Aluminum alloy sample anodizing film covering device and film covering method

Abstract

The invention discloses an aluminum alloy sample anodizing and film covering device and a film covering method, and belongs to the technical field of aluminum alloy anode film covering. The laminating device comprises a container, a clamp assembly and a direct-current power supply, the clamp assembly comprises a clamping cover plate, a fixing sleeve and a sample clamp, the clamping cover plate is arranged in a clamp mounting hole in the center of the container cover plate, an anode conducting rod is arranged in the fixing sleeve, and the bottom end of the anode conducting rod penetrates through the fixing sleeve and the clamping cover plate and extends into the film coating liquid of the container; the sample clamp is fixed at the bottom end of the anode conducting rod; the sample clamp comprises a sample groove and a sample groove cover body matched with the sample groove, and a film covering hole used for exposing a sample film covering area is formed in the center of the sample groove cover body. According to the invention, the sample clamp is designed to fix the contact area S of the sample and the film coating liquid, and the current of the direct-current power supply is adjusted according to the relational expression I = J * S, so that the film coating effect is ensured, and the film coating sample has obvious contrast, uniform crystal grain color and clear crystal boundary.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy anodizing coating, and in particular to an aluminum alloy sample anodizing coating device and a coating method. Background Art

[0002] Aluminum alloy anodizing coating refers to placing coating liquid in a container, connecting the sample to the positive pole of a DC regulated power supply through a sample clamp and a wire, and placing a cathode made of a stainless steel plate or a lead plate in the solution, and the cathode is connected to the negative pole of the DC regulated power supply. During the experiment, the DC regulated power supply is turned on at a certain voltage parameter, and the sample is used as an anode to evaporate a layer of anisotropic metal oxide film on its surface. Due to the different orientations of grains and their atomic arrangements, the coating rate of the metal oxide film is different, thereby generating oxide films of different thicknesses on the surfaces of different grains. When the light source passes through the sample and the oxide films of different thicknesses on the surface, birefringence occurs, and each grain obtains polarized light with different interference degrees. At this time, through the polarization mode observation, the grain structure with different brightness and color will be observed, so as to analyze the information such as grain size, grain boundary morphology, grain texture orientation, second phase distribution, and identify defects such as inclusions. However, in the current coating device and coating method, the coating parameters such as voltage and time are manually set during the coating process. These parameters cannot be unified, resulting in many variables in the coating process, making it difficult to accurately control the degree of electrolytic corrosion, thereby affecting the effect of anodizing film formation. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides an anodizing film-making device and method for aluminum alloy specimens, which solidify the coating parameters in the coating process, reduce the variables in the coating process, and only need to control the appropriate coating time in the coating process to obtain a stable oxide film thickness that can obviously reflect the grain orientation, ultimately presenting a good coating effect.

[0004] The technical solution adopted by the present invention is: The present invention provides an aluminum alloy sample anodizing coating device, comprising a container for containing coating liquid, a clamp assembly for clamping the sample, and a DC power supply arranged on one side of the container; A container cover is provided on the top of the container, a cathode mounting hole for mounting a cathode conductive rod is provided on one side of the container cover, the bottom end of the cathode conductive rod passes through the cathode mounting hole and extends into the coating liquid of the container, a fixture mounting hole for mounting a fixture assembly is provided at the center of the container cover, the bottom end of the fixture assembly passes through the fixture mounting hole and extends into the coating liquid of the container; The fixture assembly comprises a clamping cover plate, a fixed sleeve and a sample fixture, wherein the clamping cover plate is arranged in a fixture installation hole at the center of the container cover plate, the fixed sleeve is located above the clamping cover plate and is fixedly connected to the clamping cover plate, an anode conductive rod is arranged in the fixed sleeve, and the bottom end of the anode conductive rod passes through the fixed sleeve and the clamping cover plate and extends into the coating liquid of the container, and the sample fixture is fixed to the bottom end of the anode conductive rod; The sample fixture comprises a sample slot for holding an aluminum alloy sample and a sample slot cover body matched with the sample slot, and a coating hole for exposing a coating area of ​​the sample is arranged at the center of the sample slot cover body; The positive electrode of the DC power supply is connected to the anode conductive rod through a wire, and the negative electrode of the DC power supply is connected to the cathode conductive rod through a wire.

[0005] Furthermore, a circle of conductive platinum wire is provided inside the sample fixture, and one end of the platinum wire is connected to the anode conductive rod.

[0006] Furthermore, a locking bolt for fixing the anode conductive rod is provided on one side of the fixing sleeve, and the locking bolt is threadedly connected to the fixing sleeve.

[0007] Furthermore, the horizontal spacing between the cathode conductive rod and the anode conductive rod is 10-12 mm.

[0008] Furthermore, the area of ​​the film-covered hole of the sample slot cover is 1-2 cm 2 .

[0009] Furthermore, the container cover plate, the clamping cover plate and the sample fixture are all made of PVC material.

[0010] Based on the above-mentioned aluminum alloy sample anodizing coating device, the present invention also provides an aluminum alloy sample anodizing coating method, comprising the steps of: (1) Cut and sample the aluminum alloy to be tested, prepare aluminum alloy specimens, and embed the aluminum alloy specimens with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimen to obtain a pre-treated specimen; (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested and pour the coating liquid into the container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Adjust the output current of the DC power supply, turn on the DC power supply for coating, and take out the sample after the coating is completed; In step (6), the output current of the DC power supply is adjusted according to the following formula, namely: I = J * S; Wherein, I is the output current of the DC power supply, J is the current density of the aluminum alloy to be tested, and S is the coating hole area of ​​the sample fixture.

[0011] Furthermore, in step (4), when the alloy to be tested is 1xxx, 5xxx, or 6xxx, the coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, and the volume ratio of sulfuric acid, phosphoric acid, and water is 36-40:41-45:17-21; when the alloy to be tested is 2xxx or 7xxx, the coating liquid is a fluoroboric acid aqueous solution, and the volume ratio of fluoroboric acid to water is 4-8:92-96.

[0012] Furthermore, in step (6), the coating temperature is 20-25° C., and the coating time is 30-120 s.

[0013] Furthermore, when adjusting the output current of the DC power supply in step (6), the current density of the aluminum alloy to be tested is detected in advance. The current density detection method is: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through the DC power supply, and measure the current density.

[0014] The beneficial effects of the present invention are: (1) The present invention fixes the contact area S between the sample and the coating liquid by designing a sample fixture, and tests the actual current density J of the aluminum alloy to be tested. According to the relationship I=J*S, the current value of the DC power supply can be adjusted during the test, thereby avoiding the influence of different sample coating areas on the coating effect; at the same time, the current density is obtained by testing the actual processing state of the aluminum alloy to be tested, thereby avoiding the influence of grain size and second phase content on the current density, thereby ensuring the accuracy of the current adjustment of the DC power supply; the present invention solidifies the coating parameters in the coating process, thereby reducing the variables in the coating process. In the coating process, only the appropriate coating time needs to be controlled to obtain a stable oxide film thickness that can clearly reflect the grain orientation, thereby finally presenting a good coating effect; (2) The present invention also uses different coating solutions according to different series of alloys. 1xxx, 5xxx, and 6xxx are sulfuric acid and phosphoric acid aqueous solutions, and 2xxx and 7xxx are fluoroboric acid aqueous solutions. Different alloys contain different main alloying elements, and different second phases will be formed in the alloys. Second phases with different components have different sizes and electrode potentials. Using different coating solutions can obtain better coating effects. (3) The coated sample prepared by the coating method of the present invention has obvious contrast, uniform grain color and clear grain boundaries, which can solve the problem that the grain structure corroded by ordinary chemical etching is unclear, resulting in difficulty in grain display and statistics. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 It is a structural schematic diagram of the film coating device of the present invention; Figure 2 This is a metallographic photograph of Example 1 of the present invention; Figure 3 This is a metallographic photograph of Example 2 of the present invention; Figure 4 This is a metallographic photograph of Example 3 of the present invention; Figure 5 This is a metallographic photograph of Example 4 of the present invention; Figure 6 This is a metallographic photograph of Example 5 of the present invention; Figure 7 This is a metallographic photograph of Example 6 of the present invention; Figure 8 This is a metallographic photograph of Comparative Example 1 of the present invention; Fig. 9 It is the metallographic photograph of comparative example 2 of the present invention.

[0017] Labels in the figure: 1. container; 2. fixture assembly; 201. clamping cover; 202. fixing sleeve; 203. sample fixture; 204. locking bolt; 205. laminating hole; 3. DC power supply; 4. container cover; 5. cathode conductive rod; 6. anode conductive rod; 7. fixture mounting hole. DETAILED DESCRIPTION

[0018] The present invention provides an aluminum alloy sample anodizing coating device and coating method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Example 1

[0020] Reference Figure 1 The present embodiment provides an aluminum alloy sample anodizing coating device, comprising a container 1 for containing a coating liquid, a clamp assembly 2 for clamping the sample, and a DC power supply 3 arranged on one side of the container.

[0021] A container cover 4 is arranged on the top of the container 1, and a cathode mounting hole for mounting a cathode conductive rod 5 is arranged on one side of the container cover 4, and the bottom end of the cathode conductive rod 5 passes through the cathode mounting hole and extends into the coating liquid of the container 1; a fixture mounting hole 7 for mounting a fixture assembly 2 is arranged at the center of the container cover 4, and the bottom end of the fixture assembly 2 passes through the fixture mounting hole 7 and extends into the coating liquid of the container 1.

[0022] The fixture assembly 2 comprises a clamping cover plate 201, a fixing sleeve 202 and a sample fixture 203. The clamping cover plate 201 is arranged in the fixture mounting hole 7 at the center of the container cover plate 4. The bottom end of the clamping cover plate 201 matches with the fixture mounting hole 7 at the center of the container cover plate 4. The top diameter of the clamping cover plate 201 is larger than the fixture mounting hole 7, so that the clamping cover plate can be buckled in the fixture mounting hole and cannot fall from the fixture mounting hole. The fixing sleeve 202 is located above the clamping cover plate 201 and is in contact with the clamping cover plate 201. The clamping cover plate 201 is fixedly connected, an anode conductive rod 6 is arranged in the above-mentioned fixed sleeve 202, and the bottom end of the anode conductive rod 6 passes through the fixed sleeve and the clamping cover plate and extends into the coating liquid of the container 1, and the above-mentioned sample clamp 203 is fixed to the bottom end of the anode conductive rod 6; in addition, a locking bolt 204 for fixing the anode conductive rod 6 is arranged on one side of the above-mentioned fixed sleeve 202, and the above-mentioned locking bolt 204 is inserted into a threaded hole on one side of the fixed sleeve 202 and is threadedly connected with the fixed sleeve.

[0023] The sample fixture 203 includes a sample slot for holding the aluminum alloy sample and a sample slot cover body matched with the sample slot, and a film-coating hole 205 for exposing the sample film-coating area is arranged at the center of the sample slot cover body. The area of ​​the film-coating hole of the sample slot cover body is 1 cm 2 The coating hole is used to fix the coating area of ​​the aluminum alloy sample; in addition, a sealing gasket is provided on the inner side of the above-mentioned coating hole 205 to prevent the coating liquid from entering the sample fixture from the coating hole and affecting the coating area; in addition, a circle of conductive platinum wire is also provided inside the above-mentioned sample fixture 203, and one end of the platinum wire is connected to the anode conductive rod 6.

[0024] The positive electrode of the DC power supply 3 is connected to the anode conductive rod 6 through a wire, and the negative electrode is connected to the cathode conductive rod 5 through a wire.

[0025] The horizontal distance between the cathode conductive rod 5 and the anode conductive rod 6 is 10 mm.

[0026] The container is a transparent glass vessel, and the container cover, clamping cover and sample fixture are all made of PVC material.

[0027] The anodizing coating device for the aluminum alloy sample was used to anodize the 5059 cast aluminum alloy in the following steps: (1) Cut and sample the 5059 cast aluminum alloy to obtain an aluminum alloy sample of 20 mm × 20 mm × 4 mm, and embed the aluminum alloy sample with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 5xxx coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, and the volume ratio of sulfuric acid: phosphoric acid: water is 38:43:19. Pour the coating liquid into a container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 5059 cast aluminum alloy to be 0.19 A / cm 2 ; According to the formula I=J*S, adjust the output current of the DC power supply to 0.19A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 50s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarization mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 2 shown.

[0028] Example 2

[0029] This embodiment uses the coating device of embodiment 1 to perform anodizing coating on 5059 aluminum alloy in a work-hardened state, and the steps are as follows: (1) Cut and sample the 5059 aluminum alloy in the work-hardened state to obtain an aluminum alloy specimen of 20 mm × 20 mm × 4 mm, and embed the aluminum alloy specimen with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 5xxx coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, and the volume ratio of sulfuric acid: phosphoric acid: water is 37:44:19. Pour the coating liquid into the container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 5059 cast aluminum alloy to be 0.21 A / cm 2 ; According to the formula I=J*S, adjust the output current of the DC power supply to 0.21A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 55s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarizing mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 3 shown.

[0030] Example 3

[0031] This embodiment uses the coating device of embodiment 1 to perform anodizing coating on 6061 cast aluminum alloy, and the steps are as follows: (1) Cut and sample the 6061 cast aluminum alloy to obtain an aluminum alloy sample of 20 mm × 20 mm × 4 mm, and embed the aluminum alloy sample with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 6xxx coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, and the volume ratio of sulfuric acid: phosphoric acid: water is 36:43:21. Pour the coating liquid into a container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 6061 cast aluminum alloy to be 0.19 A / cm 2 ; According to the formula I=J*S, adjust the output current of the DC power supply to 0.19A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 60s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarizing mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 4 shown.

[0032] Example 4

[0033] This embodiment uses the coating device of embodiment 1 to perform anodizing coating on 6005 artificially aged aluminum alloy, and the steps are as follows: (1) Cut and sample the 6005 artificially aged aluminum alloy to obtain an aluminum alloy specimen of 20 mm × 20 mm × 4 mm, and then embed the aluminum alloy specimen with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 6xxx coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, with a volume ratio of sulfuric acid: phosphoric acid: water of 38:42:20. Pour the coating liquid into a container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 6005 aluminum alloy in the artificial aging state to be 0.24 A / cm 2 ; According to the formula I=J*S, adjust the output current of the DC power supply to 0.24A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 65s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarization mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 5 shown.

[0034] Example 5 This embodiment uses the coating device of embodiment 1 to perform anodizing coating on 7075 aluminum alloy in an artificially aged state, and the steps are as follows: (1) Cut and sample the 7075 aluminum alloy in the artificial aging state to obtain an aluminum alloy specimen of 20 mm × 20 mm × 4 mm, and then embed the aluminum alloy specimen with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 7xxx coating liquid is a fluoroboric acid aqueous solution with a volume ratio of fluoroboric acid to water of 8:92. Pour the coating liquid into a container. (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 7075 aluminum alloy in the artificial aging state to be 0.24 A / cm 2; According to the formula I=J*S, adjust the output current of the DC power supply to 0.24A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 35s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarization mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 6 shown.

[0035] Example 6

[0036] This embodiment uses the coating device of embodiment 1 to perform anodizing coating on 2026 artificially aged aluminum alloy, and the steps are as follows: (1) Cut and sample the 2026 artificially aged aluminum alloy to obtain an aluminum alloy specimen of 20 mm × 20 mm × 4 mm, and then embed the aluminum alloy specimen with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimens. Specifically, an automatic grinding and polishing machine is used to mechanically grind and polish the mounted specimens. The grinding process uses 180# and 320# water-abrasive sandpapers in turn. The polishing process uses 9um, 1um, and 0.04um suspensions in turn for polishing pretreatment. The grinding and polishing time is until the previous processing marks are completely covered to obtain pretreated specimens. (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested. The 2xxx coating liquid is a fluoroboric acid aqueous solution with a volume ratio of fluoroboric acid to water of 4:96. Pour the coating liquid into a container. (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Pre-detect the current density of the aluminum alloy to be tested. The current density detection method is as follows: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through a DC power supply, and measure the current density of the 2026 aluminum alloy in the artificial aging state to be 0.25 A / cm 2 ; According to the formula I=J*S, adjust the output current of the DC power supply to 0.25A, turn on the DC power supply for lamination, the temperature is 22°C, the lamination time is 45s, and take out the sample after the lamination is completed; (7) The coated sample was cleaned with water and alcohol in turn, then blown dry, and observed under the polarization mode of a metallographic microscope. The obtained metallographic photograph is as follows: Figure 7 shown.

[0037] Comparative Example 1

[0038] The difference between this comparative example and Example 4 is that the current of the DC power supply is set to 0.25A in this comparative example, and the other aspects are the same as those in Example 4. The metallographic photographs of this comparative example are shown in FIG. Figure 8 .

[0039] Comparative Example 2

[0040] The difference between this comparative example and Example 6 is that in this comparative example, the pre-treated sample is directly clamped at the bottom of the anode conductive rod, and is not placed in the sample fixture. The metallographic photograph of this comparative example is as follows: Fig. 9 .

[0041] Through Figure 2-9 According to the analysis, the metallographic photographs of Examples 1-6 have obvious contrast and clear grain boundaries, and can clearly show the grain structure; while the metallographic photographs of Comparative Examples 1 and 2 have unclear contrast and cannot clearly show the grain boundaries.

[0042] In addition, it should be noted that different alloys and different states have different corrosion resistance, and the required coating time is also different. During the anodizing coating process, the coating time is determined according to the alloy type and alloy state. Usually, for cast and aged 2xxx series aluminum alloys, the coating time is 40~50s; for cast and work-hardened 5xxx series aluminum alloys, the coating time is 45~60s; for cast and aged 6xxx series aluminum alloys, the coating time is 50~65s, but the coating time of 6 series rolled plates in the natural aging state is relatively long, which is 90~120s; for cast, solid solution and aged 7xxx series aluminum alloys, the coating time is 30~45s.

[0043] Parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0044] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An aluminum alloy sample anodizing coating device, characterized in that: It includes a container for containing a coating liquid, a clamp assembly for clamping a sample, and a DC power supply arranged on one side of the container; A container cover is provided on the top of the container, a cathode mounting hole for mounting a cathode conductive rod is provided on one side of the container cover, the bottom end of the cathode conductive rod passes through the cathode mounting hole and extends into the coating liquid of the container, a fixture mounting hole for mounting a fixture assembly is provided at the center of the container cover, the bottom end of the fixture assembly passes through the fixture mounting hole and extends into the coating liquid of the container; The fixture assembly comprises a clamping cover plate, a fixed sleeve and a sample fixture, wherein the clamping cover plate is arranged in a fixture installation hole at the center of the container cover plate, the fixed sleeve is located above the clamping cover plate and is fixedly connected to the clamping cover plate, an anode conductive rod is arranged in the fixed sleeve, and the bottom end of the anode conductive rod passes through the fixed sleeve and the clamping cover plate and extends into the coating liquid of the container, and the sample fixture is fixed to the bottom end of the anode conductive rod; The sample fixture comprises a sample slot for holding an aluminum alloy sample and a sample slot cover body matched with the sample slot, and a coating hole for exposing a coating area of ​​the sample is arranged at the center of the sample slot cover body; The positive electrode of the DC power supply is connected to the anode conductive rod through a wire, and the negative electrode of the DC power supply is connected to the cathode conductive rod through a wire.

2. The anodizing coating device for aluminum alloy samples according to claim 1 is characterized in that: A circle of conductive platinum wire is arranged inside the sample fixture, and one end of the platinum wire is connected to the anode conductive rod.

3. The anodizing coating device for aluminum alloy samples according to claim 1, characterized in that: A locking bolt for fixing the anode conductive rod is arranged on one side of the fixing sleeve, and the locking bolt is threadedly connected with the fixing sleeve.

4. The anodizing coating device for aluminum alloy samples according to claim 1, characterized in that: The horizontal spacing between the cathode conductive rod and the anode conductive rod is 10-12 mm.

5. The anodizing coating device for aluminum alloy samples according to claim 1, characterized in that: The area of ​​the film hole of the sample slot cover is 1~2cm 2 .

6. The anodizing coating device for aluminum alloy samples according to claim 1, characterized in that: The container cover plate, the clamping cover plate and the sample fixture are all made of PVC material.

7. A method for anodizing an aluminum alloy sample, using the coating device according to any one of claims 1 to 6, characterized in that: Includes steps: (1) Cut and sample the aluminum alloy to be tested, prepare aluminum alloy specimens, and embed the aluminum alloy specimens with epoxy resin; (2) Grinding and polishing the mounted aluminum alloy specimen to obtain a pre-treated specimen; (3) Take the pretreated sample out of the epoxy resin and place it into the sample holder of the laminating device, ensuring that the test surface of the pretreated sample is exposed from the laminating hole and the exposed area is the area of ​​the laminating hole; (4) Prepare the coating liquid according to the alloy series of the aluminum alloy to be tested and pour the coating liquid into the container; (5) Install the cathode conductive rod and the fixture assembly containing the pre-treated sample, and adjust their installation positions so that the cathode conductive rod and the pre-treated sample are immersed in the coating solution; (6) Adjust the output current of the DC power supply, turn on the DC power supply for coating, and take out the sample after the coating is completed; In step (6), the output current of the DC power supply is adjusted according to the following formula, namely: I = J * S; Wherein, I is the output current of the DC power supply, J is the current density of the aluminum alloy to be tested, and S is the coating hole area of ​​the sample fixture.

8. The method for anodizing and coating an aluminum alloy sample according to claim 7, characterized in that: In the step (4), when the alloy to be tested is 1xxx, 5xxx, or 6xxx, the coating liquid is a mixed aqueous solution of sulfuric acid and phosphoric acid, and the volume ratio of sulfuric acid, phosphoric acid, and water is 36-40:41-45:17-21; when the alloy to be tested is 2xxx or 7xxx, the coating liquid is a fluoroboric acid aqueous solution, and the volume ratio of fluoroboric acid to water is 4-8:92-96.

9. The method for anodizing and coating an aluminum alloy sample according to claim 7, characterized in that: In the step (6), the coating temperature is 20-25° C., and the coating time is 30-120 s.

10. The method for anodizing and coating an aluminum alloy sample according to claim 7, characterized in that: When adjusting the output current of the DC power supply in step (6), the current density of the aluminum alloy to be tested is detected in advance. The current density detection method is: take a round rod with a diameter of 8 mm and a length of 10 mm from the aluminum alloy to be tested, load current through the DC power supply, and measure the current density.

Images