Dendritic nanopore structure on surface of aluminum material, preparation method of dendritic nanopore structure and application of dendritic nanopore structure in aluminum-clad steel ground wire

Abstract

The invention provides a dendritic nanopore structure on the surface of an aluminum material, a preparation method of the dendritic nanopore structure and application of the dendritic nanopore structure in an aluminum-clad steel ground wire, and the preparation method provided by the invention comprises the following steps: carrying out electrochemical anodic oxidation in an electrolyte by taking the aluminum material to be treated as an anode strip to form a nanopore structure on the surface of the aluminum material; the voltage of electrochemical anodic oxidation is stepping voltage. According to the method, the aluminum material is used as an anode, the stepping voltage is adopted for electrochemical anodic oxidation, the multi-stage aluminum dioxide nano-pores with the pore diameters gradually increased from the surface to the inner core are formed in the surface of the aluminum material, the nano-pores communicate with one another, the structure can be regarded as a dendritic nano-porous structure, the binding force between the structure and the surface of the aluminum material is good, and the stability is high; the porous structure has the characteristics of high porosity, uniform distribution, good coherence of the transition layer, no defect and the like, the specific surface area of the porous structure is greatly increased, and the application is facilitated. In addition, the method provided by the invention is simple in preparation process and relatively low in cost.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal surface treatment, in particular to an aluminum material surface dendritic nanopore structure, a preparation method thereof and application of the aluminum material surface dendritic nanopore structure in aluminum-clad steel ground wires. BACKGROUND

[0002] Aluminum-clad steel is a composite product taking steel wire as a base material and wrapping an aluminum layer on the surface, and has high strength, excellent electrical conductivity and corrosion resistance, and is widely used in overhead lines, such as the production of wire cores and ground wires.

[0003] For overhead lines, icing disasters pose a serious threat to the safe operation of power systems. Super-lubricating surfaces (SLIPS) are based on the principle of biomimicry, which can inject lubricating oil into micro-nano structures to achieve good fusion and interlocking between the solid surface and water droplets, forming a stable lubricating layer with the characteristics of delayed freezing and extremely low adhesion strength. Based on this, a nanopore structure is prepared on the surface layer of the aluminum of the overhead line through anodic oxidation, which can fix the lubricating oil in the pore structure on the surface to form a stable lubricating layer. However, the nanopore structure prepared by the prior art has a single pore size and low surface oil storage capacity. SUMMARY

[0004] Therefore, the application provides an aluminum material surface dendritic nanopore structure, a preparation method thereof and application of the aluminum material surface dendritic nanopore structure in aluminum-clad steel ground wires. The aluminum material surface provided by the application has a dendritic nanopore structure, which can improve the surface oil storage capacity of the aluminum-clad steel ground wire.

[0005] The application provides a preparation method of an aluminum material surface nanopore structure, which comprises the following steps:

[0006] An aluminum material to be treated is used as an anode sheet, and electrochemical anodic oxidation is performed in an electrolyte to form a nanopore structure on the surface of the aluminum material.

[0007] The voltage of the electrochemical anodic oxidation is a step voltage.

[0008] In some specific implementation manners, the step voltage comprises a first voltage and a second voltage, and the second voltage is higher than the first voltage.

[0009] The first voltage and the second voltage are independently 60V-120V.

[0010] In some specific implementation manners, the electrochemical anodic oxidation is specifically as follows:

[0011] After electrochemical anodic oxidation at the first voltage for a first time, the voltage is increased to the second voltage at a rate of 0.5V / min-2V / min, and electrochemical anodic oxidation is performed at the second voltage for a second time.

[0012] In some specific embodiments, the first voltage is 60V-90V, and the first time is 1min-80min.

[0013] The second voltage is 90V-120V, and the second time is 40min-80min.

[0014] In some specific embodiments, the electrolyte is phosphoric acid or oxalic acid, and the solvent is an aqueous solution containing 0-50wt% ethylene glycol.

[0015] In some specific embodiments, the concentration of the electrolyte is 0.1mol / L-0.5mol / L.

[0016] In some specific embodiments, the electrolyte is circulated at a speed of 50mL / min-150mL / min during the electrochemical anodic oxidation.

[0017] In some specific embodiments, the cathode sheet is an aluminum sheet, a copper sheet, a stainless steel sheet or a graphite sheet.

[0018] The aluminum material to be treated is an aluminum sheet or an aluminum-clad steel sheet.

[0019] In some specific embodiments, the anode sheet and the cathode sheet are in a vertical state in the electrolyte, and the anode sheet and the cathode sheet are parallel.

[0020] The application also provides an aluminum material prepared by the preparation method described in the above technical solution, wherein the surface of the aluminum material comprises multi-stage nanopores with gradually increasing pore sizes from the surface to the core, and each stage of nanopores is interconnected.

[0021] In some specific embodiments, the first-stage nanopores have a pore size of 20nm-150nm, the second-stage nanopores have a pore size of 50nm-200nm, the first-stage nanopores have a thickness of 1μm-10μm, the second-stage nanopores have a thickness of 9μm-30μm, and the surface porosity of the aluminum material is 50%-70%.

[0022] In some specific embodiments, the aluminum material prepared by the preparation method described in the above technical solution can be used as an aluminum layer of an aluminum-clad steel ground wire, and can improve the surface oil storage capacity.

[0023] The application provides a preparation method of dendritic nano-porous structure on the surface of aluminum material, comprising the following steps: taking aluminum material to be treated as an anode sheet, and performing electrochemical anodic oxidation in an electrolyte to form nano-porous structure on the surface of the aluminum material; the voltage of the electrochemical anodic oxidation is a step voltage. The application adopts the step voltage to perform electrochemical anodic oxidation on the aluminum material with the aluminum material as an anode, to form multi-stage aluminum dioxide nano-pores on the surface of the aluminum material, which gradually increase in size from the surface to the core, and the nano-pores at different stages are interconnected, and the structure can be regarded as a dendritic nano-porous structure, which has good combination with the surface of the aluminum material, high stability, high porosity, uniform distribution, good coherence of the transition layer, no defects and other characteristics, and is beneficial to application.

[0024] For example, when the aluminum material is used as an overhead line, on the one hand, the dendritic nano-porous structure with different pore sizes can realize the "oil locking" of the upper small-pore-size capillary phenomenon and the oil storage of the lower large-pore-size, and the storage capacity of the lubricating oil on the super-lubricating surface is improved, for example, can reach more than 20 mg; on the other hand, the branch structure of the dendritic structure forms a three-dimensional interconnected pore network, which significantly improves the exudation path of the lubricating oil, and is beneficial to realize the conversion of lubricating oil locking and self-repairing rapid exudation. Therefore, the dendritic nano-porous structure prepared by the application has higher lubricating oil storage capacity and better lubricating oil exudation performance, and is beneficial to improve the long-term stability of the application of the super-lubricating surface in the anti-icing field. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure schematic diagram of the metal anode oxidation device provided for the embodiment of the application;

[0026] Figure 2 The voltage change curve for surface anodic oxidation of the embodiment 2 of the application;

[0027] Figure 3 The surface macroscopic photo of the anode aluminum sheet;

[0028] Figure 4 The surface morphology low-magnification scanning electron microscope photo of the treated anode aluminum sheet;

[0029] Figure 5 The surface morphology high-magnification scanning electron microscope photo of the treated anode aluminum sheet;

[0030] Figure 6 The cross-section morphology low-magnification scanning electron microscope photo of the treated anode aluminum sheet;

[0031] Figure 7 The cross-section morphology high-magnification scanning electron microscope photo of the treated anode aluminum sheet;

[0032] Figure 8 The cross-section morphology high-magnification scanning electron microscope photo of the treated anode aluminum sheet of the embodiment 3;

[0033] Figure 9 Cross-sectional morphology high magnification scanning electron micrograph of an anodic aluminum sheet after treatment of Example 4;

[0034] Figure 10 Cross-sectional morphology high magnification scanning electron micrograph of an anodic aluminum sheet after treatment of Example 5;

[0035] Figure 11 Cross-sectional morphology high magnification scanning electron micrograph of an anodic aluminum sheet after treatment of Example 6;

[0036] Figure 12 Cross-sectional morphology high magnification scanning electron micrograph of an anodic aluminum sheet after treatment of Example 7;

[0037] Figure 1 Reference numerals are as follows:

[0038] 1 - power supply controller; 2 - etching tank; 3 - fixing device; 4 - aluminum material to be treated; 5 - cathode sheet; 6 - inlet end of cooling circulation device; 7 - outlet end of cooling circulation device. DETAILED DESCRIPTION

[0039] It should be understood that the expression "one or more of" includes individually each of the objects recited after the expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in connection with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0040] The use of the terms "including", "has", "having" or "contains" and variations thereof, including the conjunctive use of these terms, is generally intended to be broad and unrestrictive, for example, not to exclude other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0041] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the application remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

[0042] The use of any and all examples, or exemplary language herein, for example, "such as" or "for instance", is intended merely to better illustrate the application and does not indicate a limitation on the scope of the application unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the application.

[0043] Further, the numerical ranges and parameters setting forth the broadest scope of equivalents to the application are approximations because some variations and permutations of the quantities, conditions, and / or formulations will result in values that fall within the ranges. Accordingly, unless otherwise specified herein, it is within the scope of the disclosure that every group is at least optionally substituted and / or optionally varied. Although the numerical ranges and parameters setting forth the broadest scope of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Also, as used herein, the notation "about" when in reference to a particular value is intended to encompass variations that fall within the error margin of standard testing measurements.

[0044] The present application provides a method for preparing nano-porous structure on the surface of aluminum material, comprising the following steps:

[0045] The aluminum material to be treated is used as an anode sheet, and electrochemical anodic oxidation is performed in an electrolyte to form nano-porous structure on the surface of the aluminum material.

[0046] The voltage of the electrochemical anodic oxidation is a step voltage.

[0047] The present application performs electrochemical anodic oxidation on the aluminum material to form nano-porous structure on the surface of the aluminum material. In some specific implementations, the aluminum material is a metal aluminum material or a material coated with metal aluminum on the surface, such as an aluminum sheet or an aluminum-coated copper material, such as an aluminum-coated copper sheet or an aluminum-coated copper ground wire, etc.

[0048] The present application first performs pretreatment on the aluminum material to be treated, specifically comprising the following steps:

[0049] The aluminum material to be treated is sequentially cleaned with a decontaminating agent, ethanol and deionized water under ultrasonic cleaning, then cleaned with an alkali solution, and finally cleaned with deionized water under ultrasonic cleaning and dried.

[0050] The decontaminant is not particularly limited in the present application, and can remove the oil stains and dust on the surface of the aluminum material to be processed. The ultrasonic cleaning parameters are not particularly limited in the present application, and the parameters commonly used in the art can be used. In some specific embodiments, the decontaminant cleaning time is 5 min to 20 min, preferably 10 min to 15 min, and more preferably 10 min. In some specific embodiments, the ethanol cleaning time is 5 min to 20 min, preferably 10 min to 15 min, and more preferably 10 min. In some specific embodiments, the first deionized water cleaning time is 5 min to 20 min, preferably 10 min to 15 min, and more preferably 10 min. In some specific embodiments, the alkali solution includes, but is not limited to, a sodium hydroxide solution or a potassium hydroxide solution, and preferably a sodium hydroxide solution. In some specific embodiments, the concentration of the sodium hydroxide solution is 0.5 mol / L to 1 mol / L, preferably 0.6 mol / L to 0.8 mol / L. In some specific embodiments, the alkali solution cleaning time is 1 min to 15 min, preferably 5 min to 10 min. In some specific embodiments, the second deionized water cleaning time is 5 min to 20 min, preferably 10 min to 15 min, and more preferably 10 min. After cleaning, the aluminum material to be processed is dried. The drying method is not particularly limited in the present application, and the drying method commonly used by those skilled in the art can be used.

[0051] After the aluminum material to be processed is pretreated, the aluminum material to be processed is used as an anode sheet, and electrochemical anodic oxidation is performed in an electrolyte. In some specific embodiments, the cathode sheet for electrochemical anodic oxidation includes, but is not limited to, an aluminum sheet, a copper sheet, a stainless steel sheet, or a graphite sheet, and the present application is not particularly limited. In some specific embodiments, the electrolyte in the electrolyte includes, but is not limited to, phosphoric acid or oxalic acid, etc.; the solvent in the electrolyte is a water solution containing 0 to 50 wt% of ethylene glycol, wherein the content of ethylene glycol can be 0, 30 wt%, 50 wt%, etc. In some specific embodiments, the concentration of the electrolyte is 0.1 mol / L to 0.5 mol / L, preferably 0.15 mol / L to 0.45 mol / L, more preferably 0.2 mol / L to 0.4 mol / L, and most preferably 0.25 mol / L to 0.35 mol / L.

[0052] The anode sheet and the cathode sheet are placed in an electrolyte, and after connecting a circuit, electrochemical anodization is performed. In some specific implementations, the anode sheet and the cathode sheet are in a vertical state in the electrolyte, and the anode sheet and the cathode sheet are parallel. In some specific implementations, the distance between the anode sheet and the cathode sheet is 10 mm to 15 mm, preferably 11 mm to 14 mm. In some specific implementations, during the electrochemical anodization, the electrolyte is kept circulating, and the circulation speed of the electrolyte is preferably 50 mL / min to 150 mL / min, preferably 70 mL / min to 140 mL / min, more preferably 80 mL / min to 130 mL / min, and most preferably 100 mL / min to 120 mL / min.

[0053] The step voltage is used to perform electrochemical anodization on the aluminum material to be processed. In some specific implementations, the step voltage includes a first voltage and a second voltage, and the second voltage is higher than the first voltage. The first voltage and the second voltage are independently 60 V to 120 V.

[0054] Specifically, the electrochemical anodization is specifically:

[0055] After electrochemical anodization at the first voltage for a first time, the voltage is increased to the second voltage at a rate of 0.5 V / min to 2 V / min, and electrochemical anodization is performed at the second voltage for a second time.

[0056] Specifically, the application first electrochemically anodizes for a first time at a first voltage, then increases to a second voltage, electrochemically anodizes for a second time at the second voltage, and forms a dendritic multi-level nanopore structure on the surface of the aluminum material to be processed. In some specific implementations, the first voltage is 60V-90V, preferably 60V-80V, more preferably 65V-75V, and most preferably 70V. The first time is 1min-80min, preferably 2min-75min, more preferably 2min-70min, and most preferably 2min-65min. In some specific implementations, the second voltage is 90V-120V, preferably 90V-110V, more preferably 95V-105V, and most preferably 100V; the second time is 40min-80min, preferably 45min-75min, more preferably 50min-70min, and most preferably 55min-65min. In some specific implementations, the rate of voltage increase is 0.5V / min-2V / min, preferably 0.5V / min-1.75V / min, more preferably 0.5V / min-1.5V / min, such as 0.5V / min, 0.75V / min, 1V / min, 1.25V / min, 1.5V / min, or 1.75V / min, etc. In some specific implementations, the total time of electrochemical anodization is 1h-3h, preferably 1.5h-2.5h.

[0057] After the electrochemical oxidation is completed, the obtained aluminum material is subjected to post-treatment to obtain an aluminum material with a nanopore structure on the surface. In some specific implementations, the post-treatment is specifically:

[0058] The obtained aluminum material is rinsed with deionized water and then dried.

[0059] In some specific implementations, the time for rinsing with deionized water is 5min-20min, preferably 10min-15min, and more preferably 10min. After cleaning, the aluminum material to be processed is subjected to drying treatment. The method of drying is not particularly limited in the application, and the drying method commonly used by those skilled in the art can be used.

[0060] In some specific implementations, the application can use a metal anodization device for electrochemical anodization. See Figure 1 , Figure 1 The metal anodization device provided in the embodiments of the application is shown in the structure diagram.

[0061] The metal anodization device provided in the application comprises:

[0062] A power supply controller 1 for providing a power supply;

[0063] etching tank 2 for containing electrolyte;

[0064] a plurality of fixing devices 3 arranged above the etching tank 2, the fixing devices being used for fixing the aluminum material 4 to be treated and the cathode sheet 5 and making the aluminum material 4 to be treated and the cathode sheet 5 present a completely vertical state;

[0065] the aluminum material 4 to be treated is electrically connected with the positive electrode of the power supply controller 1, and the cathode sheet 5 is electrically connected with the negative electrode of the power supply controller 1;

[0066] a cooling circulation device liquid inlet end 6 arranged at one side of the etching tank 2 and a cooling circulation device liquid outlet end 7 arranged at the other side of the etching tank 2, the cooling circulation device liquid inlet end 6 being lower than the cooling circulation device liquid outlet end 7, and the cooling circulation device liquid inlet end 6 and the cooling circulation device liquid outlet end 7 being used for circulating flow of the electrolyte in the etching tank 2.

[0067] The above-mentioned metal anodic oxidation device is used to perform surface treatment on the aluminum material according to the following steps:

[0068] the aluminum material to be treated is used as an anode sheet, and the anode sheet and the cathode sheet are fixed on the fixing devices, so that the anode sheet and the cathode sheet present a vertical state in the electrolyte, and the cathode sheet and the anode sheet are parallel;

[0069] a circulating pump is started, so that the electrolyte is circulated and flowed in the etching tank through the cooling circulation device liquid inlet end and the cooling circulation device liquid outlet end;

[0070] the anode sheet and the cathode sheet are respectively connected with the positive electrode and the negative electrode of the power supply controller, and electrochemical anodic oxidation is performed under a step voltage condition.

[0071] The aluminum material prepared by the method provided in the application has a multi-stage nanopore structure with nanopores gradually increasing in size from the surface to the core, and the nanopores of different stages are connected with each other, which can be regarded as a dendritic nanoporous structure. In some specific implementation manners, the multi-stage nanopores are aluminum dioxide nanopores.

[0072] Specifically, the aluminum material surface provided in the present application comprises first-level nanopores and second-level nanopores distributed from the surface to the core, the pore size of the first-level nanopores is smaller than that of the second-level nanopores. The first-level nanopores and the second-level nanopores are in communication with each other. In some specific implementations, the pore size of the first-level nanopores is 2 nm-150 nm, preferably 50 nm-150 nm, and more preferably 80 nm-150 nm; the pore size of the second-level nanopores is 50 nm-200 nm, preferably 6 nm-200 nm, and more preferably 80 nm-200 nm; the thickness of the first-level nanopores is 1 μm-10 μm, preferably 2 μm-10 μm, and more preferably 3 μm-10 μm; the thickness of the second-level nanopores is 9 μm-30 μm, preferably 3 μm-10 μm, and more preferably 5 μm-10 μm. The surface porosity of the aluminum material is 50%-70%, preferably 55%-65%.

[0073] The aluminum material with the multi-level nanopore surface structure provided in the present application can be used as an overhead line. When used as an overhead line, on the one hand, the dendritic nanoporous structure with different pore sizes can realize the "oil locking" of the upper layer of small-pore-size capillary phenomenon and the oil storage of the lower layer of large-pore-size capillary phenomenon, thereby improving the storage capacity of the lubricating oil on the super-lubricating surface, which can reach more than 20 mg, for example; on the other hand, the branched structure of the dendritic structure forms a three-dimensional interconnected pore network, which significantly improves the seepage path of the lubricating oil, and is conducive to realizing the conversion of lubricating oil locking and rapid seepage of self-repair. Therefore, the dendritic nanoporous structure prepared in the present application has a higher lubricating oil storage capacity and a more optimal lubricating oil seepage performance, which is conducive to improving the long-term stability of the super-lubricating surface in the field of ice prevention and removal.

[0074] The present application provides a preparation method of the nanopore structure of the surface of an aluminum material, comprising the following steps: taking an aluminum material to be treated as an anode sheet, and performing electrochemical anodic oxidation in an electrolyte to form a nanopore structure on the surface of the aluminum material; the voltage of the electrochemical anodic oxidation is a step voltage. In the present application, an aluminum material is used as an anode, and a step voltage is used for electrochemical anodic oxidation to form a multi-level aluminum dioxide nanopore on the surface of the aluminum material, which comprises nanopores with gradually increasing pore sizes from the surface to the core, and the nanopores at different levels are in communication with each other. This structure can be regarded as a dendritic nanoporous structure, which has good bonding force with the surface of the aluminum material, high stability, high porosity, uniform distribution, good continuity of the transition layer, no defects, and the like, and is conducive to its application. Moreover, the preparation method provided in the present application has simple preparation process and low cost.

[0075] The present application will be further described in combination with the following examples. The protection scope of the present application is not limited by the following examples.

[0076] Example 1

[0077] A metal anodic oxidation device as shown in Figure 1 is provided, which comprises:

[0078] a power supply controller 1 for providing power supply;

[0079] an etching tank 2 for containing electrolyte;

[0080] a plurality of fixing devices 3 for fixing the aluminum material 4 to be treated and the cathode sheet 5 and making the aluminum material 4 to be treated and the cathode sheet 5 present a completely vertical state; the aluminum material 4 to be treated is electrically connected to the positive electrode of the power supply controller 1, and the cathode sheet 5 is electrically connected to the negative electrode of the power supply controller 1;

[0081] a cooling circulating device liquid inlet end 6 arranged at one side of the etching tank 2 and a cooling circulating device liquid outlet end 7 arranged at the other side of the etching tank 2, the cooling circulating device liquid inlet end 6 being lower than the cooling circulating device liquid outlet end 7, for circulating flow of the electrolyte in the etching tank 2.

[0082] Example 2

[0083] The aluminum sheet is treated by using the metal anode oxidation device provided in Example 1, including the following steps:

[0084] (1) The size of the anode aluminum sheet 4 to be treated is 10×10×1mm, and the anode aluminum sheet 4 is sequentially cleaned by using a decontaminating agent, ethanol, deionized water, and the cleaning time is 10min, then the anode aluminum sheet 4 is cleaned by using 1mol / L NaOH alkali for 5min, cleaned by using deionized water for 10min, and then dried.

[0085] (2) The anode aluminum sheet 4 to be treated and the cathode sheet 5 are respectively fixed in the etching tank 2 by using the fixing device 3, wherein the cathode sheet 5 is a copper sheet with a size of 20×15×1mm; the anode aluminum sheet 4 and the cathode sheet 5 present a completely vertical state, and the two electrode sheets are in a parallel state to each other, the distance between the anode aluminum sheet 4 and the cathode sheet 5 is 15mm, the anode aluminum sheet 4 is electrically connected to the positive electrode of the power supply controller 1, and the cathode sheet 5 is electrically connected to the negative electrode of the power supply controller 1;

[0086] (3) The peristaltic pump is started to make the electrolyte in the etching tank 2 circulate by the circulating cooling device liquid inlet end 6 and the circulating cooling device liquid outlet end 7. The solute of the electrolyte is 0.3mol / L phosphoric acid, and the solvent is 30wt% ethylene glycol aqueous solution, and the circulating flow rate of the electrolyte is 100mL / min;

[0087] (4) The anode aluminum sheet 4 and the cathode sheet 5 are respectively connected to the power supply to perform electrochemical etching under the condition of step voltage, and the voltage change is as shown in Figure 2 Figure 2 The voltage change curve for surface anode oxidation of Example 2 of the present application is as shown in the figure, specifically: 70V for 20min, the voltage is increased to 100V at a rate of 0.75V / min, and 100V for 60min.​

[0088] (5) rinsing the anode aluminum sheet 4 with deionized water and drying to obtain an aluminum sheet with a nano-porous structure on the surface.

[0089] The untreated anode aluminum sheet and the treated anode aluminum sheet were observed, and the results are shown in Figure 3 、 Figure 4 、 Figure 5 and Figure 6 , wherein, Figure 3 is a macroscopic photograph of the surface of the anode aluminum sheet, Figure 3 , the left side of the dotted line is a photograph of the surface of the original aluminum sheet, and the right side of the dotted line is a photograph of the surface of the treated aluminum sheet, Figure 4 is a low-magnification scanning electron microscope photograph of the surface morphology of the treated anode aluminum sheet, Figure 5 is a high-magnification scanning electron microscope photograph of the surface morphology of the treated anode aluminum sheet, Figure 6 is a low-magnification scanning electron microscope photograph of the cross-sectional morphology of the treated anode aluminum sheet, Figure 7 is a high-magnification scanning electron microscope photograph of the cross-sectional morphology of the treated anode aluminum sheet. As can be seen from Figures 3 to 7 , the surface of the untreated original anode aluminum sheet is relatively smooth and flat, and after electrochemical anodization in a phosphoric acid + ethylene glycol aqueous solution, a nano-scale porous structure is prepared on the surface of the aluminum, and the porous structure presents a dendritic nano-porous structure, and the thickness of the dendritic nano-porous structure is uniform and controllable, which includes a first level of nano-pores and a second level of nano-pores from the surface to the core, the average pore size of the first level of nano-pores is 150 nm, and the thickness of the nano-pores is about 2.5 μm; the average pore size of the second level of nano-pores is 200 nm, and the thickness of the nano-pores is about 10 μm; the surface porosity of the aluminum sheet is 62%.

[0090] Example 3

[0091] The difference from Example 2 is that:

[0092] (1) the flow rate of the electrolyte in step (3) is 120 mL / min;

[0093] (2) the voltage change of the electrochemical etching in step (4) is: 70 V for 2 min, the voltage is increased to 100 V at a rate of 0.5 V / min, and the voltage is maintained at 100 V for 60 min.

[0094] The other steps and parameters are the same as in Example 1.

[0095] The results are shown in Figure 8 , Figure 8 is a high-magnification scanning electron microscope photograph of the cross-sectional morphology of the treated anode aluminum sheet of Example 3. As can be seen from Figure 8As can be seen, Example 3 prepared a nanoscale porous structure on the aluminum surface, and the porous structure exhibits a dendritic nanoporous structure. Moreover, the thickness of the dendritic nanoporous structure is uniform and controllable. It includes a first-level nanopore and a second-level nanopore from the surface to the core. The average pore size of the first-level nanopore is 130 nm and the thickness of the nanopore is about 2 μm. The average pore size of the second-level nanopore is 180 nm and the thickness of the nanopore is about 8 μm.

[0096] Example 4

[0097] The difference from Example 2 is as follows:

[0098] (1) In step (3), the electrolyte flow rate is 120 mL / min, the solute in the electrolyte is 0.3 mol / L oxalic acid, and the solvent is an aqueous solution of 30 wt% ethylene glycol;

[0099] (2) The voltage change of electrochemical etching in step (4) is: 70V for 2 min, then increased to 100V at a rate of 1V / min, and then processed at 100V for 60 min.

[0100] The other steps and parameters are the same as in Example 1.

[0101] See results Figure 9 , Figure 9 This is a high-magnification scanning electron microscope (SEM) image of the cross-sectional morphology of the anode aluminum sheet after processing in Example 4. Figure 9 As can be seen, Example 4 prepared a nanoscale porous structure on the aluminum surface, and the porous structure exhibits a dendritic nanoporous structure. Moreover, the thickness of the dendritic nanoporous structure is uniform and controllable. It includes a first-level nanopore and a second-level nanopore from the surface to the core. The average pore size of the first-level nanopore is 50 nm and the thickness of the nanopore is about 8 μm. The average pore size of the second-level nanopore is 60 nm and the thickness of the nanopore is about 21 μm.

[0102] Example 5

[0103] The difference from Example 2 is as follows:

[0104] (1) In step (3), the electrolyte flow rate is 100 mL / min, the solute in the electrolyte is 0.3 mol / L oxalic acid, and the solvent is an aqueous solution of 30 wt% ethylene glycol;

[0105] (2) The voltage change of electrochemical etching in step (4) is: 70V for 20min, then increased to 100V at a rate of 0.75V / min, and then processed at 100V for 60min.

[0106] The other steps and parameters are the same as in Example 1.

[0107] See results Figure 10 ,Figure 10 The cross-sectional morphology high-magnification scanning electron microscope photograph of the anodic aluminum sheet after treatment of Example 5 is shown in Figure 5. Figure 10 It can be seen that Example 5 prepared a nano-scale porous structure on the aluminum surface, and the porous structure presents a dendritic nano-porous structure, and the thickness of the dendritic nano-porous structure is uniform and controllable, which includes first-level nano-pores and second-level nano-pores from the surface to the core, the average pore diameter of the first-level nano-pores is 40 nm, and the thickness of the nano-pores is about 4 μm; the average pore diameter of the second-level nano-pores is 60 nm, and the thickness of the nano-pores is about 12 μm.

[0108] Example 6

[0109] The difference from Example 2 is that:

[0110] (1) In step (3), the solute in the electrolyte is 0.3 mol / L oxalic acid, and the solvent is 30 wt% ethylene glycol aqueous solution;

[0111] (2) In step (4), the voltage change of electrochemical etching is: 70V~100V, the voltage increasing rate is 0.5V / min, the etching time is 2h, and the specific process is: 70V for 2min, the voltage is increased to 100V at a rate of 0.5V / min, and 100V is treated for 60min.

[0112] The other steps and parameters are the same as those of Example 1.

[0113] The results are shown in Figure 11 , Figure 11 The cross-sectional morphology high-magnification scanning electron microscope photograph of the anodic aluminum sheet after treatment of Example 6 is shown in Figure 6. Figure 11 It can be seen that Example 6 prepared a nano-scale porous structure on the aluminum surface, and the porous structure presents a dendritic nano-porous structure, and the thickness of the dendritic nano-porous structure is uniform and controllable, which includes first-level nano-pores and second-level nano-pores from the surface to the core, the average pore diameter of the first-level nano-pores is 60 nm, and the thickness of the nano-pores is about 6 μm; the average pore diameter of the second-level nano-pores is 80 nm, and the thickness of the nano-pores is about 20 μm.

[0114] Example 7

[0115] The difference from Example 2 is that:

[0116] (1) In step (3), the flow rate of the electrolyte is 120 mL / min;

[0117] (2) In step (4), the voltage change of electrochemical etching is: 70V for 40min, the voltage is increased to 100V at a rate of 1.5V / min, and 100V is treated for 60min.

[0118] The other steps and parameters are the same as those of Example 1.

[0119] Results see Figure 12 , Figure 12 Figure 7 is a high-magnification scanning electron microscope photograph of the cross-sectional morphology of the anodic aluminum sheet after treatment of Example 7. It can be seen that Example 7 produces a nano-scale porous structure on the aluminum surface, and the porous structure exhibits a dendritic nano-porous structure, and the thickness of the dendritic nano-porous structure is uniform and controllable, and it includes a first level of nanopores and a second level of nanopores from the surface to the core, the average pore size of the first level of nanopores is 120 nm, and the thickness of the nanopores is about 3 μm; the average pore size of the second level of nanopores is 200 nm, and the thickness of the nanopores is about 8 μm. Figure 12

[0120] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.​

Claims

1. A method for preparing a dendritic nanoporous structure on the surface of an aluminum material, comprising the following steps: forming a nanoporous structure on the surface of an aluminum material by electrochemical anodization of the aluminum material in an electrolyte, wherein the aluminum material is used as an anode sheet; and the electrochemical anodization is performed at a step voltage. The electrochemical anodization is performed at a step voltage. The step voltage comprises a first voltage and a second voltage, and the second voltage is higher than the first voltage.

2. The production method according to claim 1, characterized by, The first voltage and the second voltage are independently 60 V to 120 V. The electrochemical anodization is performed at the first voltage for a first time, and then the voltage is increased to the second voltage at a rate of 0.5 V / min to 2 V / min, and the electrochemical anodization is performed at the second voltage for a second time.

3. The production method according to claim 2, characterized by, The first voltage is 60 V to 90 V, and the first time is 1 min to 80 min. The second voltage is 90 V to 120 V, and the second time is 40 min to 80 min.

4. The production method according to claim 3, characterized by, The electrolyte is phosphoric acid or oxalic acid, and the solvent is an aqueous solution containing 0 to 50 wt% ethylene glycol. The concentration of the electrolyte is 0.1 mol / L to 0.5 mol / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that, During the electrochemical anodization, the electrolyte is circulated at a rate of 50 mL / min to 150 mL / min. The cathode sheet used in the electrochemical anodization is an aluminum sheet, a copper sheet, a stainless steel sheet or a graphite sheet.

6. The production method according to claim 5, wherein The aluminum material to be treated is an aluminum sheet or an aluminum-clad steel sheet.

7. The method of any one of claims 1 to 4, wherein the method further comprises the step of: The anode sheet and the cathode sheet are perpendicular to each other in the electrolyte, and the anode sheet and the cathode sheet are parallel to each other. ​ 9.An aluminum material prepared by the method of any one of claims 1 to 8, wherein the surface of the aluminum material comprises first-level nanopores and second-level nanopores with gradually increasing pore sizes from the surface to the core, and the first-level nanopores and the second-level nanopores are connected to each other.

8. The method of any one of claims 1 to 4, wherein the method further comprises the step of: The first-level nanopores have a pore size of 20 nm to 150 nm, and the second-level nanopores have a pore size of 50 nm to 200 nm. ​ The first-level nanopores have a thickness of 1 μm to 10 μm, and the second-level nanopores have a thickness of 9 μm to 30 μm. The surface porosity of the aluminum material is 50% to 70%. 10.The aluminum material prepared by the method of any one of claims 1 to 8 or the aluminum material of claim 9 is used in an aluminum-clad steel ground wire. ​

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