Preparation method and application of Zn-Cu-Ti composite coating

Abstract

The present invention discloses a preparation method and application of a Zn-Cu-Ti composite coating. The preparation method comprises the following steps: preparing a Zn-0.15Cu-0.15Ti alloy ingot; preparing an alloy wire for spraying from the alloy ingot; preparing a Zn-0.15Cu-0.15Ti alloy coating on the surface of a steel sample; adding 0.25M of a catalyst to a 0.023M cerium salt sealing solution, and adjusting the pH thereof to 3.5-4.5; immersing the steel sample in the solution, removing the steel sample, and washing it to prepare a Zn-0.15Cu-0.15Ti / cerium salt coating; preparing a 0.2M phosphate sealing solution, adding a 2M alkaline solution, and adjusting the pH thereof to 6.5-7.5; and immersing the prepared steel sample containing the cerium salt coating in the phosphate sealing solution to prepare a Zn-0.15Cu-0.15Ti / cerium salt phosphate composite coating.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion-resistant coatings, and in particular to a preparation method of a corrosion-resistant Zn-Cu-Ti composite coating and application thereof. Background Art

[0002] Numerous studies have found that arc-sprayed coatings inevitably exhibit porous structural defects, which can reduce the coating's corrosion resistance. Corrosion resistance is closely related to defects such as pores, and pore corrosion is considered one of the most common failure types. Currently, pore sealing is an effective method for reducing coating porosity. As a post-treatment technique, pore sealing is gaining popularity due to its low cost and ease of use. It offers a solution to the limitations of arc spraying. Studies have shown that pore sealing of high-velocity air-fuel sprayed coatings with aluminum phosphate significantly improves the corrosion resistance of the coatings, reducing the passivation current density by an order of magnitude. Aluminum phosphate sealing is an effective method for filling microcracks and improving the coating's corrosion resistance in corrosive solutions. However, the application of a composite pore sealing treatment with cerium salts and phosphates to arc-sprayed Zn-Cu-Ti alloy coatings has not been reported. Pore sealing primarily involves the penetration of a pore-sealing agent into the coating, thereby filling the pores. A surface coating is often formed after pore sealing, providing dual protection alongside the pore-sealing agent within the coating's pores. The sealant effectively seals the pores of arc-sprayed Zn-Cu-Ti coatings and provides excellent barrier properties at the alloy coating / substrate interface. Zn-Cu-Ti composite coatings mitigate corrosion by isolating the metal substrate from the corrosive medium through their sacrificial anodic protection, cathodic barrier, and corrosion product layer. Therefore, the development trend of anti-corrosion coatings is to use a combination of cerium salts and phosphates to seal the pores and create highly corrosion-resistant Zn-Cu-Ti composite coatings suitable for harsh and complex environments. Summary of the Invention

[0003] In response to the problems and needs raised above, this solution proposes a method for preparing a Zn-Cu-Ti composite coating. Due to the adoption of the following technical features, the above technical objectives can be achieved and many other technical effects can be brought about.

[0004] The present invention provides a method for preparing a Zn-Cu-Ti composite coating, comprising the following steps:

[0005] S10: Smelting copper particles, zinc blocks and titanium sponge as raw materials to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots;

[0006] S20: preparing alloy wire for spraying from the alloy ingot by an isothermal extrusion process;

[0007] S30: Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of steel sample by arc spraying process;

[0008] S40: preparing a 0.023 M cerium salt sealing solution, adding a 0.25 M catalyst, and adjusting the pH of the cerium salt sealing solution to 3.5-4.5;

[0009] S50: placing the cerium salt sealing solution in a constant temperature environment of 20-30° C., immersing the steel sample containing the Zn-0.15Cu-0.15Ti alloy coating in the solution, sealing for 1-5 hours, then taking it out and washing it in deionized water and ethanol in turn to prepare a Zn-0.15Cu-0.15Ti / cerium salt coating;

[0010] S60: preparing a 0.2M phosphate sealing solution, and then adding a 2M alkaline solution to adjust the pH of the phosphate sealing solution to 6.5-7.5;

[0011] S70: The prepared phosphate sealing treatment liquid is placed in a constant temperature environment of 85-95°C, and the prepared steel sample containing the Zn-0.15Cu-0.15Ti / cerium salt coating is immersed in the phosphate sealing treatment liquid for 1-5 hours to prepare the Zn-0.15Cu-0.15Ti / cerium salt phosphate composite coating.

[0012] In addition, the preparation method of the Zn-Cu-Ti composite coating according to the present invention may also have the following technical features:

[0013] In one example of the present invention, in step S10, the diameter of the cylindrical Zn-0.15Cu-0.15Ti alloy ingot is 36 mm.

[0014] In one example of the present invention, in step S20, the isothermal extrusion process includes: 1) the extrusion temperature is 370-470°C;

[0015] 2) Extrusion speed is 1.0~3.0mm / s.

[0016] In one example of the present invention, in step S20, the alloy ingot is extruded by an isothermal extrusion process to prepare an alloy wire for spraying with a diameter of 3 mm.

[0017] In one example of the present invention, in step S30, the arc spraying process includes:

[0018] 1) The spraying voltage is 25~30V;

[0019] 2) Spraying current is 150~200A;

[0020] 3) Spraying distance is 120~170mm;

[0021] 4) Air pressure is 0.4~0.8MPa.

[0022] In an example of the present invention, in step S40, the cerium salt is Ce(NO3)3·6H2O, and the catalyst is H2O2.

[0023] In one example of the present invention, in step S50, the phosphate is NaH2PO4, and the alkaline solution is NaOH.

[0024] In an example of the present invention, in step S50, placing the cerium salt sealing solution in a constant temperature environment of 20-30°C includes placing the cerium salt sealing solution in a constant temperature water bath at 25°C.

[0025] In an example of the present invention, in step S70, placing the prepared phosphate sealing treatment liquid in a constant temperature environment of 85-95°C includes placing the prepared phosphate sealing treatment liquid in a constant temperature water bath at 90°C.

[0026] Another object of the present invention is to provide an application of a Zn-Cu-Ti composite coating prepared by the above-described preparation method, wherein the Zn-Cu-Ti composite coating is applied to a pore sealing treatment in arc spraying. The following describes a preferred embodiment of the present invention in more detail with reference to the accompanying drawings to facilitate an understanding of the features and advantages of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. The drawings are only used to illustrate some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0028] Figure 1 Flowchart of a method for preparing a Zn-Cu-Ti composite coating according to an embodiment of the present invention;

[0029] Figure 2 The macroscopic morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 1 h);

[0030] Figure 3 The macroscopic morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 3h);

[0031] Figure 4 This is the macroscopic morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 5h);

[0032] Figure 5 This is the cross-sectional morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 1 h);

[0033] Figure 6 This is the cross-sectional morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 3h);

[0034] Figure 7 This is the cross-sectional morphology of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 5 h);

[0035] Figure 8 is the open circuit voltage of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution;

[0036] Figure 9 is the AC impedance of the unsealed Zn-Cu-Ti coating;

[0037] Figure 10 is the AC impedance of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 1 h);

[0038] Figure 11 is the AC impedance of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 3h); Figure 12 is the AC impedance of the Zn-Cu-Ti / cerium salt coating after composite sealing in phosphate solution (sealed at 90°C for 5h). DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the technical solution of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of specific embodiments of the present invention. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] According to a method for preparing a Zn-Cu-Ti composite coating of the present invention, Figure 1 As shown, the following steps are included:

[0041] S10: Smelting copper particles, zinc blocks and titanium sponge as raw materials to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots;

[0042] S20: preparing alloy wire for spraying from the alloy ingot by an isothermal extrusion process;

[0043] S30: Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of steel sample by arc spraying process;

[0044] S40: preparing a 0.023 M cerium salt sealing solution, adding a 0.25 M catalyst, and adjusting the pH of the cerium salt sealing solution to 3.5-4.5;

[0045] S50: placing the cerium salt sealing solution in a constant temperature environment of 20-30° C., immersing the steel sample containing the Zn-0.15Cu-0.15Ti alloy coating in the solution, sealing for 1-5 hours, then taking it out and washing it in deionized water and ethanol in turn to prepare a Zn-0.15Cu-0.15Ti / cerium salt coating;

[0046] S60: preparing a 0.2M phosphate sealing solution, and then adding a 2M alkaline solution to adjust the pH of the phosphate sealing solution to 6.5-7.5;

[0047] S70: The prepared phosphate sealing treatment liquid is placed in a constant temperature environment of 85-95°C, and the prepared steel sample containing the Zn-0.15Cu-0.15Ti / cerium salt coating is immersed in the phosphate sealing treatment liquid for 1-5 hours to prepare the Zn-0.15Cu-0.15Ti / cerium salt phosphate composite coating.

[0048] That is to say, the preparation method of the present invention first uses an isothermal extrusion process to prepare an alloy wire for spraying, then uses an arc spraying process to prepare a Zn-Cu-Ti alloy coating on the surface of Q235 steel, and then uses a cerium salt sealing treatment to prepare Zn-Cu-Ti / cerium salt, and finally uses a phosphate sealing treatment to prepare Zn-Cu-Ti / cerium salt phosphate for composite sealing treatment; the Zn-Cu-Ti alloy coating is replaced by a Zn-Cu-Ti composite coating, and the Zn-Cu-Ti composite coating is prepared by a composite sealing process. On the one hand, the Zn-Cu-Ti composite coating further improves the problem that the corrosion resistance of the Zn-Cu-Ti composite coating has reached the upper limit; on the other hand, the problem of optimizing the cerium salt and phosphate sealing treatment process is determined, which can help improve the corrosion resistance of the Zn-Cu-Ti composite coating.

[0049] In an example of the present invention, in step S10, the material of the steel sample includes Q235 steel and Q345 steel.

[0050] In one example of the present invention, in step S10, the diameter of the cylindrical Zn-0.15Cu-0.15Ti alloy ingot is 36 mm.

[0051] In one example of the present invention, in step S20, the isothermal extrusion process includes: 1) the extrusion temperature is 370-470°C;

[0052] 2) Extrusion speed is 1.0~3.0mm / s.

[0053] In one example of the present invention, in step S20, the alloy ingot is extruded by an isothermal extrusion process to prepare an alloy wire for spraying with a diameter of 3 mm.

[0054] In one example of the present invention, in step S30, the arc spraying process includes:

[0055] 1) The spraying voltage is 25~30V;

[0056] 2) Spraying current is 150~200A;

[0057] 3) Spraying distance is 120~170mm;

[0058] 4) Air pressure is 0.4~0.8MPa.

[0059] In an example of the present invention, in step S40, the cerium salt is Ce(NO3)3·6H2O, and the catalyst is H2O2.

[0060] In one example of the present invention, in step S50, the phosphate is NaH2PO4, and the alkaline solution is NaOH.

[0061] In one example of the present invention, in step S50, placing the cerium salt sealing treatment liquid in a constant temperature environment of 20-30°C includes: placing the cerium salt sealing treatment liquid in a constant temperature water bath at 25°C. By using a constant temperature water bath, the cerium salt sealing treatment liquid can be conveniently placed in a constant temperature environment.

[0062] In one example of the present invention, in step S70, placing the configured phosphate sealing treatment liquid in a constant temperature environment of 85~95°C includes: placing the configured phosphate sealing treatment liquid in a constant temperature water bath at 90°C. By using a constant temperature water bath, the phosphate sealing treatment liquid can be conveniently placed in a constant temperature environment.

[0063] According to the second aspect of the present invention, an application of the Zn-Cu-Ti composite coating prepared by the preparation method described above is applied to the sealing treatment of arc spraying;

[0064] The Zn-Cu-Ti composite coating can slow down corrosion by isolating the metal substrate from the corrosive medium through its sacrificial anode protection cathode barrier and corrosion product layer. Applying the Zn-Cu-Ti composite coating to the sealing treatment of arc spraying can greatly improve the corrosion resistance of the Zn-Cu-Ti alloy coating. Specific embodiment:

[0066] Example 1

[0067] A method for preparing a corrosion-resistant Zn-Cu-Ti composite coating comprises the following steps:

[0068] (1) Copper particles, zinc blocks, and titanium sponge were smelted to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots with a diameter of 36 mm.

[0069] (2) The alloy ingot was extruded into a 3 mm diameter alloy wire for spraying by isothermal extrusion process, with the extrusion temperature being around 420 °C and the extrusion speed being 2 mm / s;

[0070] (3) The Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of Q235 steel by arc spraying process. The spraying voltage was 28 V, the spraying current was 180 A, the spraying distance was 150 mm, and the air pressure was 0.6 MPa.

[0071] (4) Prepare 0.023 M Ce(NO3)3·6H2O cerium salt sealing solution, add 0.25 M H2O2 as a catalyst, and adjust the pH of the sealing solution to 4.0;

[0072] (5) The prepared solution was placed in a constant temperature water bath at 25°C, and then the sample was immersed in the solution with the front side facing up. After immersion and sealing for 3 hours, the sample was taken out and washed in deionized water and ethanol in turn to prepare the Zn-0.15Cu-0.15Ti / cerium salt coating;

[0073] (6) Prepare a solution of 0.2M NaH2PO4 phosphate sealing solution and 2M NaOH, and then adjust the pH of the solution to 7.0 with NaOH;

[0074] (7) The prepared solution was placed in a constant temperature water bath. After the solution was heated to a constant temperature of 90°C, the prepared Zn-0.15Cu-0.15Ti / cerium salt coating samples were immersed in the sealing solution for 1 h to prepare Zn-0.15Cu-0.15Ti / cerium salt phosphate composites.

[0075] Example 2

[0076] A method for preparing a corrosion-resistant Zn-Cu-Ti composite coating comprises the following steps:

[0077] (1) Copper particles, zinc blocks and titanium sponge were smelted to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots with a diameter of 36 mm.

[0078] (2) The alloy ingot was extruded into a 3 mm diameter alloy wire for spraying by isothermal extrusion process. The extrusion temperature was selected to be about 420 °C and the extrusion speed was selected to be 2 mm / s.

[0079] (3) Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of Q235 steel by arc spraying process. The spraying voltage was 28 V, the spraying current was 180 A, the spraying distance was 150 mm, and the air pressure was 0.6 MPa.

[0080] (4) Prepare 0.023 M Ce(NO3)3·6H2O cerium salt sealing solution, add 0.25 M H2O2 as a catalyst, and adjust the pH of the sealing solution to 4.0.

[0081] (5) The prepared solution was placed in a constant temperature water bath at 25°C, and then the sample was immersed in the solution with the front side facing up. After immersion and sealing for 3 hours, it was taken out and washed in deionized water and ethanol in turn to prepare the Zn-0.15Cu-0.15Ti / cerium salt coating.

[0082] (6) Prepare a 0.2M NaH2PO4 phosphate sealing solution and a 2M NaOH solution, and then adjust the pH of the solution to about 7.0 with NaOH.

[0083] (7) The prepared solution was placed in a constant temperature water bath. After the solution was heated to a constant temperature of 90°C, the prepared Zn-0.15Cu-0.15Ti / cerium salt coating samples were immersed in the sealing solution for 3 h to prepare Zn-0.15Cu-0.15Ti / cerium salt phosphate composites.

[0084] Example 3

[0085] A method for preparing a corrosion-resistant Zn-Cu-Ti composite coating comprises the following steps:

[0086] (1) Copper particles, zinc blocks and titanium sponge were smelted to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots with a diameter of 36 mm.

[0087] (2) The alloy ingot was extruded into a 3 mm diameter alloy wire for spraying by isothermal extrusion process. The extrusion temperature was selected to be about 420 °C and the extrusion speed was selected to be 2 mm / s.

[0088] (3) Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of Q235 steel by arc spraying process. The spraying voltage was 28 V, the spraying current was 180 A, the spraying distance was 150 mm, and the air pressure was 0.6 MPa.

[0089] (4) Prepare 0.023 M Ce(NO3)3·6H2O cerium salt sealing solution, add 0.25 M H2O2 as a catalyst, and adjust the pH of the sealing solution to 4.0.

[0090] (5) The prepared solution was placed in a constant temperature water bath at 25°C, and then the sample was immersed in the solution with the front side facing up. After immersion and sealing for 3 hours, it was taken out and washed in deionized water and ethanol in turn to prepare the Zn-0.15Cu-0.15Ti / cerium salt coating.

[0091] (6) Prepare a 0.2M NaH2PO4 phosphate sealing solution and a 2M NaOH solution, and then adjust the pH of the solution to about 7.0 with NaOH.

[0092] (7) The prepared solution was placed in a constant temperature water bath. After the solution was heated to a constant temperature of 90°C, the prepared Zn-0.15Cu-0.15Ti / cerium salt coating samples were immersed in the sealing solution for 5 h to prepare Zn-0.15Cu-0.15Ti / cerium salt phosphate composites.

[0093] The composite treatment of multiple sealing agents provides a method to solve the limitations of arc spraying process. The preparation of Zn-Cu-Ti composite coatings with high corrosion resistance to adapt to harsh and complex environments is the future development trend of anti-corrosion coatings. Figure 2-Figure 4 The following images show the macroscopic morphology of a Zn-Cu-Ti alloy coating after immersion in a cerium salt phosphate solution for different composite sealing times. The images show that the coating surface appears dark gray after sealing, with the coating sealed for 5 hours showing the darkest color. Compared to the unsealed coating, the coating surface becomes relatively smoother and has a denser structure. Figure 5-Figure 7The cross-sectional morphology of the Zn-Cu-Ti coating after immersion in a cerium phosphate solution for different composite sealing times is shown. As the composite sealing treatment time increases, the sealing film (cerium oxide and Na(ZnPO4)·H2O) deposited on the surface of the Zn-Cu-Ti coating becomes increasingly thicker. After the sealing treatment, large amounts of elements such as Ce, Na, and P penetrate into the interior of the Zn-Cu-Ti coating, providing a good coating and protective effect. Open-circuit voltage tests were conducted on three samples treated with composite sealing for 1, 3, and 5 hours. The results are shown in the figure below. Figure 8 As shown in the figure, the open circuit potential of the three samples generally shows a trend of moving in the positive direction over time, indicating that the corrosion rate is reduced and excellent corrosion resistance is exhibited. Figures 9-12 The Nyquist plots before and after fitting for samples without sealing treatment and with composite sealing treatment for 1h, 3h and 5h, respectively. It can be clearly seen from the Nyquist plot that the impedance spectrum of the coating after composite sealing treatment shows a capacitive arc, and the larger the diameter of the capacitive arc, the better the corrosion resistance. The capacitive arc diameters are significantly larger than the impedance values ​​of the unsealed samples, indicating that the composite sealing treatment can effectively improve the corrosion resistance of the Zn-Cu-Ti alloy coating. The exemplary implementation of the method for preparing the Zn-Cu-Ti composite coating proposed in the present invention is described in detail above with reference to the preferred embodiments. However, it will be understood by those skilled in the art that, without departing from the concept of the present invention, various modifications and variations can be made to the above-mentioned specific embodiments, and various combinations of the various technical features and structures proposed in the present invention can be made without exceeding the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A method for preparing a Zn-Cu-Ti composite coating, characterized in that: The steps include: S10: Smelting copper particles, zinc blocks and titanium sponge as raw materials to prepare cylindrical Zn-0.15Cu-0.15Ti alloy ingots; S20: preparing alloy wire for spraying from the alloy ingot by an isothermal extrusion process; S30: Zn-0.15Cu-0.15Ti alloy coating was prepared on the surface of steel sample by arc spraying process; S40: preparing a 0.023 M cerium salt sealing solution, adding a 0.25 M catalyst, and adjusting the pH of the cerium salt sealing solution to 3.5-4.5; S50: placing the cerium salt sealing solution in a constant temperature environment of 20-30° C., immersing the steel sample containing the Zn-0.15Cu-0.15Ti alloy coating in the solution, sealing for 1-5 hours, then taking it out, and washing it in deionized water and ethanol in turn to prepare a Zn-0.15Cu-0.15Ti / cerium salt coating; S60: preparing a 0.2M phosphate sealing solution, and then adding a 2M alkaline solution to adjust the pH of the phosphate sealing solution to 6.5-7.5; S70: The prepared phosphate sealing treatment liquid is placed in a constant temperature environment of 85-95°C, and the prepared steel sample containing the Zn-0.15Cu-0.15Ti / cerium salt coating is immersed in the phosphate sealing treatment liquid for 1-5 hours to prepare the Zn-0.15Cu-0.15Ti / cerium salt phosphate composite coating.

2. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S10, the diameter of the cylindrical Zn-0.15Cu-0.15Ti alloy ingot is 36 mm.

3. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S20, the isothermal extrusion process includes: 1) extrusion temperature is 370-470°C; 2) Extrusion speed is 1.0~3.0mm / s.

4. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S20, the alloy ingot is extruded into an alloy wire for spraying with a diameter of 3 mm.

5. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S30, the arc spraying process includes: 1) The spraying voltage is 25~30V; 2) Spraying current is 150~200A; 3) Spraying distance is 120~170mm; 4) Air pressure is 0.4~0.8MPa.

6. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S40, the cerium salt is Ce(NO3)3·6H2O, and the catalyst is H2O2.

7. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S50, the phosphate is NaH2PO4, and the alkaline solution is NaOH.

8. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S50, placing the cerium salt sealing solution in a constant temperature environment of 20-30°C includes placing the cerium salt sealing solution in a constant temperature water bath at 25°C.

9. The method for preparing the Zn-Cu-Ti composite coating according to claim 1, wherein: In step S70, placing the prepared phosphate sealing treatment liquid in a constant temperature environment of 85-95°C includes placing the prepared phosphate sealing treatment liquid in a constant temperature water bath at 90°C.

10. An application of a Zn-Cu-Ti composite coating prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The Zn-Cu-Ti composite coating is applied to the sealing treatment of arc spraying.

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