate are hot-rolled together and then cold-rolled to the target thickness; wherein the preheating temperature during hot rolling is 520℃;

[0170] (3) After the composite material that has reached the target thickness is annealed to the H22 state, the aluminum alloy composite plate is obtained; wherein the annealing temperature is 320℃.

[0171] The final aluminum alloy composite sheet has a double-layer structure, consisting of a core layer (made of the same material as the first sheet) and an anti-corrosion layer (made of the same material as the second sheet).

[0172] The finished aluminum alloy composite sheet has a thickness of 0.55mm, with a 17% composite rate for the anti-corrosion layer.

[0173] A method for preparing a corrosion-resistant aluminum alloy composite plate, the specific process of which is as follows: the aluminum alloy composite plate is subjected to zinc diffusion treatment to obtain the corrosion-resistant aluminum alloy composite plate; wherein, the zinc diffusion treatment temperature is 460℃ and the time is 6h.

[0174] Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer was 326mV;

[0175] After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is 64mV.

[0176] After zinc diffusion treatment, the potential difference between the non-Zn diffusion region of the anti-corrosion layer and the innermost layer of the core layer is 137mV.

[0177] After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 216μm;

[0178] The corrosion resistance of corrosion-resistant aluminum alloy composite plates can be tested by method A3 in ASTM G85 standard for 3847 hours.

Claims

1. An aluminum alloy composite sheet, characterized in that, It has a dual-layer structure, consisting of a core layer and an anti-corrosion layer; By weight percentage, the core layer includes no more than 1.3% Si, no more than 0.7% Fe, no less than 0.3% Cu, 1%-1.82% Mn, and no less than 1% Mg. By weight percentage, the anti-corrosion layer includes 2%-3% Zn, Si, and Fe elements, of which the total content of Si and Fe elements does not exceed 0.7%, and the content of Mg elements does not exceed 0.05%.

2. The aluminum alloy composite sheet according to claim 1, characterized in that, By weight percentage, the content of Cu in the core layer does not exceed 1%, and the content of Mg does not exceed 2%.

3. The aluminum alloy composite sheet according to claim 1, characterized in that, The composite rate of the anti-corrosion layer in aluminum alloy composite sheets is 15%-20%.

4. The aluminum alloy composite sheet according to claim 1, characterized in that, The finished thickness of aluminum alloy composite sheets is 0.4-0.8mm.

5. An aluminum alloy composite sheet according to claim 4, characterized in that, The preparation method of aluminum alloy composite sheet is as follows: hot rolling the first sheet and the second sheet together, then cold rolling to the target thickness, and then annealing to H2x or O state to obtain aluminum alloy composite sheet. The material of the first sheet is the same as that of the core layer, and the material of the second sheet is the same as that of the anti-corrosion layer.

6. A corrosion-resistant aluminum alloy composite sheet, characterized in that, The aluminum alloy composite sheet as described in any one of claims 1-5 is obtained by zinc diffusion treatment; Before zinc diffusion treatment, the potential difference between the anti-corrosion layer and the core layer is 200-350mV; After zinc diffusion treatment, the potential difference between the outermost layer of the anti-corrosion layer and the outermost layer of the core layer is ≥50mV; After zinc diffusion treatment, the potential difference between the Zn-free diffusion zone of the anti-corrosion layer and the potential of the innermost layer of the core layer is ≤150mV.

7. The corrosion-resistant aluminum alloy composite plate according to claim 6, characterized in that, After zinc diffusion treatment, the diffusion depth of Zn element in the anti-corrosion layer into the core layer is 100-300μm.

8. The corrosion-resistant aluminum alloy composite plate according to claim 6, characterized in that, The zinc diffusion treatment is carried out at a temperature of 450-500℃ for 3-7 hours.

9. The corrosion-resistant aluminum alloy composite plate according to claim 6, characterized in that, The corrosion resistance of corrosion-resistant aluminum alloy composite plates can pass ASTM G85 A3 for more than 3000 hours.