Preparation method of wear-resistant and corrosion-resistant coating on surface of aluminum alloy

Abstract

The invention discloses a preparation method of a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy, and relates to the technical field of intelligent manufacturing of new materials. The embodiment of the invention provides a preparation method of a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy, the wear-resistant and corrosion-resistant coating is prepared by a two-step method, and the preparation method comprises the following specific steps: firstly, preparing an anodic oxidation coating on the surface of an aluminum alloy matrix by adopting an anodic oxidation method; and then plasma discharge treatment is conducted on the anodic oxidation coating, crystallization transformation of the anodic oxidation coating is induced, and the thick and compact crystalline-state aluminum oxide coating is prepared on the surface of the aluminum alloy matrix. According to the preparation method of the wear-resistant and corrosion-resistant coating on the surface of the aluminum alloy, the problem that the service life of aluminum alloy parts is short is solved, meanwhile, the wear-resistant and corrosion-resistant performance of the surface of the aluminum alloy is improved, the application range of the aluminum alloy is widened, and the service life of the aluminum alloy parts is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of new material intelligent manufacturing, and in particular to a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. Background Art

[0002] Aluminum alloy has become the most widely used material in lightweight equipment manufacturing due to its high specific strength, excellent thermal and electrical conductivity, and strong decorative properties. It has been widely used in many fields in my country, such as transportation, electronics and electrical engineering, aerospace, construction, and chemical industry. With the rapid development of my country's automobile industry, the main direction of the development of the automobile industry is to use aluminum alloys to replace steel components in the process of lightweight automobile production. In order to save energy consumption and improve driving safety, aluminum alloy has become the preferred material for the preparation of automobile wheels, engines and other parts.

[0003] However, aluminum alloy is an active metal, which can corrode in acidic, alkaline or even neutral environments to generate acid or alkaline salts. In addition, the dry friction coefficient of steel is about 0.2, while the dry friction coefficient of aluminum alloy is about 0.6. When aluminum alloy is used to replace steel materials to prepare engine piston rings and other operating parts, it is more prone to wear, resulting in insufficient engine stability, which limits the further widespread application of aluminum alloy. Therefore, research and development of aluminum alloy surface coating preparation technology to meet the high specific strength of automotive parts while improving the long-term working stability of parts is an urgent problem to be solved in the lightweight manufacturing process of the automotive industry. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy, in order to address the problem of insufficient service life of the above-mentioned aluminum alloy parts, while improving the wear resistance and corrosion resistance of the aluminum alloy surface, broadening the application scope of the aluminum alloy, and extending the service life of the aluminum alloy parts.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The embodiment of the present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The wear-resistant and corrosion-resistant coating is prepared by a two-step method, and the specific steps include:

[0007] Firstly, an anodic oxidation method is adopted to prepare an anodic oxidation coating on the surface of an aluminum alloy substrate;

[0008] Then, the anodic oxidation coating is subjected to plasma discharge treatment to induce crystallization transformation of the anodic oxidation coating, so as to prepare a thick and dense crystalline aluminum oxide coating on the surface of the aluminum alloy substrate.

[0009] In some embodiments, the preparation method uses an electrochemical coating preparation system to prepare a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy; the electrochemical coating preparation system includes an external pulse power supply, an electrolyte system, and a cooling system;

[0010] The external pulse power supply adopts a DC power supply;

[0011] The electrolyte system includes an anodic oxidation electrolyte and a plasma discharge electrolyte; the anodic oxidation electrolyte adopts a sulfur-phosphoric acid electrolyte system, and the plasma discharge electrolyte adopts a silicate electrolyte system;

[0012] The cooling system adopts an external circulation cooling method of the electrolyte tank.

[0013] In some embodiments, the anodizing electrolyte includes: sulfuric acid at a concentration of 10 to 200 g / L, phosphoric acid at a concentration of 10 to 150 g / L, and ethylene glycol at a concentration of 10 to 80 g / L;

[0014] The plasma discharge electrolyte comprises: sodium silicate with a concentration of 5 to 15 g / L, sodium hydroxide with a concentration of 0 to 5 g / L, and sodium hexametaphosphate with a concentration of 0 to 5 g / L.

[0015] In some embodiments, the electrochemical coating preparation system uses an aluminum alloy substrate as an anode and a stainless steel plate as a cathode, and both are connected to the positive and negative electrodes of the external pulse power supply respectively with aluminum wires.

[0016] In some embodiments, the electrolyte system uses an electrolytic cell, which is made of polypropylene with a size of 600×300×50cm3, the size of the aluminum alloy substrate is 2×2×0.5cm3~10×10×5cm3, and the size of the stainless steel plate is 10×5×2cm3~300×100×10cm3.

[0017] In some embodiments, a peristaltic pump is provided between the electrolyte system and the cooling system, and the electrolyte is transported by the peristaltic pump to exchange heat between the electrolyte and the cooling liquid of the cooling system.

[0018] In some embodiments, the operating process parameters of the anodizing method are: oxidation temperature 0 to 15° C., and oxidation time 10 to 40 min.

[0019] In some embodiments, the power supply parameters of the plasma discharge treatment are: current density 0.1-1 A / cm2, duty cycle 10-50%, pulse frequency 1-100 kHz, plasma discharge temperature 15-40°C, and plasma discharge time 5-30 min.

[0020] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The method utilizes the characteristics of aluminum alloy as a valve metal and adopts a two-step method in an electrochemical system, coupling anodizing technology and plasma discharge treatment technology. That is, a growing anodized coating is first prepared on the surface of an aluminum alloy substrate, and then plasma discharge treatment is performed to induce crystallization transformation of the anodized coating, so as to prepare a thick and dense crystalline aluminum oxide coating on the surface of the aluminum alloy substrate, and at the same time, the wear resistance and corrosion resistance of the aluminum alloy substrate can be greatly improved.

[0021] After the aluminum alloy substrate is treated, its insulation resistance is increased from 60kΩ·cm 2 Increased to 120 kΩ·cm 2 The dry friction coefficient is reduced from 0.64 to 0.44, which is conducive to expanding the application of aluminum alloy components in running equipment. The present invention also provides theoretical reference for further research and development of aluminum alloy products to replace traditional steel equipment parts and components, and develops in the direction of lightweight, which has important academic significance and engineering value.

[0022] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The aluminum alloy substrate is subjected to anodizing treatment to grow amorphous aluminum oxide on its surface. Subsequently, under the action of plasma discharge treatment, the discharge point generates in-situ high heat. Under the action of this high heat, the amorphous aluminum oxide at the discharge point and its adjacent area crystallizes and transforms, so that a crystalline aluminum oxide coating that is well bonded to the substrate can be prepared and grown on the surface of the aluminum alloy substrate. Since the wear resistance and corrosion resistance of the crystalline aluminum oxide are significantly better than those of the aluminum alloy substrate, the wear resistance and corrosion resistance of the aluminum alloy substrate are enhanced.

[0023] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The two-step method is used to prepare a crystallized aluminum oxide coating on the surface of an aluminum alloy substrate. According to the characteristic that the hardness of crystalline aluminum oxide is only lower than that of diamond, the wear resistance of the aluminum alloy is improved. According to the characteristic that crystalline aluminum oxide is stable in a weak acid and alkali environment, the corrosion resistance of the aluminum alloy is improved. The present invention adopts an electrochemical method for preparation. The aluminum oxide coating has good bonding strength with the aluminum alloy substrate. The preparation process is simple, not limited by the shape of parts, and the preparation cost is low, which is convenient for the practical promotion and application of the wear-resistant and corrosion-resistant coating on the surface of the aluminum alloy substrate.

[0024] The wear-resistant and corrosion-resistant coating on the surface of the aluminum alloy of the present invention has simple preparation process, stable coating performance, simple equipment structure, low price, and is easy to mass produce and commercialize.

[0025] The invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. According to the fact that an aluminum alloy can be prepared to generate an anodic oxidation coating with a thickness of several hundred micrometers in a sulfuric acid electrolyte, and an aluminum alloy can be prepared to generate an anodic oxidation coating with a pore size of 30 nanometers in a phosphoric acid electrolyte, sulfur-phosphoric acid is used as the electrolyte system, and a high-thickness, large-pore anodic oxidation coating can be prepared on the surface of an aluminum alloy substrate, meeting the conditions for subsequent plasma discharge treatment to induce uniform crystallization transformation of the coating. Therefore, sulfur-phosphoric acid is selected as the anodic oxidation electrolyte system in the anodic oxidation process.

[0026] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. According to the method, ethylene glycol is added to the electrolyte during the anodizing process to form a double electric layer on the surface of the aluminum alloy anode, thereby promoting a uniform increase in the thickness of the anodized coating, which is beneficial to the subsequent plasma discharge treatment to occur uniformly on the surface of the aluminum alloy substrate. Therefore, ethylene glycol is selected as an anodizing electrolyte additive.

[0027] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The crystallization transformation degree of the anodized coating is controlled by the plasma discharge intensity, and the plasma discharge intensity is related to the parameters of the unipolar pulse power supply. Therefore, the plasma discharge intensity is regulated by adjusting the current density, duty cycle, and pulse frequency of the unipolar pulse power supply, thereby inducing the crystallization transformation of the anodized coating on the surface of the aluminum alloy substrate.

[0028] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface. In the electrochemical process, the aluminum oxide coating on the surface of the aluminum alloy substrate is prepared by the following reaction equation:

[0029] Al 3+ +3OH-=Al(OH)3-77.1kJ / mol (1)

[0030] 2Al(OH)3=Al2O3+3H2O+194.6kJ / mol (2)

[0031] 4OH-+4e - =2H2O+O2-46.6kJ / mol (3)

[0032] In summary, the present invention adopts a two-step method to prepare a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy substrate. First, an anodic oxidation method is used, sulfur-phosphorus mixed acid is used as an electrolyte system, and ethylene glycol is added to the electrolyte, which can form a double electric layer on the anode surface of the aluminum alloy substrate under an electrochemical environment to prepare an anodic oxidation coating with uniform thickness and suitable pore size; then, plasma discharge treatment is used to apply heat to induce the crystallization transformation of amorphous aluminum oxide in the anodic oxidation coating, and a thick and dense crystalline aluminum oxide coating with good bonding strength with the substrate is prepared and grown on the surface of the aluminum alloy substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings required for use in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the products involved in the embodiments of the present disclosure, the actual process of the method, etc.

[0034] Figure 1 A schematic diagram of an electrochemical coating preparation system according to some embodiments of the present disclosure;

[0035] FIG2( a ) is a micro-surface photograph of a crystallized aluminum oxide coating on the surface of an aluminum alloy according to Example 1 in some embodiments of the present disclosure;

[0036] FIG2( b ) is a cross-sectional photograph of a crystallized aluminum oxide coating on the surface of an aluminum alloy according to Example 1 in some embodiments of the present disclosure;

[0037] Figure 3 It is a comparison curve diagram of insulation resistance of Comparative Example 1, Example 2 and aluminum alloy substrate according to some embodiments of the present disclosure;

[0038] Figure 4 It is a comparison curve diagram of dry friction coefficient of Comparative Example 1, Example 3 and an aluminum alloy substrate according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0039] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0040] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics described may be included in any one or more embodiments or examples in any appropriate manner.

[0041] The embodiment of the present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The wear-resistant and corrosion-resistant coating is prepared by a two-step method, and the specific steps include: S100-S200.

[0042] S100, firstly, an anodic oxidation method is used to prepare an anodic oxidation coating on the surface of an aluminum alloy substrate.

[0043] S200, the anodic oxidation coating is then subjected to plasma discharge treatment to induce crystallization transformation of the anodic oxidation coating, and a thick and dense crystalline aluminum oxide coating is prepared on the surface of the aluminum alloy substrate.

[0044] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The aluminum alloy substrate is subjected to anodizing treatment to grow amorphous aluminum oxide on its surface. Subsequently, under the action of plasma discharge treatment, the discharge point generates in-situ high heat. Under the action of this high heat, the amorphous aluminum oxide at the discharge point and its adjacent area crystallizes and transforms, so that a crystalline aluminum oxide coating that is well bonded to the substrate can be prepared and grown on the surface of the aluminum alloy substrate. Since the wear resistance and corrosion resistance of the crystalline aluminum oxide are significantly better than those of the aluminum alloy substrate, the wear resistance and corrosion resistance of the aluminum alloy substrate are enhanced.

[0045] In some embodiments, the preparation method uses an electrochemical coating preparation system to prepare a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy; the electrochemical coating preparation system includes an external pulse power supply, an electrolyte system, and a cooling system.

[0046] In some embodiments, the external pulse power supply is a direct current power supply.

[0047] For example, the external pulse power supply adopts a unipolar pulse power supply, and the anodic oxidation and plasma discharge treatment processes are processed in a constant current mode. The pulse frequency of the external pulse power supply is adjustable from 1kHz to 100kHz, and the current density is 0.1A / cm 2 ~10A / cm 2 Adjustable, duty cycle 10%~90% adjustable.

[0048] In some examples, the external pulse power supply uses a centralized control panel to control power supply parameters, and has built-in sound and light alarms and self-protection programs. The starting voltage of the self-protection program is 1500V, and the starting current of the self-protection program is 15A. After the self-protection program is started, the external pulse power supply automatically cuts off power and goes into standby mode.

[0049] In some embodiments, the electrolyte system includes an anodic oxidation electrolyte and a plasma discharge electrolyte; the anodic oxidation electrolyte adopts a sulfur-phosphoric acid electrolyte system, and the plasma discharge electrolyte adopts a silicate electrolyte system.

[0050] The electrolyte is stored in an electrolytic cell, and the electrolyte storage capacity of the electrolytic cell is: 2L~10L.

[0051] In some embodiments, the cooling system adopts an external circulation cooling method of the electrolyte tank.

[0052] In some examples, the anodizing electrolyte includes: sulfuric acid concentration of 10 to 200 g / L, phosphoric acid concentration of 10 to 150 g / L, and ethylene glycol concentration of 10 to 80 g / L; the plasma discharge electrolyte includes: sodium silicate concentration of 5 to 15 g / L, sodium hydroxide concentration of 0 to 5 g / L, and sodium hexametaphosphate concentration of 0 to 5 g / L.

[0053] By adding ethylene glycol to the anodizing electrolyte, the thickness of different parts of the anodizing coating is promoted to be uniform, thereby improving the wear resistance and corrosion resistance of the coating; by controlling the parameters of the external pulse power supply, the crystallization transformation of the anodizing coating is promoted to occur uniformly on the surface of the aluminum alloy substrate, thereby improving the wear resistance and corrosion resistance of the coating.

[0054] In some examples, the operating process parameters of the anodizing method are: oxidation temperature 0 to 15° C., and oxidation time 10 to 40 min.

[0055] In some examples, the power supply parameters for plasma discharge treatment are: current density 0.1-1 A / cm 2 , duty cycle 10-50%, pulse frequency 1-100kHz, plasma discharge temperature 15-40°C, plasma discharge time 5-30min.

[0056] In some examples, the electrochemical coating preparation system uses an aluminum alloy substrate as an anode and a stainless steel plate as a cathode, and connects the two to the positive and negative electrodes of an external pulse power supply with aluminum wires, respectively.

[0057] Exemplarily, in a sulfur-phosphoric acid electrolyte system, an aluminum alloy substrate is used as an anode and a stainless steel plate is used as a cathode, and the two are connected to the positive and negative electrodes of an external pulse power supply with aluminum wires, respectively, to prepare an anodic oxide coating on the surface of the aluminum alloy substrate; in a silicate electrolyte system, an aluminum alloy substrate is used as an anode and a stainless steel plate is used as a cathode, and the two are connected to the positive and negative electrodes of an external pulse power supply with aluminum wires, respectively, to induce the crystallization transformation of amorphous aluminum oxide in the anodic oxide coating on the surface of the aluminum alloy substrate to generate a crystalline aluminum oxide coating.

[0058] In some examples, the electrolyte system uses an electrolytic cell having a size of 600×300×50 cm. 3 Made of polypropylene, the size of the aluminum alloy substrate is 2×2×0.5cm 3 ~10×10×5cm 3 , the size of the stainless steel plate is 10×5×2cm 3 ~300×100×10cm 3 .

[0059] Exemplarily, a through hole with a size of φ3cm-φ5cm is drilled on the aluminum alloy substrate, and connected to the positive electrode of an external pulse power supply with an aluminum wire.

[0060] In some examples, a peristaltic pump is provided between the electrolyte system and the cooling system, and the electrolyte is transported by the peristaltic pump for heat exchange between the electrolyte and the cooling liquid of the cooling system. The electrolyte circulation volume is 20-50% of the electrolyte storage capacity of the electrolytic cell. In this way, the system temperature can be maintained during the anodic oxidation and plasma discharge process.

[0061] Exemplarily, during the anodic oxidation and plasma discharge processes, the electrolyte temperature is maintained constant at 0-15° C. and 15-40° C., respectively, by circulating the electrolyte outside the electrolyte tank.

[0062] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention and the accompanying drawings.

[0063] Example 1

[0064] like Figure 1 As shown, the electrochemical coating preparation system for wear-resistant and corrosion-resistant coating on aluminum alloy surface is constructed. The size of the aluminum alloy substrate is 5×5×0.5cm 3 , the size of the stainless steel plate is 10×10×2cm 3 , in size 30×60×20cm 3 In the electrolytic cell, 5L of electrolyte with sulfuric acid concentration of 100g / L, phosphoric acid concentration of 50g / L, and ethylene glycol concentration of 11g / L was filled, and the aluminum alloy substrate and the stainless steel plate were connected to the positive and negative electrodes of the pulse power supply respectively. After the power was turned on, the reaction was carried out at 5°C for 40 minutes, and the anodic oxidation coating was prepared on the surface of the aluminum alloy substrate.

[0065] Subsequently, the aluminum alloy substrate and the stainless steel plate were used as the anode and cathode in 5L of an electrolyte with a sodium silicate concentration of 15g / L, a sodium hydroxide concentration of 5g / L, and a sodium hexametaphosphate concentration of 5g / L at 25°C and a constant current density of 0.5A / cm 2 , a pulse frequency of 20 kHz, and a duty cycle of 10% for 15 min, the amorphous alumina coating on the surface of the aluminum alloy substrate can be transformed into crystalline alumina. The micro-surface morphology and cross-sectional morphology of the aluminum alloy after electrochemical treatment are shown in Figure 2(a) and Figure 2(b), respectively.

[0066] The insulation resistance of aluminum alloy before and after surface treatment is as follows Figure 3 As shown, 60 kΩ·cm 2 Up to 120 kΩ·cm 2 , the dry friction coefficient of aluminum alloy before and after surface treatment is as follows Figure 4 As shown in the figure, it drops from 0.64 to 0.44. The corrosion resistance and wear resistance of aluminum alloy are greatly improved.

[0067] Example 2

[0068] like Figure 1 As shown, the electrochemical coating preparation system for wear-resistant and corrosion-resistant coating on aluminum alloy surface is constructed. The size of the aluminum alloy substrate is 5×5×0.5cm 3 , the size of the stainless steel plate is 10×10×2cm 3 , in size 30×60×20cm 3 In the electrolytic cell, 5L of electrolyte with sulfuric acid concentration of 100g / L, phosphoric acid concentration of 50g / L, and ethylene glycol concentration of 11g / L was filled, and the aluminum alloy substrate and the stainless steel plate were connected to the positive and negative electrodes of the pulse power supply respectively. After the power was turned on, the reaction was carried out at 5°C for 40 minutes, and the anodic oxidation coating was prepared on the surface of the aluminum alloy substrate.

[0069] like Figure 3 and Figure 4 As shown, by comparing the insulation resistance of the samples in the aluminum alloy substrate, Example 1, and Example 2, it is found that the corrosion resistance of the aluminum alloy substrate is improved to a certain extent after anodizing treatment, but the corrosion resistance of the anodized coating on the surface of the aluminum alloy substrate is further improved after plasma discharge treatment.

[0070] Example 3

[0071] like Figure 1 As shown, the electrochemical coating preparation system for wear-resistant and corrosion-resistant coating on aluminum alloy surface is constructed. The size of the aluminum alloy substrate is 5×5×0.5cm 3 , the size of the stainless steel plate is 10×10×2cm 3 , in size 30×60×20cm 3 The electrolytic cell was filled with 5L of electrolyte containing 15g / L sodium silicate, 5g / L sodium hydroxide and 5g / L sodium hexametaphosphate. The aluminum alloy substrate and the stainless steel plate were connected to the positive and negative electrodes of the pulse power supply respectively. After the power was turned on, the constant current density was 0.5A / cm at 25°C. 2 , a pulse frequency of 20kHz, and a duty cycle of 10% for 15 minutes, a crystalline alumina coating can be prepared on the surface of the aluminum alloy substrate.

[0072] like Figure 3 and Figure 4As shown, by comparing the dry friction coefficients of the aluminum alloy substrate and the samples in Example 3, it is found that after the aluminum alloy substrate is treated with plasma discharge, the dry friction coefficient decreases from 0.64 to 0.53, and by comparing the samples of Example 1 and Example 3, it is found that the dry friction coefficient of the sample in Example 1 is lower than that of the sample in Example 3, indicating that the wear resistance of the surface coating of the aluminum alloy substrate using the two-step method is better than the wear resistance of the surface coating obtained by direct plasma discharge treatment of the aluminum alloy substrate.

[0073] By comparing the three embodiments, it can be seen that although both anodizing technology and plasma discharge treatment technology can improve the wear resistance and corrosion resistance of the aluminum alloy substrate, since the aluminum oxide coating prepared by the anodizing technology is composed of amorphous aluminum oxide, the corrosion resistance is difficult to meet the current industrial development requirements, and the aluminum oxide coating prepared by plasma discharge treatment is limited in thickness and wear resistance.

[0074] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The method utilizes the characteristics of aluminum alloy as a valve metal and adopts a two-step method in an electrochemical system, coupling anodizing technology and plasma discharge treatment technology. That is, a growing anodized coating is first prepared on the surface of an aluminum alloy substrate, and then plasma discharge treatment is performed to induce crystallization transformation of the anodized coating, so as to prepare a thick and dense crystalline aluminum oxide coating on the surface of the aluminum alloy substrate, and at the same time, the wear resistance and corrosion resistance of the aluminum alloy substrate can be greatly improved.

[0075] After the aluminum alloy substrate is treated, its insulation resistance is increased from 60kΩ·cm 2 Increased to 120 kΩ·cm 2 The dry friction coefficient is reduced from 0.64 to 0.44, which is conducive to expanding the application of aluminum alloy components in running equipment. The present invention also provides theoretical reference for further research and development of aluminum alloy products to replace traditional steel equipment parts and components, and develops in the direction of lightweight, which has important academic significance and engineering value.

[0076] The present invention provides a method for preparing a wear-resistant and corrosion-resistant coating on the surface of an aluminum alloy. The aluminum alloy substrate is subjected to anodizing treatment to grow amorphous aluminum oxide on its surface. Subsequently, under the action of plasma discharge treatment, the discharge point generates in-situ high heat. Under the action of this high heat, the amorphous aluminum oxide at the discharge point and its adjacent area crystallizes and transforms, so that a crystalline aluminum oxide coating that is well bonded to the substrate can be prepared and grown on the surface of the aluminum alloy substrate. Since the wear resistance and corrosion resistance of the crystalline aluminum oxide are significantly better than those of the aluminum alloy substrate, the wear resistance and corrosion resistance of the aluminum alloy substrate are enhanced.

[0077] The wear-resistant and corrosion-resistant coating on the surface of the aluminum alloy of the present invention has simple preparation process, stable coating performance, simple equipment structure, low price, and is easy to mass produce and commercialize.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface, characterized in that: The wear-resistant and corrosion-resistant coating is prepared by a two-step method, and the specific steps include: Firstly, an anodic oxidation method is adopted to prepare an anodic oxidation coating on the surface of an aluminum alloy substrate; Then, the anodic oxidation coating is subjected to plasma discharge treatment to induce crystallization transformation of the anodic oxidation coating, so as to prepare a thick and dense crystalline aluminum oxide coating on the surface of the aluminum alloy substrate.

2. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface according to claim 1, characterized in that: The preparation method adopts an electrochemical coating preparation system to prepare the wear-resistant and corrosion-resistant coating on the surface of the aluminum alloy; The electrochemical coating preparation system includes an external pulse power supply, an electrolyte system and a cooling system; The external pulse power supply adopts a DC power supply; The electrolyte system includes an anodic oxidation electrolyte and a plasma discharge electrolyte; The anodizing electrolyte adopts a sulfur-phosphoric acid electrolyte system, and the plasma discharge electrolyte adopts a silicate electrolyte system; The cooling system adopts an external circulation cooling method of the electrolyte tank.

3. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface according to claim 2, characterized in that: The anodizing electrolyte comprises: sulfuric acid concentration of 10 to 200 g / L, phosphoric acid concentration of 10 to 150 g / L, and ethylene glycol concentration of 10 to 80 g / L; The plasma discharge electrolyte comprises: sodium silicate with a concentration of 5 to 15 g / L, sodium hydroxide with a concentration of 0 to 5 g / L, and sodium hexametaphosphate with a concentration of 0 to 5 g / L.

4. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface according to claim 2, characterized in that: The electrochemical coating preparation system uses an aluminum alloy substrate as an anode and a stainless steel plate as a cathode, and the two are respectively connected to the positive and negative electrodes of the external pulse power supply by aluminum wires.

5. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface as claimed in claim 4, characterized in that: The electrolyte system uses an electrolytic cell, and the size of the electrolytic cell is 600×300×50 cm 3 The size of the aluminum alloy substrate is 2×2×0.5 cm 3 ~10×10×5cm 3 The size of the stainless steel plate is 10×5×2cm 3 ~300×100×10cm 3 .

6. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface as claimed in claim 2, characterized in that: A peristaltic pump is provided between the electrolyte system and the cooling system, and the electrolyte is transported by the peristaltic pump to exchange heat between the electrolyte and the cooling liquid of the cooling system.

7. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface according to claim 1, characterized in that: The operating process parameters of the anodizing method are: oxidation temperature 0 to 15° C., oxidation time 10 to 40 minutes.

8. The method for preparing a wear-resistant and corrosion-resistant coating on an aluminum alloy surface according to claim 1, characterized in that: The power supply parameters of the plasma discharge treatment are: current density 0.1-1A / cm 2 , duty cycle 10-50%, pulse frequency 1-100kHz, plasma discharge temperature 15-40°C, plasma discharge time 5-30min.

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