WO2022206588A1 - 一种焊接接头防护涂层的制备方法及其应用 - Google Patents

一种焊接接头防护涂层的制备方法及其应用 Download PDF

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WO2022206588A1
WO2022206588A1 PCT/CN2022/082978 CN2022082978W WO2022206588A1 WO 2022206588 A1 WO2022206588 A1 WO 2022206588A1 CN 2022082978 W CN2022082978 W CN 2022082978W WO 2022206588 A1 WO2022206588 A1 WO 2022206588A1
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aluminum alloy
treatment
protective coating
nickel
electrochemical
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PCT/CN2022/082978
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English (en)
French (fr)
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王宇鑫
陈佳欢
杨一凡
何震
陈书锦
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江苏科技大学
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Publication of WO2022206588A1 publication Critical patent/WO2022206588A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/16—Pretreatment, e.g. desmutting
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/18—After-treatment, e.g. pore-sealing
    • C25D11/24—Chemical after-treatment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/562—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of iron or nickel or cobalt
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • C25F3/18—Polishing of light metals
    • C25F3/20—Polishing of light metals of aluminium

Definitions

  • the invention relates to the field of aluminum alloy friction stir welding, in particular to a preparation method and application of a protective coating for a welded joint.
  • Friction stir welding is a purely mechanical solid-phase joining technology, which was invented by the Welding Institute (TWI) in 1991 and applied for patent protection worldwide, because the technology can greatly Improve the performance of aluminum alloy joints, so it is mainly used in aluminum alloy welding.
  • TWI Welding Institute
  • the accelerated wear and corrosion failure of the aluminum alloy weld surface after welding greatly reduces the service life of aluminum alloy weldments and limits the industrial application of friction stir welded aluminum alloy products.
  • the welded seam after friction stir welding is usually subjected to electrochemical nickel plating treatment.
  • the aluminum alloy surface can form an aluminum alloy electroless nickel-phosphorus coating .
  • This kind of coating has the advantages of uniform thickness, high hardness and good wear and corrosion resistance, but due to the existence of defects on the weld after friction stir welding, the adhesion between the nickel coating and the weld surface is reduced, which limits the Application of Electrochemical Nickel Plating on the Weld Surface of Aluminum Alloy Friction Stir Welding.
  • the technical problem to be solved by the present invention is, in view of the deficiencies of the prior art, to provide a method for preparing a protective coating for a welded joint, which is applied to the surface of the welding seam of friction stir welding of aluminum alloys.
  • the present invention adopts the following technical solutions:
  • the utility model relates to a protective coating for welded joints.
  • the protective coating for welded joints has a double-layer structure of anodized aluminum layer and Ni-P plating layer.
  • the preparation method of the welding joint protective coating comprises the following steps:
  • step 2) performing anodizing treatment on the surface of the aluminum alloy weld to be reinforced obtained after the treatment in step 1) to obtain a dense and porous anodized aluminum oxide intermediate layer;
  • step 3 Activating and expanding the anodic aluminum oxide intermediate layer obtained by the treatment in step 2) to obtain the surface of the nickel-aluminum alloy weld to be plated;
  • Electrochemical nickel plating is performed on the surface of the nickel-plated aluminum alloy weld seam obtained by the treatment in step 3) to obtain the welded joint protective coating.
  • the pretreatment in step 1) comprises the following steps:
  • step b The surface of the aluminum alloy weld seam treated in step a is placed in a polishing solution for electrochemical polishing.
  • the specific implementation of the electrochemical polishing treatment in step b is: the polishing solution is formed by mixing a phosphoric acid solution and anhydrous ethanol, and the volume ratio of the phosphoric acid solution to the anhydrous ethanol solution is 3 :2;
  • the current density during the electrochemical polishing treatment is 10-30 A/dm 2 , and the electrochemical polishing time is 15-20 min.
  • the specific implementation method of the anodizing treatment in step 2) is: at normal temperature, the surface of the aluminum alloy weld to be reinforced after the pretreatment in step 1) is placed in a reinforcing solution for anodizing treatment;
  • the enhancement solution is a phosphoric acid solution of 300 g/L, the anodization voltage during the anodization treatment is 60-100V, and the anodization time is 15-20min.
  • the specific implementation of the pore-enlarging activation treatment in step 3) is: placing the anodic aluminum oxide intermediate layer obtained by the treatment in step 2) in a pore-enlarging solution for activation and pore-enlarging treatment;
  • the hole-expanding solution is a phosphoric acid solution with a volume fraction of 5%, and the hole-expanding activation treatment time is 20-30 minutes.
  • the specific implementation method of the electrochemical nickel plating treatment in step 4) is: placing the anodic aluminum oxide intermediate layer that has undergone the pore expansion activation treatment in an electrochemical nickel plating solution for electrochemical nickel plating treatment;
  • the electrochemical nickel plating solution is composed of a nickel salt, a reducing agent and a complexing agent, the pH of the electrochemical nickel plating solution is 5, and the current density during the electrochemical nickel plating treatment is 1-3 A/dm 2 , The temperature of the electrochemical nickel plating solution is 60-65° C., and the plating time is 10-30 minutes.
  • the nickel salt is a mixture of nickel sulfate and nickel chloride
  • the activator is composed of sodium citrate, sodium gluconate and saccharin
  • the reducing agent is sodium hypophosphite.
  • the mass concentration ratio of nickel sulfate, nickel chloride, sodium hypophosphite, sodium citrate, sodium gluconate and saccharin in the electrochemical nickel plating solution is: 200:(30-35):30:140 : (30 to 35): 0.5.
  • the present invention has the following beneficial effects:
  • the welding joint protective coating of the present invention has a double-layer structure of anodized aluminum layer and Ni-P coating.
  • the welding joint protective coating is suitable for the welding surface of aluminum alloy friction stir welding, and the welding joint protective coating mainly adopts
  • the anodic oxidation method prepares a dense and porous anodized aluminum intermediate layer on the surface of the aluminum alloy weld, and then activates and expands the hole to eliminate the surface defects at the aluminum alloy welded joint, which is more conducive to the formation of the nickel layer on the surface of the aluminum alloy welded joint.
  • the adhesion improves the bonding strength between the nickel plating layer and the substrate.
  • a double-layer structure with an anodized aluminum oxide layer and a Ni-P plating layer is formed on the surface of the welded joint.
  • the present invention mainly adopts the method of combining anodic oxidation and electrochemical deposition. Compared with the samples plated with Ni-P after no strengthening treatment and galvanizing, it can not only improve the bonding strength between the nickel-plated layer and the substrate, but also The corrosion resistance and wear resistance of the aluminum alloy welding seam can also be improved at the same time, and the preparation method of the welding joint protective coating is simple to operate, safe and reliable, has good repeatability, is economical and environmentally friendly, and can be used for mass production.
  • Fig. 1 (a) is the SEM image of the welding joint protective coating prepared in Example 1 of the present invention
  • Fig. 1(b) is a partial enlarged view of the SEM image of the protective coating for the welded joint prepared in Example 1 of the present invention
  • Fig. 1 (c) is the SEM image of the welding joint protective coating prepared in Example 3 of the present invention.
  • Fig. 1(d) is a partial enlarged view of the SEM image of the protective coating of the welded joint prepared in Example 3 of the present invention
  • Fig. 2 (a) is the surface topography of the sample of Comparative Example 2 of the present invention.
  • Fig. 2 (b) is the sectional topography of the sample of Comparative Example 2 of the present invention.
  • Fig. 2 (c) is the surface topography diagram of the sample of Example 2 of the present invention.
  • Figure 2(d) is a cross-sectional topography diagram of the sample in Example 2 of the present invention.
  • Fig. 3 is the SEM image of the surface of the aluminum alloy weld seam after anodization and activation expansion treatment of the present invention
  • Example 4 is a graph of potentiodynamic polarization curves of samples prepared in Example 2, Comparative Example 1 and Comparative Example 2 of the present invention
  • Fig. 5 is the friction coefficient curve diagram of the samples prepared by Example 2, Comparative Example 1 and Comparative Example 2 of the present invention
  • Fig. 6 (a) is the surface wear topography diagram of the sample of Comparative Example 1 of the present invention.
  • Figure 6(b) is a cross-sectional profile view corresponding to the surface wear topography of the sample of Comparative Example 1 of the present invention
  • Fig. 6 (c) is the surface wear topography of the sample of Comparative Example 2 of the present invention.
  • Figure 6(d) is a cross-sectional profile view corresponding to the surface wear topography of the sample of Comparative Example 2 of the present invention.
  • Fig. 6 (e) is the surface wear topography of the sample of Example 2 of the present invention.
  • Figure 6(f) is a cross-sectional profile view corresponding to the surface wear topography of the sample in Example 2 of the present invention.
  • Figure 7 (a) is a bending test diagram of the sample of Comparative Example 2 under the test condition that the bending angle of the present invention is 90°;
  • Fig. 7 (b) is that the bending angle of the present invention is 180 ° under the test condition, the bending test diagram of the comparative example 2 sample;
  • Figure 7 (c) is a bending test diagram of the sample of Example 2 under the test condition that the bending angle of the present invention is 90°;
  • Figure 7(d) is a bending test diagram of the sample of Example 2 under the test condition of the bending angle of 180° according to the present invention.
  • the welding joint protective coating of the invention has a double-layer structure of an anodic aluminum oxide layer and a Ni-P plating layer, and the welding joint protective coating is applied to the welding seam surface of aluminum alloy friction stir welding.
  • the preparation method of the welding joint protective coating of the present invention comprises the following steps:
  • Preprocessing includes the following steps:
  • a polishing solution for electrochemical polishing specifically: performing electrochemical polishing on the aluminum alloy weld surface treated in step a in an atmosphere of about 25°C,
  • the alloy weld sample is the anode, and the stainless steel plate is the cathode;
  • the polishing solution is mixed with phosphoric acid solution and anhydrous ethanol, and the volume ratio of phosphoric acid solution and the anhydrous ethanol solution is 3:2.
  • the current during electrochemical polishing treatment The density was 20A/dm 2 and the electrochemical polishing time was 20min.
  • step 2) Anodizing the surface of the aluminum alloy weld seam to be reinforced obtained after the treatment in step 1) to obtain a dense and porous anodized aluminum oxide intermediate layer.
  • the aluminum alloy weld sample to be reinforced in step 1) is placed in a reinforcing solution for anodization treatment, the aluminum alloy weld sample to be reinforced is used as the anode, the pure lead plate is used as the cathode, and placed in a 25°C constant temperature water bath In the pot, and stir with a magnetic stirrer, the rotation speed is 300r/min; the enhancement solution is a phosphoric acid solution of 300g/L, the anodizing voltage during anodizing treatment is 60V, and the anodizing time is 20min
  • step 3 Carrying out hole expansion and activation treatment on the anodic aluminum oxide intermediate layer obtained by the treatment in step 2) to obtain the surface of the nickel-aluminum alloy weld to be plated.
  • the specific implementation of the pore-enlarging activation treatment is as follows: the sample with the anodic aluminum oxide intermediate layer is placed in the pore-enlarging solution for pore-enlarging treatment. .
  • Electrochemical nickel plating is performed on the surface of the nickel-plated aluminum alloy weld seam obtained through the treatment in step 3) to obtain a protective coating for the welded joint, and the anodic aluminum oxide intermediate layer that has undergone the hole expansion activation treatment is placed in an electrochemical nickel plating solution.
  • Electrochemical nickel plating treatment was carried out in the process, the nickel-aluminum alloy weld sample to be nickel-plated was the cathode, the pure nickel plate was the anode, and the electrochemical nickel-plating solution was placed in a water bath at 65 °C, stirred with a magnetic stirrer, and the rotation speed was 300r/min, and the plating time is 10min.
  • the pH of the electrochemical nickel plating solution is 5
  • the current density during the electrochemical nickel plating treatment is 2A/dm 2
  • the electrochemical nickel plating solution is composed of a nickel salt, a reducing agent and a complexing agent
  • the nickel salt is nickel sulfate
  • the activator is composed of sodium citrate, sodium gluconate and saccharin
  • the reducing agent is sodium hypophosphite, nickel sulfate, nickel chloride, sodium hypophosphite, sodium citrate in the electrochemical nickel plating solution
  • the mass concentration ratio of , sodium gluconate and saccharin is: 200:30:30:140:30:0.5.
  • Example 2 The difference from Example 1 is that 4) the surface of the nickel-plated aluminum alloy weld seam obtained through step 3) is subjected to electrochemical nickel-plating treatment to obtain the protective coating for the welded joint, and the anode that has undergone hole expansion activation treatment is subjected to electrochemical nickel plating treatment.
  • the alumina intermediate layer is placed in an electrochemical nickel plating solution for electrochemical nickel plating treatment.
  • the aluminum alloy weld sample to be nickel-plated is the cathode, the pure nickel plate is the anode, and the electrochemical nickel plating solution is placed in a water bath at 65°C. In the pot, use a magnetic stirrer to stir, the rotating speed is 300r/min, and the plating time is 20min.
  • the pH of the electrochemical nickel plating solution is 5
  • the current density during the electrochemical nickel plating treatment is 2A/dm 2
  • the electrochemical nickel plating solution is composed of a nickel salt, a reducing agent and a complexing agent
  • the nickel salt is nickel sulfate
  • the activator is composed of sodium citrate, sodium gluconate and saccharin
  • the reducing agent is sodium hypophosphite, nickel sulfate, nickel chloride, sodium hypophosphite, sodium citrate in the electrochemical nickel plating solution
  • the mass concentration ratio of , sodium gluconate and saccharin is: 200:30:30:140:30:0.5.
  • Example 2 The difference from Example 1 is that 4) electrochemical nickel plating is performed on the surface of the nickel-plated aluminum alloy weld seam obtained through step 3) to obtain a protective coating for the welded joint, and the anodized aluminum alloy that has undergone hole expansion activation treatment is treated with electrochemical nickel plating.
  • the intermediate layer is placed in an electrochemical nickel-plating solution for electrochemical nickel-plating treatment.
  • the aluminum alloy weld sample to be nickel-plated is the cathode, the pure nickel plate is the anode, and the electrochemical nickel-plating solution is placed in a water bath at 65°C. , use a magnetic stirrer to stir, the rotation speed is 300r/min, and the plating time is 30min.
  • the pH of the electrochemical nickel plating solution is 5
  • the current density during the electrochemical nickel plating treatment is 2A/dm 2
  • the electrochemical nickel plating solution is composed of a nickel salt, a reducing agent and a complexing agent
  • the nickel salt is nickel sulfate
  • the activator is composed of sodium citrate, sodium gluconate and saccharin
  • the reducing agent is sodium hypophosphite, nickel sulfate, nickel chloride, sodium hypophosphite, sodium citrate in the electrochemical nickel plating solution
  • the mass concentration ratio of , sodium gluconate and saccharin is: 200:30:30:140:30:0.5.
  • the pre-grinded aluminum alloy weld surface is cleaned with an anhydrous ethanol solution in an ultrasonic cleaner.
  • the aluminum alloy weld surface is placed in anhydrous ethanol and washed with The cleaning temperature is 25 °C, the cleaning time is 5 minutes, and the compressed air is used for drying.
  • the preparation method of welding joint protective coating comprises the following steps:
  • Zinc immersion treatment including degreasing ⁇ alkali etching ⁇ pickling ⁇ activation ⁇ one-time zinc immersion ⁇ zinc removal ⁇ second galvanization process.
  • Degreasing soak the surface of the aluminum alloy weld in a degreasing agent for 5 minutes, the temperature of the degreasing agent is 60 °C, the formula of the degreasing agent is a mixture of anhydrous sodium carbonate and trisodium phosphate, and the anhydrous sodium carbonate: trisodium phosphate mass concentration ratio is 1:1;
  • Alkaline etching Soak the degreasing aluminum alloy weld surface in an alkaline etchant for 1 min, the temperature of the alkaline etchant is 25°C, and the alkaline etchant is a sodium hydroxide solution with a mass concentration of 50g/L;
  • Pickling soak the surface of the aluminum alloy weld after alkali etching in pickling agent for 1min, the temperature of the pickling agent is 25°C, and the pickling agent is a nitric acid solution with a concentration of 600ml/L;
  • Activation soak the pickled aluminum alloy weld surface in the activator for 30s, the temperature of the activator is 25°C, and the activator is a sulfuric acid solution with a concentration of 25ml/L;
  • One galvanizing the surface of the activated aluminum alloy weld is immersed in a galvanizing solution for 1 min, the temperature of the first dipping solution is 25 °C, and the first dipping solution includes sodium hydroxide and zinc oxide, and sodium hydroxide: oxidation
  • the mass concentration ratio of zinc is 3:1;
  • Zinc removal the surface of the aluminum alloy weld after one dipping is immersed in the zinc removal solution for 30s, the temperature of the zinc removal solution is 25 °C, and the zinc removal solution is a nitric acid solution with a volume fraction of 20%;
  • Secondary galvanizing the surface of the aluminum alloy weld after zinc removal is immersed in the secondary galvanizing solution for 1 min.
  • the temperature of the secondary galvanizing solution is 25 °C. It is composed of potassium sodium and ferric chloride, and the mass concentration ratio of sodium hydroxide and sodium hydroxide is: 300:100:10:1.
  • the aluminum alloy weld sample that has undergone secondary galvanizing treatment is placed in an electrochemical nickel plating solution for electrochemical nickel plating treatment.
  • the aluminum alloy weld sample is the cathode, and the pure nickel plate is the anode.
  • the solution was placed in a water bath at 65°C, stirred with a magnetic stirrer, the rotating speed was 300 r/min, and the plating time was 20 min.
  • the pH of the electrochemical nickel plating solution is 5
  • the current density during the electrochemical nickel plating treatment is 2A/dm 2
  • the electrochemical nickel plating solution is composed of a nickel salt, a reducing agent and a complexing agent
  • the nickel salt is nickel sulfate
  • the activator is composed of sodium citrate, sodium gluconate and saccharin
  • the reducing agent is sodium hypophosphite, nickel sulfate, nickel chloride, sodium hypophosphite, sodium citrate in the electrochemical nickel plating solution
  • the mass concentration ratio of , sodium gluconate and saccharin is: 200:30:30:140:30:0.5.
  • Figure 1(a) shows the protective coating for welding joints prepared in Example 1 of the present invention.
  • SEM image; Fig. 1(b) is a partial enlarged view of the SEM image of the protective coating for welded joints prepared in Example 1 of the present invention;
  • Fig. 1(c) is the SEM of the protective coating for welded joints prepared in Example 3 of the present invention
  • Fig. 1(d) is a partial enlarged view of the SEM image of the protective coating for welded joints prepared in Example 3 of the present invention.
  • the Ni-P coating basically covers the surface of the aluminum alloy, and it can be observed that the Ni-P convex
  • the Ni-P convex hull growth is incomplete, the size of the Ni-P convex hull is small, and there are still gaps between the convex hulls, which will affect the corrosion and friction of the weld surface. performance.
  • Figure 2 is the surface and cross-sectional topography of Comparative Example 2 and Example 2, wherein Figure 2(a) is the surface topography of the sample of Comparative Example 2; Figure 2(b) is the cross-section of the sample of Comparative Example 2 Figure 2(c) is the surface topography of the sample in Example 2; Figure 2(d) is the cross-sectional topography of the sample in Example 2.
  • the surface of the aluminum alloy weld prepared by the method of Ni-P plating after dipping in Comparative Example 2 and the method of Ni-P plating after anodic oxidation in Example 2 both formed a dense convex hull structure.
  • the dipping zinc layer is only conducive to the subsequent plating of the Ni-P layer, and does not form a single-layer Ni-P coating. the actual middle layer.
  • a double-layer structure can be obtained by anodizing followed by Ni-P plating, and the double-layer structure is a dense and porous anodic aluminum oxide (AAO) + Ni-P coating.
  • AAO anodic aluminum oxide
  • the AAO film is grown from the aluminum substrate and forms an intermediate layer, the Ni-P coating can penetrate well into this special anodic aluminum oxide (AAO) structure, and the two layers are connected together by mechanical interlocking, A mechanical interlocking zone is formed, which will improve the bond strength between the coating and the substrate.
  • Figure 3 shows the SEM image of the aluminum alloy weld surface after anodization and activation expansion treatment. porous structure.
  • the invention mainly adopts the method of combining anodic oxidation and electrochemical deposition. Compared with the untreated weld seam sample, the invention can not only improve the bonding strength between the nickel plating layer and the substrate, but also improve the aluminum alloy welding seam at the same time. The corrosion resistance and wear resistance of the seam are improved, and the preparation method of the protective coating for the welded joint is simple to operate, safe and reliable, has good repeatability, is economical and environmentally friendly, and can be used for mass production.
  • AAO anodic aluminum oxide
  • the CS2350 bipotentiostat was used to test the corrosion resistance of the samples of Example 2 and Comparative Example 2.
  • the corrosion medium was a sodium chloride solution with a mass fraction of 3.5%, and a flat corrosion cell with a platinum electrode was used.
  • the three-electrode system composed of saturated calomel electrode as the reference electrode can be measured to obtain the potentiodynamic polarization curve, as shown in Figure 4; the self-corrosion voltage E corr and self-corrosion voltage E corr and self-corrosion voltage can be measured by the Tafel linear extrapolation method and CS Studio5 software analysis. Corrosion current I corr , the test results are shown in Table 1:
  • the Ni-P coating on the surface of the sample may be partially peeled off during the corrosion process, and the galvanized layer and the unstripped Ni-P coating may form a galvanic couple, which accelerates the corrosion and leads to a large self-corrosion current.
  • the UMT-2 friction and wear testing machine was used to test the wear resistance of the samples of Comparative Example 1, Comparative Example 2 and Example 2.
  • the friction form was dry sliding linear friction at room temperature, and the friction head was Al with a diameter of 9.58 mm. 2 O 3 ball, the loading force is 3N, the scratch length is 6mm, the friction speed is 10mm/s, and the friction time is 10 minutes.
  • FIG. 5 is a graph showing the friction coefficient of the samples prepared in Example 2, Comparative Example 1 and Comparative Example 2.
  • Figure 6 The surface wear topography and corresponding cross-sectional profile of the sample of Comparative Example 1, Comparative Example 2 and Example 2 are shown in Figure 6, of which Figure 6(a) is the surface of the sample of Comparative Example 1 Wear topography; Figure 6(b) is the cross-sectional profile corresponding to the surface wear topography of the sample in Comparative Example 1; Figure 6(c) is the surface wear topography of the sample in Comparative Example 2; Figure 6(d) is the cross-sectional profile corresponding to the surface wear topography of the sample in Comparative Example 2; Figure 6(e) is the surface wear topography of the Example 2 sample; Figure 6(f) is the surface wear topography of the Example 2 sample The corresponding cross-sectional profile of Fig.
  • Figure 7(a) is the bending test diagram of the sample of Comparative Example 2 under the test condition that the bending angle is 90°
  • Figure 7(b) is the bending test diagram of the sample of Comparative Example 2 under the test condition of the bending angle of 180°
  • Figure 7(c) is the bending test diagram of the sample of Example 2 under the test condition of the bending angle of 90°
  • Fig. 7(d) is a bending test diagram of the sample of Example 2 under the test condition that the bending angle is 180°.
  • the samples prepared under the parameter conditions of Example 2 have the best wear resistance and corrosion resistance, which is because a layer of dense and porous anode can be formed on the surface of the aluminum alloy weld after the anodizing method.
  • the alumina intermediate layer is activated and expanded to eliminate the surface defects at the aluminum alloy welded joint, which is more conducive to the adhesion of the nickel layer on the surface of the aluminum alloy welded joint, and improves the bonding strength between the nickel plating layer and the substrate.
  • the electrochemical deposition method can not only improve the bonding strength between the nickel plating layer and the substrate, but also improve the corrosion resistance and wear resistance of the aluminum alloy welding seam at the same time, and the preparation method of the welding joint protective coating is simple and easy to operate. Safe and reliable, good repeatability, economical and environmentally friendly, and can be used for mass production.

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Abstract

本发明公开了一种焊接接头防护涂层的制备方法及其应用，焊接接头防护涂层具有阳极氧化铝层与Ni-P镀层的双层结构，焊接接头防护涂层应用于铝合金搅拌摩擦焊的焊缝表面上，该焊接接头防护涂层的制备方法包括如下步骤：1)对铝合金焊缝表面进行预处理，得到平整光滑的待增强铝合金焊缝表面；2)对待增强铝合金焊缝表面进行阳极氧化处理得到致密多孔的阳极氧化铝中间层；3)对阳极氧化铝中间层进行活化扩孔处理得到待镀镍铝合金焊缝表面；4)对待镀镍铝合金焊缝表面进行电化学镀镍处理得到所述焊接接头防护涂层。本发明不仅可以提高镀镍层和基体之间的结合强度，还可以同时提高铝合金焊缝的耐蚀性和耐磨性。

Description

一种焊接接头防护涂层的制备方法及其应用 技术领域：
本发明涉及铝合金搅拌摩擦焊领域，具体涉及一种焊接接头防护涂层的制备方法及其应用。
背景技术：
铝及铝合金具有较好的导电热性、可成型性和较高的强度等特点。因此，铝及铝合金地广泛应用于航空航天，船舶制造，轨道交通，医疗卫生等国家支柱型产业。搅拌摩擦焊(Friction stir welding，简称FSW)是一种纯机械的固相连接技术，它是由英国焊接研究所(TWI)在1991年发明并在全世界范围申请专利保护，因为该技术可以大大提高铝合金接头的性能，所以它主要应用于铝合金焊接。铝合金在搅拌摩擦焊(FSW)焊接后，焊缝处由于焊接参数设置不当或者材料本身缺陷等因素会导致铝合金焊缝处出现气孔、微裂纹等缺陷，这些缺陷的存在会导致搅拌摩擦焊焊后的铝合金焊缝表面的加速磨损和腐蚀失效，极大地降低了铝合金焊件的使用寿命，限制了搅拌摩擦焊铝合金制品在工业上的应用。
现有技术中为提高铝合金焊件的防护性能，通常对搅拌摩擦焊后的焊缝进行电化学镀镍处理，经电化学镀镍处理后，铝合金表面可形成铝合金化学镀镍磷镀层，这种镀层具有厚度均匀，硬度高，耐磨耐蚀性好的优点，但由于搅拌摩擦焊后的焊缝上缺陷的存在，使得镀镍层与焊缝表面的附着力下降，从而限制了电化学镀镍处理在铝合金搅拌摩擦焊的焊缝表面上的应用。
发明内容：
本发明要解决的技术问题是，针对现有技术的不足，提供一种焊接接头防护涂层的制备方法并应用于铝合金搅拌摩擦焊的焊缝表面上。为解决上述技术问题，本发明采用以下技术方案：
一种焊接接头防护涂层，焊接接头防护涂层具有阳极氧化铝层与Ni-P镀层的双层结构，所述焊接接头防护涂层应用于铝合金搅拌摩擦焊的焊缝表面上。
优选的是，所述焊接接头防护涂层的制备方法，包括如下步骤：
1)对铝合金焊缝表面进行预处理，得到平整光滑的待增强铝合金焊缝表面；
2)对经过步骤1)处理得到的待增强铝合金焊缝表面进行阳极氧化处理得到致密多孔的阳极氧化铝中间层；
3)对经过步骤2)处理得到的阳极氧化铝中间层进行活化扩孔处理得到待镀镍铝合金焊缝表面；
4)对经过步骤3)处理得到的待镀镍铝合金焊缝表面进行电化学镀镍处理得到所述焊接接头防护涂层。
优选的是，步骤1)中预处理包括以下步骤：
a用无水乙醇溶液在超声波清洗仪中清洗预磨的铝合金焊缝表面；
b将经过步骤a处理的铝合金焊缝表面置于抛光液中进行电化学抛光处理。
优选的是，步骤b中所述电化学抛光处理的具体实现方式是：所述抛光液由磷酸溶液与无水乙醇混合而成，所述磷酸溶液与所述无水乙醇溶液的体积比为3:2；
所述电化学抛光处理时的电流密度为10～30A/dm 2，电化学抛光时间15～20min。
优选的是，步骤2)中阳极氧化处理的具体实现方式是：常温下，将步骤1)中预处理后的待增强铝合金焊缝表面置于增强溶液中进行阳极氧化处理；
所述增强溶液为300g/L的磷酸溶液，所述阳极氧化处理时的阳极氧化电压为60～100V，阳极氧化时间为15～20min。
优选的是，步骤3)中的扩孔活化处理的具体实现方式是：将经过步骤2)处理得到的所述阳极氧化铝中间层置于扩孔液中进行活化扩孔处理；
所述扩孔液为体积分数为5％磷酸溶液，所述扩孔活化处理时间为20～30min。
优选的是，步骤4)中的电化学镀镍处理的具体实现方式是：将经过扩孔活化处理的阳极氧化铝中间层置于电化学镀镍溶液中进行电化学镀镍处理；
所述电化学镀镍溶液由镍盐、还原剂和络合剂组成，所述电化学镀镍溶液的PH＝5，所述电化学镀镍处理时的电流密度为1～3A/dm 2，所述电化学镀镍溶液的温度为60～65℃，施镀时间为10～30min。
优选的是，所述镍盐为硫酸镍与氯化镍的混合物，所述活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，所述还原剂为次亚磷酸钠。
优选的是，所述电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：(30～35)：30：140：(30～35)：0.5。
由于采用了上述技术方案，本发明具有以下有益效果：
1、本发明的焊接接头防护涂层具有阳极氧化铝层与Ni-P镀层的双层结构，该焊接接头防护涂层适用于铝合金搅拌摩擦焊的焊缝表面，焊接接头防护涂层主要采用阳极氧化法在铝合金焊缝表面制备一层致密多孔的阳极氧化铝中间层，再经活化扩孔，消除了铝合金焊接接头处的表面缺陷，更有利于镍层在铝合金焊接接头表面的附着，提高了镀镍层和基体之间的结合强度，经电化学镀镍表面改性处理后在焊接接头表面形成了具有阳极氧化铝层与Ni-P镀层的双层结构。
2、本发明主要通过阳极氧化和电化学沉积相结合的方法，相较于不经过强化处理和浸锌后镀Ni-P的试样，不仅可以提高镀镍层和基体之间的结合强度，还可以同时提高铝合金焊缝的耐蚀性和耐磨性，且该焊接接头防护涂层 的制备方法操作简单、安全可靠，重复性好，经济环保，可用于大批量生产。
附图说明：
图1(a)为本发明实施例1制备得到的焊接接头防护涂层的SEM图；
图1(b)为为本发明实施例1制备得到的焊接接头防护涂层SEM图的局部放大图；
图1(c)为本发明实施例3制备得到的焊接接头防护涂层的SEM图；
图1(d)为本发明实施例3制备得到的焊接接头防护涂层SEM图的局部放大图；
图2(a)为本发明对比例2试样的表面形貌图；
图2(b)为本发明对比例2试样的截面形貌图；
图2(c)为本发明实施例2试样的表面形貌图；
图2(d)为本发明实施例2试样的截面形貌图；
图3为本发明经阳极氧化与活化扩孔处理后铝合金焊缝表面的SEM图；
图4为本发明实施例2、对比例1和对比例2制备的试样的动电位极化曲线图；
图5为本发明实施例2、对比例1和对比例2制备的试样的摩擦系数曲线图；
图6(a)为本发明对比例1试样的表面磨损形貌图；
图6(b)为本发明对比例1试样表面磨损形貌图对应的截面轮廓图；
图6(c)为本发明对比例2试样的表面磨损形貌图；
图6(d)为本发明对比例2试样表面磨损形貌图对应的截面轮廓图；
图6(e)为本发明实施例2试样的表面磨损形貌图；
图6(f)为本发明实施例2试样表面磨损形貌图对应的截面轮廓图；
图7(a)为本发明弯曲角度为90°试验条件下，对比例2试样的弯曲试验图；
图7(b)为本发明弯曲角度为180°试验条件下，对比例2试样的弯曲试 验图；
图7(c)为本发明弯曲角度为90°试验条件下，实施例2试样的弯曲试验图；
图7(d)为本发明弯曲角度为180°试验条件下，实施例2试样的弯曲试验图。
具体实施方式：
下面通过实施例对本发明进一步说明，实施例只用于解释本发明，不会对本发明构成任何的限定。
本发明的焊接接头防护涂层具有阳极氧化铝层与Ni-P镀层的双层结构，焊接接头防护涂层应用于铝合金搅拌摩擦焊的焊缝表面上。
实施例1
本发明的焊接接头防护涂层的制备方法包括如下步骤：
1)对铝合金焊缝表面进行预处理，得到平整光滑的待增强铝合金焊缝表面。
预处理包括以下步骤：
a用无水乙醇溶液在超声波清洗仪中清洗预磨的铝合金焊缝表面，具体为：将铝合金焊缝表面放入无水乙醇中，并用超声波清洗仪进行清洗，清洗温度为25℃，清洗时间为5min，使用压缩空气吹干；
b将经过步骤a处理的铝合金焊缝表面置于抛光液中进行电化学抛光处理，具体为：在25℃左右的气氛中对经过步骤a处理的铝合金焊缝表面进行电化学抛光，铝合金焊缝试样为阳极，不锈钢板为阴极；抛光液由磷酸溶液与无水乙醇混合而成，磷酸溶液与所述无水乙醇溶液的体积比为3:2，电化学抛光处理时的电流密度为20A/dm 2，电化学抛光时间20min。
2)对经过步骤1)处理得到的待增强铝合金焊缝表面进行阳极氧化处理得到致密多孔的阳极氧化铝中间层。
具体为：将步骤1)中待增强铝合金焊缝试样置于增强溶液中进行阳极 氧化处理，待增强铝合金焊缝试样作为阳极，纯铅板作为阴极，并置于25℃恒温水浴锅中，并使用磁力搅拌器搅拌，转速为300r/min；增强溶液为300g/L的磷酸溶液，阳极氧化处理时的阳极氧化电压为60V，阳极氧化时间为20min
3)对经过步骤2)处理得到的阳极氧化铝中间层进行扩孔活化处理得到待镀镍铝合金焊缝表面。扩孔活化处理的具体实现方式是：将具有阳极氧化铝中间层的试样置于扩孔液中进行扩孔处理，扩孔液为体积分数为5％磷酸溶液，扩孔活化处理时间为20min。
4)对经过步骤3)处理得到的待镀镍铝合金焊缝表面进行电化学镀镍处理得到焊接接头防护涂层，将经过扩孔活化处理的阳极氧化铝中间层置于电化学镀镍溶液中进行电化学镀镍处理，待镀镍铝合金焊缝试样为阴极，纯镍板为阳极，并将电化学镀镍溶液置于65℃的水浴锅中，使用磁力搅拌器搅拌，转速为300r/min，施镀时间为10min。
具体为：电化学镀镍溶液的PH＝5，电化学镀镍处理时的电流密度为2A/dm 2，电化学镀镍溶液由镍盐、还原剂和络合剂组成，镍盐为硫酸镍与氯化镍的混合物，活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，还原剂为次亚磷酸钠，电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：30：30：140：30：0.5。
实施例2
区别于实施例1的地方在于，4)对经过步骤3)处理得到的待镀镍铝合金焊缝表面进行电化学镀镍处理得到所述焊接接头防护涂层，将经过扩孔活化处理的阳极氧化铝中间层置于电化学镀镍溶液中进行电化学镀镍处理，待镀镍铝合金焊缝试样为阴极，纯镍板为阳极，并将电化学镀镍溶液置于65℃的水浴锅中，使用磁力搅拌器搅拌，转速为300r/min，施镀时间为20min。
具体为：电化学镀镍溶液的PH＝5，电化学镀镍处理时的电流密度为2A/dm 2，电化学镀镍溶液由镍盐、还原剂和络合剂组成，镍盐为硫酸镍与氯化镍的混合物，活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，还原剂为次亚 磷酸钠，电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：30：30：140：30：0.5。
实施例3
区别于实施例1的地方在于，4)对经过步骤3)处理得到的待镀镍铝合金焊缝表面进行电化学镀镍处理得到焊接接头防护涂层，将经过扩孔活化处理的阳极氧化铝中间层置于电化学镀镍溶液中进行电化学镀镍处理，待镀镍铝合金焊缝试样为阴极，纯镍板为阳极，并将电化学镀镍溶液置于65℃的水浴锅中，使用磁力搅拌器搅拌，转速为300r/min，施镀时间为30min。
具体为：电化学镀镍溶液的PH＝5，电化学镀镍处理时的电流密度为2A/dm 2，电化学镀镍溶液由镍盐、还原剂和络合剂组成，镍盐为硫酸镍与氯化镍的混合物，活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，还原剂为次亚磷酸钠，电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：30：30：140：30：0.5。
对比例1
对焊接接头试样只做简单清洗，具体的，用无水乙醇溶液在超声波清洗仪中清洗预磨的铝合金焊缝表面，具体为：将铝合金焊缝表面放入无水乙醇中，并用超声波清洗仪进行清洗，清洗温度为25℃，清洗时间为5min，使用压缩空气吹干。
对比例2
焊接接头防护涂层的制备方法包括如下步骤：
1)浸锌处理，包括脱脂→碱蚀→酸洗→活化→一次浸锌→退锌→二次浸锌七道工序。
具体为：
脱脂：将铝合金焊缝表面置于脱脂剂中浸泡5min，脱脂剂温度为60℃，脱脂剂配方为无水碳酸钠与磷酸三钠的混合物，且无水碳酸钠：磷酸三钠质量浓度比为1:1；
碱蚀：将脱脂后的铝合金焊缝表面置于碱蚀剂中浸泡1min，碱蚀剂温度为25℃，碱蚀剂是质量浓度为50g/L的氢氧化钠溶液；
酸洗：将碱蚀后的铝合金焊缝表面置于酸洗剂中浸泡1min，酸洗剂温度为25℃，酸洗剂是浓度为600ml/L的硝酸溶液；
活化：将酸洗后的铝合金焊缝表面置于活化剂中浸泡30s，活化剂温度为25℃，活化剂是浓度为25ml/L的硫酸溶液；
一次浸锌：将活化后的铝合金焊缝表面置于一次浸锌液中浸泡1min，一次浸锌液温度为25℃，一次浸锌液包括氢氧化钠和氧化锌，且氢氧化钠：氧化锌的质量浓度比为3:1；
退锌：将一次浸锌后的铝合金焊缝表面置于退锌液中浸泡30s，退锌液温度为25℃，退锌液是体积分数为20％的硝酸溶液；
二次浸锌：将退锌后的铝合金焊缝表面置于二次浸锌液中浸泡1min，二次浸锌液温度为25℃，二次浸锌液由氢氧化钠、氧化锌、酒石酸钾钠和三氯化铁组成，且氢氧化钠、的质量浓度比为:300：100：10:1。
2)电化学镀镍处理
将经过二次浸锌处理的铝合金焊缝试样置于电化学镀镍溶液中进行电化学镀镍处理，铝合金焊缝试样为阴极，纯镍板为阳极，并将电化学镀镍溶液置于65℃的水浴锅中，使用磁力搅拌器搅拌，转速为300r/min，施镀时间为20min。
具体为：电化学镀镍溶液的PH＝5，电化学镀镍处理时的电流密度为2A/dm 2，电化学镀镍溶液由镍盐、还原剂和络合剂组成，镍盐为硫酸镍与氯化镍的混合物，活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，还原剂为次亚磷酸钠，电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：30：30：140：30：0.5。
一、观察比较实施例1和实施例3制备的焊接接头防护涂层的SEM图
分别观察由实施例1和实施例3制备得到的焊接接头防护涂层的表面形 貌，如图1所示，其中图1(a)为本发明实施例1制备得到的焊接接头防护涂层的SEM图；图1(b)为本发明实施例1制备得到的焊接接头防护涂层SEM图的局部放大图；图1(c)为本发明实施例3制备得到的焊接接头防护涂层的SEM图；图1(d)为本发明实施例3制备得到的焊接接头防护涂层SEM图的局部放大图。
从图1(a)、图1(b)中可以看出，对于施镀时间为10min制备的焊接接头防护涂层，Ni-P镀层基本覆盖于铝合金表面，可观测到，Ni-P凸包结构，但由于电化学沉积时间较短，Ni-P凸包生长不完全，Ni-P凸包的尺寸较小，且凸包间仍存在间隙，这种缺陷将影响焊缝表面的腐蚀和摩擦性能。
从图1(c)、图1(d)中可以看出，对于施镀时间为30min制备的焊接接头防护涂层，铝合金焊缝表面完全被Ni-P镀层覆盖，镀层致密无间隙。但是，由于焊缝表面高低起伏，在表面凸起处的Ni-P凸包由于表面能较大，优先长大，而铝合金表面较低处Ni-P凸包生长缓慢，颗粒尺寸较小。这种凸包尺寸大小带来的较大差异会导致表面质量变差，耐磨性和耐蚀性将受到较大影响。
由图1可知，在实施例1和实施例3的参数条件下制备的焊接接头防护涂层都具有缺陷，将影响焊接接头防护涂层的防护性能。
二、观察、比较实施例2和对比例2的SEM图
图2为对比例2和实施例2的表面和截面形貌图，其中，图2(a)为对比例2试样的表面形貌图；图2(b)为对比例2试样的截面形貌图；图2(c)为实施例2试样的表面形貌图；图2(d)为实施例2试样的截面形貌图。
从图中可以看出，采用浸锌后镀Ni-P方法的对比例2和采用阳极氧化后镀Ni-P方法的实施例2制备的铝合金焊缝表面均形成了致密的凸包结构。从图2(b)可以看出，通过传统的浸锌后镀Ni-P的方法获得的单层Ni-P涂层，浸锌层仅利于后续Ni-P层的施镀，而并不形成实际的中间层。而从图2(d)可以看出，通过阳极氧化后镀Ni-P方法可获得双层结构，该双层结构为致密 且多孔的阳极氧化铝(AAO)+Ni-P涂层。本发明中AAO膜从铝基板上生长并形成中间层，Ni-P涂层可以很好地渗透到这种特殊的阳极氧化铝(AAO)结构中，并且两层通过机械互锁连接在一起，形成机械互锁区，这将提高涂层和基材之间的结合强度。
为进一步证实阳极氧化铝(AAO)中间层的存在，图3示出了铝合金焊缝经阳极氧化与活化扩孔处理后铝合金焊缝表面的SEM图，从图3中可观察到致密的多孔结构。本发明主要通过阳极氧化和电化学沉积相结合的方法，相较于焊缝表面无处理的焊缝试样，不仅可以提高镀镍层和基体之间的结合强度，还可以同时提高铝合金焊缝的耐蚀性和耐磨性，且该焊接接头防护涂层的制备方法操作简单、安全可靠，重复性好，经济环保，可用于大批量生产。
三、比较实施例2和对比例2参数条件下制备焊接接头防护涂层的各项性能。
(1)耐蚀性测试
采用CS2350双恒电位仪对实施例2试样和对比例2试样进行耐蚀性测试，其中，腐蚀介质为质量分数为3.5％的氯化钠溶液，采用带有铂电极的平板腐蚀池及饱和甘汞电极为参比电极组成的三电极体系进行测量可得到动电位极化曲线，如图4所示；利用Tafel直线外推法及CS Studio5软件分析可测量得到自腐蚀电压E corr和自腐蚀电流I corr，测试结果如表1所示：
/ 自腐蚀电压E corr/V 自腐蚀电流I corr/A·cm -2
对比例1 -0.7078 2.0135×10 -5
对比例2 -0.6067 3.4658×10 -5
实施例2 -0.3349 1.4968×10 -5
从图4可以看出在实施例2参数条件下，自腐蚀电压E corr由-0.7078V提高到了-0.3349V，自腐蚀电流I corr由2.0135×10 -5A·cm -2减小到了1.4968×10 -5A·cm -2，耐腐蚀性能显著改善；但是，浸锌后镀Ni-P试样的自腐 蚀电流I corr最大，为3.4658×10 -5A·cm -2。试样表面的Ni-P涂层在腐蚀过程中可能会部分剥落，镀锌层和未剥离的Ni-P涂层可能会形成电偶，从而加速腐蚀，导致自腐蚀电流较大。
(2)耐摩擦、耐磨损性能测试
采用UMT-2摩擦磨损试验机对对比例1试样、对比例2试样和实施例2试样进行耐磨损性能测试，摩擦形式为常温干滑动线性摩擦，摩擦头为直径9.58mm的Al 2O 3球，加载力为3N，划痕长度为6mm，摩擦速度为10mm/s，摩擦时间为10分钟。图5为实施例2、对比例1和对比例2制备的试样的摩擦系数曲线图。对比例1试样、对比例2试样和实施例2试样的表面磨损形貌图和对应的截面轮廓图如图6所示，其中，图6(a)为对比例1试样的表面磨损形貌图；图6(b)为对比例1试样表面磨损形貌图对应的截面轮廓图；图6(c)为对比例2试样的表面磨损形貌图；图6(d)为对比例2试样表面磨损形貌图对应的截面轮廓图；图6(e)为实施例2试样的表面磨损形貌图；图6(f)为实施例2试样表面磨损形貌图对应的截面轮廓图。
耐摩擦、耐磨损性能测试结果如表2所示：
Figure PCTCN2022082978-appb-000001
(3)膜层结合力测试
根据GB/T 5270-2005/ISO 2819：1980，对实施例2试样和对比例2试样涂层试样进行弯曲试验，弯曲角度为90°和180°。试验后，实施例2试样和对比例2试样弯曲试验图如图7所示，其中，图7(a)为弯曲角度为90° 试验条件下，对比例2试样的弯曲试验图；图7(b)为弯曲角度为180°试验条件下，对比例2试样的弯曲试验图；图7(c)为弯曲角度为90°试验条件下，实施例2试样的弯曲试验图；图7(d)为弯曲角度为180°试验条件下，实施例2试样的弯曲试验图。
由上可知，本实施例2参数条件下制备的试样具有最佳的耐磨性和耐蚀性，这是由于采用阳极氧化法处理后可在铝合金焊缝表面形成一层致密多孔的阳极氧化铝中间层，再经活化扩孔，消除了铝合金焊接接头处的表面缺陷，更有利于镍层在铝合金焊接接头表面的附着，提高了镀镍层和基体之间的结合强度，再结合电化学沉积法，不仅可以提高镀镍层和基体之间的结合强度，还可以同时提高铝合金焊缝的耐蚀性和耐磨性，且该焊接接头防护涂层的制备方法操作简单、安全可靠，重复性好，经济环保，可用于大批量生产。
虽然已经对本发明的具体实施方案进行了描述，但是本发明的许多其他形式和改变对本领域技术人员而言是显而易见的。应理解所附权利要求和本发明通常涵盖本发明真实精神和范围内的所有这些明显的形式和改变。

Claims (9)

  1. 一种焊接接头防护涂层的应用，其特征在于，焊接接头防护涂层具有阳极氧化铝层与Ni-P镀层的双层结构，所述焊接接头防护涂层应用于铝合金搅拌摩擦焊的焊缝表面上。
  2. 一种焊接接头防护涂层的制备方法，其特征在于，包括如下步骤：
    1)对铝合金焊缝表面进行预处理，得到平整光滑的待增强铝合金焊缝表面；
    2)对经过步骤1)处理得到的待增强铝合金焊缝表面进行阳极氧化处理得到致密多孔的阳极氧化铝中间层；
    3)对经过步骤2)处理得到的阳极氧化铝中间层进行活化扩孔处理得到待镀镍铝合金焊缝表面；
    4)对经过步骤3)处理得到的待镀镍铝合金焊缝表面进行电化学镀镍处理得到所述焊接接头防护涂层。
  3. 根据权利要求2所述的焊接接头防护涂层的制备方法，其特征在于，步骤1)中预处理包括以下步骤：
    a)用无水乙醇溶液在超声波清洗仪中清洗预磨的铝合金焊缝表面；
    b)将经过步骤a处理的铝合金焊缝表面置于抛光液中进行电化学抛光处理。
  4. 根据权利要求3所述的焊接接头防护涂层的制备方法，其特征在于，步骤b中所述电化学抛光处理的方式是：所述抛光液采用磷酸溶液与无水乙醇混合而成，所述磷酸溶液与所述无水乙醇溶液的体积比为3:2；
    所述电化学抛光处理时的电流密度为10～30A/dm 2，电化学抛光时间15～20min。
  5. 根据权利要求2所述的焊接接头防护涂层的制备方法，其特征在于，步 骤2)中阳极氧化处理的具体实现方式是：常温下，将步骤1)中预处理后的待增强铝合金焊缝表面置于增强溶液中进行阳极氧化处理；
    所述增强溶液为300g/L的磷酸溶液，所述阳极氧化处理时的阳极氧化电压为60～100V，阳极氧化时间为15～20min。
  6. 根据权利要求2所述的焊接接头防护涂层的制备方法，其特征在于，步骤3)中的扩孔活化处理方式是：将经过步骤2)处理得到的所述阳极氧化铝中间层置于扩孔液中进行扩孔处理；
    所述扩孔液为体积分数为5％磷酸溶液，所述扩孔活化处理时间为20～30min。
  7. 根据权利要求5所述的焊接接头防护涂层的制备方法，其特征在于，步骤4)中的电化学镀镍处理方式是：将经过扩孔活化处理的阳极氧化铝中间层置于电化学镀镍溶液中进行电化学镀镍处理；
    所述电化学镀镍溶液由镍盐、还原剂和络合剂组成，所述电化学镀镍溶液的PH＝5，所述电化学镀镍处理时的电流密度为1～3A/dm 2，所述电化学镀镍溶液的温度为60～65℃，施镀时间为10～30min。
  8. 根据权利要求7所述的焊接接头防护涂层的制备方法，其特征在于，所述镍盐为硫酸镍与氯化镍的混合物，所述活化剂由柠檬酸钠、葡萄糖酸钠和糖精组成，所述还原剂为次亚磷酸钠。
  9. 根据权利要求8所述的焊接接头防护涂层的制备方法，其特征在于，所述电化学镀镍溶液中硫酸镍、氯化镍、次亚磷酸钠、柠檬酸钠、葡萄糖酸钠和糖精的质量浓度比为：200：(30～35)：30：140：(30～35)：0.5。
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