Composite oxide film and preparation method thereof

Abstract

This application relates to the field of anodizing technology, and more particularly to a composite oxide film and its preparation method. The preparation method includes the following steps: anodizing the surface of a metal workpiece to form an oxide layer; depositing a modified organosilicon polymer onto the oxide layer using cathodic electrophoretic coating technology to form a deposition layer, thereby obtaining a composite oxide film; wherein the modified organosilicon polymer contains positively charged modified epoxy resin units and negatively charged hydrophobic fluorinated groups. The composite oxide film and its preparation method provided in this application utilize a deposition layer with strong adhesion and hydrophobic properties on the surface of the oxide layer to improve the performance and service life of the oxide layer.

Description

[Technical Field]

[0001] This application relates to the field of anodizing technology, and in particular to a composite oxide film and its preparation method. [Previous Technology]

[0002] Anodizing is a commonly used metal surface treatment technology. This technology forms a dense oxide film on the surface of a metal workpiece. This oxide film has good anti-corrosion, wear resistance and insulation properties.

[0003] After the oxide layer is prepared, it is easy to gradually lose its original properties due to physical or chemical action. For example, during the use of metal workpieces, the oxide layer may be damaged due to friction, collision or other reasons, resulting in the oxide layer falling off, thinning or scratching; or the oxide layer of the metal workpiece may be exposed to special environments such as acid and alkali, high humidity, and high temperature for a long time, and the oxide layer may be corroded by moisture, acid, alkali and other substances, the corrosion rate or aging process may be accelerated, which may lead to the destruction of the oxide layer. [Summary of the Invention]

[0004] In view of this, this application provides a composite oxide film and a method for preparing the same, by depositing a deposition layer with strong adhesion and hydrophobic properties on the surface of the oxide layer to improve the service life of the oxide layer.

[0005] In a first aspect, this application provides a method for preparing a composite oxide film, the method comprising the following steps: anodic oxidation treatment of a metal workpiece surface to form an oxide layer; and depositing a modified organosilicon polymer onto the oxide layer using cathodic electrophoretic coating technology to form a deposition layer, thereby obtaining a composite oxide film; wherein the modified organosilicon polymer contains positively charged modified epoxy resin units and negatively charged hydrophobic fluorine-containing groups.

[0006] In conjunction with the first aspect, the method further includes preparing the modified organosilicone polymer, wherein preparing the modified organosilicone polymer comprises: reacting an organosilicone modified epoxy acrylate resin with an amine ring-opening agent to obtain a ring-opening product; wherein the amine ring-opening agent comprises at least one of monoethanolamine, diethanolamine, and triethanolamine;

[0007] The ring-opening product is subjected to acidification treatment to obtain the modified organosilicone polymer.

[0008] In conjunction with the first aspect, the method further includes preparing the organosilicone modified epoxy acrylate resin, wherein preparing the organosilicone modified epoxy acrylate resin includes: mixing epoxy resin, hydroxyl chain extender, methacrylamide and modified organosilicone quantum dots in a preset mass ratio and then performing a polymerization reaction to obtain the organosilicone modified epoxy acrylate resin; wherein the preset mass ratio is (50~100):(2~30):(10~50):(1~10).

[0009] In conjunction with the first aspect, the hydroxyl chain extender includes at least one of ethylene glycol ethyl ether, dimethylolpropionic acid and dimethylolbutyric acid.

[0010] In conjunction with the first aspect, the method further includes preparing the modified organosilicon quantum dots, wherein preparing the organosilicon quantum dots includes:

[0011] Hydroxypropyl methacrylate and perfluorooctyltriethoxysilane are mixed in a preset mass ratio and then reacted to obtain modified organosilicon quantum dots; wherein the preset mass ratio is (2~8):(1~3).

[0012] In conjunction with the first aspect, after anodizing the surface of the metal workpiece to form an oxide layer, the method further includes:

[0013] The oxide layer is etched with an etching solution to form diffuse reflection microcracks.

[0014] In conjunction with the first aspect, the corrosive solution contains SO₄²⁻, and the concentration of SO₄²⁻ is 0.03 mol / L to 3 mol / L.

[0015] In conjunction with the first aspect, the modified organosilicon polymer is deposited on the oxide layer to form a deposition layer by using cathodic electrophoretic coating technology, which has at least one of the following characteristics: (1) the reaction temperature is 25℃~30℃; (2) the voltage is 60V~70V; (3) the reaction time is 25s~30s.

[0016] In a second aspect, this application provides a composite oxide film, the composite oxide film comprising an oxide layer and a deposition layer formed on the oxide layer, the deposition layer comprising a modified organosilicon polymer containing positively charged modified epoxy resin units and negatively charged hydrophobic fluorinated groups.

[0017] In conjunction with the second aspect, the oxide layer contains diffuse reflection microcracks, and the deposited layer is formed on the surface of the oxide layer and within the diffuse reflection microcracks.

[0018] In conjunction with the second aspect, the composite oxide film has at least one of the following characteristics: (1) the thickness of the composite oxide film is 10 μm to 30 μm; (2) the pore size of the composite oxide film is 40 nm to 80 nm; (3) the width of the diffuse reflection microcrack is 5 nm to 20 nm; (4) the depth of the diffuse reflection microcrack is 30 nm to 50 nm; (5) the thickness of the deposited layer is 5 μm to 20 μm; (6) the L value of the composite oxide film is ≥90; (7) the water contact angle of the composite oxide film is ≥130°.

[0019] By adopting the above technical solution, this application has at least the following beneficial effects: The method for preparing the composite oxide film provided in this application uses cathodic electrophoretic coating technology to deposit modified organosilicon polymers onto the oxide layer to form a deposition layer. The deposition layer attached to the oxide layer can provide protection, improve the wear resistance of the oxide layer, and extend the service life of the oxide layer. Moreover, the deposition layer contains positively charged modified epoxy resin units. The positive charge can enhance the bonding force between the deposition layer and the oxide layer on the negatively charged surface of the metal workpiece, preventing the deposition layer from falling off during use and extending the protection time of the oxide layer by the deposition layer. In addition, the deposition layer also contains negatively charged hydrophobic fluorine-containing groups. The hydrophobicity of the fluorine-containing groups can significantly reduce the interaction between water molecules, acids, alkalis, and other corrosive substances and the surface of the deposition layer, allowing the metal workpiece to be used in special environments such as acid and alkali, high humidity, and high temperature.

Implementation Method

[0021] In order to better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the drawings.

[0022] It should be understood that the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] It should be understood that the term "and / or" used in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Furthermore, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0025] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are described in terms of the angles shown in the diagram and should not be construed as limiting the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that a component is connected to another component "upper" or "lower," it can not only be directly connected to another component "upper" or "lower," but also indirectly connected to another component "upper" or "lower" through an intermediate component.

[0026] This application provides a method for preparing a composite oxide film, the method comprising:

[0027] Anodizing is performed on the surface of a metal workpiece to form an oxide layer;

[0028] A modified organosilicon polymer is deposited on an oxide layer using cathodic electrophoretic coating technology to form a composite oxide film; wherein the modified organosilicon polymer contains positively charged modified epoxy resin units and negatively charged hydrophobic fluorine-containing groups.

[0029] The method for preparing the composite oxide film in the above scheme uses cathodic electrophoretic coating technology to deposit modified organosilicon polymers onto the oxide layer to form a deposition layer. The deposition layer attached to the oxide layer can provide protection, improve the wear resistance of the oxide layer, and extend the service life of the oxide layer. Moreover, the deposition layer contains positively charged modified epoxy resin units. The positive charge can enhance the bonding force between the deposition layer and the oxide layer on the negatively charged surface of the metal workpiece, prevent the deposition layer from falling off during use, and extend the protection time of the oxide layer by the deposition layer. In addition, the deposition layer also contains negatively charged hydrophobic fluorinated groups. The hydrophobicity of the fluorinated groups can significantly reduce the interaction between water molecules, acids, alkalis and other corrosive substances and the surface of the deposition layer, so that the metal workpiece can be used in special environments such as acid and alkali, high humidity, and high temperature.

[0030] Please refer to Figure 1. The preparation method of the composite oxide film of this application is described below:

[0031] Step S10: Perform anodizing treatment on the surface of the metal workpiece to form an oxide layer.

[0032] In step S10, the metal workpiece used in this application is made of aluminum or its alloy. The anodizing treatment of aluminum or its alloy specifically includes pretreatment, preparation of electrolyte, anodizing and post-treatment steps.

[0033] Pretreatment specifically includes cleaning, polishing or grinding, pickling, etc. Among them, the cleaning process usually uses cleaning agents to remove grease, dust and other contaminants from the surface of the metal workpiece. The type of cleaning agent can be selected according to the material of the metal workpiece and is not limited here; polishing or grinding can obtain a smoother surface of the metal workpiece; pickling can remove oxides and impurities from the surface of the metal workpiece and improve the quality of the oxide layer prepared subsequently.

[0034] The type of electrolyte used in anodizing can be selected according to the characteristics of the oxide layer to be formed and the type of metal workpiece. For example, for aluminum or its alloys, electrolytes such as sulfuric acid, oxalic acid, and chromic acid can be used, and there is no limitation here.

[0035] In the anodizing process, the metal workpiece is used as the anode and the inert material such as platinum or stainless steel is used as the cathode and placed in the electrolyte. At this time, a direct current is applied by the power supply to cause the metal surface on the anode to undergo an oxidation reaction, forming a dense oxide film. The current density, electrolyte temperature, processing time and other parameters are controlled according to the required oxide layer thickness and characteristics.

[0036] The post-processing involves cleaning the surface of the metal workpiece with a cleaning solution such as deionized water to remove residual electrolyte, thereby obtaining a metal workpiece with a dense oxide layer, which can significantly improve the corrosion resistance, wear resistance and aesthetics of the metal workpiece.

[0037] The oxide layer formed by the anodizing process in this application is an aluminum oxide layer, and the thickness of the aluminum oxide layer is 500nm~700nm. Optionally, the specific thickness of the oxide layer can be 500nm, 550nm, 600nm, 650nm and 700nm, or other values ​​within the range, which can be selected according to actual needs and are not limited here. Understandably, an excessively thick aluminum oxide layer reduces its toughness and increases the preparation cost, while an excessively thin aluminum oxide layer may not provide sufficient protection, and its corrosion resistance and wear resistance are affected. The thickness of the oxide layer in this application is within the above range, which can obtain an aluminum oxide layer that has both low cost, long service life and excellent wear and corrosion resistance.

[0038] In some embodiments, after step S10, step S11 is further included: using an etching solution to etch the oxide layer to form diffuse reflection microcracks.

[0039] In step S11, the corrosion solution contains SO₄²⁻, and the concentration of SO₄²⁻ is 0.03 mol / L to 3 mol / L. Optionally, the concentration of SO₄²⁻ can be 0.03 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, and 0.3 mol / L, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Preferably, the SO₄²⁻-containing corrosion solution used in this application is Al₂(SO₄)₃, and the concentration of Al₂(SO₄)₃ is 0.01 mol / L to 1 mol / L. The specific reaction process between Al₂(SO₄)₃ and the alumina layer is as follows: Al₂(SO₄)₃ + 6H₂O ⇌ 2Al(OH)₃ + 3H₂SO₄ (dilute); 3H₂SO₄ (dilute) + Al₂O₃ (oxide film) → Al₂(SO₄)₃ + 3H₂O;

[0040] Understandably, please refer to Figures 2 and 3. The oxide layer formed after anodizing has a complex porous structure. With the action of the Al2(SO4)3 corrosion solution, the surface and micropore structure of the oxide layer change, which increases the pore size of the micropores in the oxide layer. The surface of the oxide layer and the inner wall of the micropores form a complex number of tiny cracks and depressions, i.e. diffuse reflection microcracks. At this time, the cracks and depressions cause the reflection of light on the oxide layer to no longer be a specular reflection in a single direction, but to be scattered in multiple directions, thus producing a diffuse reflection effect, making the appearance of the metal workpiece with the oxide layer appear white.

[0041] The reaction temperature of the above corrosion treatment is 40℃~70℃, and the reaction time is 2min~8min. Optionally, the specific reaction temperature can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, and 70℃, and the specific reaction time can be 2min, 3min, 4min, 5min, 6min, 7min, and 8min, or other values ​​within the range. It can be selected according to actual needs and is not limited here. It is understood that the reaction temperature will affect the corrosion rate, and thus affect the formation rate and size of diffuse reflection microcracks. The reaction time will affect the number and size of diffuse reflection microcracks. The reaction time and temperature of the corrosion treatment in this application are within the above range, which can form diffuse reflection microcracks of appropriate size and number on the oxide layer. Moreover, the structure of the diffuse reflection microcracks formed by the Al2(SO4)3 corrosion solution is stable and not easily damaged under the action of external force.

[0042] The width of the diffuse reflection microcrack is 5nm~20nm, and the depth is 30nm~50nm. Optionally, the specific width of the diffuse reflection microcrack can be 5nm, 10nm, 15nm, and 20nm, and the specific depth can be 30nm, 35nm, 40nm, 45nm, and 50nm, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, the width of the diffuse reflection microcrack affects the light scattering effect. A wider microcrack will result in a larger light scattering angle, increasing the number of scattering directions, thereby producing a stronger diffuse reflection effect. The depth of the microcrack affects the light propagation path length. A longer propagation path increases the chance of light interacting with the surface structure of the metal workpiece. However, excessive width and depth will affect the structural integrity of the oxide layer and reduce its service life. The width and depth of the diffuse reflection microcrack in this application are within the above range. While ensuring the structural integrity of the oxide layer, it can produce a stronger diffuse reflection effect, making the white effect of the metal surface better and the color distribution more uniform.

[0043] Before corrosion, the pore size of the oxide layer is 20nm~50nm. After corrosion, the pore size of the oxide layer is 40nm~80nm. Optionally, the pore size of the oxide layer after corrosion can be 40nm, 50nm, 60nm, 70nm, and 80nm, or other values ​​within the range, which can be selected according to actual needs and are not limited here. Understandably, the pore size of the oxide layer after corrosion within the above range can ensure that the oxide layer has good density, thereby effectively preventing water, acidic substances, and alkaline substances from penetrating into the metal workpiece.

[0044] Step S20: The modified organosilicon polymer is deposited on the oxide layer using cathodic electrophoretic coating technology to form a deposition layer and obtain a composite oxide film; wherein the modified organosilicon polymer contains positively charged modified epoxy resin units and negatively charged hydrophobic fluorine-containing groups.

[0045] In step S20, during the cathodic electrophoretic coating process, the metal workpiece with an oxide layer is used as the cathode, and the modified organosilicon polymer with a positive charge is used as the anode. When a DC voltage is applied, the positively charged modified organosilicon polymer moves toward the cathode and deposits on the surface of the metal workpiece to form a deposition layer.

[0046] The reaction temperature of the cathodic electrophoretic coating technology is 25℃~30℃, the reaction voltage is 60V~70V, and the reaction time is 25s~30s. Optionally, the reaction temperature can be 25℃, 26℃, 27℃, 28℃, 29℃, and 30℃, the voltage can be 60V, 62V, 64V, 66V, 68V, and 70V, and the reaction time can be 25s, 26s, 27s, 28s, 29s, and 30s, or other values ​​within the range. These can be selected according to actual needs and are not limited here. Understandably, the reaction temperature of the electrophoresis process affects the viscosity of the modified organosilicon polymer coating, thereby affecting its flowability; the reaction voltage is the power source that drives the deposited particles to move towards the metal surface, affecting the movement speed of the coating particles and thus improving the deposition efficiency; the reaction time affects the deposition thickness and uniformity of the deposited layer. In this application, the reaction temperature, voltage and time of the electrophoresis process are within the above range, which can accelerate the formation of the deposited layer and ensure the deposition quality of the deposited layer.

[0047] The deposition layer prepared by cathodic electrophoretic coating technology is formed on the surface of the oxide layer, within the pores of the oxide layer, and within the diffuse reflection cracks. It can fix the microcracks, and its deposition thickness is 5μm~20μm. Optionally, the deposition thickness of the deposition layer can be 5μm, 10μm, 25μm, and 20μm, or other values ​​within the range, which can be selected according to actual needs and are not limited here. Understandably, the thickness of the deposition layer within the above range not only fixes the microcracks but also enhances the light transmittance of the deposition layer and reduces the influence of the deposition layer on the diffuse reflection effect of the microcracks.

[0048] In some embodiments, step S12 is included before step S20: preparing a modified organosilicon polymer, wherein preparing the modified organosilicon polymer includes:

[0049] First, the organosilicone modified epoxy acrylate resin is reacted with an amine ring-opening agent to obtain a ring-opening product; then, the ring-opening product is acidified to obtain a modified organosilicone polymer.

[0050] The reaction process in step S12 is as follows:

[0051] Among them, the amine ring-opening agent includes at least one of monoethanolamine, diethanolamine and triethanolamine, which can be selected according to actual needs and is not limited here.

[0052] The addition ratio of amine ring-opening agents is 5%~10%. Optionally, the specific addition ratio of amine ring-opening agents can be 5%, 6%, 7%, 8%, 9%, and 10%, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, amine compounds, as ring-opening agents, can react with the epoxy groups in organosilicon-modified epoxy acrylate resin to generate intermediates containing more active functional groups. In addition, amine groups have strong nucleophilic properties. In the subsequent deposition process, amine groups can attract H+ ions, making the modified organosilicon polymer positively charged, which helps to promote the movement of the modified organosilicon polymer towards the cathode, thereby depositing a deposition layer on the metal surface. The addition ratio of amine ring-opening agents within the above range can accelerate the ring-opening process.

[0053] A curing agent is also required in the ring-opening reaction. The curing agent used in this application may be at least one of phthalic diisocyanate, toluene diisocyanate, hexamethyl diisocyanate, and ethylene glycol ethyl ether. The choice can be made according to actual needs and is not limited here. Understandably, the curing agent can promote the ring-opening of epoxy groups.

[0054] The ring-opening reaction temperature is 40℃~60℃, and the time is 0.5h~2h. Optionally, the specific time of the ring-opening reaction can be 40℃, 40℃, 40℃, 40℃, 40℃, 40℃, and 40℃, etc., and the specific time can be 0.5h, 0.5h, 1.1h, 1.1h, 1.1h, and 2h, etc., or other values ​​within the range. It can be selected according to actual needs and is not limited here.

[0055] After the ring-opening reaction, an acidification treatment is performed. The acidification treatment can promote the amine matrix protonation in the intermediate of the active functional group, and the resulting modified organosilicon polymer is positively charged, which helps to promote the movement of the modified organosilicon polymer to the cathode during the cathodic electrophoretic coating process, thereby depositing a deposition layer on the metal surface.

[0056] In some embodiments, step S13 is included before step S12: preparing organosilicon-modified epoxy acrylate resin, wherein preparing organosilicon-modified epoxy acrylate resin includes:

[0057] Epoxy resin, hydroxyl chain extender, methacrylamide and modified organosilicon quantum dots are mixed in a preset mass ratio and then subjected to polymerization reaction to obtain organosilicon modified epoxy acrylic resin; wherein, the preset mass ratio is (50~100):(2~30):(10~50):(1~10).

[0058] The reaction process in step S13 is as follows:

[0059] Among them, epoxy resin is the main component of organosilicon-modified epoxy acrylate resin; hydroxyl chain extender can react with epoxy groups in epoxy resin to introduce new hydroxyl functional groups, which can further react with epoxy groups to form longer chains, thereby increasing the molecular weight of epoxy resin and improving material strength. The hydroxyl chain extender used in this application can be ethylene glycol ethyl ether, dimethylolpropionic acid, and dimethylolbutyric acid, etc.; the addition of modified organosilicon quantum dots can enhance the white appearance of the composite oxide layer. Methacrylamide and modified organosilicon quantum dots are the main components of organosilicon-modified epoxy acrylate resin.

[0060] The ratio of epoxy resin, hydroxyl chain extender, methacrylamide and modified organosilicon quantum dots is (50~100):(2~30):(10~50):(1~10). Understandably, epoxy resin is the main material, and the amount of hydroxyl chain extender will affect the crosslinking density and molecular weight of organosilicon modified epoxy acrylate resin. When the ratio of epoxy resin, hydroxyl chain extender, methacrylamide and modified organosilicon quantum dots is within the above range, the obtained organosilicon modified epoxy acrylate resin can be used to prepare composite oxide layers with properties such as strength and hardness.

[0061] Preferably, the amount of modified organosilicon quantum dots added is 1wt%~2wt%. It is understood that the addition of modified organosilicon quantum dots can improve the transparency of the deposited layer. As the Si content in the modified organosilicon quantum dots increases, the Si-O bonds in the prepared composite oxide film increase, and the strength of the composite oxide film increases. However, when the amount of modified organosilicon quantum dots added is greater than 2wt%, the brittleness of the composite oxide film will increase, affecting its adhesion to the surface of the metal workpiece.

[0062] The above polymerization reaction also requires the addition of a polymerization initiator. The polymerization initiator can be azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, etc., and the amount of polymerization initiator added is 0.1%~5%. Optionally, the specific amount of polymerization initiator added can be 0.1%, 1%, 2%, 3%, 4%, and 5%, etc., or other values ​​within the range. It can be selected according to actual needs and is not limited here. It is understood that the amount of polymerization initiator added will affect the rate of polymerization reaction and the molecular weight of organosilicon-modified epoxy acrylate resin. For example, too little polymerization initiator will reduce the reaction rate and the molecular weight of organosilicon-modified epoxy acrylate resin, while too much polymerization initiator will lead to an excessively fast reaction rate that is difficult to control. The amount of polymerization initiator added in this application is within the above range, which can ensure the smooth progress of the polymerization reaction.

[0063] The polymerization temperature is 40℃~85℃ and the time is 2h~8h. Optionally, the specific polymerization temperature can be 40℃, 50℃, 60℃, 70℃, 80℃ and 85℃, etc., and the specific time can be 2h, 3h, 4h, 5h, 6h, 7h and 8h, etc., or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, temperature affects the reaction rate of polymerization. Higher temperature can accelerate the reaction rate; a longer reaction time can ensure that more monomers participate in the reaction and form longer polymer chains; however, excessively high temperature and excessively long time will lead to the occurrence of side reactions, and excessively low temperature and excessively short time will result in organosilicone modified epoxy acrylate resin with insufficient molecular weight. The polymerization temperature and time of this application are within the above range, which can ensure the acquisition of organosilicone modified epoxy acrylate resin with excellent performance and reduce the occurrence of side reactions.

[0064] In some embodiments, step S14 is included before step S13: preparing modified organosilicon quantum dots, wherein preparing modified organosilicon quantum dots includes:

[0065] Hydroxypropyl methacrylate and perfluorooctyltriethoxysilane are mixed in a preset mass ratio and reacted to obtain modified organosilicon quantum dots; wherein the preset mass ratio is (2~8):(1~3).

[0066] The reaction process in step S14 is as follows:

[0067] The mass ratio of hydroxypropyl methacrylate to perfluorooctyltriethoxysilane is (2~8):(1~3). Understandably, hydroxypropyl methacrylate is used to prepare modified organosilicon quantum dots, which can then be grafted and copolymerized with epoxy resin. Polysiloxane possesses good hydrophobicity, heat resistance, and biocompatibility, and the perfluorinated groups in perfluorooctyltriethoxysilane further enhance the hydrophobicity of the composite oxide film. Furthermore, the Si-OC in polysiloxane has higher strength than conventional CC, which can further improve the strength of the composite oxide film. When the ratio of the two is within the above range, the modified organosilicon quantum dots obtained can be used to prepare composite oxide films with excellent performance.

[0068] In the above reaction process, a catalyst also needs to be added. The catalyst used in this application is K2CO3, Na2CO3, NaHCO3, etc., which can be selected according to actual needs and are not limited here.

[0069] The temperature of the catalytic reaction is 30℃~90℃, and the time is 0.5h~5h. Optionally, the specific temperature of the catalytic reaction can be 3℃, 40℃, 50℃, 60℃, 70℃, 80℃, and 90℃, and the specific time can be 0.5h, 1h, 2h, 3h, 4h, and 5h, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, temperature affects the reaction rate of the catalytic reaction. Higher temperatures will accelerate the reaction rate; longer reaction times can ensure a more complete reaction. However, excessively high temperatures and excessively long times can lead to side reactions, while excessively low temperatures and excessively short times can lead to incomplete reactions. The temperature and time of the catalytic reaction in this application are within the above-mentioned range, which can ensure the stable progress of the preparation process of modified organosilicon quantum dots.

[0070] After step S20, a modified organosilicon polymer with a negatively charged perfluorinated group at one end and a positively charged group at the other end can be obtained.

[0071] Modified organosilicon polymers can be used to prepare the composite oxide film of this application. The composite oxide film includes an oxide layer and a deposition layer formed on the oxide layer. The deposition layer includes a modified organosilicon polymer containing positively charged modified epoxy resin units and negatively charged hydrophobic fluorine-containing groups. The oxide layer contains diffuse reflection microcracks. The deposition layer is formed on the surface of the oxide layer and within the diffuse reflection cracks.

[0072] The thickness of the composite oxide film is 10μm to 30μm. Optionally, the specific thickness of the composite oxide film can be 10μm, 15μm, 20μm, 25μm, and 30μm, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, this ensures that the composite oxide film has good density, thereby effectively preventing water, acidic substances, and alkaline substances from penetrating into the metal workpiece.

[0073] The L value of the composite oxide film is ≥90. Optionally, the L value of the composite oxide film can be 90, 91, 92, 93, 94, 95, and 96, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, the L value of the composite oxide film refers to the brightness value of the oxide film in the CIE Lab color space. The L value represents the lightness or darkness of the color. The higher the L value, the closer the color is to white or the brighter it is. The L value of the composite oxide film of this application is ≥90, that is, the composite oxide film has a white appearance.

[0074] The water contact angle of the composite oxide film is ≥130°. Optionally, the water contact angle of the composite oxide film can be 130°, 131°, 132°, 133°, 134°, and 135°, or other values ​​within the range. It can be selected according to actual needs and is not limited here. Understandably, a water contact angle ≥130° indicates that the composite oxide film has superhydrophobicity. Superhydrophobicity can significantly reduce the interaction between water molecules, acids, alkalis, and other corrosive substances and the surface of the deposited layer, allowing metal workpieces to be used in special environments such as acid and alkali, high humidity, and high temperature.

[0075] The technical solution of this application will be described below with reference to specific embodiments:

[0076] Example 1

[0077] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.02mol / L, the temperature of the etching reaction is 55℃ and the time is 7min;

[0078] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0079] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 30℃, the voltage is 60V, and the time is 30s.

[0080] Example 2

[0081] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.05mol / L, the temperature of the etching reaction is 55℃ and the time is 7min;

[0082] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0083] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 60℃, the voltage is 60V, and the time is 30s.

[0084] Example 3

[0085] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.1mol / L, the temperature of the etching reaction is 55℃ and the time is 7min;

[0086] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0087] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 80℃, the voltage is 60V, and the time is 30s.

[0088] Example 4

[0089] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.05mol / L, the temperature of the etching reaction is 40℃ and the time is 5min;

[0090] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0091] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 25℃, the voltage is 10V, and the time is 25s.

[0092] Example 5

[0093] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.05mol / L, the temperature of the etching reaction is 60℃ and the time is 5min;

[0094] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots, and azobisisobutyronitrile are polymerized to form organosilicon-modified epoxy acrylate resin. The organosilicon-modified epoxy acrylate resin is then subjected to a ring-opening reaction with monoethanolamine and acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0095] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 25℃, the voltage is 70V, and the time is 25s.

[0096] Example 6

[0097] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.05mol / L, the temperature of the etching reaction is 80℃ and the time is 5min;

[0098] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0099] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 25℃, the voltage is 100V, and the time is 25s.

[0100] Example 7

[0101] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.04mol / L, the temperature of the etching reaction is 50℃ and the time is 2min;

[0102] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0103] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 40℃, the voltage is 55V, and the time is 10s.

[0104] Example 8

[0105] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.04mol / L, the temperature of the etching reaction is 50℃ and the time is 6min;

[0106] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0107] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 40℃, the voltage is 55V, and the time is 60s.

[0108] Example 9

[0109] (1) Anodizing is performed on the surface of an aluminum substrate to form an aluminum oxide layer, and the aluminum oxide layer is etched with Al2(SO4)3·18H2O solution to form diffuse reflection microcracks; wherein, the concentration of Al2(SO4)3·18H2O solution is 0.04mol / L, the temperature of the etching reaction is 50℃ and the time is 10min;

[0110] (2) Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 66:14:18:2. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is subjected to a ring-opening reaction with monoethanolamine and then acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 2 wt%.

[0111] (3) A modified organic silicon polymer is deposited on an alumina layer to form a deposition layer by using cathodic electrophoretic coating technology to obtain a composite oxide film; wherein the temperature of the electrophoresis process is 40℃, the voltage is 55V, and the time is 120s.

[0112] Example 10

[0113] Different from Example 1: Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 100:30:50:1. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is then subjected to a ring-opening reaction with monoethanolamine and acidified to obtain a modified organosilicon polymer. The mass fraction of modified organosilicon quantum dots is 0.5 wt%.

[0114] Example 11

[0115] Different from Example 1: Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 100:30:50:1.82. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is then subjected to a ring-opening reaction with monoethanolamine and acidified to obtain a modified organosilicon polymer. The mass fraction of the modified organosilicon quantum dots is 1 wt%.

[0116] Example 12

[0117] Different from Example 1: Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 100:30:50:2.74. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is then subjected to a ring-opening reaction with monoethanolamine and acidified to obtain a modified organosilicon polymer. The mass fraction of modified organosilicon quantum dots is 1.5 wt%.

[0118] Example 13

[0119] Different from Example 1: Epoxy resin, ethylene glycol ethyl ether, methacrylamide, modified organosilicon quantum dots and azobisisobutyronitrile are mixed in a ratio of 100:30:50:4.62. The mixture undergoes a polymerization reaction to form organosilicon modified epoxy acrylate resin. The organosilicon modified epoxy acrylate resin is then subjected to a ring-opening reaction with monoethanolamine and acidified to obtain a modified organosilicon polymer. The mass fraction of modified organosilicon quantum dots is 2.5 wt%.

[0120] Comparative Example 1

[0121] Unlike Example 1, no modified organosilicon quantum dots were added.

[0122] The composite oxide films obtained in Examples 1-13 and Comparative Example 1 were cured at 100℃~200℃ for 0.5h~3h and tested: (1) The pore size of the composite oxide films of Examples 1-9 was tested; (2) The appearance of the composite oxide films of Examples 1-9 was observed; (3) The L / a / b values ​​of the composite oxide films of Examples 1, Examples 10-13 and Comparative Example 1 were tested using a colorimeter; (4) The Delam value of the composite oxide films of Examples 1, Examples 10-13 and Comparative Example 1 was tested using a microhardness tester; (5) The WCA value of the composite oxide films of Examples 1, Examples 10-13 and Comparative Example 1 was tested using a water droplet angle tester.

[0123] Test Results:

[0124] Table 1 Corrosion solution composition Concentration (mol / L) Reaction temperature (°C) Reaction time (min) Aperture (nm) Example 1 Al2(SO4)3·18H2O 0.02 55 7 41.7 Example 2 0.05 55 7 48.9 Example 3 0.1 55 7 73.2 Example 4 0.05 40 5 45.3 Example 5 0.05 60 5 47.2 Example 6 0.05 80 5 86.4 Example 7 0.04 50 2 38.8 Example 8 0.04 50 6 41.8 Example 9 0.04 50 10 84.1

[0125] Table 2 Temperature (°C) Voltage (V) Time (s) Appearance Example 1 30 60 30 qualified Example 2 60 60 30 There are particulate bubbles Example 3 80 60 30 Roughness and cracking Example 4 25 10 25 The membrane was too thin and broke. Example 5 25 70 25 qualified Example 6 25 100 25 Roughness and discoloration Example 7 40 55 10 The membrane was too thin and broke. Example 8 40 55 60 Roughness and discoloration Example 9 40 55 120 Roughness and cracking

[0126] Table 3 Addition amount of modified organosilicon quantum dots (wt%) L / a / b value Delam Test WCA Test Example 1 90.05 / -0.34 / 0.17 qualified 137.9° Example 10 92.89 / -0.33 / 0.53 Unqualified 126.1° Example 11 91.75 / -0.27 / 0.62 qualified 132.5° Example 12 91.56 / -0.31 / 0.37 qualified 133.9° Example 13 88.27 / -0.36 / -0.44 Unqualified 141.6° Comparative Example 1 93.73 / -0.25 / 0.76 Unqualified 37.2°

[0127] Test Result Analysis:

[0128] As shown in Table 1, the reaction temperature affects the corrosion rate during the formation of diffuse reflection microcracks, which in turn affects the formation rate and size of microcracks. The reaction time affects the number and size of microcracks. If the reaction temperature is too high or the reaction time is too long, the pore size of the oxide layer will be too large after the microcracks are formed, affecting its protective effect. In this application, the reaction temperature is within the range of 40℃ to 70℃ and the reaction time is within the range of 2 min to 8 min, which can obtain a microcrack oxide layer with appropriate pore size and ensure its structural stability.

[0129] As shown in Table 2, during the cathodic electrophoretic coating process, the reaction temperature of the electrophoresis process affects the viscosity of the modified organosilicon polymer coating, thereby affecting the fluidity of the modified organosilicon polymer coating; the reaction voltage is the power source that drives the deposited particles to move towards the metal surface, affecting the movement speed of the coating particles, thereby improving the deposition efficiency; the reaction time affects the deposition thickness and uniformity of the deposited layer; if the temperature, voltage, or time of the electrophoresis process is too high, the deposited layer solidifies too quickly, the internal structure of the film is uneven, bubbles cannot be discharged in time, and its surface roughness may cause cracking, thus reducing the transparency of the deposited layer and affecting the appearance color of the metal workpiece; if the temperature, voltage, or time of the electrophoresis process is too low, the thickness of the deposited layer is too thin. In this application, the electrophoresis process temperature is within the range of 25℃~30℃, the voltage is within the range of 60V~70V, and the time is within the range of 25s~30s, which can obtain a deposited layer with acceptable appearance.

[0130] As shown in Table 3, the addition of modified organosilicon quantum dots can improve the transparency of the deposited layer. When the amount of modified organosilicon quantum dots added is 1wt%~2wt%, the L value is >90, and the composite oxide film appears white. As the amount of modified organosilicon quantum dots increases, the Si content increases, the Si-O bond of the composite oxide film increases, the strength of the composite oxide film increases, and the bonding force between the deposited layer and the oxide layer is strong. However, when the amount of modified organosilicon quantum dots is greater than 2.5wt%, the film becomes more brittle and the adhesion decreases. In addition, the surface hydrophobicity of the composite oxide film is positively correlated with the content of perfluorinated groups. As the amount of modified organosilicon quantum dots added increases, the hydrophobic fluorinated groups increase, and the hydrophobicity of the composite oxide film is enhanced.

[0131] Refer to Figure 4. In Examples 1, 11 and 12, the mass fraction of modified organosilicon quantum dots is between 0.5wt% and 2wt%, resulting in high strength of the composite oxide film. The surface of the composite oxide film after the Delam test is basically free of damaged areas. In Example 10, the amount of modified organosilicon quantum dots added is too low. In Example 13, the amount of modified organosilicon quantum dots added is too high. In Comparative Example 1, no modified organosilicon quantum dots are added. All of these factors affect the strength of the composite oxide film, and the surface of the composite oxide film after the Delam test is damaged.

[0132] The structure, features and effects of the present invention have been described in detail above with reference to the embodiments shown in the figures. The above description is only a preferred embodiment of the present invention. However, the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall be within the protection scope of the present invention if they do not exceed the spirit covered by the specification and figures. [Simplified Explanation of the Diagram]

[0020] Figure 1 is a flowchart of the preparation method of the composite oxide film provided in this application; Figure 2 is a comparison diagram of the pore size of the composite oxide film before and after microporous corrosion provided in this application; Figure 3 is a comparison diagram of the cross-section of the composite oxide film before and after microporous corrosion provided in this application; Figure 4 is a partial schematic diagram of the composite oxide film after Delamination in Examples 1, 10-13 and Comparative Example 1 of this application. [Biomaterial Storage]

[0134] None

Claims

1. A method for preparing a composite oxide film, the improvement of which is that the method for preparing the composite oxide film includes the steps of: anodic oxidation treatment of the surface of a metal workpiece to form an oxide layer; and depositing a modified organosilicon polymer onto the oxide layer using cathodic electrophoretic coating technology to form a deposition layer, thereby obtaining a composite oxide film; wherein, The modified organosilicone polymer contains positively charged modified epoxy resin units and negatively charged hydrophobic fluorinated groups.

2. The method for preparing the composite oxide film as described in claim 1, wherein, The method also includes preparing the modified organosilicone polymer, wherein preparing the modified organosilicone polymer comprises: reacting an organosilicone modified epoxy acrylate resin with an amine ring-opening agent to obtain a ring-opening product; wherein the amine ring-opening agent includes at least one of monoethanolamine, diethanolamine, and triethanolamine; and acidifying the ring-opening product to obtain the modified organosilicone polymer.

3. The method for preparing the composite oxide film as described in claim 2, wherein, The method also includes preparing the organosilicone modified epoxy acrylate resin, wherein preparing the organosilicone modified epoxy acrylate resin includes: mixing epoxy resin, hydroxyl chain extender, methacrylamide and modified organosilicone quantum dots in a preset weight ratio and then carrying out a polymerization reaction to obtain the organosilicone modified epoxy acrylate resin; wherein the preset weight ratio is (50~100):(2~30):(10~50):(1~10).

4. The method for preparing the composite oxide film as described in claim 3, wherein, The hydroxyl chain extender includes at least one of ethylene glycol ethyl ether, dimethylolpropionic acid, and dimethylolbutyric acid.

5. The method for preparing the composite oxide film as described in claim 2, wherein, The method also includes preparing the modified organosilicon quantum dots, wherein preparing the organosilicon quantum dots includes: mixing hydroxypropyl methacrylate and perfluorooctyltriethoxysilane in a preset weight ratio and then reacting them to obtain modified organosilicon quantum dots; wherein the preset weight ratio is (2~8):(1~3).

6. The method for preparing the composite oxide film as described in claim 1, wherein, After anodizing the surface of a metal workpiece to form an oxide layer, the process further includes: etching the oxide layer with a corrosion solution to form diffuse reflection microcracks.

7. The method for preparing the composite oxide film as described in claim 6, wherein, The corrosive solution contains SO₄²⁻, and the concentration of SO₄²⁻ is 0.03 mol / L to 3 mol / L.

8. The method for preparing the composite oxide film as described in claim 6, wherein, The modified organosilicon polymer is deposited on the oxide layer using cathodic electrophoretic coating technology to form the deposited layer, which has at least one of the following characteristics: (1) the reaction temperature is 25℃~30℃; (2) the voltage is 60V~70V; (3) the reaction time is 25s~30s.

9. A composite oxide film, wherein the composite oxide film comprises an oxide layer and a deposition layer formed on the surface of the oxide layer, the deposition layer comprising a modified organosilicon polymer containing positively charged modified epoxy resin units and negatively charged hydrophobic fluorinated groups.

10. The composite oxide film as claimed in claim 9, wherein, The oxide layer contains diffuse reflection microcracks, and the deposited layer is formed on the surface of the oxide layer and within the diffuse reflection microcracks.

11. The composite oxide film as claimed in claim 10, wherein, The composite oxide film has at least one of the following characteristics: (1) the thickness of the composite oxide film is 10 μm to 30 μm; (2) the pore size of the composite oxide film is 40 nm to 80 nm; (3) the width of the diffuse reflection microcrack is 5 nm to 20 nm; (4) the depth of the diffuse reflection microcrack is 30 nm to 50 nm; (5) the thickness of the deposited layer is 5 μm to 20 μm; (6) the L value of the composite oxide film is ≥90; (7) the water contact angle of the composite oxide film is ≥130°.

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