CN111321440A - Preparation method of metal surface composite coating and modified metal material - Google Patents
Preparation method of metal surface composite coating and modified metal material Download PDFInfo
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Abstract
The invention provides a preparation method of a metal surface composite coating and a modified metal material. The preparation method of the metal surface composite coating comprises the following steps: preparing a composite electrolyte containing low-surface-energy organic nano powder; controlling the temperature of the composite electrolyte to be 60-90 ℃, and forming a composite coating on the surface of the metal matrix by utilizing a strong pulse high-frequency discharge reaction and auxiliary crosslinking solidification in the composite electrolyte under the pulse voltage of 400-1000V, wherein the composite coating comprises a ceramic layer and a polymer layer. According to the invention, the low-surface-energy organic nano powder is added into the electrolyte, and is deposited on the surface of the metal matrix in one step under the synergistic effects of activation induction, electrostatic adsorption, auxiliary crosslinking and chemical embedding under the micro-area environment of strong pulse voltage and high-temperature electrolyte, so that the large-thickness coating with the hierarchical micro-nano structure is prepared, the full coverage of the low-surface-energy organic polymer on the surface of the ceramic layer is realized, and the corrosion resistance of the metal matrix is greatly improved.
Description
Technical Field
The invention relates to the technical field of alloy surface treatment, in particular to a preparation method of a metal surface composite coating and a modified metal material.
Background
Metal corrosion is a common phenomenon that metal materials and surrounding media are damaged by chemical or electrochemical multiphase reactions, and the application development of metals and their alloys is often influenced by their corrosion resistance, for example, magnesium alloys are widely used in the aerospace, automotive and electronic industries due to their high strength, low density, high damping capacity, plasticity and easy processing. However, the wide application of magnesium and its alloys as parts is limited due to their poor corrosion resistance and low wear resistance, for example, magnesium and its alloys rapidly lose their function under the action of corrosive active media. Therefore, in order to prolong the life cycle of the metal and the metal alloy products and control the corrosion rate of the metal and the metal alloy products, the metal and the metal alloy are subjected to surface treatment to prepare the high-efficiency protective coating, so that the method is simple, convenient and effective.
At present, the method for treating the metal surface is mainly micro-arc oxidation treatment, but the method has a limited degree for improving the corrosion resistance of the metal. In order to further improve the corrosion resistance and chemical stability of the metal alloy and enable the metal alloy to have multifunctional characteristics, in the prior art, organic emulsion is added into electrolyte to prepare a micro-arc oxidation composite coating on the surface of the metal, however, in the prepared composite coating, organic particles are only slightly covered or distributed in a very thin layer (within a thickness micron) on the surface of the micro-arc oxidation layer, the difference between the thickness of the composite coating and the thickness of the micro-arc oxidation layer is very small, and the effect of further improving the corrosion resistance of the magnesium alloy is limited.
Disclosure of Invention
The problem addressed by the present invention is the lack of an effective method in the prior art to improve the corrosion resistance of metals and their alloys.
In order to solve the problems, the invention provides a preparation method of a metal surface composite coating, which comprises the following steps:
preparing a composite electrolyte containing low-surface-energy organic nano powder;
controlling the temperature of the electrolyte to be 60-90 ℃, and forming a multilayer composite coating on the surface of the metal matrix by using a strong pulse high-frequency discharge reaction and auxiliary crosslinking curing in the composite electrolyte under a pulse voltage of 400-1000V, wherein the multilayer composite coating comprises a ceramic layer and a polymer layer.
According to the invention, the low-surface-energy organic nano powder is added into the electrolyte, and is deposited on the surface of the metal matrix in one step under the synergistic effects of activation induction, electrostatic adsorption, auxiliary crosslinking and chemical embedding under the micro-area environment of strong pulse voltage and high-temperature electrolyte, so that a coating with a large thickness and a hierarchical micro-nano structure is prepared, the full coverage of a polymer layer with low surface energy on the surface of a ceramic layer is realized, and the corrosion resistance of the metal matrix is greatly improved.
Preferably, the mass fraction of the low surface energy organic nano powder in the composite electrolyte is 50-100 g/L.
The low surface energy organic nano powder can realize full coverage on the surface of the metal matrix within the concentration range, thereby improving the corrosion resistance of the metal matrix.
Preferably, the reaction time of the strong pulse high-frequency discharge reaction and the auxiliary crosslinking solidification on the surface of the metal matrix in the composite electrolyte is 10-50 min.
Under the special preparation environment of strong pulse voltage, high-temperature solution and long-time reaction, the preparation method is favorable for preparing a coating with a large thickness and a polymer ceramic multilayer structure on the surface of the metal matrix and improving the corrosion resistance of the metal matrix.
Preferably, in order to further regulate and control the micro-nano structure and performance of the polymer layer, the method further comprises the following steps: and carrying out heat curing treatment on the multilayer coating, wherein the temperature of the heat curing treatment is 50-300 ℃.
The compactness and the chemical stability of the coating are further improved through the thermocuring treatment, the polymer layer on the outer layer of the composite coating is further subjected to crosslinking polymerization within the temperature range, a micro-nano rough composite hierarchical structure is further formed on the surface of the polymer layer, and under the action of low surface energy, the solid-liquid interaction is realized, so that the surface of the composite coating is in a super-hydrophobic state, and a corrosive solution is effectively inhibited from entering the coating, so that a metal matrix is protected to form a high-inhibition film layer. In addition, under the action of thermal drive, the low-surface-energy nano organic powder is rearranged, part of organic chains are disconnected and rearranged, the organic polymer is further bonded with the ceramic template layer, and the low-surface-energy organic nano powder is more uniformly and compactly distributed in the ceramic layer so as to be tightly combined.
Preferably, the low surface energy organic nano powder comprises fluorine-containing resin and organosilane polymers.
Preferably, the preparation steps of the composite electrolyte are as follows:
dissolving sodium silicate, sodium hexametaphosphate, potassium fluoride, a pH regulator and sodium tungstate in water to obtain a basic solution;
and adding the low-surface-energy organic nano powder into the basic solution, and performing ultrasonic dispersion to obtain the composite electrolyte.
Preferably, the concentration of the sodium silicate is 1-20g/L, the concentration of the sodium hexametaphosphate is 1-20g/L, the concentration of the potassium fluoride is 1-10g/L, the concentration of the pH regulator is 1-10g/L, and the concentration of the sodium tungstate is 1-20 g/L.
Sodium tungstate is added into the basic solution, which is beneficial to improving the roughness and the wear resistance of the ceramic layer, thereby being beneficial to the deposition and the adsorption of the low-surface-energy organic nano powder on the ceramic layer.
The invention also provides a modified metal material which comprises a metal substrate and the composite coating prepared by the preparation method of the metal surface composite coating, wherein a ceramic layer in the composite coating grows on the surface of the metal substrate in situ, and a polymer layer in the composite coating covers the ceramic layer.
Preferably, the thickness of the composite coating is 60-200 μm.
Preferably, the thickness of the polymer layer accounts for more than 50% of the thickness of the composite coating.
The modified metal material prepared by the invention has the advantages that the composite coating with large thickness, full coverage, high compactness, super hydrophobicity and self-cleaning is formed on the metal surface, and the corrosion resistance of the metal is effectively improved.
Drawings
FIG. 1 is a surface microtopography photograph of a metal surface composite coating prepared in example 1 of the present invention;
FIG. 2 is a cross-sectional micro-topography photograph of a metal surface composite coating prepared in example 1 of the present invention;
FIG. 3 is a physical diagram of the contact angle and a schematic diagram of the static contact angle of the composite coating on the metal surface prepared in example 1 of the present invention;
FIG. 4 is a polarization curve of the composite coating on the metal surface prepared in example 1 of the present invention;
FIG. 5 is a test chart of the self-cleaning function of the composite coating on the metal surface prepared in example 1 of the present invention;
FIG. 6 is a surface micro-topography photograph of a micro-arc oxidized ceramic coating on a metal surface prepared in comparative example 1 of the present invention;
FIG. 7 is a cross-sectional micro-topography photograph of a micro-arc oxidized ceramic coating on a metal surface prepared in comparative example 1 of the present invention;
FIG. 8 is a schematic view of the static contact angle of the micro-arc oxidized ceramic coating on the surface of the metal prepared in comparative example 1 of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
The embodiment of the invention provides a preparation method of a metal surface composite coating, which comprises the following steps:
preparing a composite electrolyte containing low-surface-energy organic nano powder;
the temperature of the composite electrolyte is controlled to be 60-90 ℃, under the pulse voltage of 400-1000V, the composite electrolyte is cured on the surface of a metal matrix by utilizing a strong pulse high-frequency discharge reaction and auxiliary crosslinking to form a composite coating, and the composite coating comprises a ceramic layer and a polymer layer, which can be referred to as a ceramic polymer coating for short.
In this embodiment, the process of preparing the ceramic polymer composite coating on the surface of the metal matrix by using the strong pulse high-frequency discharge reaction and the auxiliary crosslinking curing is as follows: taking a stainless steel plate or a stainless steel pool as a cathode, taking a metal matrix as an anode, heating the composite electrolyte, continuously stirring the heated composite electrolyte to be used as the electrolyte, or adding the composite electrolyte into an electrolytic bath, and controlling the temperature of the electrolyte in the electrolytic bath to keep the solution temperature of the electrolyte at 60-90 ℃. Applying pulse voltage between a cathode and an anode, promoting strong pulse discharge on a metal matrix under the micro-area environment of the pulse voltage and high-temperature composite electrolyte, inducing the metal matrix to be activated to generate plasma, further generating a rough ceramic layer on the surface of the metal matrix in situ, further depositing and curing the rough ceramic layer on the ceramic layer by taking the ceramic layer as a template under the combined action of strong electrostatic adsorption and auxiliary crosslinking deposition to form a polymer layer, and then depositing and growing a ceramic polymer composite coating on the surface of the metal matrix.
In the embodiment, under the combined action of plasma surface oxidation and high-temperature cladding assisted cross-linking deposition, a rough ceramic layer is regulated and controlled on the surface of a metal matrix, the ceramic layer is used as a deposition template, the ceramic layer is sealed by low-surface-energy nano organic powder in an electrophoretic deposition, electrostatic adsorption and assisted cross-linking mode, and a multi-layer coating with a hierarchical micro-nano structure is formed on the surface of the metal matrix in a mechanical riveting and chemical combination mode. Thereby realizing the full coverage of the organic nano powder on the surface of the metal matrix and leading the surface of the metal matrix to have high corrosion resistance.
The preparation process of the composite electrolyte comprises the following steps:
(1) preparing a basic solution, specifically: dissolving 1-20g/L sodium silicate, 1-20g/L sodium hexametaphosphate and 1-10g/L potassium fluoride in water, and adding 1-10g/LpH regulator and 1-20g/L sodium tungstate, wherein the pH regulator comprises sodium hydroxide or potassium hydroxide.
In the base solution configured in this example, potassium fluoride is used as a film-forming aid to facilitate smooth formation of a ceramic layer. Sodium tungstate can generate tungsten compounds which are beneficial to improving the roughness and the wear resistance in the coating forming process, thereby being beneficial to the deposition of low-surface-energy organic nano powder on the ceramic layer. Sodium hydroxide or potassium hydroxide is used to adjust the pH of the base solution.
Preferably, the mass concentration ratio of the sodium silicate to the sodium hexametaphosphate to the potassium fluoride is 5:2:1-3:6:2, and the ceramic layer is easier to generate smoothly within the range.
The base solution prepared by adopting the components and the contents has the characteristics of good film forming property and high surface roughness of the ceramic layer.
(2) Preparing a composite electrolyte, specifically: adding low surface energy organic nano powder with the mass fraction of 50-100g/L into the basic solution, and carrying out ultrasonic dispersion for 30-100 min.
When the concentration of the low surface energy organic nano-powder exceeds a threshold value, the low surface energy organic nano-powder can realize full coverage on the surface of the metal matrix, and therefore, the mass fraction of the low surface energy organic nano-powder in the embodiment is preferably 50-100 g/L.
Wherein the low surface energy organic nano powder comprises fluorine-containing resin and organosilane low surface energy nano powder materials, such as polytetrafluoroethylene nano powder or organic silicon ultrafine powder. Of course, the present embodiment is also applicable to other low surface energy organic nano powder materials.
Adding the composite electrolyte into an electrolytic tank, continuously stirring the electrolyte, taking a stainless steel plate or a stainless steel pool as a cathode, taking a metal matrix as an anode, applying a pulse voltage of 400-1000V between a positive electrode and a negative electrode, and applying a current density of 4000-2. And (3) preparing the coating by electrodeposition for 10-50min under high pulse voltage and higher-temperature electrolyte. Finally, a multilayer coating with the thickness of 60-200 mu m is formed on the surface of the metal matrix, the multilayer coating comprises a ceramic layer with a high rough structure formed on the surface of the metal matrix by oxidation and a polymer layer deposited on the surface of the ceramic layer, wherein the thickness of the polymer layer accounts for more than 50% of the thickness of the multilayer coating, and compared with the prior art that organic particles only cover and distribute a small amount of the organic particles on the surface of a micro-arc oxidation layer, the composite coating prepared by the embodiment has large thickness and large thickness ratio of the polymer layer, thereby effectively improving the corrosion resistance of the metal matrix.
In order to facilitate the generation of a coating on the surface of the metal substrate, the metal substrate is pretreated, and the pretreatment steps are as follows:
the surface of the metal substrate is polished with sandpaper to remove impurities, oxide layers and the like on the surface of the metal substrate, and specifically, the surface of the metal substrate is polished with 800#, 1200# and 1500# sandpaper in this order.
Then, respectively ultrasonically cleaning the metal substrate by absolute ethyl alcohol and deionized water for 15-30min to improve the cleanliness of the surface of the metal substrate.
In this embodiment, the metal matrix is selected from at least one of magnesium alloy, aluminum alloy, titanium alloy, zirconium alloy, and the like, but the preparation method provided in this embodiment is applicable to all metals in principle.
The composite coating prepared by the embodiment is large in thickness, and the low-surface-energy polymer layer is fully covered on the surface of the ceramic layer to seal the ceramic layer, so that the corrosion resistance of the surface coating of the metal matrix is greatly improved.
The preparation method of the metal surface composite coating provided by the embodiment deposits, crosslinks and solidifies the low surface energy organic nano-powder on the surface of the metal substrate in one step under the synergistic effect of activation induction, electrostatic adsorption, auxiliary crosslinking and chemical inlaying. In addition, the ceramic layer is generated in situ on the surface of the metal matrix, so that the coating has high growth speed and good bonding force with the metal matrix; the polymer layer and the ceramic layer are combined in the modes of electrostatic adsorption, cross-linking polymerization and the like, so that the composite coating on the surface of the metal matrix has stronger binding force and higher stability. In this embodiment, the composite coating prepared on the surface of the metal substrate is a ceramic-polymer coating, so that the surface of the metal substrate also has super-hydrophobic and self-cleaning functions.
In the embodiment, the low-surface-energy organic nano powder is added into the basic solution to form the composite electrolyte, and under the strong pulse voltage, the low-surface-energy organic nano powder has charges and directionally migrates to the anode to grow together with the ceramic layer, so that the film forming rate of the composite coating is greatly improved. Compared with organic polymer materials in other forms such as emulsion and the like, the organic polymer material in the form of powder has the advantages of simple modification treatment or activation treatment without the need of modification treatment, lower cost and simpler steps.
Preferably, since the low surface energy organic nano powder material is a hydrophobic material, in order to improve the stability of the low surface energy organic nano powder material in the electrolyte, the present embodiment further performs an activation treatment on the low surface energy organic nano powder material, where the activation method is to wrap the low surface energy organic nano powder material with a surfactant or a solution stabilizer to improve the surface characteristics of the organic nano powder material and facilitate control of the surface charges of the organic nano powder material.
Further, in order to further regulate and control the micro-nano structure and the performance of the polymer layer, the preparation method of the metal surface composite coating further comprises the following steps:
carrying out thermocuring treatment on the multilayer coating obtained after the strong pulse high-frequency discharge reaction and the auxiliary crosslinking curing, wherein the thermocuring temperature is 50-300 ℃.
Under the effects of plasma surface oxidation and auxiliary cross-linking polymerization, the low-surface-energy organic nano powder further permeates to the inner layer along the residual discharge channel, so that the compactness and the chemical stability of the coating are obviously improved, and a shielding layer with high inhibition is provided for the corrosion of the solution. After the thermosetting treatment, on one hand, the polymer layer on the outer layer of the coating is further subjected to cross-linking polymerization at a certain temperature, a micro-nano rough composite hierarchical structure is further assembled on the surface of the polymer layer, and under the action of low surface energy, the solid-liquid interaction is carried out, so that the surface of the composite coating forms a super-hydrophobic state, and the solution is effectively inhibited from entering the coating, thereby protecting the metal matrix to form a high-inhibition film layer. On the other hand, under the action of thermal driving, the low-surface-energy nano organic powder is rearranged, part of organic chains are disconnected and rearranged, the organic polymer is further bonded with the ceramic template layer, and the low-surface-energy organic nano powder is more uniformly and compactly distributed in the ceramic layer to be tightly combined.
The following is a detailed description by way of specific examples:
example 1
The embodiment provides a preparation method of a magnesium alloy surface composite coating, which comprises the following steps:
1.1, selecting AZ31 magnesium alloy as a substrate, polishing the surface of the substrate by using 800#, 1200# and 1500# sandpaper in sequence, and then ultrasonically cleaning the substrate for 20min by using absolute ethyl alcohol and deionized water respectively;
1.2 mixing and mechanically stirring uniformly 15g/L sodium silicate, 6g/L sodium hexametaphosphate, 3g/L potassium fluoride, 2g/L sodium hydroxide and 5g/L sodium tungstate to prepare a basic solution;
1.3 adding 50g/L of modified organic polytetrafluoroethylene nano powder into a basic solution, and ultrasonically dispersing for 30min to prepare a composite electrolyte with good stability, dispersibility and fluidity;
1.4 heating the composite electrolyte to 70 ℃ and continuously stirring;
1.5 using stainless steel plate or stainless steel pool as cathode, AZ31 magnesium alloy as anode, applying 500V pulse voltage at both ends of the electrolytic cell, and current density of 28000A/m2And under the conditions of solution temperature of 70 ℃ and stirring, carrying out strong pulse high-frequency discharge reaction and auxiliary crosslinking curing for 30min to obtain the ceramic polymer multilayer coating formed on the surface of the magnesium alloy substrate.
1.6 carrying out heat curing treatment on the multilayer coating at 150 ℃ to obtain the composite coating formed on the surface of the magnesium alloy substrate.
The surface micro-morphology and the cross-section micro-morphology of the magnesium alloy surface composite coating prepared in the embodiment are analyzed, and the results are shown in fig. 1 and 2, and it can be known from fig. 1 that the surface morphology with the micro-nano hierarchical structure comprising polytetrafluoroethylene nano-powder is formed on the surface of the magnesium alloy substrate, and the morphology endows the composite coating with super-hydrophobic performance. As can be seen from fig. 2, the composite coating layer has a distinct two-layer structure, and the ceramic layer is tightly bonded to the polymer layer. The test shows that the thickness of the composite coating is 120 μm, wherein the thickness of the ceramic layer is 40-60 μm, and the thickness of the polymer layer is 60-80 μm. The ceramic polymer multilayer coating with large thickness and high compactness has excellent super-hydrophobic property, ultrahigh pollutant self-cleaning property and ultrahigh corrosion resistance, and the corrosion rate value of the coating is very low in the long-term soaking process of a sample.
The contact angle of the composite coating on the surface of the magnesium alloy prepared in the embodiment is tested, and the result is shown in fig. 3, and as can be seen from fig. 3, the contact angle of the composite coating is greater than 160 °, and the composite coating has excellent hydrophobicity.
FIG. 4 is a polarization curve of the composite coating on the surface of the magnesium alloy prepared in this example, wherein the abscissa showsCurrent in units of A/m2The ordinate is the potential in volts V. From the combination of the corrosion potential, corrosion current and polarization resistance in fig. 4, the composite coating has excellent corrosion resistance compared to the magnesium alloy substrate.
Table 1 shows polarization test fitting data for magnesium alloys and ceramic polymer coatings. As can be seen from Table 1, the corrosion potential (-0.56V) of the ceramic polymer coating is significantly higher than that (-1.5V) of the magnesium alloy substrate, and the corrosion current of the ceramic polymer coating is significantly lower than that of the magnesium alloy substrate by 3 orders of magnitude. Meanwhile, the resistance of the polarization resistor Rp of the ceramic polymer coating is obviously higher than that of the polarization resistor Rp of the magnesium alloy substrate by more than 3 orders of magnitude. Therefore, compared with a magnesium alloy matrix, the corrosion resistance of the ceramic polymer coating is improved by more than 3 orders of magnitude, and the ceramic polymer coating has excellent corrosion resistance.
TABLE 1
The self-cleaning performance of the magnesium alloy surface composite coating prepared in the embodiment is tested, and the result is shown in fig. 5, and fig. 5 shows the self-cleaning performance of the magnesium alloy surface composite coating from top to bottom when the simulated pollutants are ink, sand and ceramic powder respectively. In addition, pollutants (dust and ceramic powder) can be easily removed by water flow, and no 'residue' is observed on the surface of the composite coating, so that the composite coating on the surface of the magnesium alloy has excellent self-cleaning capability, the pollution on the surface of the magnesium alloy substrate is reduced, and the magnesium alloy substrate is effectively protected.
Comparative example 1
The embodiment provides a preparation method of a magnesium alloy surface micro-arc oxidation coating, which comprises the following steps:
1.1' selecting AZ31 magnesium alloy as a substrate, polishing the surface by using 800#, 1200# and 1500# sandpaper in sequence, and then respectively ultrasonically cleaning for 20min by using absolute ethyl alcohol and deionized water;
1.2' mixing and mechanically stirring 15g/L sodium silicate, 6g/L sodium hexametaphosphate, 3g/L potassium fluoride, 2g/L sodium hydroxide and 5g/L sodium tungstate uniformly to prepare a basic solution;
1.3' using stainless steel plate or stainless steel pool as cathode, AZ31 magnesium alloy as anode, and basic solution as electrolyte, applying 500V pulse voltage at two ends of the electrolytic cell, with current density of 28000A/m2And preparing the coating for 30min to obtain the micro-arc oxidation ceramic coating.
The surface micro-topography and the cross-sectional micro-topography of the micro-arc oxidation coating on the surface of the magnesium alloy prepared in the embodiment were analyzed, and the results are shown in fig. 6 and 7, and it can be seen from fig. 6 that the coating has a hydrophilic porous surface. As can be seen from FIG. 7, the micro-arc oxidized coating has many connected pores throughout the coating and is less dense. The micro-arc oxidation coating was tested to have a thickness of 30 μm, which is much less than the thickness of the composite coating in example 1.
The contact angle of the micro-arc oxidation coating on the surface of the magnesium alloy prepared in the embodiment is tested, and the result is shown in fig. 8, and it can be known from fig. 8 that the contact angle of the composite coating is less than 50 degrees, which shows that the composite coating is hydrophilic, has poor hydrophobicity, and does not have the self-cleaning property of pollutants.
Table 2 shows the polarization test fit data for the magnesium alloy, the ceramic polymer coating of example 1, and the micro-arc oxidized coating of this example. As can be seen from Table 2, the corrosion potential (-1.42V) of the micro-arc oxidized coating is slightly higher than that (-1.5V) of the magnesium alloy substrate, but is much lower than that (-0.56V) of the ceramic polymer coating prepared in example 1. The corrosion current of the micro-arc oxidation coating is lower than that of the magnesium alloy substrate, but higher than that of the ceramic polymer coating prepared in the example 1. It can be seen that the corrosion resistance of the micro-arc oxidation coating is higher than that of the magnesium alloy substrate, but is far lower than that of the ceramic polymer coating prepared in example 1.
TABLE 2
Compared with the comparative example 1, in the example 1, the low-surface-energy nano organic powder is added into the base solution under the same condition, the ceramic layer and the polymer layer are deposited on the surface of the metal matrix in one step, the thickness of the surface coating of the metal matrix is increased, and the ceramic layer and the polymer layer are compactly combined, so that the super-hydrophobic performance, the self-cleaning performance and the high corrosion resistance are realized.
Example 2
The embodiment provides a preparation method of a magnesium alloy surface composite coating, which comprises the following steps:
2.1, selecting AZ31 magnesium alloy as a substrate, polishing the surface by using 800#, 1200# and 1500# sandpaper in sequence, and then respectively ultrasonically cleaning for 30min by using absolute ethyl alcohol and deionized water;
2.2 mixing 6g/L sodium silicate, 12g/L sodium phosphate, 4g/L potassium fluoride, 5g/L sodium hydroxide and 5g/L sodium tungstate and mechanically stirring uniformly to prepare a basic solution;
2.3 adding 80g/L of low surface energy organic polytetrafluoroethylene nano powder into the basic solution, and ultrasonically dispersing for 50min to prepare the composite electrolyte with good stability, dispersibility and fluidity;
2.4 heating the composite electrolyte to 80 ℃ and continuously stirring;
2.5 applying 650V pulse voltage with current density of 34000A/m to both ends of the electrolytic cell by using a stainless steel plate or a stainless steel pool as a cathode and AZ31 magnesium alloy as an anode2Preparing a coating for 40min by using a strong pulse high-frequency discharge reaction and auxiliary crosslinking curing under the conditions that the solution temperature is 80 ℃ and stirring is carried out, so as to obtain a multilayer coating formed on the surface of the magnesium alloy substrate;
2.6 carrying out heat curing treatment on the multilayer coating at 150 ℃ to obtain the composite coating formed on the surface of the magnesium alloy substrate.
The thickness of the magnesium alloy composite coating prepared by the embodiment can reach 140 microns, the thickness of the polymer layer can reach 80-100 microns, the magnesium alloy composite coating has excellent super-hydrophobic performance, the static contact angle of the composite coating is larger than 152 degrees, the self-cleaning performance of pollutants is high, and the corrosion resistance is high.
Example 3
3.1, selecting AZ31 magnesium alloy as a substrate, polishing the surface by using 800#, 1200# and 1500# sandpaper in sequence, and then respectively ultrasonically cleaning for 30min by using absolute ethyl alcohol and deionized water;
3.2 mixing 6g/L sodium silicate, 12g/L sodium phosphate, 4g/L potassium fluoride, 5g/L sodium hydroxide and 5g/L sodium tungstate, and mechanically stirring uniformly to prepare a basic solution;
3.3 adding 50g/L of organic silicon ultrafine powder into the basic solution, and ultrasonically dispersing for 60min to prepare the composite electrolyte with good stability, dispersibility and fluidity;
3.4 heating the composite electrolyte to 80 ℃ and continuously stirring;
3.5 applying 650V pulse voltage with current density of 34000A/m to both ends of the electrolytic cell by using a stainless steel plate or a stainless steel pool as a cathode and AZ31 magnesium alloy as an anode2Preparing a coating on the surface of the magnesium alloy for 30min by strong pulse high-frequency discharge reaction and auxiliary crosslinking solidification at the solution temperature of 80 ℃ under the stirring condition to obtain a multilayer coating formed on the surface of the magnesium alloy substrate;
and 3.6 performing heat curing treatment on the multilayer coating at the temperature of 200 ℃ to obtain the composite coating formed on the surface of the magnesium alloy substrate.
The thickness of the magnesium alloy surface composite coating prepared by the embodiment can reach 80 microns, the thickness of the polymer layer can reach 40-60 microns, the composite coating has excellent super-hydrophobic performance, the static contact angle of the composite coating is larger than 158 degrees, the self-cleaning performance of pollutants is high, and the corrosion resistance is high.
Example 4
4.1 selecting aluminum alloy as a substrate, polishing the surface by using 800#, 1200# and 1500# sandpaper in sequence, and then respectively ultrasonically cleaning for 10min by using absolute ethyl alcohol and deionized water;
4.2 mixing and mechanically stirring uniformly 20g/L sodium silicate, 3g/L sodium phosphate, 2g/L potassium fluoride, 1g/L sodium hydroxide and 2g/L sodium tungstate to prepare a basic solution;
4.3 adding 60g/L of organic silicon ultrafine powder into the basic solution, and performing ultrasonic dispersion for 40min to prepare a composite electrolyte with good stability, dispersibility and fluidity;
4.4 heating the composite electrolyte to 60 ℃ and continuously stirring;
4.5 stainless steel plateOr the stainless steel pool is used as a cathode, the aluminum alloy is used as an anode, 400V pulse voltage is applied to the two ends of the electrolytic tank, and the current density is 4000A/m2Preparing a coating for 20min by using a strong pulse high-frequency discharge reaction and auxiliary crosslinking curing at the solution temperature of 60 ℃ under the stirring condition to obtain a multi-layer composite coating formed on the surface of an aluminum alloy substrate;
although the aluminum alloy surface composite coating prepared by the strong pulse high-frequency discharge reaction and the auxiliary crosslinking curing is not subjected to the thermosetting treatment, the thickness of the prepared composite coating reaches 50 micrometers, the thickness of the polymer layer reaches 20-30 micrometers, the composite coating has certain hydrophobic property, the static contact angle is larger than 135 degrees, and the composite coating has certain self-cleaning property and excellent corrosion resistance. For the condition that the requirements on the super-hydrophobicity and the self-cleaning property of the composite coating are low, the composite coating can be not subjected to thermosetting treatment based on the economic aspect, and the prepared composite coating still has larger thickness, and the polymer layer has larger thickness and is completely covered on the surface of the ceramic layer.
Example 5
5.1 selecting aluminum alloy as a substrate, polishing the surface by using 800#, 1200# and 1500# sandpaper in sequence, and then respectively ultrasonically cleaning for 30min by using absolute ethyl alcohol and deionized water;
5.2 mixing and mechanically stirring 3g/L sodium silicate, 20g/L sodium phosphate, 10g/L potassium fluoride, 10g/L sodium hydroxide and 20g/L sodium tungstate uniformly to prepare a basic solution;
5.3 adding 100g/L of organic silicon ultrafine powder into the basic solution, and ultrasonically dispersing for 100min to prepare the composite electrolyte with good stability, dispersibility and fluidity;
5.4 heating the composite electrolyte to 90 ℃, and continuously stirring;
5.5 applying 1000V pulse voltage with current density of 40000A/m to both ends of the electrolytic bath by using a stainless steel plate or a stainless steel pool as a cathode and an aluminum alloy as an anode2Preparing a coating for 50min by using strong pulse high-frequency discharge reaction/auxiliary crosslinking curing at the solution temperature of 90 ℃ under the stirring condition to obtain a multi-layer coating formed on the surface of an aluminum alloy substrate;
and 5.6, carrying out heat curing treatment on the multilayer coating at 210 ℃ to obtain the composite coating formed on the surface of the aluminum alloy substrate.
The thickness of the composite coating on the surface of the aluminum alloy prepared by the embodiment can reach 70 micrometers, the thickness of the polymer layer can reach 40-50 micrometers, the composite coating has excellent super-hydrophobic performance, the static contact angle of the composite coating is larger than 155 degrees, the self-cleaning performance is high, and the composite coating has excellent corrosion resistance.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. A preparation method of a metal surface composite coating is characterized by comprising the following steps:
preparing a composite electrolyte containing low-surface-energy organic nano powder;
controlling the temperature of the composite electrolyte to be 60-90 ℃, and forming a composite coating on the surface of the metal matrix by utilizing a strong pulse high-frequency discharge reaction and auxiliary crosslinking solidification in the composite electrolyte under the pulse voltage of 400-1000V, wherein the composite coating comprises a ceramic layer and a polymer layer.
2. The preparation method of the metal surface composite coating according to claim 1, wherein the mass fraction of the low surface energy organic nano powder in the composite electrolyte is 50-100 g/L.
3. The method for preparing the metal surface composite coating according to claim 1, wherein the reaction time of the strong pulse high-frequency discharge reaction and the auxiliary crosslinking curing on the surface of the metal matrix in the composite electrolyte is 10-50 min.
4. The method for preparing the metal surface composite coating according to claim 1, further comprising the steps of: and carrying out thermal curing treatment on the composite coating, wherein the temperature of the thermal curing treatment is 50-300 ℃.
5. The method for preparing the metal surface composite coating according to claim 1, wherein the low surface energy organic nano powder comprises fluorine-containing resin and organosilane polymer powder.
6. The method for preparing the metal surface composite coating according to any one of claims 1 to 5, wherein the preparation process of the composite electrolyte comprises the following steps:
dissolving sodium silicate, sodium hexametaphosphate, potassium fluoride, a pH regulator and sodium tungstate in water to obtain a basic solution;
and adding the low-surface-energy organic nano powder into the basic solution, and performing ultrasonic dispersion to obtain the composite electrolyte.
7. The method for preparing the metal surface composite coating according to claim 6, wherein the concentration of the sodium silicate is 1-20g/L, the concentration of the sodium hexametaphosphate is 1-20g/L, the concentration of the potassium fluoride is 1-10g/L, the concentration of the pH regulator is 1-10g/L, and the concentration of the sodium tungstate is 1-20 g/L.
8. A modified metal material, which is characterized by comprising a metal substrate and a composite coating prepared by the preparation method of the metal surface composite coating according to any one of claims 1 to 7, wherein a ceramic layer in the composite coating grows on the surface of the metal substrate in situ, and a polymer layer in the composite coating covers the ceramic layer.
9. The modified metallic material of claim 8, wherein the composite coating has a thickness of 60-200 μ ι η.
10. The modified metallic material of claim 8 or 9, wherein the polymer layer thickness comprises more than 50% of the composite coating thickness.
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| CN114957765A (en) * | 2022-06-17 | 2022-08-30 | 哈尔滨工业大学 | Method for coating ceramic layer on surface of resin and resin-based composite material |
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