High-density integrated coating for marine environment and preparation method thereof

Abstract

The invention discloses a high-density integrated coating for a marine environment and a preparation method of the high-density integrated coating, and belongs to a coating protection technology. The preparation method comprises the steps that (1) micron-sized nickel-copper alloy powder and micron-sized titanium oxide powder are subjected to ball milling, mixing and drying, mixed powder is obtained, and the micron-sized nickel-copper alloy powder contains Al; (2) the mixed powder and polyether-ether-ketone powder are evenly mixed and dried, and a spraying raw material is obtained; and (3) spraying the spraying raw material to the surface of the substrate by using flame spraying. And (4) after spraying is completed, the surface of the coating is treated through a flame spraying technology. By optimizing the formula of the coating and combining the preparation method, the comprehensive properties such as corrosion resistance and wear resistance of the coating are effectively improved, and the coating can form long-acting protection on a metal matrix.

Description

Technical Field

[0001] The invention belongs to the technical field of coating protection, and relates to a high-density integrated coating for marine environment and a preparation method thereof. Background Art

[0002] With the expansion of the global market and the development of naval modernization, higher requirements are placed on the research and development, manufacturing technology and production capacity regulation of my country's shipbuilding industry. Metal components used in the shipbuilding industry will be corroded by seawater during long-term service. Therefore, the surface of metal components must be treated with long-term protection to inhibit the occurrence of corrosion and ensure the long-term stable operation of complete sets of equipment in the shipbuilding industry. At present, it is usually adopted to coat the surface of metal components with a coating to protect the metal components. Therefore, the performance of the coating directly affects its protective effect on the metal components. The better the density and corrosion resistance of the coating, the better the protective effect it can have on the metal components for a longer period of time.

[0003] Therefore, it is necessary to provide a high-density integrated coating for marine environment and a preparation method thereof, so as to obtain a coating with excellent density and corrosion resistance to provide long-term protection for metal components. Summary of the invention

[0004] In order to overcome the problems in the background technology, the present invention optimizes the coating composition and combines the preparation method to make the coating have excellent density and corrosion resistance, so that the coating of the present invention can provide long-term protection for metal components, extend the service life of metal components, and improve the stability of metal components.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing a high-density integrated coating for a marine environment, the preparation method comprising the following steps:

[0007] (1) ball-milling and mixing a micron-sized nickel-copper alloy powder and a micron-sized titanium oxide powder, and drying the mixture to obtain a mixed powder, wherein the micron-sized nickel-copper alloy powder contains Al;

[0008] (2) uniformly mixing the mixed powder obtained in step (1) and the polyetheretherketone powder and drying them to obtain a spraying raw material;

[0009] (3) Using flame spraying, spray the spraying raw material obtained in the step (2) onto the surface of the substrate.

[0010] (4) After the spraying in step (3) is completed, the coating surface is treated by flame spraying technology. The preferred coating thickness of the present invention is 200 to 300 μm.

[0011] Preferably, in step (1), the ball-to-material ratio of ball milling is 8:1, and the ball milling speed is 500 rpm.

[0012] Preferably, in step (2), the drying temperature is 120° C. and the drying time is 4 hours.

[0013] Preferably, in steps (3) and (4), the oxygen flow rate of flame spraying is 800 L / min, the oxygen pressure is 1.5 MPa, the kerosene flow rate is 25 L / h, the kerosene pressure is 0.8 MPa, the spraying distance is 350-380 mm, and the feed rate is 3.5 g / min.

[0014] On the other hand, the present invention provides a coating prepared by the above preparation method, wherein the components of the nickel-copper alloy powder include, by mass fraction, Cu: 20%, Al: 10-12%, Cr: 5-8%, Fe: 2.5%, Mn: 2%, Y: 0.5-0.8%, and the balance is Ni.

[0015] Preferably, the coating comprises, by mass fraction, 20% nickel-copper alloy powder with a particle size of 5 μm, 20% nickel-copper alloy powder with a particle size of 15 μm, 20% nickel-copper alloy powder with a particle size of 30 μm, 20% titanium oxide, and 20% polyetheretherketone with a particle size of 15 μm.

[0016] Beneficial effects of the present invention:

[0017] 1. The present invention forms an amorphous oxide film between metal particles and PEEK by mixing polyetheretherketone (PEEK) into the spraying raw material and spraying the spraying raw material onto the surface of the metal substrate by flame spraying. The C=O bond in PEEK and the Al in the amorphous oxide film are bonded to each other. 3+ The metal-polymer complex is formed at the PEEK / amorphous oxide interface through the reaction, and the chemical bonding between the two helps to improve the density of the coating.

[0018] 2. The present invention can significantly improve the wear resistance and strength of the coating by adding TiO2 hard ceramic particles to the spraying raw materials, thereby enhancing the comprehensive performance of the coating and enabling the coating to exert a better protective effect.

[0019] 3. The present invention optimizes the formula of nickel-copper alloy powder and forms dense aluminum oxide and chromium oxide layers after flame spraying on the coating surface, which effectively isolates the coating surface from the external environment and improves the high-temperature oxidation resistance of the coating. Aluminum and chromium are easily passivated metals, and the formation of a dense oxide film can effectively improve the corrosion resistance of the coating. The addition of yttrium can catalyze grain refinement, improve defects such as micropores and microcracks, and is beneficial to improving the density of the coating, thereby making the coating more protective.

[0020] 4. The addition of yttrium can not only improve the density of the coating, but also dissolve oxygen and inhibit Cl - Migration into the corrosion product and Al 3+ The migration of corrosion products to the outside increases the impedance of the coating, thereby making the coating exhibit better corrosion resistance.

[0021] 5. The present invention can form an integrated coating on the surface of the metal substrate through a single flame spraying to provide long-term protection for the metal substrate, and the coating preparation process is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a metallographic image of the sample after the coating is sprayed according to the present invention;

[0023] Figure 2 is a graph of the coefficient of friction of the coating of the present invention;

[0024] Figure 3 The impedance diagram of the sample after being sprayed with the coating according to the present invention and immersed in a 3.5% NaCl solution for 0.5 h. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific embodiments.

[0026] In the examples and comparative examples of the present invention, chemical reagents not specifically described were commercially available analytically pure reagents for the experiments.

[0027] During the experiments of the embodiments of the present invention and the comparative examples, conventional nickel-copper alloy was selected as the metal substrate, and the metal substrate sample was prepared into a Φ28mm*2mm disc by using electric spark wire cutting. The sample surface was polished in sequence using 240 mesh, 400 mesh, 600 mesh, 800 mesh, and 1000 mesh sandpapers, and then the polished sample was sandblasted. After sandblasting, the sample was ultrasonically cleaned in alcohol for 30 minutes.

[0028] Sand blasting is the process of accelerating white corundum sand particles through a high-speed airflow generated by compressed air, causing them to impact the sample surface at high speed. Under this strong and continuous impact force, the grease and oxide layer on the sample surface are peeled off until they are completely removed and the fresh metal matrix is ​​exposed. At the same time, many tiny pits will be formed on the sample surface due to the impact, making the surface rough.

[0029] Sandblasting is carried out using a mobile sandblasting machine with the following process parameters: the compressed air pressure used is 0.6MPa, the distance between the sandblasting gun nozzle and the sample surface is 30-50mm, the sandblasting angle range is 50-90°, the spray gun moving speed is 2m / min, and the surface roughness after sandblasting reaches Sa2 level or above.

[0030] Before spraying the coating, the surface of the metal substrate sample is preheated to 300-500°C to remove moisture and condensate on the workpiece surface, improve the bonding strength between the coating and the substrate, and reduce the stress caused by the temperature difference between the coating and the substrate.

[0031] In the embodiments of the present invention and the comparative examples, the nickel-copper alloy treated as above is used as the metal substrate, and the coating thickness is 200-300 μm.

[0032] Example 1

[0033] In this embodiment, the coating is prepared according to the following steps:

[0034] (1) According to the mass fraction of Cu: 20%, Al: 10%, Cr: 8%, Fe: 2.5%, Mn: 2%, Y: 0.5%, and the remainder is Ni, the nickel-copper alloy powder raw material is weighed, and the raw material is ground into nickel-copper alloy powder of different particle sizes using a sand mill. Grinding line speed: 10m / s, cooling water flow: 750L / h, cooling water temperature: 7-12℃, grinding medium size: 1mm (L95 zirconia beads). The grinding time is controlled to adjust the powder particle size. The nickel-copper alloy powders with particle sizes of 5μm, 15μm and 20μm need to be ground for 10h, 8h and 6h respectively.

[0035] (2) Weigh 20% of nickel-copper alloy powder with a particle size of 5 μm, 20% of nickel-copper alloy powder with a particle size of 15 μm, 20% of nickel-copper alloy powder with a particle size of 20 μm, 20% of titanium oxide powder, and 20% of polyetheretherketone powder with a particle size of 15 μm, respectively, and firstly ball-mill the nickel-copper alloy powder with different particle sizes and titanium oxide at a ball-to-material ratio of 8:1 and a ball milling speed of 500 rpm, and then dry at 120° C. for 4 hours to obtain a mixed powder. By adopting a reasonable ratio of different particle sizes, the small particle size powder can effectively fill the gaps in the coating during the spraying process, thereby forming a dense coating structure.

[0036] (3) The mixed powder obtained in step (2) and the weighed polyetheretherketone powder are uniformly mixed and dried at 120° C. for 4 hours to obtain a spraying raw material. The mixing method can be a powder mixer for stirring and mixing. The motor power of the powder mixer is 0.25KW, the stirring speed is 50rpm, the mixing time is 30min, the mixing tank flip angle is 25.3°, and the mixing tank flip speed is 45° / s. After the mixing is completed, the spraying raw material is obtained.

[0037] (4) The flame spraying oxygen flow rate was set to 800 L / min, the oxygen pressure was set to 1.5 MPa, the kerosene flow rate was set to 25 L / h, the kerosene pressure was set to 0.8 MPa, the spraying distance was set to 350 mm, and the feed rate was set to 3.5 g / min. The spraying raw material was sprayed onto the surface of the metal substrate by flame spraying.

[0038] (5) After spraying is completed, the flame spraying parameters are kept unchanged, and the coating surface is subjected to high temperature treatment using a flame spray gun to complete the coating preparation process.

[0039] The metal substrate on which the coating was prepared in this embodiment was subjected to a metallographic experiment, and the results are as follows: Figure 1 As shown, the metal substrate prepared with the coating in this embodiment was subjected to a wear test, and the results are shown in FIG. Figure 2 As shown, the corrosion resistance of the metal substrate was tested using an electrochemical workstation. The results are shown in Figure 3 shown.

[0040] pass Figure 1 It can be seen that there are no obvious defects such as cracks, slag inclusions and continuous holes in the coating and the interface of this embodiment, showing good compactness. The high-speed particles of the flame spraying technology impact the surface of the metal substrate to form many pit structures. The alloy coating is combined with the substrate metal by mechanical embedding and micro-metallurgical bonding. At the same time, an amorphous oxide film is formed between the metal particles and PEEK in the coating. The C=O bonds in PEEK and Al in the amorphous oxide film 3+ The reaction forms a metal-polymer complex at the PEEK / amorphous oxide interface, which improves the microstructure of the coating, further enhances the density of the coating, reduces pores and defects, effectively prevents the penetration of corrosive media and reduces stress concentration, thereby improving the overall corrosion resistance and durability of the coating.

[0041] pass Figure 2 It can be seen that the friction coefficient of the coating in this embodiment is 0.31, which is significantly reduced compared with the Ni-Cu coating, indicating that the addition of ceramic particles significantly enhances the wear resistance of the coating.

[0042] pass Figure 3 It can be seen that the coating impedance value of this embodiment is 85 kΩ, which is 65% higher than that of the Ni-Cu coating. Since the coating is uniform and dense and there is a metal-polymer complex inside, the complex can improve the electrochemical stability of the coating. In addition, the complex can promote the synergistic effect of different metals to form a more complex phase structure, thereby improving the corrosion resistance of the coating.

[0043] Example 2

[0044] This embodiment adopts the same method as that of embodiment 1 to prepare a metal substrate with a coating, except that: in this embodiment, the mass fraction of the nickel-copper alloy powder raw material is Cu: 20%, Al: 11%, Cr: 6.5%, Fe: 2.5%, Mn: 2%, Y: 0.65%, and the balance is Ni. The flame spraying distance is 380 mm.

[0045] The performance of the coating in this example is similar to that in Example 1.

[0046] Example 3

[0047] This embodiment adopts the same method as that of embodiment 1 to prepare a metal substrate with a coating, except that: in this embodiment, the mass fraction of the nickel-copper alloy powder raw material is: Cu: 20%, Al: 12%, Cr: 5%, Fe: 2.5%, Mn: 2%, Y: 0.8%, and the balance is Ni. The flame spraying distance is 360 mm.

[0048] The performance of the coating in this example is similar to that in Example 1.

[0049] Comparative Example 1

[0050] This comparative example adopts the same method as Example 1 to prepare a metal substrate with a coating, with the difference that: in this comparative example, the spraying raw material is sprayed onto the surface of the metal substrate twice. First, a mixed powder of nickel-copper alloy powder and titanium oxide powder is sprayed onto the surface of the metal substrate by flame spraying technology, and then PEEK is sprayed on the surface of the mixed powder coating to form a final coating.

[0051] In this comparative example, the interface between the PEEK layer and the nickel-copper alloy-titanium oxide layer is relatively obvious, and the complex will only be formed at the interface between the metal particles and PEEK in the coating. If a complex is formed, the interface will be blocked during observation, making the interface relatively unclear. Therefore, the interface between the PEEK layer and the nickel-copper alloy-titanium oxide layer is relatively obvious, indicating that no complex or very few complexes are produced in this comparative example, resulting in a significant reduction in the chemical bonding force between the coatings. The chemical bonding force between the coatings is the key to affecting the density of the coating and resistance to external factors (such as corrosive media, mechanical stress, etc.), and its weakening will directly affect the durability and reliability of the coating. At the same time, due to the significant performance differences between the PEEK coating and the alloy coating, this performance difference is mainly manifested in the thermal expansion coefficient, mechanical strength and chemical stability, etc., and the resulting stress will accelerate the peeling process of the coating, thereby affecting the service life of the coating.

[0052] In summary, the present invention can effectively improve the corrosion resistance, wear resistance, density, high-temperature oxidation resistance and other properties of the coating by optimizing the coating formula and combining it with the preparation method, so that the coating can form a long-term protection for the metal substrate.

[0053] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-density integrated coating for a marine environment, characterized in that: The preparation method comprises the following steps: (1) ball-milling and mixing a micron-sized nickel-copper alloy powder and a micron-sized titanium oxide powder, and drying the mixture to obtain a mixed powder, wherein the micron-sized nickel-copper alloy powder contains Al; (2) uniformly mixing the mixed powder obtained in step (1) and the polyetheretherketone powder and drying them to obtain a spraying raw material; (3) using flame spraying to spray the spraying raw material obtained in step (2) onto the surface of the substrate; (4) After the spraying in step (3) is completed, the coating surface is treated by flame spraying technology.

2. The method for preparing a high-density integrated coating for a marine environment according to claim 1, characterized in that: In the step (1), the ball-to-material ratio of the ball milling is 8:1, and the ball milling speed is 500 rpm.

3. The method for preparing a high-density integrated coating for a marine environment according to claim 1, characterized in that: In the step (2), the drying temperature is 120° C. and the drying time is 4 hours.

4. The method for preparing a high-density integrated coating for a marine environment according to claim 1, characterized in that: In the steps (3) and (4), the oxygen flow rate of the flame spraying is 800 L / min, the oxygen pressure is 1.5 MPa, the kerosene flow rate is 25 L / h, the kerosene pressure is 0.8 MPa, the spraying distance is 350-380 mm, and the feed rate is 3.5 g / min.

5. The coating prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The nickel-copper alloy powder comprises, by mass fraction, 20% Cu, 10-12% Al, 5-8% Cr, 2.5% Fe, 2% Mn, 0.5-0.8% Y, and the balance is Ni.

6. The coating according to claim 5, characterized in that: The coating comprises, by mass fraction, 20% nickel-copper alloy powder with a particle size of 5 μm, 20% nickel-copper alloy powder with a particle size of 15 μm, 20% nickel-copper alloy powder with a particle size of 20 μm, 20% titanium oxide, and 20% polyetheretherketone with a particle size of 15 μm.

Images