CN114887858A - Method for preparing conductive anticorrosive coating on surface of magnesium alloy micro-arc oxidation layer - Google Patents
Method for preparing conductive anticorrosive coating on surface of magnesium alloy micro-arc oxidation layer Download PDFInfo
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- CN114887858A CN114887858A CN202210506015.XA CN202210506015A CN114887858A CN 114887858 A CN114887858 A CN 114887858A CN 202210506015 A CN202210506015 A CN 202210506015A CN 114887858 A CN114887858 A CN 114887858A
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- 238000000576 coating method Methods 0.000 title claims abstract description 57
- 239000011248 coating agent Substances 0.000 title claims abstract description 56
- 238000007745 plasma electrolytic oxidation reaction Methods 0.000 title claims abstract description 48
- 229910000861 Mg alloy Inorganic materials 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 34
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000008367 deionised water Substances 0.000 claims abstract description 23
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 23
- 239000003792 electrolyte Substances 0.000 claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
- 239000003822 epoxy resin Substances 0.000 claims abstract description 19
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 19
- 238000004528 spin coating Methods 0.000 claims abstract description 19
- 238000005260 corrosion Methods 0.000 claims abstract description 16
- 239000004020 conductor Substances 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 14
- 230000007797 corrosion Effects 0.000 claims abstract description 13
- 239000004952 Polyamide Substances 0.000 claims abstract description 12
- 238000005498 polishing Methods 0.000 claims abstract description 12
- 229920002647 polyamide Polymers 0.000 claims abstract description 12
- 239000002131 composite material Substances 0.000 claims abstract description 11
- 239000000725 suspension Substances 0.000 claims abstract description 11
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 239000007800 oxidant agent Substances 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 10
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 8
- 239000000178 monomer Substances 0.000 claims abstract description 7
- 239000003973 paint Substances 0.000 claims abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 42
- 239000000243 solution Substances 0.000 claims description 31
- 238000009210 therapy by ultrasound Methods 0.000 claims description 16
- 239000004115 Sodium Silicate Substances 0.000 claims description 11
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 11
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 8
- 239000010935 stainless steel Substances 0.000 claims description 5
- 229910001220 stainless steel Inorganic materials 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- 239000011734 sodium Substances 0.000 claims description 4
- 238000010907 mechanical stirring Methods 0.000 claims description 3
- 239000011253 protective coating Substances 0.000 claims 1
- 239000010410 layer Substances 0.000 description 11
- 238000002360 preparation method Methods 0.000 description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 239000003921 oil Substances 0.000 description 5
- 229910003460 diamond Inorganic materials 0.000 description 4
- 239000010432 diamond Substances 0.000 description 4
- 230000010287 polarization Effects 0.000 description 4
- 239000004744 fabric Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229920002379 silicone rubber Polymers 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D5/12—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain a coating with specific electrical properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
- B05D3/102—Pretreatment of metallic substrates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
-
- 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
- C25D11/30—Anodisation of magnesium or alloys based thereon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2202/00—Metallic substrate
- B05D2202/20—Metallic substrate based on light metals
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- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2350/00—Pretreatment of the substrate
- B05D2350/30—Change of the surface
- B05D2350/33—Roughening
- B05D2350/40—Roughening by adding a porous layer
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- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
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- B05D2504/00—Epoxy polymers
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- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2601/00—Inorganic fillers
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Abstract
The invention discloses a method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer, which comprises the following steps of 1) polishing a magnesium alloy until the surface is bright, and carrying out micro-arc oxidation treatment on an AZ91 magnesium alloy by using a micro-arc oxidation electrolyte; (2) mixing Py monomer with C 6 H 5 SO 3 Adding Na into deionized water or graphene suspension, and dropwise adding an oxidant solution to obtain a PPy conductive material or a PPy/graphene conductive composite material; the oxidant being FeCl 3 (ii) a (3) Dissolving the PPy conductive material or the PPy/graphene composite material, the epoxy resin and the polyamide curing agent in the step (2) in n-butyl alcohol to obtain a conductive anticorrosive paint; (4) and (3) spin-coating the conductive anticorrosive coating in the step (3) on the surface of the micro-arc oxidation layer in the step (1), and drying to obtain the coating. The coating obtained by the invention has certain conductivity and corrosion resistance.
Description
Technical Field
The invention belongs to the field of magnesium alloy surface conductive anticorrosion, and particularly relates to a method for preparing a conductive anticorrosion coating on the surface of a magnesium alloy micro-arc oxidation layer.
Background
Magnesium is the eighth most abundant element in earth crust, and its alloy has attracted attention in the fields of vehicles, spaceflight, biology and electronic products due to its advantages of light weight, high strength-to-weight ratio, good biocompatibility and the like. However, since the standard potential is about-2.363V, corrosion occurs in the atmospheric environment with time, which causes aging of the product and thus limits its use in large quantities. Therefore, it is necessary to surface-treat magnesium alloys to enhance their corrosion resistance.
Micro-arc oxidation belongs to anodic oxidation, an oxide ceramic layer is generated in situ on the surface of the magnesium alloy by locally applying high pressure, the bonding capability with a matrix is good, and the method is a surface treatment mode which is applied more at present. However, in an environment where high voltage is applied, micropores are inevitably generated on the ceramic layer due to an arc discharge effect and gas overflow, and the micropores can provide channels for corrosion products, so that the corrosion of a substrate can be accelerated, and the substrate is not effectively protected for a long time.
Disclosure of Invention
The invention aims to provide a method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer, which has the advantages of simplicity, lower cost and the like.
The invention provides a method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer, which comprises the following steps:
(1) polishing the magnesium alloy until the surface is bright, and carrying out micro-arc oxidation treatment on the AZ91 magnesium alloy by using micro-arc oxidation electrolyte;
(2) mixing Py monomer with C 6 H 5 SO 3 Adding Na into deionized water or graphene suspension, and dropwise adding an oxidant solution to obtain a PPy conductive material or a PPy/graphene conductive composite material; the oxidant being FeCl 3 ，Py：C 6 H 5 SO 3 Na：FeCl 3 The molar ratio is (1-1.5): (0.5-0.75): 2-2.5), the addition amount of the graphene is 10-20wt% of Py;
(3) dissolving 1-2 parts by weight of the PPy conductive material or the PPy/graphene composite material in the step (2), 10-15 parts by weight of epoxy resin and 4-6 parts by weight of polyamide curing agent in 6-10 parts by weight of n-butyl alcohol to obtain a conductive anticorrosive coating;
(4) and (3) spin-coating the conductive anticorrosive coating in the step (3) on the surface of the micro-arc oxidation layer in the step (1), and drying to obtain the coating.
Further, the micro-arc oxidation electrolyte consists of sodium silicate, sodium hydroxide and deionized water, wherein the concentration of the sodium silicate in the micro-arc oxidation electrolyte is 25-35 g/L, and the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte is 1-3 g/L, specifically, the concentration of the sodium silicate in the micro-arc oxidation electrolyte is 30 g/L, and the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte is 2 g/L. And during micro-arc oxidation treatment, treating the magnesium alloy sample as an anode and the stainless steel as a cathode for 10-20 min under a 250V constant-pressure mode to obtain the micro-arc oxidation layer.
Further, the specific process of the step (2) is as follows:
s1, dispersing 1-1.5 g of graphene in 250-300 mL of deionized water, performing ultrasonic treatment for 30-60 min to obtain a graphene suspension,
s2, mixing 0.1 mol to 0.15 mol of Py monomer and 0.05 mol to 0.075 mol of C 6 H 5 SO 3 Adding Na into the graphene suspension or deionized water with the same volume as the graphene suspension, stirring for 20-40 min,
s3, adding 0.2-0.25 mol of FeCl 3 ·6H 2 Adding of OAdding into deionized water to prepare 100-200 ml oxidant solution,
s4, dropwise adding the oxidant solution of S3 into the solution of S2, and after dropwise adding, placing the solution in a thermostat at 0-5 ℃ for standing for 8-12 hours;
and S5, washing the product with a mixed solution of deionized water and absolute ethyl alcohol until the solution is colorless, and drying (drying at 60 ℃ for 20-25 h) to obtain the product.
Further, the specific process of step (3) is as follows:
and (3) mixing the PPy conductive material or the PPy/graphene composite material prepared in the step (2) with n-butyl alcohol, performing ultrasonic treatment for 30-60 min, adding epoxy resin, performing ultrasonic treatment for 5-15 min, then performing mechanical stirring for 40-60 min, adding polyamide, performing ultrasonic treatment at normal temperature for 1-3 min after stirring for 15-45 min at 40-50 ℃, and standing for 20-40 min to obtain the conductive anticorrosive paint, wherein the mass ratio of the PPy conductive material or the PPy/graphene composite material to the n-butyl alcohol to the epoxy resin to the polyamide is 1:6:10: 5. Specifically, the epoxy resin is E-44 and the polyamide is 651.
During spin coating in the step (4), spin coating parameters are as follows: the spin speed is 1000-.
In the step (4), the drying means natural drying at room temperature for five days.
The magnesium alloy is preferably AZ91 magnesium alloy.
The conductive anticorrosive coating prepared by the method. Coating thickness of 50μm~85 μm。
The invention is characterized in that: the conductive anticorrosive coating is prepared on the micro-arc oxidation surface of the insulating porous structure, so that the application of the magnesium alloy in the fields of military electronic products and the like can be expanded. The conductive anticorrosive paint has the advantages of simple preparation process, controllable cost, light weight of the composite material and no influence on the weight reduction effect of the magnesium alloy.
Drawings
FIG. 1 is a scanning electron microscope image of a sample of coated magnesium alloy prepared in examples 1 to 3 of the present invention: (a) example 1; (b) example 2; (c) example 3;
FIG. 2 is a graph showing polarization curves of samples of coated magnesium alloys obtained in examples 1 to 3 of the present invention;
fig. 3 is a graph of the resistivity of samples of coated magnesium alloys produced in inventive examples 1 to 3.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to the drawings and examples, but the scope of the present invention is not limited thereto.
Example 1
A method for preparing a pure epoxy resin coating on the surface of a magnesium alloy micro-arc oxidation layer comprises the following steps:
(1) micro arc oxidation treatment
Cutting AZ91 magnesium alloy into 15 × 15 × 4 mm pieces, and applying 0.25 on one sideμThe polishing agent of the AIPU diamond is polished on the golden velvet cloth made of real velvet until the surface is bright, the other surfaces are sealed by silicon rubber, and then the polishing agent is put into 50 g/L sodium hydroxide solution to remove oil for 30 s. The micro-arc oxidation electrolyte consists of sodium silicate, sodium hydroxide and deionized water, the concentration of the sodium silicate in the micro-arc oxidation electrolyte is 30 g/L, the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte is 2 g/L, a sealed sample is placed in the micro-arc oxidation electrolyte, a magnesium alloy sample is used as an anode, stainless steel is used as a cathode, the voltage is adjusted to be 250V, the duration is 15 min, and the thickness is 4-5μAnd m, taking out the sample, washing the residual electrolyte on the surface by using deionized water, and naturally drying.
(2) Preparation of pure epoxy resin coating
6 g of n-butanol and 10 g of epoxy resin E-44 were placed in a beaker and sonicated for 10 min at a sonication power of 30W and then mechanically stirred for 30 min, then 5 g of polyamide 651 was added and mechanically stirred at 45 ℃ for 20 min, then sonicated at room temperature for 2 min and allowed to stand for 30 min (to remove some bubbles in the solution) to give a pure epoxy resin coating.
(3) Preparation of pure epoxy resin coatings
Placing the AZ91 magnesium alloy obtained in the step (1) on a sample platform of a spin coater, spin-coating the coating prepared in the step (2), dropwise adding the coating with the volume of 0.05-0.08 mL for spin-coating, and repeating the steps for three times to ensure that the thickness of the prepared coating is 58 +/-6μAnd m is selected. Spin coating parameters:the spin speed parameter was 1000 rpm and the spin coating time was 10 s. The resulting coating was dried at room temperature for 5 days.
The sample prepared in example 1 was characterized:
the coating obtained in example 1 was examined for its microtopography using a scanning electron microscope, which is shown in detail in FIG. 1. It can be seen from a in fig. 1 that the epoxy resin is uniformly coated on the surface of the sample, and the coating is flat and has no obvious defects.
The polarization curve of example 1 in 3.5 wt% NaCl solution was tested using RST5200F electrochemical workstation, and it can be seen from FIG. 2 that the self-corrosion potential of the coating was-1.46V and the corrosion current density was 1.54X 10 -5 A·cm -2 。
Example 1 was resistance tested using an ST2643 high resistance tester according to the formulaρ=R×d，RD is the film thickness, and the resistivity is calculatedρThe results are shown in FIG. 3, and it can be seen from FIG. 3 that the resistivity of the sample of example 1 was measured to be 5.76X 10 8 Ω·m。
Example 2
A method for preparing a PPy/EP conductive coating on the surface of a magnesium alloy micro-arc oxidation layer comprises the following steps:
(1) micro arc oxidation treatment
Cutting AZ91 magnesium alloy into 15 × 15 × 4 mm, polishing one surface to remove oil, and processing to obtain 0.25μPolishing the polishing agent of the AIPU diamond on a piece of golden velvet cloth made of real velvet until the surface is bright, sealing other surfaces with silicon rubber, and then putting the polishing agent into 50 g/L sodium hydroxide solution to remove oil for 30 s. The micro-arc oxidation electrolyte consists of sodium silicate, sodium hydroxide and deionized water, the concentration of the sodium silicate and the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte are respectively 30 g/L and 2 g/L, a sealed sample is put into the electrolyte, a magnesium alloy sample is used as an anode, stainless steel is used as a cathode, the voltage is adjusted to be 250V, the duration is 15 min, and the thickness is 4-5μAnd m, taking out the sample, washing the residual electrolyte on the surface by using deionized water, and naturally drying.
(2) Preparation of PPy conductive material
8mL of Py (0.1 mol) monomer and 12g C 6 H 5 SO 3 Na (0.067 mol) was placed in 250 mL deionized water and mechanically stirred for 30 min. FeCl of 1.5 mol/L is prepared 3 ·6H 2 150 mL of O solution. FeCl was added dropwise to Py solution at a rate of 2 s/drop 3 And (3) controlling the solution to be dripped within 40 min, and then placing the solution in a thermostat at 0-5 ℃ for standing for 12 h. And washing the powder product by using a mixed solution of deionized water and absolute ethyl alcohol in a volume ratio of 1:1 until the solution is colorless, and placing the solution in a drying oven at 60 ℃ for drying for 24 hours to obtain the PPy conductive material.
(3) Preparation of EP/PPy conductive coating
And (3) mixing 1 g of the PPy conductive material prepared in the step (2) with 6 g of n-butanol, performing ultrasonic treatment for 60 min, then adding 10 g of epoxy resin E-44, performing ultrasonic treatment for 10 min (the ultrasonic power is 30W, the same applies below), mechanically stirring for 60 min, adding 5 g of polyamide 651, stirring at 45 ℃ for 30 min, performing ultrasonic treatment at normal temperature for 2 min, performing ultrasonic treatment at the ultrasonic power of 30W, and standing for 30 min to obtain the EP/PPy conductive coating.
(4) Preparation of PPy/EP conductive coating
Placing the AZ91 magnesium alloy obtained in the step (1) on a sample platform of a spin coater, spin-coating the coating prepared in the step (3), dropwise adding the coating with the volume of 0.05-0.08 mL for spin-coating, and repeating the steps for three times to ensure that the thickness of the prepared coating is 58 +/-6μAnd m is selected. Spin coating parameters: the spin speed parameter was 1000 rpm, the spin coating time was 10 s, and the resulting coating was dried at room temperature for 5 days.
The sample prepared in example 2 was characterized:
microscopic morphology examination was performed using a scanning electron microscope for example 2, detailed in figure 1. It can be seen from b in fig. 1 that the epoxy resin/PPy is uniformly coated on the surface of the sample, and sporadically distributed PPy particles appear on the surface of the coating, so that the surface of the coating is relatively flat.
The polarization curve of example 2 in 3.5 wt% NaCl solution was tested using RST5200F electrochemical workstation, and it can be seen from FIG. 2 that the self-corrosion potential of the coating was-1.41V and the corrosion current density was 9.85X 10 -8 A·cm -2 The corrosion current density is reduced by nearly three orders of magnitude compared with example 1, and the corrosion resistance is enhanced.
Implemented by using ST2643 high-impedance instrumentExample 2 resistance test was carried out according to the formulaρ=R×d，RD is the film thickness, and the resistivity is calculatedρThe results are shown in FIG. 3, and it can be seen from FIG. 3 that the resistivity of the sample of example 2 was measured to be 3.17X 10 5 Ω · m, a 3-order decrease in resistance compared to example 1.
Example 3
(1) Micro arc oxidation treatment
Cutting AZ91 magnesium alloy into 15 × 15 × 4 mm, polishing one surface to remove oil, and processing to obtain 0.25μPolishing the polishing agent of the AIPU diamond on a piece of golden velvet cloth made of real velvet until the surface is bright, then putting the polished piece of the AIPU diamond on 50 g/L sodium hydroxide solution to remove oil for 30 s, and sealing other surfaces with silicon rubber. The micro-arc oxidation electrolyte consists of sodium silicate, sodium hydroxide and deionized water, the concentration of the sodium silicate and the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte are respectively 30 g/L and 2 g/L, a sealed sample is placed into the electrolyte, a magnesium alloy sample is used as an anode, stainless steel is used as a cathode, the voltage is adjusted to be 250V and lasts for 15 min, the sample is taken out of the electrolyte remained on the surface of the sample washed by the deionized water, and the sample is naturally dried.
(2) Preparation of PPy/graphene conductive material
Adding about 1 g of graphene (scientific research grade single-layer graphene, Kaina carbon new material Co., Ltd.) into 250 mL of deionized water, mechanically stirring for 30 min and performing ultrasonic treatment for 30 min at the ultrasonic power of 30W to obtain a graphene suspension, mixing 8mL of Py monomer and 12g C 6 H 5 SO 3 Na is put into the graphene suspension and mechanically stirred for 30 min. FeCl of 1.5 mol/L is prepared 3 ·6H 2 150 mL of O solution. FeCl was added dropwise to Py solution at a rate of 2 s/drop 3 And (3) controlling the solution to be dripped within 40 min, and then placing the solution in a thermostat at 0-5 ℃ for standing for 12 h. The powder product is washed by a mixed solution of deionized water and absolute ethyl alcohol in a volume ratio of 1:1 until the solution is colorless, and is placed in a drying oven at 60 ℃ for drying for 24 hours.
(3) Preparation of EP/PPy/graphene conductive coating
And (3) mixing 1 g of the PPy/graphene obtained in the step (2) with 6 g of n-butanol, performing ultrasonic treatment for 60 min, adding 10 g of epoxy resin, performing ultrasonic treatment for 10 min, then performing mechanical stirring for 60 min, adding 5 g of polyamide 651, performing stirring at 45 ℃ for 30 min, then performing ultrasonic treatment at normal temperature for 2 min, and standing for 30 min to obtain the EP/PPy/graphene conductive coating.
(4) Preparation of EP/PPy/graphene conductive coating
Placing the AZ91 magnesium alloy obtained in the step (1) on a sample platform of a spin coater, spin-coating the coating prepared in the step (3), dropwise adding the coating with the volume of 0.05-0.08 mL for spin-coating, and repeating the steps for three times to ensure that the thickness of the prepared coating is 76 +/-7μAnd m is selected. Spin coating parameters: the spin speed parameter was 1000 rpm and the spin coating time was 10 s. The resulting coating was dried at room temperature for 5 days.
The sample prepared in example 3 was characterized:
microscopic morphology examination was performed using a scanning electron microscope for example 3, detailed in FIG. 1. It can be seen from c in fig. 1 that the epoxy/PPy/graphene is uniformly coated on the surface of the sample, and there appears sporadically distributed PPy/graphene particles on the surface of the coating, the surface of the coating becomes more complex, and many ravines appear, probably due to the powder being stacked and distributed in layers in the epoxy resin.
The RST5200F electrochemical workstation was used to test the polarization curve of example 3 in 3.5 wt% NaCl solution, and from FIG. 2, it can be seen that the self-corrosion potential of the coating was-1.37V and the corrosion current density was 4.89X 10 -6 A·cm -2 Compared with the embodiment 1, the corrosion current density is reduced by about 1 order of magnitude, and the corrosion resistance is enhanced.
Example 3 was resistance tested using an ST2643 high resistance tester according to the formulaρ=R×d，RD is the film thickness, and the resistivity is calculatedρThe results are shown in FIG. 3, and it can be seen from FIG. 3 that the resistivity of the sample of example 3 was measured to be 4.64X 10 4 Ω · m, a drop in resistance of 4 orders of magnitude compared to example 1.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that are not thought of through the inventive work should be included in the scope of the present invention.
Claims (8)
1. A method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer is characterized by comprising the following steps:
(1) polishing the magnesium alloy until the surface is bright, and carrying out micro-arc oxidation treatment on the AZ91 magnesium alloy by using micro-arc oxidation electrolyte;
(2) mixing Py monomer with C 6 H 5 SO 3 Adding Na into deionized water or graphene suspension, and dropwise adding an oxidant solution to obtain a PPy conductive material or a PPy/graphene conductive composite material; the oxidant being FeCl 3 ，Py：C 6 H 5 SO 3 Na：FeCl 3 The molar ratio is (1-1.5): (0.5-0.75): 2-2.5), the addition amount of the graphene is 10-20wt% of Py;
(3) dissolving 1-2 parts by weight of the PPy conductive material or the PPy/graphene composite material in the step (2), 10-15 parts by weight of epoxy resin and 4-6 parts by weight of polyamide curing agent in 6-10 parts by weight of n-butyl alcohol to obtain a conductive anticorrosive coating;
(4) and (3) spin-coating the conductive anticorrosive coating in the step (3) on the surface of the micro-arc oxidation layer in the step (1), and drying to obtain the coating.
2. The method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer according to claim 1, wherein the micro-arc oxidation electrolyte consists of sodium silicate, sodium hydroxide and deionized water, and the concentration of the sodium silicate and the concentration of the sodium hydroxide in the micro-arc oxidation electrolyte are respectively 30 g/L and 2 g/L.
3. The method for preparing the conductive anticorrosive coating on the surface of the magnesium alloy micro-arc oxidation layer according to claim 1 or 2, characterized in that during micro-arc oxidation treatment, a magnesium alloy sample is used as an anode, stainless steel is used as a cathode, and the micro-arc oxidation layer is obtained after treatment for 10 min to 20 min under a 250V constant voltage mode.
4. The method for preparing the conductive anticorrosive coating on the surface of the magnesium alloy micro-arc oxidation layer according to claim 1, wherein the specific process of the step (2) is as follows:
s1, dispersing 1-1.5 g of graphene in 250-300 mL of deionized water, performing ultrasonic treatment for 30-60 min to obtain a graphene suspension,
s2, mixing 0.1 mol to 0.15 mol of Py monomer and 0.05 mol to 0.075 mol of C 6 H 5 SO 3 Adding Na into the graphene suspension or deionized water with the same volume as the graphene suspension, stirring for 20-40 min,
s3, adding 0.2-0.25 mol of FeCl 3 ·6H 2 Adding O into deionized water to prepare 100-200 ml oxidant solution,
s4, dropwise adding the oxidant solution of S3 into the solution of S2, and after dropwise adding, placing the solution in a thermostat at 0-5 ℃ for standing for 8-12 hours;
and S5, washing the product with a mixed solution of deionized water and absolute ethyl alcohol until the solution is colorless, and drying to obtain the product.
5. The method for preparing the conductive anticorrosive coating on the surface of the magnesium alloy micro-arc oxidation layer according to claim 1, wherein the specific process of the step (3) is as follows:
and (3) mixing the PPy conductive material or the PPy/graphene composite material prepared in the step (2) with n-butyl alcohol, performing ultrasonic treatment for 30-60 min, adding epoxy resin, performing ultrasonic treatment for 5-15 min, then performing mechanical stirring for 40-60 min, adding polyamide, performing ultrasonic treatment at normal temperature for 1-3 min after stirring for 15-45 min at 40-50 ℃, and standing for 20-40 min to obtain the conductive anticorrosive paint, wherein the mass ratio of the PPy conductive material or the PPy/graphene composite material to the n-butyl alcohol to the epoxy resin to the polyamide is 1:6:10: 5.
6. The method for preparing a conductive anticorrosive coating on the surface of a magnesium alloy micro-arc oxidation layer according to claim 1 or 5, wherein the epoxy resin is E-44, and the polyamide is 651.
7. The method for preparing the conductive anticorrosive coating on the surface of the micro-arc oxidation layer of the magnesium alloy according to claim 1, wherein during the spin coating in the step (4), the spin coating parameters are as follows: the spin speed is 1000-.
8. An electrically conductive corrosion protective coating produced by the method of any one of claims 1 to 7.
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| CN115678383A (en) * | 2022-11-08 | 2023-02-03 | 河南大学 | Preparation method and application of magnesium alloy surface photodynamic antibacterial anticorrosive coating |
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