Aluminum alloy surface enamel-imitated structure Ni-W plating layer and preparation method thereof

Abstract

The application discloses an aluminum alloy surface imitation tooth enamel structure Ni-W plating layer and a preparation method thereof, and belongs to the technical field of surface modification of metal materials. The aluminum alloy surface imitation tooth enamel structure Ni-W plating layer is a mixed structure of nanocrystals and amorphous crystals, wherein the amorphous crystal content of the inner layer of the Ni-W plating layer combined with the aluminum alloy surface is lower than the amorphous crystal content of the outer surface layer of the Ni-W plating layer. The Ni-W plating layer has the characteristics of small crystal grains, high density, low porosity and the like, and the outer surface layer of the Ni-W plating layer has a high proportion of amorphous particles, so that the corrosion resistance and wear resistance of the plating layer are improved; the inner layer of the Ni-W plating layer combined with the aluminum alloy has a high proportion of crystal particles, so that the crystal type of the aluminum alloy is highly adaptable, and the binding force is good; the mixed structure has hardness and toughness, and the corrosion resistance, wear resistance and the like of the aluminum alloy pipe in various application scenarios are greatly enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface modification of metal materials, and particularly relates to an aluminum alloy surface enamel-structure-like Ni-W plating layer and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for oil and gas resources, the development of deep / ultra-deep oil and gas resources has become a new direction for the development of the current oil and gas industry, and the lightening of drilling tools and downhole strings is a development trend. Aluminum alloy has the advantages of high specific strength, low hardness, good extrusion forming performance, and low price, and has great potential in the lightening of drilling tools and downhole string materials. However, under the conditions of high formation temperature, salinity and high pressure, aluminum alloy is prone to corrosion. In addition, due to the low hardness of aluminum alloy, it is easily worn by external forces such as friction and impact during the downhole process, resulting in rough surface and reduced strength, which further accelerates the speed and degree of corrosion. The superimposed effect of wear and corrosion seriously affects the structural performance and service life of aluminum alloy pipes. Surface treatment technologies of aluminum alloy pipes, such as anodic oxidation, electroplating, coating, etc., have become the key means to solve this problem. Ni-W alloy plating layer is widely used in industrial fields due to its excellent wear resistance and corrosion resistance. However, traditional Ni-W plating layer has problems such as stress concentration, low adhesion to the substrate, and limited wear resistance, which limits the application of Ni-W plating layer. However, designing the structure of the plating layer is an effective optimization strategy that can synergistically improve the overall performance of the plating layer.

[0003] Enamel is the most wear-resistant structure in the human body, mainly because it contains tightly arranged crystal and amorphous structures in its structure. These amorphous structures have very high hardness and can effectively resist external mechanical wear. In addition, the crystal region inside the enamel can increase the toughness of the tooth and reduce the formation of cracks, further improving the wear resistance of the tooth during the chewing process. Therefore, enamel can maintain its wear resistance in long-term use under the balance of hardness and toughness. Inspired by this, a hybrid structure composed of crystals and amorphous structures is designed to mimic the structure of human enamel. By changing the composition of the alloy and thus the organizational properties, the overall performance of the material is improved.

[0004] The electrodeposited crystal and amorphous structure Ni-W plating layer mainly changes the crystal structure of the Ni-W plating layer by controlling the electroplating parameters, so that part of the crystal structure of the plating layer exhibits amorphous characteristics, thereby improving the overall performance of the plating layer. However, when depositing Ni-W plating layer on the surface of aluminum alloy, the amorphization is uncontrollable, which will have a series of negative effects on the quality, performance and application of the plating layer, such as: non-uniform composition causing amorphous segregation, which will reduce the mechanical properties of the plating layer, the surface quality is not high, and the adhesion to the substrate is insufficient, etc. SUMMARY

[0005] To overcome the aforementioned shortcomings, the main objective of this invention is to provide a Ni-W coating with a tooth-enamel-like structure on the surface of aluminum alloy and its preparation method. By providing a Ni-W coating with a tooth-enamel-like structure on the aluminum alloy surface, the adhesion and stress dispersion of the Ni-W coating to the aluminum alloy are significantly improved, thereby effectively enhancing the wear resistance and corrosion resistance of the aluminum alloy. Furthermore, the preparation method provided by this invention solves the problems of component segregation and uneven distribution of crystalline and amorphous materials in the mixed crystalline and amorphous structure during Ni-W coating deposition on the aluminum alloy substrate, which result in poor overall coating performance.

[0006] To achieve the above objectives, the present invention provides a tooth-enamel-like Ni-W coating on an aluminum alloy surface. The Ni-W coating on the aluminum alloy surface has a mixed structure of nanocrystalline and amorphous materials, wherein the amorphous content of the inner layer of the Ni-W coating bonded to the aluminum alloy surface is lower than the amorphous content of the outer layer of the Ni-W coating.

[0007] Furthermore, the amorphous content in the bottom layer of the Ni-W coating is less than 30%, and the amorphous content in the outer layer of the Ni-W coating is greater than 50%.

[0008] Furthermore, the particle size distribution of the crystalline and amorphous particles in the Ni-W coating is 5~50nm.

[0009] Furthermore, the thickness of the Ni-W coating is 100~130μm.

[0010] In another aspect, the present invention provides a method for preparing the aforementioned tooth enamel-like Ni-W coating on an aluminum alloy surface, comprising the following steps:

[0011] An aluminum alloy substrate is placed in a plating bath for ultrasonic-assisted electrodeposition, with nickel as a consumable anode and aluminum alloy as a cathode.

[0012] By controlling the current density and additive concentration to increase over time during the ultrasonic-assisted electrodeposition process, a tooth-like enamel structure Ni-W coating is obtained on the aluminum alloy surface.

[0013] Furthermore, the current density is adjusted from 0.01 to 0.05 A / cm². 2 Increase to 0.1~0.2 A / cm 2 .

[0014] Furthermore, the current density is adjusted to be between 0.01 and 0.02 A / cm². 2 Maintain the current density for 10-30 minutes, then gradually increase it to 0.05-0.10 A / cm² over 10-20 minutes. 2 Then, within 10-30 minutes, the current density is increased to 0.10-0.15 A / cm.2 Then, within 10-30 minutes, increase the current density to 0.15-0.20 A / cm. 2 .

[0015] Furthermore, the concentration of the additive was adjusted from 0.5~1.0 g / L to 5~8 g / L.

[0016] Furthermore, the additive is added at intervals of 10 to 20 minutes, increasing the additive concentration from 0.5 to 1.0 g / L to 5 to 8 g / L.

[0017] Furthermore, the additives include tungstate, citrate or citric acid, and sodium saccharin.

[0018] Furthermore, the mass ratio of tungstate, citrate, and sodium saccharin is 100~300:200~700:1.

[0019] Further, the plating solution comprises: NiSO4: 10~20g / L; Na2WO4: 55~65g / L; Na3C6H5O7: 140~150g / L; NH4Cl: 20~30g / L; C7H4NO3SNa: 0.2~0.7g / L; NaBr: 10~20g / L.

[0020] Furthermore, the conditions for ultrasonic-assisted electrodeposition include: a duty cycle of 90-95%, a frequency of 45-50Hz, a stirring speed of 250-350r / min, an electroplating time of 120-180min, and a rated ultrasonic power of 100-400W.

[0021] Furthermore, before the aluminum alloy substrate is placed in the plating bath for ultrasonic-assisted electrodeposition, the following steps are also included:

[0022] The surface of the aluminum alloy substrate is polished and cleaned. The cleaning is performed by ultrasonic cleaning with an organic solvent, or by activating with hydrochloric acid and then ultrasonic cleaning with an organic solvent.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The aluminum alloy surface imitation tooth enamel structure Ni-W coating provided by the present invention presents a mixed structure of uniformly distributed nanocrystals and amorphous materials, with the characteristics of fine grains, high density and low porosity. Moreover, the outer layer of the Ni-W coating has a high proportion of amorphous particles, which improves the corrosion resistance and wear resistance of the coating. The inner layer of the coating has a high proportion of crystal particles that are bonded to the aluminum alloy, which has a high degree of compatibility with the crystal form of the aluminum alloy and good bonding force. This mixed structure has both hardness and toughness, which greatly enhances the corrosion resistance, wear resistance and other properties of aluminum alloy pipes in various application scenarios.

[0025] (2) The ultrasonic-assisted electrodeposition method of the present invention can optimize the microstructure of Ni-W alloy coating, significantly improve the adhesion, wear resistance and corrosion resistance of the coating, and help to achieve uniform distribution of coating thickness and nanocrystalline and amorphous materials, providing an efficient way to realize high-performance dental enamel structure coating. Attached Figure Description

[0026] Figure 1 The surface morphology of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared according to Example 1 of the present invention is shown.

[0027] Figure 2 A cross-sectional morphology diagram of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared according to Example 1 of the present invention is shown.

[0028] Figure 3 A schematic diagram of the elemental content distribution of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared in Example 1 of the present invention is shown. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. The invention will now be described in detail with reference to embodiments.

[0030] To achieve the above objectives, a first aspect of the present invention provides a tooth-enamel-like Ni-W coating on an aluminum alloy surface, wherein the Ni-W coating on the aluminum alloy surface has a mixed structure of nanocrystalline and amorphous materials, wherein the amorphous content of the inner layer of the Ni-W coating bonded to the aluminum alloy surface is lower than the amorphous content of the outer layer of the Ni-W coating.

[0031] Traditional bottom-layer nanocrystalline and top-layer amorphous structures form a discontinuous, gradual transition structure. This performance mismatch leads to uneven stress distribution and reduces overall load-bearing capacity. In the hybrid structure of this invention, the crystalline and amorphous phases are uniform, interwoven, and interpenetrating in three-dimensional space, without a clear macroscopic interface. The nanocrystalline and amorphous grains are mutually "embedded" and "anchored," mutually constraining each other with extremely strong bonding. Under shear stress, the stress is uniformly distributed throughout the composite, greatly suppressing delamination and spalling tendencies. This hybrid structure combines hardness and toughness; the amorphous phase provides high hardness, resisting indentation and plastic deformation. The nanocrystalline phase effectively blunts crack tips and prevents crack propagation through mechanisms such as grain boundary slip and dislocation movement, thus providing excellent toughness. The process is simple, and the product exhibits good consistency and reliability.

[0032] In order to further improve the bonding strength between aluminum alloy and Ni-W coating and the corrosion resistance and wear resistance of coating, in a preferred embodiment of the present invention, the amorphous content in the inner layer of Ni-W coating is less than 30%, more preferably 20-30%, and the amorphous content in the outer layer of Ni-W coating is more than 50%, more preferably 50-70%.

[0033] The amorphous content in the inner layer of the Ni-W coating is 20-30%. This range of low amorphous content and high crystalline content is beneficial to increasing the adhesion between the coating and the substrate, as well as dispersing stress concentration inside the film. The amorphous content in the outer layer of the Ni-W coating is 50-70%. The higher amorphous content in the outer layer is beneficial to increasing the surface hardness of the film and improving its wear resistance.

[0034] In a preferred embodiment of the present invention, the particle size distribution of the crystalline and amorphous particles in the Ni-W coating is 5~50 nm. The amorphous structure of the coating has high hardness, which can resist wear caused by external forces such as friction and impact on the aluminum alloy surface. The amorphous particles of this size can further enhance the corrosion resistance and wear resistance of the aluminum alloy surface.

[0035] In a preferred embodiment of the present invention, the thickness of the Ni-W coating is 100-130 μm. The present invention ensures high wear resistance and corrosion resistance by controlling the coating to be sufficiently thick. Further, the thickness of the underlying layer of the Ni-W coating, with an amorphous particle content of less than 30%, is 20-30 μm, and the thickness of the surface layer, with an amorphous particle content of more than 50%, is 30-40 μm.

[0036] In a preferred embodiment of the present invention, the tungsten content of the Ni-W coating increases uniformly from 10-15% to 45-50% along the coating growth direction.

[0037] A second aspect of the present invention provides a method for preparing the aforementioned tooth-enamel-like Ni-W coating on an aluminum alloy surface, comprising the following steps:

[0038] An aluminum alloy substrate is placed in a plating bath for ultrasonic-assisted electrodeposition, with nickel as a consumable anode and aluminum alloy as a cathode.

[0039] By controlling the current density and additive concentration to increase uniformly over time during the ultrasonic-assisted electrodeposition process, a tooth-like enamel structure Ni-W coating is obtained on the aluminum alloy surface.

[0040] Ultrasound is a sound wave with a frequency higher than 20kHz. It has good directionality, strong penetrating power, and can easily obtain concentrated sound energy. The effects that may be produced when it propagates in a medium mainly include cavitation effect, acoustic flow effect, acoustic radiation force effect, mechanical vibration effect, and thermal effect.

[0041] In the preparation method of this invention, ultrasonic vibration effectively improves solution flow and ion transport during the ultrasonic-assisted electrodeposition of the Ni-W coating with a dental enamel structure. This promotes the uniformity and density of the electrodeposited layer, reduces deposition defects, and significantly improves the quality of the deposited layer. The microjets and shock waves generated by the cavitation effect can refine grains, reduce porosity, and improve smoothness. Furthermore, it can increase the deposition rate and shorten the preparation time by enhancing ion diffusion and promoting electrode reactions. Simultaneously, the mechanical action of ultrasound can prevent particle agglomeration in the plating solution, remove impurities, and improve the performance of the plating solution. Through the synergistic effect of the above, a uniform distribution of nanocrystals and amorphous materials is achieved in the crystalline-amorphous hybrid structure of the coating.

[0042] Furthermore, ultrasound-assisted electrodeposition helps maintain the ion concentration at the cathode interface under high-rate, thick-deposition conditions, reducing concentration polarization and thus achieving higher coating thicknesses (reaching over 100 μm). Ultrasonic cavitation and acoustic flow effects reduce internal stress in the coating, which is crucial for depositing thick Ni-W layers on aluminum alloys and maintaining good adhesion, preventing cracking or peeling. Regarding the coating's microstructure, ultrasound can refine the grains of the initial deposit, promoting amorphous formation in high-W content regions.

[0043] In summary, the ultrasonic-assisted electrodeposition method of this invention can optimize the microstructure of Ni-W alloy coatings, significantly improve the adhesion, wear resistance, and corrosion resistance of the coatings, and help achieve uniform distribution of coating thickness and nanocrystalline and amorphous materials, providing an efficient way to realize high-performance dental enamel-like coating structures.

[0044] In a preferred embodiment of the present invention, the current density is adjusted from 0.01 to 0.05 A / cm². 2 Increase to 0.1~0.2 A / cm2 Furthermore, specifically including: adjusting the current density to 0.01~0.02 A / cm². 2 Maintain the current density for 10-30 minutes, then gradually increase it to 0.05-0.10 A / cm² over 10-20 minutes. 2 Then, within 10-30 minutes, the current density is increased to 0.10-0.15 A / cm. 2 Then, within 10-30 minutes, increase the current density to 0.15-0.20 A / cm. 2 The present invention selects a lower current density compared to a higher current density, and this range of current densities enables the coating to be denser and more easily form an amorphous structure.

[0045] In a preferred embodiment of the present invention, the concentration of the additive is adjusted from 0.5~1.0 g / L to 5~8 g / L. More specifically, this includes adjusting the additive concentration by adding 0.2~1.5 g / L, preferably 0.2~0.5 g / L, at intervals of 10~20 minutes, thereby increasing the additive concentration from 0.5~1.0 g / L to 5~8 g / L. Additives within this range can optimize the internal stress of the coating, promote Ni-W co-deposition, and stabilize the plating bath.

[0046] In a preferred embodiment of the present invention, the additive comprises tungstate, citrate, and sodium saccharin. In the additive of the present invention, tungstate provides tungsten in the nickel-tungsten alloy coating, sodium saccharin optimizes the internal stress of the coating, and citrate can complex Ni… 2+ and W 6+ Promoting Ni-W co-deposition and stabilizing the plating bath are key to achieving the desired enamel structure in the coating. More preferably, the mass ratio of tungstate, citrate, and sodium saccharin is 100-300:200-700:1. This invention synergistically controls the composition ratio of tungstate, citrate, and sodium saccharin, with a higher mass of citrate to ensure Ni-W co-deposition. The synergistic effect of these three components ensures the uniformity of the coating structure.

[0047] In a preferred embodiment of the present invention, the plating solution comprises: NiSO4: 10~20 g / L; Na2WO4: 55~65 g / L; Na3C6H5O7: 140~150 g / L; NH4Cl: 20~30 g / L; C7H4NO3SNa: 0.2~0.7 g / L; NaBr: 10~20 g / L. The present invention further designs the composition and proportions of the plating solution, using high-concentration sodium citrate as the dominant complexing agent, synergistically with Na2WO4 and NiSO4 to ensure uniform co-deposition of W / Ni ions. An appropriate concentration of sodium saccharin reduces internal stress, NaBr refines the grains, and NH4Cl improves the conductivity and stabilizes the pH value of the plating solution. The plating solution designed in this invention, combined with ultrasonic-assisted electrodeposition, ensures that the coating thickness reaches over 100 μm without cracks. More preferably, the pH value of the plating solution is adjusted to 3.5~4.5.

[0048] In a preferred embodiment of the present invention, the electroplating conditions for ultrasonic-assisted electrodeposition include: a duty cycle of 90-95%, a frequency of 45-50 Hz, a stirring speed of 250-350 r / min, and an electroplating time of 120-180 min. The duty cycle refers to the ratio of the actual ultrasonic wave emission time (i.e., the energy output of the vibrating element) to the total working cycle (emission time + interval time) within a complete working cycle of the ultrasonic device. Further, the rated ultrasonic power for ultrasonic-assisted electrodeposition is 100-400 W. More preferably, the ultrasonic power is controlled in two stages: first, the ultrasonic power is set to 80-150 W and maintained for 20-40 min, then the ultrasonic power is increased to 150-400 W until deposition is complete. This two-stage ultrasonic setting is more conducive to obtaining a thick, uniform coating with low internal stress, strong adhesion, and a specific crystalline / amorphous structure.

[0049] To further improve the adhesion between the Ni-W coating on the dental enamel structure and the aluminum alloy, in a preferred embodiment of the present invention, before the aluminum alloy substrate is placed in the plating solution for ultrasonic-assisted electrodeposition, the following steps are included: grinding and cleaning the surface of the aluminum alloy substrate. The cleaning is performed using an organic solvent (e.g., ethanol or acetone) for ultrasonic cleaning, or by activating with hydrochloric acid followed by ultrasonic cleaning with an organic solvent (e.g., ethanol or acetone). Further, the grinding can be performed, for example, by sanding with sandpaper in the following order: 600#, 800#, 1000#, 2000#.

[0050] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0051] Example 1

[0052] A method for preparing a Ni-W coating with a tooth enamel-like structure on an aluminum alloy surface, specifically including the following steps:

[0053] S1: Grinding and cleaning the 6061 aluminum alloy sample.

[0054] Cut a suitable aluminum alloy sample and sand it with sandpaper (sanding sequence: 600#, 800#, 1000#, 2000#). Use ethanol to remove oil stains from the surface of the substrate.

[0055] S2: The cleaned 6061 aluminum alloy sample substrate was placed in the plating solution, and a Ni-W coating with a thickness of 118 μm with a dental enamel structure was prepared by ultrasonic-assisted electrodeposition.

[0056] (1) Prepare the electroplating solution.

[0057] Weigh out NiSO4 (16 g / L), Na2WO4 (60 g / L), Na3C6H5O7 (147 g / L), NH4Cl (26 g / L), C7H4NO3SNa (0.5 g / L), and NaBr (15 g / L) using a balance. Dissolve the chemicals in distilled water, stir until dissolved, and then add NH4Cl to adjust the pH of the plating solution to 4.

[0058] (2) Electroplating treatment.

[0059] The cleaned 6061 aluminum alloy substrate was placed in a plating bath to deposit a Ni-W coating with a dental enamel structure. The plating conditions were as follows: nickel as the consumable anode, 6061 aluminum alloy as the cathode, duty cycle 95%, frequency 48Hz, stirring speed 350r / min, and current density controlled at 0.02A / cm². 2 Maintain this position for 20 minutes, then increase the current density uniformly to 0.1 A / cm² over the next 20 minutes. 2 Then, the current density is increased uniformly to 0.15 A / cm² over 20 minutes. 2 Then, the current density is increased uniformly to 0.2 A / cm² over 20 minutes. 2 Finally, the current density was maintained at 0.2 A / cm². 2 Deposition for 80 minutes.

[0060] Meanwhile, the concentration of the additives was adjusted: according to the ratio of tungstate, citrate and sodium saccharin of 100:300:1, 0.28 g / L of additives were added every 10 minutes, and the concentration was gradually increased from 0.5 g / L to 5 g / L.

[0061] (3) Ultrasonic assistance.

[0062] Meanwhile, during the electroplating process, the ultrasonic probe is placed in the plating solution for electrodeposition assistance. The rated power is set to 100W for 30 minutes, and then increased to 300W until the deposition is completed.

[0063] Example 2

[0064] A method for preparing a Ni-W coating with a tooth enamel-like structure on an aluminum alloy surface, specifically including the following steps:

[0065] S1: Grinding and cleaning the 6061 aluminum alloy sample.

[0066] Cut a suitable aluminum alloy sample and sand it with sandpaper (sanding sequence: 600#, 800#, 1000#, 2000#). Use ethanol to remove oil stains from the surface of the substrate.

[0067] S2: The cleaned 6061 aluminum alloy sample substrate was placed in the plating solution and electroplated to obtain a 130μm thick tooth-like enamel structure Ni-W coating.

[0068] (1) Prepare the electroplating solution.

[0069] Weigh out NiSO4 (20 g / L), Na2WO4 (65 g / L), Na3C6H5O7 (150 g / L), NH4Cl (30 g / L), C7H4NO3SNa (0.7 g / L), and NaBr (20 g / L) using a balance. Dissolve the reagents in distilled water, stir until dissolved, and then add NH4Cl to adjust the pH to 4.

[0070] (2) Electroplating treatment.

[0071] The cleaned 6061 aluminum alloy substrate was placed in a plating bath to deposit a Ni-W coating with a dental enamel structure. The plating conditions were as follows: nickel as the consumable anode, 6061 aluminum alloy as the cathode, duty cycle 92%, frequency 50 Hz, stirring speed 300 r / min, and current density controlled at 0.02 A / cm². 2 Maintain this position for 30 minutes, then increase the current density uniformly to 0.1 A / cm² over 20 minutes. 2 Then, the current density is increased uniformly to 0.15 A / cm² over 30 minutes. 2 Then, the current density is increased uniformly to 0.2 A / cm² over 20 minutes. 2 Finally, the current density was maintained at 0.2 A / cm². 2 Deposition for 80 minutes.

[0072] Meanwhile, the concentration of the additives was adjusted: according to the ratio of tungstate, citrate and sodium saccharin of 100:300:1, 0.25 g / L of additives were added every 10 minutes, and the concentration was gradually increased from 0.5 g / L to 5 g / L.

[0073] (3) Ultrasonic assistance.

[0074] Meanwhile, during the electroplating process, the ultrasonic probe is placed in the plating solution to assist in electrodeposition. The rated power is set to 100 W for 30 minutes, and then increased to 400 W until the deposition is completed.

[0075] Example 3

[0076] A method for preparing a Ni-W coating with a tooth enamel-like structure on an aluminum alloy surface, specifically including the following steps:

[0077] S1: Grind the appropriate aluminum alloy sample with sandpaper (grinding sequence is 600#, 800#, 1000#, 2000#), and use ethanol to remove oil stains from the substrate surface.

[0078] S2: The cleaned 6061 aluminum alloy sample substrate was placed in the plating solution and electroplated to obtain a 110μm thick tooth-like enamel structure Ni-W coating.

[0079] (1) Prepare the electroplating solution.

[0080] Weigh out NiSO4 (10 g / L), Na2WO4 (55 g / L), Na3C6H5O7 (140 g / L), NH4Cl (20 g / L), C7H4NO3SNa (0.2 g / L), and NaBr (10 g / L) using a balance. Dissolve the reagents in distilled water, stir until dissolved, and then add NH4Cl to adjust the pH to 4.

[0081] (2) Electroplating treatment.

[0082] The cleaned 6061 aluminum alloy substrate was placed in a plating bath to deposit a Ni-W coating with a dental enamel structure. The plating conditions were as follows: nickel as the consumable anode, 6061 aluminum alloy as the cathode, duty cycle 90%, frequency 45Hz, stirring speed 250r / min, and current density controlled at 0.01A / cm². 2 Maintain this position for 10 minutes, then increase the current density uniformly to 0.1 A / cm² over the next 10 minutes. 2 Then, the current density is increased uniformly to 0.15 A / cm² over 10 minutes. 2 Then, the current density is increased uniformly to 0.2 A / cm² over 10 minutes. 2 Finally, the current density was maintained at 0.2 A / cm². 2 Deposition for 80 minutes.

[0083] Meanwhile, the concentration of the additives was adjusted: according to the ratio of tungstate, citrate and sodium saccharin of 100:300:1, 0.375 g / L of additives were added every 10 minutes, and the concentration was gradually increased from 0.5 g / L to 5 g / L.

[0084] (3) Ultrasonic assistance.

[0085] Meanwhile, during the electroplating process, an ultrasonic probe is placed in the plating solution to assist in electrodeposition, with the rated power set to 100W, until the deposition is completed.

[0086] Example 4

[0087] A method for preparing a tooth-enamel-like Ni-W coating on an aluminum alloy surface differs from Example 1 only in that the mass ratio of tungstate, citrate, and sodium saccharin is 300:700:1.

[0088] Example 5

[0089] A method for preparing a tooth-enamel-like Ni-W coating on an aluminum alloy surface differs from Example 1 only in that the mass ratio of tungstate, citrate, and sodium saccharin is 100:200:1.

[0090] Example 6

[0091] A method for preparing a Ni-W coating with a tooth-like enamel structure on an aluminum alloy surface differs from Example 3 in that the ultrasonic-assisted process is different. It adopts a two-stage ultrasonic electrodeposition assistance, specifically: at the same time, during the electroplating process, the ultrasonic probe is placed in the plating solution for electrodeposition assistance, the rated power is set to 100 W for 30 min, and then increased to 400 W until the deposition is completed.

[0092] Example 7

[0093] A method for preparing a tooth-enamel-like Ni-W coating on an aluminum alloy surface differs from Example 1 only in that the mass ratio of tungstate, citrate, and sodium saccharin is 50:100:1.

[0094] Example 8

[0095] A method for preparing a tooth-enamel-like Ni-W coating on an aluminum alloy surface, differing from Example 1 only in that the current density is controlled at 1 A / cm². 2 Maintain the current density for 10 minutes, then increase it uniformly to 2 A / cm² over the next 10 minutes. 2 Then, the current density is increased uniformly to 3 A / cm² over 10 minutes. 2 Then, the current density is increased uniformly to 3.5 A / cm² over 10 minutes. 2Finally, the current density was maintained at 3.5 A / cm². 2 Deposition for 30 minutes.

[0096] Example 9

[0097] A method for preparing a tooth-like enamel structure Ni-W coating on an aluminum alloy surface differs from Example 1 only in that the concentration of the plating solution is as follows: NiSO4: 5 g / L; Na2WO4: 40 g / L; Na3C6H5O7: 100 g / L; NH4Cl: 40 g / L; C7H4NO3SNa: 0.1 g / L; NaBr: 5 g / L.

[0098] Performance testing:

[0099] The surface morphology of the tooth-enamel-like Ni-W coating on the aluminum alloy surface prepared in Example 1 was characterized using scanning electron microscopy (SEM). Figure 1 As shown, from Figure 1 It can be seen that the coated nanoparticles and amorphous particles are dense and uniform, without defects such as pores, and the particle size distribution of the crystalline and amorphous particles is 5~50nm.

[0100] The cross-sectional morphology of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared in Example 1 was characterized (using scanning electron microscopy), as follows: Figure 2 As shown, from Figure 2 It can be seen that the coating has good adhesion to the substrate, and the coating thickness is 118 micrometers.

[0101] The elemental composition distribution of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared in Example 1 was tested, and the test results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the tungsten atom content gradually increases and the nickel atom content gradually decreases along the growth direction of the coating, indicating that the proportion of amorphous particles in the coating gradually increases. The amorphous content accounts for 25% in the inner layer of the Ni-W coating bonded to the aluminum alloy surface and 60% in the outer layer.

[0102] The friction coefficient and wear resistance of the tooth-like enamel structure Ni-W coating on the aluminum alloy surface prepared in the above embodiments were tested according to GB / T 45593-2025. The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105] From the above tests on the coating friction coefficient and wear rate, it can be concluded that the average friction coefficient of the aluminum alloy surface Ni-W coating with a tooth-like enamel structure in Examples 1-6 of the present invention is all below 0.4, and the wear amount is all below 0.6 mg. Example 6 uses two-stage ultrasonic control, which is more conducive to obtaining a thicker and more uniform coating with low internal stress and strong adhesion than Example 3, thereby improving its wear resistance. However, Examples 7-9, which are outside the parameter range of the present invention, show a deterioration in coating performance, with a significant increase in both the average friction coefficient and wear amount.

[0106] As can be seen from the above description, the present invention achieves the following technical effects: The aluminum alloy surface imitation tooth enamel structure Ni-W coating provided by the present invention presents a mixed structure of uniformly distributed nanocrystalline and amorphous materials, which has the characteristics of fine grains, high density, and low porosity. Moreover, the outer layer of the Ni-W coating has a high proportion of amorphous particles, which improves the corrosion resistance and wear resistance of the coating. The inner layer of the coating has a high proportion of crystalline particles that are bonded to the aluminum alloy, which has a high degree of compatibility with the crystal form of the aluminum alloy and good bonding force. This mixed structure has both hardness and toughness, which greatly enhances the corrosion resistance, wear resistance and other properties of aluminum alloy tubes in various application scenarios, and provides a new and effective way for aluminum alloy surface treatment.

[0107] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. The present invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A method for preparing a Ni-W coating with a dental enamel-like structure on an aluminum alloy surface, characterized in that, Includes the following steps: An aluminum alloy substrate is placed in a plating bath for ultrasonic-assisted electrodeposition, with nickel as a consumable anode and aluminum alloy as a cathode. The conditions for ultrasonic-assisted electrodeposition include: a duty cycle of 90-95%, a frequency of 45-50Hz, a stirring speed of 250-350r / min, an electroplating time of 120-180min, and a rated ultrasonic power of 100-400W. By controlling the current density and the concentration of additives in the plating bath as a time gradient during the ultrasonic-assisted electrodeposition process, a tooth-like enamel structure Ni-W coating is obtained on the aluminum alloy surface; the tooth-like enamel structure Ni-W coating is a hybrid structure of nanocrystalline and amorphous materials, wherein the Ni bonded to the aluminum alloy surface... The amorphous content in the inner layer of the W coating is lower than that in the Ni. W coating outer layer amorphous content; The current density is adjusted from 0.01 to 0.02 A / cm². 2 Increase to 0.1~0.2 A / cm 2 This includes: adjusting the current density to 0.01~0.02 A / cm². 2 Maintain the current density for 10-30 minutes, then gradually increase it to 0.05-0.10 A / cm² over 10-20 minutes. 2 Then, within 10-30 minutes, the current density is increased to 0.10-0.15 A / cm. 2 Then, within 10-30 minutes, increase the current density to 0.15-0.20 A / cm. 2 ; Specifically, adjusting the concentration of the additive from 0.5~1.0 g / L to 5~8 g / L involves adding 0.2~1.5 g / L of the additive at 10~20 min intervals, increasing the concentration from 0.5~1.0 g / L to 5~8 g / L. The additive includes tungstate, citrate, and sodium saccharin, with a mass ratio of 100~300:200~700:

1. The plating solution includes NiSO4: 10~20 g / L; Na2WO4: 55~65 g / L; Na3C6H5O7: 140~150 g / L; NH4Cl: 20~30 g / L; C7H4NO3SNa: 0.2~0.7 g / L; and NaBr: 10~20 g / L.

2. The method for preparing a tooth-enamel-like Ni-W coating on an aluminum alloy surface according to claim 1, characterized in that, Before the aluminum alloy substrate is placed in the plating bath for ultrasonic-assisted electrodeposition, the following steps are also included: The surface of the aluminum alloy substrate is polished and cleaned. The cleaning is performed by ultrasonic cleaning with an organic solvent, or by activating with hydrochloric acid and then performing ultrasonic cleaning with an organic solvent.

3. A Ni-W coating with a dental enamel-like structure on an aluminum alloy surface, characterized in that, The Ni-W coating with a dental enamel structure on the aluminum alloy surface was prepared using the method described in claim 1 or 2.

4. The Ni-W coating with a tooth-like enamel structure on the aluminum alloy surface according to claim 3, characterized in that, The Ni The amorphous content in the inner layer of the W coating is less than 30%, and the Ni... The amorphous content in the outer layer of the W coating is higher than 50%.

5. The Ni-W coating with a dental enamel structure on the aluminum alloy surface according to claim 3, characterized in that, The thickness of the Ni-W coating is 100~130μm; the particle size distribution of the crystalline and amorphous particles in the Ni-W coating is 5~50nm.

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