Preparation method of appearance film layer of aluminum alloy part and aluminum alloy part

Abstract

The invention provides an aluminum alloy part appearance film layer preparation method and an aluminum alloy part, and belongs to the technical field of aluminum alloy surface treatment.The method comprises the steps that surface pretreatment is conducted on an aluminum alloy basic part, so that the surface of the aluminum alloy basic part meets the preset clean requirement; the pretreated aluminum alloy basic part is sequentially subjected to at least two times of micro-arc oxidation treatment, after each time of micro-arc oxidation treatment, a ceramic film layer formed on the surface of the aluminum alloy basic part is subjected to polishing treatment, so that a loose layer on the outermost layer of the ceramic film layer is removed, and a compact layer of the ceramic film layer is reserved; and the compact layer on the outermost layer of the aluminum alloy basic part is subjected to fine polishing treatment, so that the appearance film layer prepared on the surface of the aluminum alloy basic part is completed. By means of the method, the problems that in the prior art, when aluminum alloy serves as an outer part, an outer film layer machined through anodic oxidation and physical vapor deposition is low in hardness and glossiness, the requirement for materials of an aluminum alloy basic part is high, and the film layer is prone to falling off can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy surface treatment, and more specifically, to a method for preparing an appearance film layer of an aluminum alloy part and the aluminum alloy part. Background Art

[0002] The appearance structural parts of consumer electronic products have very high requirements for the surface treatment effect of the structural parts on the basis of meeting the structural strength. From the demand perspective, the decorative effect of the appearance is even the most important.

[0003] At present, when aluminum alloy is used as an appearance part, its surface treatment process mostly adopts anodizing process and physical vapor deposition process. However, it is found in practice that the hardness and glossiness of the anodized film layer formed on the surface of aluminum alloy parts by anodizing process are relatively low, and the requirements for the material itself are high. The grain size and second phase of aluminum alloy will have a significant impact on the anode effect. Therefore, the aluminum alloys that can be used for appearance anode are mainly some 6 series and 7 series aluminum alloys. The decorative film layer prepared on the surface of aluminum alloy parts by physical vapor deposition process has the problem of easy film shedding.

[0004] In summary, when aluminum alloy is used as an appearance part in the prior art, the appearance film layer processed by anodizing process and physical vapor deposition process has problems such as low hardness and glossiness, high material requirements for aluminum alloy base parts, and easy film shedding. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method for preparing an appearance film layer of an aluminum alloy part and an aluminum alloy part, so as to solve the problems in the prior art that when aluminum alloy is used as an appearance part, the appearance film layer processed by anodizing process and physical vapor deposition process has low hardness and glossiness, high material requirements for aluminum alloy base parts, and easy film shedding.

[0006] The present invention provides a method for preparing an appearance film layer of an aluminum alloy part, comprising the following steps:

[0007] Performing surface pretreatment on the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements;

[0008] The pretreated aluminum alloy base member is subjected to at least two micro-arc oxidation treatments in sequence, and after each micro-arc oxidation treatment, the ceramic film layer formed on the surface of the aluminum alloy base member is polished to remove the outermost loose layer of the ceramic film layer and retain the dense layer of the ceramic film layer;

[0009] The outermost dense layer of the aluminum alloy base part is finely polished to complete the appearance film layer prepared on the surface of the aluminum alloy base part.

[0010] In addition, a preferred solution is that before the surface of the aluminum alloy base part is pretreated to make the surface of the aluminum alloy base part meet the preset cleanliness requirements, the method further comprises:

[0011] The aluminum alloy substrate is processed into an aluminum alloy basic part by CNC machining equipment.

[0012] In addition, a preferred solution is that the surface pretreatment of the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements includes:

[0013] The surface of the aluminum alloy base part is polished, sandblasted and cleaned in sequence so that the surface of the aluminum alloy base part meets the preset cleanliness requirements.

[0014] In addition, a preferred solution is that the steps of performing micro-arc oxidation treatment on the pretreated aluminum alloy base member each time include:

[0015] Using the pretreated aluminum alloy base part as an anode and an electrolytic cell as a cathode, immersing the aluminum alloy base part in the electrolyte of the electrolytic cell;

[0016] The aluminum alloy base part immersed in the electrolyte is subjected to micro-arc oxidation treatment by an AC pulse power supply in a constant voltage mode until a preset thickness is reached to complete the micro-arc oxidation treatment.

[0017] In addition, a preferred solution is to perform two micro-arc oxidation treatments on the pretreated aluminum alloy base member, namely, a first micro-arc oxidation treatment and a second micro-arc oxidation treatment; wherein,

[0018] During the first micro-arc oxidation treatment and the second micro-arc oxidation treatment, the electrolytes used are composite solutions composed of 1g / L-20g / L aluminate, 1g / L-10g / L phosphate and 1g / L-10g / L sodium fluoride; and the temperatures of the electrolytes are both 10°C-50°C.

[0019] In addition, the preferred solution is that during the first micro-arc oxidation treatment, the voltage used is 200V-400V and the current density is 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

[0020] In addition, the preferred solution is that during the second micro-arc oxidation treatment, the voltage used is 400V-700V and the current density is 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

[0021] In addition, a preferred solution is that the first ceramic film layer formed by the first micro-arc oxidation treatment has a thickness of 25 μm-40 μm and a hardness of 500 HV-1000 HV.

[0022] In addition, a preferred solution is that after the second micro-arc oxidation treatment, the total thickness of the ceramic film layer formed on the surface of the aluminum alloy base part is 40 μm-60 μm, and the hardness is 700 HV-1500 HV.

[0023] The present invention provides an aluminum alloy part, which is obtained by preparing an appearance film layer on the surface of an aluminum alloy base part using the appearance film layer preparation method of the aluminum alloy part as described above.

[0024] It can be seen from the above technical scheme that the method for preparing the appearance film layer of an aluminum alloy part and the aluminum alloy part provided by the present invention prepare a ceramic film layer on the surface of an aluminum alloy base part through micro-arc oxidation treatment technology to form a film layer with ceramic texture and both functional and decorative properties, broadening the high-quality appearance surface treatment process of aluminum alloy parts and realizing the manufacturing of lightweight ceramic-textured structural parts; by performing at least two micro-arc oxidation treatments on the pretreated aluminum alloy base part in sequence, after each micro-arc oxidation treatment, the ceramic film layer formed on the surface of the aluminum alloy base part is polished to remove the outermost loose layer of the ceramic film layer and retain the dense layer of the ceramic film layer, so that the surface of the aluminum alloy base part can fully retain a dense layer with good density and functional effects, avoiding the conflict between the single micro-arc oxidation thickness causing the density of the ceramic film layer to be reduced due to excessive thickness and the polishing allowance requiring a certain film thickness; the present invention can achieve the purpose of both increasing the overall film thickness and ensuring the overall film density by controlling the quality of the micro-arc oxidation ceramic film layer in multiple stages respectively.

[0025] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By referring to the following description in conjunction with the accompanying drawings, and with a more complete understanding of the present invention, other objects and results of the present invention will become more apparent and easily understood.

[0027] Figure 1 Flow chart of a method for preparing an appearance film layer of an aluminum alloy part according to an embodiment of the present invention;

[0028] Figure 2is a schematic structural diagram of a first ceramic film layer formed on the surface of an aluminum alloy base member after a first micro-arc oxidation treatment according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the structure of a ceramic film layer after the first ceramic film layer is polished for the first time according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it is apparent that these embodiments may also be implemented without these specific details.

[0031] In view of the above-mentioned prior art, when aluminum alloy is used as an appearance part, the appearance film layer processed by anodizing process and physical vapor deposition process has low hardness and glossiness, high material requirements for aluminum alloy base parts, and easy film shedding and other problems. A method for preparing the appearance film layer of an aluminum alloy part and an aluminum alloy part are proposed.

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] In order to illustrate the appearance film preparation method of the aluminum alloy part and the aluminum alloy part provided by the present invention, Figure 1 The process of the method for preparing the appearance film layer of an aluminum alloy part according to an embodiment of the present invention is shown; Figure 2 The structure of the first ceramic film layer formed on the surface of the aluminum alloy base member after the first micro-arc oxidation treatment according to an embodiment of the present invention is shown; Figure 3 The ceramic film layer structure after the first ceramic film layer is polished for the first time according to an embodiment of the present invention is shown.

[0034] like Figures 1 to 3 As shown together, the method for preparing the appearance film layer of an aluminum alloy part provided by the present invention comprises the following steps:

[0035] Step S1, performing surface pretreatment on the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements.

[0036] Specifically, in order to ensure that the ceramic film layer formed on the surface of the aluminum alloy base part during the subsequent micro-arc oxidation treatment has a better effect, the aluminum alloy base part needs to be pretreated to make the surface of the aluminum alloy base part smooth and clean. The preset cleanliness requirement is set according to actual needs, and the present invention does not make any special limitation on this.

[0037] As a preferred embodiment of the present invention, before the surface of the aluminum alloy base part is pretreated to make the surface of the aluminum alloy base part meet the preset cleanliness requirements, the method further comprises:

[0038] The aluminum alloy substrate is processed into an aluminum alloy basic part by CNC machining equipment.

[0039] Specifically, in order to avoid damaging the external light film layer by first preparing the appearance film layer on the substrate and then processing the product, it is necessary to first process the aluminum alloy substrate to form an aluminum alloy base part, and then prepare the appearance film layer on the surface of the aluminum alloy base part. The processing method is preferably CNC processing equipment (CNC), which is suitable for batch processing and has high processing accuracy. It should be noted that the present invention does not specifically limit the technical means used to process the aluminum alloy base part, and the use of CNC processing equipment is only a preferred solution of the present invention.

[0040] As a preferred solution of the present invention, the aluminum alloy base part is subjected to surface pretreatment so that the surface of the aluminum alloy base part meets the preset cleanliness requirements, including:

[0041] The surface of the aluminum alloy base part is polished, sandblasted and cleaned in sequence so that the surface of the aluminum alloy base part meets the preset cleanliness requirements.

[0042] Specifically, the barbs and other redundant materials on the surface of the aluminum alloy base part are removed by polishing, the surface of the aluminum alloy base part is polished smooth by sandblasting, and the aluminum alloy base part is cleaned to remove residual impurities on the surface.

[0043] Step S2, performing micro-arc oxidation treatment on the pretreated aluminum alloy base part at least twice in sequence, and after each micro-arc oxidation treatment, polishing the ceramic film layer formed on the surface of the aluminum alloy base part to remove the outermost loose layer of the ceramic film layer and retain the dense layer of the ceramic film layer.

[0044] Specifically, the aluminum alloy base part can be cast apart from the middle, ground and polished, and observed under an ultra-depth-of-field microscope / scanning electron microscope, so that the loose layer and the dense layer can be clearly seen to determine the polishing removal amount of the ceramic film layer formed after each micro-arc oxidation.

[0045] After the pre-treated aluminum alloy base parts are micro-arc oxidized, the ceramic film layer generated on its surface has a high surface roughness, usually accompanied by more discharge holes. If a high-gloss ceramic film layer is to be obtained, the ceramic film layer must be polished. Generally speaking, the thickness of the aluminum alloy micro-arc oxidation film layer is difficult to meet the polishing requirements. The increase in polishing process requires that the film layer must have a certain thickness to ensure a certain polishing allowance. However, the increase in film thickness usually reduces the density of the ceramic film layer, and the decrease in density will lead to a decrease in gloss after polishing. This is also the reason why in the prior art, micro-arc oxidation technology is generally used to improve the corrosion resistance and wear resistance of the material surface, but not for processing the appearance film layer.

[0046] The present invention divides the micro-arc oxidation treatment of the pretreated aluminum alloy base into at least two stages, and can control the thickness of the ceramic film layer formed in each stage, thereby avoiding a single micro-arc oxidation treatment to ensure the polishing margin, resulting in low density due to excessive thickness of the film layer. The purpose of increasing the thickness and density of the entire film layer can be achieved by separately controlling the quality of the ceramic film layer formed by micro-arc oxidation in each stage.

[0047] As a preferred embodiment of the present invention, the step of performing micro-arc oxidation treatment on the pretreated aluminum alloy base member each time comprises:

[0048] The pretreated aluminum alloy base member is used as an anode and the electrolytic cell is used as a cathode, and the aluminum alloy base member is immersed in the electrolyte of the electrolytic cell;

[0049] In constant voltage mode, an aluminum alloy base part immersed in an electrolyte is subjected to micro-arc oxidation treatment by an AC pulse power supply until a preset thickness is reached to complete the micro-arc oxidation treatment.

[0050] Specifically, in the process of micro-arc oxidation treatment of the pre-treated aluminum alloy base part, each micro-arc oxidation treatment uses the aluminum alloy base part as the anode and the electrolytic cell (generally a stainless steel cell) as the cathode. In the constant voltage mode, the aluminum alloy base part immersed in the electrolyte is subjected to micro-arc oxidation treatment by an AC pulse power supply. During each micro-arc oxidation treatment, the thickness of the ceramic film layer formed each time is controlled by controlling the micro-arc oxidation time and various process parameters to achieve a preset thickness. It should be noted that the thickness of the ceramic film layer formed by each micro-arc oxidation can be the same or different, and is determined according to the actual process conditions. The preset thickness is controlled by various process parameters, and the corresponding process parameters and treatment time of the preset thickness can be obtained in advance through experiments. The present invention does not make any special restrictions on this.

[0051] As a preferred embodiment of the present invention, the pretreated aluminum alloy base member is subjected to two micro-arc oxidation treatments in sequence, namely, a first micro-arc oxidation treatment and a second micro-arc oxidation treatment; wherein,

[0052] During the first micro-arc oxidation treatment and the second micro-arc oxidation treatment, the electrolyte used was a composite solution composed of 1g / L-20g / L aluminate, 1g / L-10g / L phosphate and 1g / L-10g / L sodium fluoride; and the temperature of the electrolyte was 10°C-50°C.

[0053] Specifically, the pretreated aluminum alloy base part can be set to be processed twice or more times according to the actual situation. The specific number of times is determined according to the actual situation. Generally, two times can achieve the purpose of pursuing the thickness of the film layer while ensuring the density of the film layer.

[0054] The high-strength aluminum alloys used for consumer electronic structural parts are mainly 6-series and 7-series aluminum alloys, both of which contain Mg as their main elements, while Zn is also the main element of 7-series aluminum alloys. As the content of Mg and Zn increases, the content of α-Al2O3 decreases, and the content of Mg and Zn elements in 6-series aluminum alloys is significantly lower than that in 7-series aluminum alloys. Therefore, when the present invention is used to prepare the outer light film layer of aluminum alloy consumer electronic structural parts, the material of the aluminum alloy base part is preferably 6-series aluminum alloy.

[0055] A composite solution composed of 1g / L-20g / L aluminate, 1g / L-10g / L phosphate and 1g / L-10g / L sodium fluoride is selected as the electrolyte. The purpose is, on the one hand, to make the dense layer generate more α-Al2O3 phase with higher density, hardness, corrosion resistance, etc., and on the other hand, to increase the thickness of the ceramic layer as much as possible while ensuring the density.

[0056] As a preferred embodiment of the present invention, during the first micro-arc oxidation treatment, the voltage used is 200V-400V and the current density is 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

[0057] As a preferred embodiment of the present invention, during the second micro-arc oxidation treatment, the voltage used is 400V-700V and the current density is 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

[0058] As a preferred embodiment of the present invention, the first ceramic film layer formed by the first micro-arc oxidation treatment has a thickness of 25 μm-40 μm and a hardness of 500 HV-1000 HV.

[0059] As a preferred embodiment of the present invention, after the second micro-arc oxidation treatment, the total thickness of the ceramic film layer formed on the surface of the aluminum alloy base part is 40 μm-60 μm, and the hardness is 700 HV-1500 HV.

[0060] Specifically, during the micro-arc oxidation treatment of aluminum alloy base parts, the metastable phase γ-Al2O3 is first generated. As the reaction temperature continues to rise, part of the γ-Al2O3 phase gradually transforms into the α-Al2O3 phase. The increase in current density can increase the content of the α-Al2O3 phase in the micro-arc oxidation film. Mainly by increasing the current density during the micro-arc oxidation process, more γ-Al2O3 phases are transformed into α-Al2O3 phases. When the current density increases, the quality of the film layer will be reduced, and it is also easy to burn. The process parameters in the above-mentioned micro-arc oxidation treatment process are preferred parameters, which can ensure the content of the α-Al2O3 phase without burning.

[0061] Step S3, performing fine polishing on the outermost dense layer of the aluminum alloy base part to complete the appearance film layer prepared on the surface of the aluminum alloy base part.

[0062] Specifically, the ceramic film layer on the outermost layer of the aluminum alloy base part can first be rough-polished and medium-polished using sponge sand and polishing cloth of different mesh sizes to remove the loose layer, and finally fine-polished using a wool wheel and diamond grinding paste to obtain a high-gloss crystalline alumina ceramic film layer with a ceramic texture.

[0063] like Figure 2 Combination Figure 3 As shown, the ceramic film layer formed after micro-arc oxidation treatment is divided into three layers: taking the first micro-arc oxidation treatment in the present invention as an example, from the inside to the outside, they are: a transition layer close to the substrate (base component) side (innermost side), a dense layer in the middle, and a loose layer on the outside, wherein the thickness of the transition layer is generally 3-5 μm and is mainly composed of α-Al2O3, γ-Al2O3, etc.; the main functional layer is the dense layer in the middle, with a maximum thickness of no more than 150-250 μm, mainly composed of α-Al2O3 and γ-Al2O3, the theoretical porosity can be controlled to about 2%, and the micro-Vickers hardness can reach 1000HV-2000HV; the porosity and surface roughness of the loose layer are very high, and the density is poor, and it is mainly composed of Al2SiO5 and γ-Al2O3. Since the loose layer has high roughness, poor density, and its main components are γ-Al2O3, etc., it has poor corrosion resistance. Therefore, it needs to be removed by polishing to make the dense layer with better performance as the surface layer.

[0064] The aluminum alloy part provided by the present invention adopts the appearance film layer preparation method of the aluminum alloy part as described above to prepare the appearance film layer on the surface of the aluminum alloy base part to obtain the aluminum alloy part.

[0065] In order to better explain the method for preparing the appearance film layer of the aluminum alloy part provided by the present invention in detail, the following examples are given:

[0066] 81 aluminum alloy base parts were prepared, and surface pretreatment was performed on each of them to ensure that the surface smoothness and cleanliness of the 81 aluminum alloy base parts remained consistent. The 81 aluminum alloy base parts were evenly divided into 9 groups, with each group having 9 aluminum alloy base parts.

[0067] The electrolyte used is a composite solution composed of 10 g / L aluminate, 5 g / L phosphate and 5 g / L sodium fluoride.

[0068] Example 1

[0069] The first group of aluminum alloy base parts, the second group of aluminum alloy base parts, the third group of aluminum alloy base parts and the fourth group of aluminum alloy base parts were respectively subjected to micro-arc oxidation treatment. During the micro-arc oxidation treatment, the process parameters shown in Table 1 were used.

[0070]

[0071] Table 1

[0072] It should be noted that the film thickness of each group in Table 1 is the average estimated value of 9 aluminum alloy base parts, and there is a slight error between the film thickness values ​​on the individual base parts.

[0073] As can be seen from Table 1, the increase in current density can increase the content of α-Al2O3 phase in the micro-arc oxidation film. Mainly by increasing the current density during the micro-arc oxidation process, more γ-Al2O3 phase is transformed into α-Al2O3 phase, but too high current density will lead to a decrease in the quality of the film layer and is also prone to burnout. Therefore, the process parameters used in the micro-arc oxidation process of the present invention can transform more γ-Al2O3 phase into α-Al2O3 phase, thereby improving the density of the film layer and avoiding burnout.

[0074] Example 2

[0075] The aluminum alloy base parts of Group 5 to Group 9 were subjected to the first micro-arc oxidation treatment. During the first micro-arc oxidation treatment, the process parameters shown in Table 2 were used, and the ceramic film layers formed on the surfaces of the aluminum alloy base parts were polished.

[0076]

[0077] Table 2

[0078] It should be noted that the film thickness and film hardness of each group in Table 2 are the average estimated values ​​of 9 aluminum alloy base parts, and there are slight errors between the film thickness values ​​and hardness values ​​on the single base parts.

[0079] Example 3

[0080] The aluminum alloy base parts in Group 7 in Example 2 are divided into three groups, with an average of three aluminum alloy base parts in each group. The three groups of aluminum alloy base parts are renumbered as 7a, 7b and 7c, respectively. The three groups of aluminum alloy base parts numbered 7a, 7b and 7c are subjected to a second micro-arc oxidation treatment. During the second micro-arc oxidation treatment, the process parameters shown in Table 3 are adopted, and the ceramic film layer formed on the surface of the aluminum alloy base parts is polished.

[0081]

[0082] Table 3

[0083] It should be noted that the film thickness and film hardness of each group in Table 3 are the average estimated values ​​of three aluminum alloy base parts, and there are slight errors between the film thickness values ​​and hardness values ​​on the single base parts.

[0084] In the above embodiments, OK means the effect is qualified, and NG means the effect is poor or unqualified. As can be seen from Example 2, a ceramic film layer that is too thick or too thin will result in an unqualified appearance effect if a single micro-arc oxidation treatment is used. A single thickness that is too thick may even result in an unqualified polishing effect. However, a two-time micro-arc oxidation treatment can obtain an appearance effect that meets the requirements.

[0085] It should be noted that the above specific implementation is only for the purpose of verifying the effect of the method for preparing the appearance film layer of the aluminum alloy part provided by the present invention in the actual experimental process, and does not limit the technical solution provided by the present invention.

[0086] It can be seen from the above specific embodiments that the appearance film preparation method and aluminum alloy parts provided by the present invention prepare a ceramic film layer on the surface of the aluminum alloy base part through micro-arc oxidation treatment technology to form a film layer with ceramic texture and both functional and decorative properties, broadening the high-quality appearance surface treatment process of aluminum alloy parts and realizing the manufacturing of lightweight ceramic texture structural parts; by performing at least two micro-arc oxidation treatments on the pretreated aluminum alloy base part in sequence, after each micro-arc oxidation treatment, the ceramic film layer formed on the surface of the aluminum alloy base part is polished to remove the outermost loose layer of the ceramic film layer and retain the dense layer of the ceramic film layer, so that the surface of the aluminum alloy base part can fully retain a dense layer with good density and functional effects, avoiding the conflict between the single micro-arc oxidation thickness causing the density of the ceramic film layer to be reduced due to excessive thickness and the polishing allowance requiring a certain film thickness; the present invention can achieve the purpose of both increasing the overall film thickness and ensuring the overall film density by controlling the quality of the micro-arc oxidation ceramic film layer in multiple stages respectively.

[0087] As described above, the appearance film preparation method of the aluminum alloy part and the aluminum alloy part according to the present invention are described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the appearance film preparation method of the aluminum alloy part and the aluminum alloy part according to the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A method for preparing an appearance film layer of an aluminum alloy part, characterized in that: The steps include: Performing surface pretreatment on the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements; The pretreated aluminum alloy base member is subjected to at least two micro-arc oxidation treatments in sequence, and after each micro-arc oxidation treatment, the ceramic film layer formed on the surface of the aluminum alloy base member is polished to remove the outermost loose layer of the ceramic film layer and retain the dense layer of the ceramic film layer; The outermost dense layer of the aluminum alloy base part is finely polished to complete the appearance film layer prepared on the surface of the aluminum alloy base part.

2. The method for preparing an appearance film layer of an aluminum alloy part according to claim 1, characterized in that: Before performing surface pretreatment on the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements, the method further includes: The aluminum alloy substrate is processed into an aluminum alloy basic part by CNC machining equipment.

3. The method for preparing an appearance film layer of an aluminum alloy part according to claim 1, characterized in that: The surface pretreatment of the aluminum alloy base part so that the surface of the aluminum alloy base part meets the preset cleanliness requirements includes: The surface of the aluminum alloy base part is polished, sandblasted and cleaned in sequence so that the surface of the aluminum alloy base part meets the preset cleanliness requirements.

4. The method for preparing an appearance film layer of an aluminum alloy part according to claim 1, characterized in that: The steps of each micro-arc oxidation treatment of the pre-treated aluminum alloy base part include: Using the pretreated aluminum alloy base part as an anode and an electrolytic cell as a cathode, immersing the aluminum alloy base part in the electrolyte of the electrolytic cell; The aluminum alloy base part immersed in the electrolyte is subjected to micro-arc oxidation treatment by an AC pulse power supply in a constant voltage mode until a preset thickness is reached to complete the micro-arc oxidation treatment.

5. The method for preparing an appearance film layer of an aluminum alloy part according to claim 1, characterized in that: The pretreated aluminum alloy base parts are subjected to two micro-arc oxidation treatments in sequence, namely the first micro-arc oxidation treatment and the second micro-arc oxidation treatment; wherein, During the first micro-arc oxidation treatment and the second micro-arc oxidation treatment, the electrolytes used are composite solutions composed of 1g / L-20g / L aluminate, 1g / L-10g / L phosphate and 1g / L-10g / L sodium fluoride; and the temperatures of the electrolytes are both 10°C-50°C.

6. The method for preparing an appearance film layer of an aluminum alloy part according to claim 5, characterized in that: During the first micro-arc oxidation treatment, the voltage used was 200V-400V and the current density was 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

7. The method for preparing an appearance film layer of an aluminum alloy part according to claim 5, characterized in that: During the second micro-arc oxidation treatment, the voltage used was 400V-700V and the current density was 25A / dm 2 -50A / dm 2 , the duty cycle is 10%-50%, and the pulse frequency is 100Hz-700Hz.

8. The method for preparing an appearance film layer of an aluminum alloy part according to claim 5, characterized in that: The first ceramic film layer formed by the first micro-arc oxidation treatment has a thickness of 25 μm-40 μm and a hardness of 500 HV-1000 HV.

9. The method for preparing an appearance film layer of an aluminum alloy part according to claim 5, characterized in that: After the second micro-arc oxidation treatment, the total thickness of the ceramic film layer formed on the surface of the aluminum alloy base part is 40 μm-60 μm, and the hardness is 700 HV-1500 HV.

10. An aluminum alloy part, characterized in that: The appearance film layer is prepared on the surface of the aluminum alloy base part by using the appearance film layer preparation method of the aluminum alloy part as described in any one of claims 1 to 9 to obtain the aluminum alloy part.

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