Method for testing interface strength of magnesium-aluminum layered composite plate

Abstract

The application discloses a kind of magnesium-aluminum layered composite board interface strength test methods, belong to composite board performance test technical field.The method includes the following steps: according to Q Al =(t Al / t 总 )×σ 复合板 ×k calculate the tensile strength of aluminium layer in the magnesium-aluminum layered composite board to be measured;Q Al It is the tensile strength of aluminium layer in the composite board to be measured, t Al It is the thickness of aluminium layer in the composite board to be measured, t 总 It is the total thickness of the composite board to be measured, σ 复合板 It is the tensile strength of the composite board to be measured, k is the tensile strength ratio of aluminium plate and magnesium plate in the composite board to be measured;If Q Al ≤70Mpa, using adhesive method to test the interface strength between magnesium layer and aluminium layer in the composite board to be measured;If Q Al >70MPa, using shearing method to test the interface strength between magnesium layer and aluminium layer in the composite board to be measured.The method is suitable for the test of magnesium-aluminum composite board in magnesium layer and aluminium layer interface bonding strength of different layer thickness design, and the test result is accurate and stable.

Description

Technical Field

[0001] This invention relates to the field of composite plate performance testing technology, and more specifically, to a method for testing the interfacial strength of magnesium-aluminum layered composite plates. Background Technology

[0002] Metal layered composite materials are novel materials obtained by using composite technology to achieve a strong metallurgical bond between two or more metals with different physical, chemical, and mechanical properties. Each metal layer retains its original characteristics, but its overall physical, chemical, and mechanical properties are greatly improved compared to a single metal, thus meeting the material performance requirements under special environments.

[0003] Magnesium-aluminum layered composite plates combine the low density, high specific strength, and high specific stiffness of magnesium with the high strength and corrosion resistance of aluminum, making them a new research hotspot. The aluminum layer significantly improves the formability and corrosion resistance of magnesium alloys. Magnesium-aluminum layered composite plates have broad application prospects in petrochemicals, marine engineering, oil and gas transportation, aerospace, machinery and metallurgy, and household appliances.

[0004] The key technical indicators of magnesium-aluminum layered composite panels mainly focus on strength, formability, bending performance, and interfacial strength. Currently, there are relevant test methods for strength, formability, and bending performance, but the evaluation methods for interfacial strength are very complicated. Different methods have failed to accurately reflect the interfacial bonding performance of magnesium-aluminum composite panels (especially magnesium-aluminum composite panels with different layer thicknesses).

[0005] In other words, the current testing method for the interfacial bonding strength of magnesium-aluminum layered composite panels has problems such as low accuracy and poor stability of the results.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for testing the interfacial strength of magnesium-aluminum layered composite plates, so as to solve or improve the above-mentioned technical problems.

[0008] This invention can be implemented as follows:

[0009] In a first aspect, the present invention provides a method for testing the interfacial strength of a magnesium-aluminum layered composite plate, comprising the following steps: according to Q... Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Alt represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be measured. 复合板 denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested.

[0010] If Q Al ≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al The interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate was tested using the shear method, with a strength >70MPa.

[0011] In an optional embodiment, the adhesive bonding method includes: cutting a test sample containing the interface between the magnesium layer and the aluminum layer along the thickness direction of the magnesium-aluminum layered composite plate to be tested, and performing pretreatment on the test sample; taking a first stainless steel specimen and a second stainless steel specimen respectively, and performing pretreatment on the surfaces of the two stainless steel specimens.

[0012] The pretreated test sample is placed between the pretreated first stainless steel specimen and the pretreated second stainless steel specimen, and the first stainless steel specimen, the test sample and the second stainless steel specimen are bonded together in sequence by an adhesive.

[0013] Two stainless steel specimens were fixed to their non-bonded surfaces using a clamp, and then tensile tests were performed on a universal testing machine. The maximum interfacial strength obtained was the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0014] In an optional implementation, the test sample is a circular piece with a diameter of 10 mm to 16 mm;

[0015] And / or, both the first stainless steel specimen and the second stainless steel specimen are stainless steel cylinders.

[0016] In an optional embodiment, the diameter of the stainless steel cylinder is larger than the diameter of the disc.

[0017] In an optional embodiment, the pretreatment of the test sample and the first and second stainless steel specimens each independently includes: cleaning, sandblasting, grinding, removal of surface impurities, and solution treatment.

[0018] In an optional embodiment, the solution used for solution treatment is a sulfuric acid-sodium dichromate solution with a concentration of 0.4 mol / L to 0.8 mol / L.

[0019] In an optional implementation, the surface roughness of the pretreated test specimen, the first stainless steel specimen, and the second stainless steel specimen is independently ≥3.2Ra.

[0020] In an optional embodiment, the main component of the adhesive is an amino tetrafunctional epoxy resin;

[0021] The bonding process includes: first treating at 130℃~150℃ for 1h~2h, and then treating at 195℃~205℃ for 1.5h~2.5h.

[0022] In an optional embodiment, the contact pressure between the clamp and the two stainless steel specimens is 0.03 MPa to 0.1 MPa.

[0023] In an optional embodiment, the contact pressure between the clamp and the two stainless steel specimens is 0.05 MPa.

[0024] In an optional implementation, the clamping force for the tensile test is ≤50N, and the test speed is 0.1m / min to 1m / min.

[0025] In an optional implementation, the test speed is 0.1 m / min to 0.5 m / min.

[0026] In an optional embodiment, the shearing method includes: cutting downwards from the upper surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a first notch; and cutting upwards from the lower surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a second notch; the projections of the first notch and the second notch on the same horizontal plane do not overlap; the depth of the first notch or the second notch is the thickness of a single aluminum layer or a single magnesium layer in the magnesium-aluminum layered composite plate to be tested;

[0027] The magnesium-aluminum layered composite plate to be tested, which has a first notch and a second notch, is subjected to tensile testing on a universal testing machine. The maximum interfacial strength obtained from the test is the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0028] In an optional implementation, the shortest horizontal distance between the first notch and the second notch is the overlap width, which is 1mm to 3mm.

[0029] The distance of the first notch along the length direction of the magnesium-aluminum layered composite plate to be tested is 2mm, and the distance of the first notch along the width direction of the magnesium-aluminum layered composite plate to be tested is 10mm.

[0030] In an optional implementation, the clamping force for the tensile test is ≤10N, and the test speed is 0.05m / min to 0.5m / min.

[0031] In an optional implementation, the test speed is 0.1 m / min to 0.5 m / min.

[0032] The beneficial effects of this invention include:

[0033] This invention creatively provides a unified method for testing the interfacial strength of magnesium-aluminum composite panels with different layer thickness ratios. Specifically, different test methods are selected based on different conditions. This method is convenient, time-saving, and produces test results with small fluctuations, high stability, and good accuracy. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure after the circular piece is fixed to the two stainless steel columns in Embodiment 1 of the present invention;

[0036] Figure 2 This is a graph showing the interface strength test results in Embodiment 1 of the present invention.

[0037] Figure 3 This is a schematic diagram of the notch cutting in Embodiment 2 of the present invention;

[0038] Figure 4 This is a graph showing the interface strength test in Embodiment 2 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0040] The following is a detailed description of the test method for the interface strength of the magnesium-aluminum layered composite plate provided by the present invention.

[0041] This invention provides a method for testing the interfacial strength of a magnesium-aluminum layered composite plate, comprising the following steps: according to Q... Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be measured. 复合板denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested.

[0042] If Q Al ≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al The interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate was tested using the shear method, with a strength >70MPa.

[0043] In this invention, the magnesium-aluminum layered composite plate is obtained by metallurgically combining an initial magnesium plate and an initial aluminum plate, and the surfaces of the initial magnesium plate and the initial aluminum plate are both planar.

[0044] The tensile strength of the initial aluminum and magnesium plates can be determined using the method specified in GB 228-2020. Alternatively, it can be obtained based on the specific grades of the aluminum and magnesium plates and known material properties. Similarly, the tensile strength of the magnesium-aluminum layered composite plate to be tested can also be directly determined using the method specified in GB 228-2020.

[0045] The thickness of the aluminum layer in the magnesium-aluminum layered composite plate under test can be obtained by scanning electron microscopy. The total thickness of the magnesium-aluminum layered composite plate under test can be directly measured.

[0046] In this invention, the above-mentioned adhesive method may include: cutting a test sample containing the interface between the magnesium layer and the aluminum layer along the thickness direction of the magnesium-aluminum layered composite plate to be tested, and performing pretreatment on the test sample; taking a first stainless steel specimen and a second stainless steel specimen respectively, and performing pretreatment on the surfaces of the two stainless steel specimens.

[0047] The pretreated test sample is placed between the pretreated first stainless steel specimen and the pretreated second stainless steel specimen, and the first stainless steel specimen, the test sample and the second stainless steel specimen are bonded together in sequence by an adhesive.

[0048] Two stainless steel specimens were fixed to their non-bonded surfaces using a clamp, and then tensile tests were performed on a universal testing machine. The maximum interfacial strength obtained was the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0049] In some alternative implementations, the test sample can be a disc with a diameter of 10 mm to 16 mm (e.g., 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm or 16 mm).

[0050] Both the first and second stainless steel specimens are stainless steel cylinders. The diameter of the stainless steel cylinder is larger than the diameter of the disc; for example, the diameter of the stainless steel cylinder can be 20 mm.

[0051] In some alternative embodiments, the pretreatment of the test sample and the first and second stainless steel specimens each independently includes: cleaning, sandblasting, grinding, removal of surface impurities, and solution treatment.

[0052] For cleaning, acetone can be used, and for polishing, sandpaper can be used. The solution used for solution treatment is a sulfuric acid-sodium dichromate solution with a concentration of 0.4 mol / L to 0.8 mol / L (such as 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, or 0.8 mol / L).

[0053] The surface roughness of the pretreated test specimen, the first stainless steel specimen, and the second stainless steel specimen is independently ≥3.2Ra.

[0054] In some alternative embodiments, the main component of the adhesive is an amino tetrafunctional epoxy resin.

[0055] For example, the bonding process may include: first treating at 130°C to 150°C (e.g., 130°C, 135°C, 140°C, 145°C, or 150°C) for 1 hour to 2 hours (e.g., 1 hour, 1.5 hours, or 2 hours), and then treating at 195°C to 205°C (e.g., 195°C, 200°C, or 250°C) for 1.5 hours to 2.5 hours (e.g., 1.5 hours, 2 hours, or 2.5 hours). By performing the bonding process described above, the first stainless steel specimen, the test sample, and the second stainless steel specimen can be effectively bonded together.

[0056] In some alternative embodiments, the contact pressure between the clamp and the two stainless steel specimens can be 0.03 MPa to 0.1 MPa, such as 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, or 0.1 MPa, or other values ​​within the range of 0.03 MPa to 0.1 MPa. In some more typical embodiments, the contact pressure between the clamp and the two stainless steel specimens is 0.05 MPa.

[0057] In some optional embodiments, the clamping force for the tensile test is ≤50N, such as 50N, 45N, 40N, or 35N. The test speed can be 0.1m / min to 1m / min, such as 0.1m / min, 0.2m / min, 0.4m / min, 0.6m / min, 0.8m / min, or 1m / min, or other values ​​within the range of 0.1m / min to 1m / min. In some more typical embodiments, the test speed is 0.1m / min to 0.5m / min.

[0058] In the above adhesive bonding test, the maximum interfacial strength obtained from the tensile test on the universal testing machine refers to the maximum force required for interface separation as indicated by the universal testing machine. This maximum force is the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0059] In this invention, the shearing method may include: cutting downwards from the upper surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a first notch; and cutting upwards from the lower surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a second notch; the projections of the first notch and the second notch on the same horizontal plane do not overlap; the depth of the first notch or the second notch is the thickness of a single aluminum layer or a single magnesium layer in the magnesium-aluminum layered composite plate to be tested.

[0060] The magnesium-aluminum layered composite plate to be tested, which has a first notch and a second notch, is subjected to tensile testing on a universal testing machine. The maximum interfacial strength obtained from the test is the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0061] In some alternative embodiments, both the first notch and the second notch are located in the middle region of the magnesium-aluminum layered composite plate to be tested, and the shortest distance from the first notch to the center of the magnesium-aluminum layered composite plate to be tested is equal to the shortest distance from the second notch to the center of the magnesium-aluminum layered composite plate to be tested.

[0062] In some alternative implementations, the shortest horizontal distance between the first notch and the second notch is the overlap width, which can be 1mm to 3mm, such as 1mm, 1.5mm, 2mm, 2.5mm or 3mm, or other values ​​within the range of 1mm to 3mm.

[0063] In some alternative embodiments, a strip-shaped sample (e.g., 45 mm in length and 10 mm in width) can be cut from the magnesium-aluminum layered composite plate to be tested. This sample contains the interface between the aluminum and magnesium layers. Then, a first notch and a second notch are cut into this sample.

[0064] In some alternative embodiments, the distance of the first notch along the length direction of the magnesium-aluminum layered composite plate to be tested can be 2 mm, and the distance of the first notch along the width direction of the magnesium-aluminum layered composite plate to be tested can be 10 mm.

[0065] In some optional embodiments, the clamping force for the tensile test is ≤10N, such as 10N, 8N, or 5N. The test speed can be 0.05m / min to 0.5m / min, such as 0.05m / min, 0.1m / min, 0.2m / min, 0.3m / min, 0.4m / min, or 0.5m / min, or other values ​​within the range of 0.05m / min to 0.5m / min. In some more typical embodiments, the test speed is 0.1m / min to 0.5m / min.

[0066] During the shear test described above, the maximum interfacial strength obtained from the tensile test performed on the universal testing machine refers to the maximum force required by the universal testing machine to separate the interfaces. This maximum force is the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

[0067] It should be noted that the principle of tensile testing on the universal testing machine in this invention can be referred to the relevant existing technology, and will not be elaborated or limited here.

[0068] As mentioned above, the test method provided by this invention is applicable to testing the interfacial bonding strength between the magnesium layer and the aluminum layer in magnesium-aluminum composite panels with different layer thicknesses, and the test results are accurate and stable.

[0069] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0070] Example 1

[0071] In this embodiment, a magnesium-aluminum layered composite plate with a known interfacial strength of 70 MPa is used as the magnesium-aluminum layered composite plate to be tested to verify the feasibility of the method provided by the present invention.

[0072] Specifically, the magnesium-aluminum layered composite board to be tested is a three-layer magnesium-aluminum composite board, with the layers consisting of an aluminum layer, a magnesium layer, and an aluminum layer with a thickness ratio of 1:4:1.

[0073] The interfacial bond strength of the magnesium-aluminum layered composite plate shall be tested using the following method, which includes the following steps:

[0074] S1: According to Q Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is... Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be tested. 复合板denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested.

[0075] If Q Al ≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al >70MPa, the interfacial strength between the magnesium and aluminum layers in the magnesium-aluminum layered composite plate was tested using the shear method based on Q. Al When the strength of the composite board interface is ≤70MPa, the bonding strength is tested by adhesive method.

[0076] The tensile strengths of the magnesium-aluminum layered composite plate, the initial aluminum plate, and the initial magnesium plate were all tested using the GB 228-2020 method. The results were as follows: the tensile strength of the magnesium-aluminum layered composite plate was 275 MPa, the tensile strength of the initial aluminum plate was 280 MPa, and the tensile strength of the initial magnesium plate was 260 MPa.

[0077] Therefore, Q Al =(1 / 6)×275×1.07=49.04MPa.

[0078] S2: Based on Q Al When the strength is less than 70 MPa, the adhesive method is used to test the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate to be tested.

[0079] The method for testing adhesive bonding is as follows:

[0080] S21: A test sample (a 14mm diameter disc) containing the interface between the magnesium and aluminum layers was cut along the thickness direction of the magnesium-aluminum layered composite plate to be tested. The surface of the disc was cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surface was treated with a 0.6mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness of 3.2Ra. Two 20mm diameter stainless steel columns were selected. The surfaces of each column that would contact the disc were also cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surfaces were treated with a 0.6mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness of 4.5Ra.

[0081] S22: Apply an adhesive (a glue composed of amino tetrafunctional epoxy resin) to the surface of the disc treated by S21. Place the disc between the surfaces of two stainless steel pillars treated by S21. Fix the two stainless steel pillars with a clamp. The contact pressure between the clamp and the stainless steel pillars is 0.05 MPa. Then treat it at 140°C for 1.5 hours and then at 200°C for 2 hours to bond and fix the disc to the two stainless steel pillars.

[0082] S23: As Figure 1 As shown, after the circular piece was bonded and fixed to two stainless steel columns, the entire assembly was placed on a universal testing machine for tensile testing. The clamping force was 30 N, and the testing speed was 0.1 m / min to 1 m / min. The maximum interfacial strength obtained from the tensile test was 69.6 MPa. Figure 2 (As shown).

[0083] Therefore, the interfacial bonding strength of the magnesium-aluminum layered composite plate provided in this embodiment is 69.6 MPa.

[0084] The results are consistent with the actual interface strength, indicating that the testing method provided by this invention is accurate and feasible.

[0085] Example 2

[0086] In this embodiment, a magnesium-aluminum layered composite plate with a known interfacial strength of 100 MPa is used as the magnesium-aluminum layered composite plate to be tested to verify the feasibility of the method provided by the present invention.

[0087] Specifically, the magnesium-aluminum layered composite board to be tested is a three-layer magnesium-aluminum composite board, with the layers consisting of an aluminum layer, a magnesium layer, and an aluminum layer with a thickness ratio of 2:2:2.

[0088] The interfacial bond strength of the magnesium-aluminum layered composite plate shall be tested using the following method, which includes the following steps:

[0089] S1: According to Q Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is... Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be tested. 复合板 denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested.

[0090] If Q Al≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al >70MPa, the interfacial strength between the magnesium and aluminum layers in the magnesium-aluminum layered composite plate was tested using the shear method based on Q. Al When the strength of the composite board interface is ≤70MPa, the bonding strength is tested by adhesive method.

[0091] The tensile strengths of the magnesium-aluminum layered composite plate, the initial aluminum plate, and the initial magnesium plate were all tested using the GB 228-2020 method. The results were as follows: the tensile strength of the magnesium-aluminum layered composite plate was 300 MPa, the tensile strength of the initial aluminum plate was 320 MPa, and the tensile strength of the initial magnesium plate was 280 MPa.

[0092] Therefore, Q Al =(2 / 6)×300×1.14=114MPa.

[0093] S2: Based on Q Al When the strength is greater than 70 MPa, the shear method is used to test the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate to be tested.

[0094] The shear test method is as follows:

[0095] S21: Cut a strip sample with a length of 45 mm and a width of 10 mm along the thickness direction of the magnesium-aluminum layered composite plate to be tested (this strip sample contains the interface between the aluminum layer and the magnesium layer). Figure 3 As shown, a first notch of 2mm × 10mm is obtained by cutting downwards from the upper surface of the long strip sample; a second notch of 2mm × 10mm is obtained by cutting upwards from the lower surface of the long strip sample. The depth of the second notch is the depth of a single layer of aluminum, and the depth of the first notch is the total thickness of the long strip sample minus the depth of the first notch. The projections of the first and second notches on the same horizontal plane do not overlap, and the shortest horizontal distance between the first and second notches is the overlap width, which is 2mm.

[0096] S22: The entire strip specimen with the first and second notches from S21 is placed on a universal testing machine for tensile testing. The clamping force is 10N, and the testing speed is 0.1m / min to 1m / min. The maximum interfacial strength obtained after the tensile test is 100.50MPa (e.g., ...). Figure 4 (As shown).

[0097] Therefore, the interfacial bonding strength of the magnesium-aluminum layered composite plate provided in this embodiment is 100.50 MPa.

[0098] The results are consistent with the actual interface strength, indicating that the testing method provided by this invention is accurate and feasible.

[0099] Example 3

[0100] In this embodiment, a magnesium-aluminum layered composite plate with a known interfacial strength of 85 MPa is used as the magnesium-aluminum layered composite plate to be tested to verify the feasibility of the method provided by the present invention.

[0101] Specifically, the magnesium-aluminum layered composite plate to be tested is a two-layer magnesium-aluminum composite plate, with an aluminum layer and a magnesium layer having a thickness ratio of 1:4.

[0102] The interfacial bond strength of the magnesium-aluminum layered composite plate shall be tested using the following method, which includes the following steps:

[0103] S1: According to Q Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be measured. 复合板 denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested.

[0104] If Q Al ≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al >70MPa, the interfacial strength between the magnesium and aluminum layers in the magnesium-aluminum layered composite plate was tested using the shear method based on Q. Al When the strength of the composite board interface is ≤70MPa, the bonding strength is tested by adhesive method.

[0105] The tensile strength of the magnesium-aluminum layered composite plate, the initial aluminum plate, and the initial magnesium plate were all tested using the GB 228-2020 method. The results were as follows: the tensile strength of the magnesium-aluminum layered composite plate was 260 MPa, the tensile strength of the initial aluminum plate was 280 MPa, and the tensile strength of the initial magnesium plate was 250 MPa.

[0106] Therefore, Q Al =(1 / 5)×260×1.12=58.24MPa.

[0107] S2: Based on Q Al When the strength is less than 70 MPa, the adhesive method is used to test the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate to be tested.

[0108] The method for testing adhesive bonding is as follows:

[0109] S21: A test sample (a 16mm diameter disc) containing the interface between the magnesium and aluminum layers was cut along the thickness direction of the magnesium-aluminum layered composite plate to be tested. The surface of the disc was cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surface was treated with a 0.6mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness of 3.2Ra. Two 20mm diameter stainless steel columns were selected. The surfaces of each column that would contact the disc were also cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surfaces were treated with a 0.4mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness of 3.2Ra for the treated stainless steel column surfaces that would contact the disc.

[0110] S22: Apply an adhesive (a glue composed of amino tetrafunctional epoxy resin) to the surface of the disc treated by S21. Place the disc between the surfaces of two stainless steel pillars treated by S21. Fix the two stainless steel pillars with a clamp. The contact pressure between the clamp and the stainless steel pillars is 0.1 MPa. Then treat it at 150°C for 1 hour and then at 205°C for 1.5 hours to bond and fix the disc to the two stainless steel pillars.

[0111] S23: After bonding and fixing the circular piece to the two stainless steel columns, the whole assembly was placed on a universal testing machine for tensile testing. The clamping force was 30N, and the testing speed was 0.1m / min to 1m / min. The maximum interfacial strength obtained after the tensile test was 84.6MPa.

[0112] Therefore, the interfacial bonding strength of the magnesium-aluminum layered composite plate provided in this embodiment is 84.6 MPa.

[0113] The results are consistent with the actual interface strength, indicating that the testing method provided by this invention is accurate and feasible.

[0114] Comparative Example 1

[0115] The materials used in this comparative example are the same as those in Example 1, except that the shear method was used for testing.

[0116] The shear test method is as follows:

[0117] A strip sample with a length of 45 mm and a width of 10 mm was cut along the thickness direction of the magnesium-aluminum layered composite plate to be tested (this strip sample contains the interface between the aluminum and magnesium layers). A first notch of 2 mm × 10 mm was obtained by cutting downwards from the top surface of the strip sample; a second notch of 2 mm × 10 mm was obtained by cutting upwards from the bottom surface of the strip sample. The depth of the first notch is the depth of a single aluminum layer, and the depth of the second notch is the total thickness of the strip sample minus the depth of the first notch. The projections of the first and second notches on the same horizontal plane do not overlap, and the shortest horizontal distance between the first and second notches is the overlap width, which is 2 mm.

[0118] The long strip specimen with the first and second notches was placed on a universal testing machine for tensile testing. The clamping force was 10N and the testing speed was 0.1m / min to 1m / min.

[0119] Tensile testing revealed that the aluminum side fractured, and the interface did not separate, making it impossible to obtain the interface strength.

[0120] Comparative Example 2

[0121] The materials used in this comparative example are the same as those in Example 2, except that the adhesive method is used for testing.

[0122] The method for testing adhesive bonding is as follows:

[0123] A test sample (a 14mm diameter disc) containing the interface between the magnesium and aluminum layers was cut along the thickness direction of the magnesium-aluminum layered composite plate to be tested. The surface of the disc was cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surface was treated with a 0.6mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness ≥3.2Ra. Two 20mm diameter stainless steel columns were selected. The surfaces of each column that would contact the disc were also cleaned with acetone, sandblasted, and polished with sandpaper to remove surface impurities. Then, the surfaces were treated with a 0.6mol / L sulfuric acid-sodium dichromate solution to achieve a surface roughness of 3.2Ra for the treated stainless steel column surfaces that would contact the disc.

[0124] An adhesive (an adhesive composed of amino tetrafunctional epoxy resin) is applied to the surface of the disc after the above treatment. The disc is placed between the surfaces of two stainless steel pillars after the above treatment. The two stainless steel pillars are fixed with a clamp. The contact pressure between the clamp and the stainless steel pillars is 0.05 MPa. Then, it is treated at 140°C for 1.5 hours and then at 200°C for 2 hours to bond and fix the disc to the two stainless steel pillars.

[0125] After the disc is bonded and fixed to the two stainless steel columns, the whole assembly is placed on a universal testing machine for tensile testing. The clamping force is ≤50N and the testing speed is 0.1m / min~1m / min.

[0126] The interface did not stretch during the stretching test, so the interface strength could not be obtained.

[0127] In summary, this invention provides a unified method for testing the interfacial strength of magnesium-aluminum composite panels with different layer thickness ratios. The testing method is convenient, time-saving, and produces test results with small fluctuations, high stability, and good accuracy.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the interfacial strength of a magnesium-aluminum layered composite plate, characterized in that, Includes the following steps: According to Q Al =(t Al / t 总 )×σ 复合板 Calculate the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested using the formula ×k; where Q is the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the tensile strength of the aluminum layer in the magnesium-aluminum layered composite plate to be tested. Al t represents the thickness of the aluminum layer in the magnesium-aluminum layered composite plate to be measured. 总 σ represents the total thickness of the magnesium-aluminum layered composite plate to be measured. 复合板 denoted as , where is the tensile strength of the magnesium-aluminum layered composite plate to be tested, and k is the ratio of the tensile strength of the initial aluminum plate to the initial magnesium plate in the magnesium-aluminum layered composite plate to be tested. If Q Al ≤70MPa, the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate under test is tested using the adhesive method; if Q Al The interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate was tested using the shear method, with a strength >70MPa.

2. The test method according to claim 1, characterized in that, The adhesive bonding method includes: cutting a test sample containing the interface between the magnesium layer and the aluminum layer along the thickness direction of the magnesium-aluminum layered composite plate to be tested, and performing pretreatment on the test sample; taking a first stainless steel specimen and a second stainless steel specimen respectively, and performing pretreatment on the surfaces of the two stainless steel specimens. The pretreated test sample is placed between the pretreated first stainless steel specimen and the pretreated second stainless steel specimen, and the first stainless steel specimen, the test sample, and the second stainless steel specimen are bonded together in sequence by an adhesive. The non-bonded surfaces of the two stainless steel specimens were fixed using a clamp, and then a tensile test was performed on a universal testing machine. The maximum interfacial strength obtained from the test was the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

3. The test method according to claim 2, characterized in that, The test sample is a circular piece with a diameter of 10mm to 16mm; And / or, both the first stainless steel specimen and the second stainless steel specimen are stainless steel cylinders.

4. The test method according to claim 3, characterized in that, The diameter of the stainless steel cylinder is larger than the diameter of the disc.

5. The test method according to claim 2, characterized in that, The pretreatment of the test sample and the first and second stainless steel specimens independently includes: cleaning, sandblasting, grinding, removal of surface impurities, and solution treatment.

6. The test method according to claim 5, characterized in that, The solution used for solution treatment is a sulfuric acid-sodium dichromate solution with a concentration of 0.4 mol / L to 0.8 mol / L.

7. The test method according to claim 5, characterized in that, The surface roughness of the pretreated test specimen, the first stainless steel specimen, and the second stainless steel specimen is independently ≥3.2Ra.

8. The test method according to claim 2, characterized in that, The main component of the adhesive is an amino tetrafunctional epoxy resin; The bonding process includes: first treating at 130℃~150℃ for 1h~2h, and then treating at 195℃~205℃ for 1.5h~2.5h.

9. The test method according to claim 2, characterized in that, The contact pressure between the clamp and the two stainless steel specimens is 0.03 MPa to 0.1 MPa.

10. The test method according to claim 9, characterized in that, The contact pressure between the clamp and the two stainless steel specimens is 0.05 MPa.

11. The test method according to claim 2, characterized in that, The clamping force for the tensile test is ≤50N, and the test speed is 0.1m / min~1m / min.

12. The test method according to claim 11, characterized in that, The test speed is 0.1m / min to 0.5m / min.

13. The test method according to claim 1, characterized in that, The shearing method includes: cutting downwards from the upper surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a first notch; and cutting upwards from the lower surface of the magnesium-aluminum layered composite plate to be tested along the thickness direction to obtain a second notch; the projections of the first notch and the second notch on the same horizontal plane do not overlap; the depth of the first notch or the second notch is the thickness of a single aluminum layer or a single magnesium layer in the magnesium-aluminum layered composite plate to be tested; The magnesium-aluminum layered composite plate to be tested, which has the first notch and the second notch, is subjected to tensile testing on a universal testing machine. The maximum interfacial strength obtained from the test is the interfacial strength between the magnesium layer and the aluminum layer in the magnesium-aluminum layered composite plate.

14. The test method according to claim 13, characterized in that, The shortest horizontal distance between the first notch and the second notch is the overlap width, which is 1mm to 3mm.

15. The test method according to claim 14, characterized in that, The clamping force for the tensile test is ≤10N, and the test speed is 0.05m / min~0.5m / min.

16. The test method according to claim 15, characterized in that, The test speed is 0.1m / min to 0.5m / min.

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