CN115896763A - Method for preparing Ni/P coating on surface of Al-Mg-Si alloy polar plate - Google Patents
Method for preparing Ni/P coating on surface of Al-Mg-Si alloy polar plate Download PDFInfo
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- CN115896763A CN115896763A CN202211417184.2A CN202211417184A CN115896763A CN 115896763 A CN115896763 A CN 115896763A CN 202211417184 A CN202211417184 A CN 202211417184A CN 115896763 A CN115896763 A CN 115896763A
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Abstract
The invention relates to the field of Al-Mg-Si alloy polar plates, in particular to a method for preparing a Ni/P coating on the surface of an Al-Mg-Si alloy polar plate. The invention firstly generates a hydrophilic surface film on the surface of Al-Mg-Si alloy, deposits a firm and uniform zinc layer in a zinc dipping method through the hydrophilic film, then plates nickel in an alkaline solution, plates a Ni/P layer in an acidic solution, and finally eliminates the hydrophilic film on the surface and reduces the defects in the coating through a heat treatment process. The invention has the advantages that: (1) The existence of a surface film with good hydrophilicity is combined to accelerate the deposition of a zinc coating and a Ni/P coating on the surface of the alloy; (2) The hydrophilic film on the surface is eliminated and the defects in the coating are reduced by carrying out heat treatment in a vacuum environment, so that the Ni/P coating which is flat, bright, compact, uniform, firm and corrosion-resistant is prepared; (3) The method has the advantages of simple process, low energy consumption, low cost and great practical and popularization value.
Description
Technical Field
The invention relates to the field of Al-Mg-Si alloy polar plates, in particular to a method for preparing a Ni/P coating on the surface of an Al-Mg-Si alloy polar plate.
Background
In the 21 st century, the traditional steel materials can not fully meet the use requirements of human beings, and light materials similar to aluminum alloy are produced. Aluminum and aluminum alloy are light metal materials with the largest usage amount in nonferrous metals and the widest application range, and have more excellent physical, chemical, mechanical and processing properties and characteristics, such as low density, corrosion resistance, good electric conductivity, easy strengthening, easy surface treatment and the like. However, as the use requirements of the manufacturing industry for materials become higher and higher, people have higher standards for the use performance of the materials. In recent years and even decades, aluminum and aluminum alloys have been widely used in the aerospace, automotive, electronic, and household appliance industries after being treated by various surface treatment techniques.
The Ni/P alloy chemically plated on the surface of the aluminum-based material is a better surface treatment process at present, and the obtained plating layer has the advantages of corrosion resistance, high surface hardness, wear resistance and the like, and has decoration, so that the service life of the aluminum-based material can be prolonged, and the application range of the aluminum-based material is expanded. However, aluminum and its alloys are metals that are difficult to plate, mainly for the following reasons: 1) The coating has high affinity to oxygen, and an oxide film is easily formed on the surface of the coating when the coating is in contact with air, so that the binding force of the coating is seriously influenced; 2) The metal (nickel) ion exchange membrane has lower standard potential and stronger electronegativity, so that the metal (nickel) ion exchange membrane can quickly generate a displacement reaction with metal (nickel) ions with higher positive potential in plating solution; 3) Due to the occurrence of the displacement reaction, aluminum ions become impurity ions to enter the plating solution, and the stability of the plating solution is influenced.
In publication No. CN111364030A entitled "pretreatment method for improving flatness of electroless NiP plating on aluminum substrate", the surface of aluminum substrate is pretreated by degreasing and pickling processes, and then soaked in Cu-containing solution 2+ In the acid solution, a thin copper film is firstly prepared on the surface of aluminum to become an active point during zinc dipping, and then secondary zinc dipping is adopted to prepare a fine and uniform zinc layer on the surface of a substrate, so that N with obviously improved flatness is obtained after chemical platingi/P plating. Although the process is simple and low cost, the aluminum is dipped in the Cu-containing alloy 2+ The acid solution of (2) may generate an uneven Al-Cu phase on the surface of aluminum, and the uneven Al-Cu phase may become a cathode phase of galvanic corrosion in the acid solution, so that a plurality of corrosion pits are formed on the surface of the alloy, and finally, the surface of the plating layer may be uneven. In the publication No. CN108034932A, entitled "a process method for chemically plating nickel and phosphorus on the surface of 7A19 aluminum alloy material", a secondary zinc dipping method is adopted to carry out chemical plating of Ni/P on the surface of 7A19 aluminum alloy, the prepared Ni/P plating layer has good bonding force with a substrate, and the plating layer not only has high brightness, but also has compact and uniform crystallization. However, under the conditions of 86-88 ℃ and pH 4.4-4.6, the alloy needs to be plated for 2-5 h in chemical nickel-phosphorus plating solution, and the process flow of secondary galvanizing is more burdensome than that of primary galvanizing.
Disclosure of Invention
The technical problem to be solved by the invention is to solve the defects of the prior art, and the invention aims to provide a method for preparing a Ni/P coating on the surface of an Al-Mg-Si alloy pole plate, which accelerates the deposition of a Ni/P coating on the alloy surface by combining the existence of a surface film with good hydrophilicity, and finally removes the hydrophilic film and reduces the defects in the coating by carrying out heat treatment in a vacuum environment. The method has the advantages of simple process, low cost, mild reaction conditions and the like, and has great practical and popularization values.
The technical scheme adopted by the invention is as follows:
a method for preparing a Ni/P coating on the surface of an Al-Mg-Si alloy polar plate specifically comprises the following steps:
(8) Preparing materials: the Al-Mg-Si alloy polar plate comprises the following elements in percentage by weight: 0.8 to 1.2 wt% of Mg, 0.4 to 0.8 wt% of Si, and the balance of Al and unavoidable impurities.
(9) Removing oil and impurities from the polar plate: sequentially polishing the polar plates by using sand paper of 400#, 1000#, 2000#, and 5000#, sequentially ultrasonically cleaning the aluminum alloy plates in ethanol and acetone for 5-10 min, ultrasonically cleaning the aluminum alloy plates by using deionized water for 5-10 min, finally corroding the aluminum alloy plates by using 10% NaOH solution at the temperature of 50-70 ℃ for 1-2 min to remove surface oxidation films, and placing the aluminum alloy plates in a vacuum drying box for later use.
(10) Solution preparation: 1) Hydrophilic membrane mixed solution: 1.0-1.5 g/L of polyvinyl alcohol, 0.15-0.25 g/L of glyoxal and the balance of deionized water. 2) Zinc dipping solution: 100-150 g/L NaOH, 8-12 g/L ZnO, 8-12 g/L NiCl 2 1-1.5 g/L FeCl 3 1-1.2 g/L of NaNO 2 A proper amount of complexing agent and the balance of deionized water. 3) Alkaline nickel leaching solution: 20-30 g/L of nickel sulfate, 20-30 g/L of sodium hypophosphite and 40-60 g/L of ammonium citrate, and the PH value is adjusted to 9-11. 4) Acid Ni/P plating solution: 250-300g/L of nickel sulfate, 30-40 g/L of nickel chloride, 300-400 g/L of sodium hypophosphite, 40-50 g/L of citric acid, 1.5-2.5 g/L of benzenesulfonic acid main brightener, a proper amount of organic phosphate complexing agent and the balance of deionized water, and the PH is adjusted to 4.5-5.
(11) Zinc dipping on the surface layer: soaking the polar plate after deoiling and impurity removal in a hydrophilic film solution for 30-60 s to generate a thin hydrophilic film on the surface of the polar plate. And (3) placing the polar plate with the hydrophilic film into a zinc dipping solution for 60-90 s to deposit a uniform and fine zinc layer on the surface, then washing the surface with deionized water at 75-85 ℃, and then washing with cold deionized water.
(12) Alkaline nickel leaching: and (3) soaking the zinc-dipped pole plate in an alkaline nickel dipping solution for 3-5 min, keeping the temperature at 30-50 ℃, then washing the surface with deionized water at 75-85 ℃, and then washing with cold deionized water.
(13) Chemical nickel plating: immersing the polar plate after being dipped with nickel in the hydrophilic film solution for 30-60 min to generate a thin hydrophilic film on the surface of the polar plate, and then chemically plating nickel on the polar plate in the acidic Ni/P plating solution for 60-90 min at the temperature of 75-85 ℃.
(14) And (3) heat treatment: finally, the pole plate is annealed for 120-180 min at 300-350 ℃ in vacuum to remove the hydrophilic film and reduce the defects in the coating, so as to prepare the Al-Mg-Si alloy pole plate with the uniform and bright Ni/P coating.
Compared with the prior art, the invention has the beneficial effects that:
the invention firstly generates a hydrophilic surface film on the surface of Al-Mg-Si alloy, a firm and uniform zinc layer is deposited in a zinc dipping method through the hydrophilic film, then nickel is plated in an alkaline solution, then a Ni/P layer is plated in an acidic solution, and finally the hydrophilic film on the surface is eliminated and the defects in the coating are reduced through a heat treatment process. The invention has the following uniqueness: (1) The deposition of the zinc coating and the Ni/P coating on the alloy surface is accelerated by combining the existence of the surface film with good hydrophilicity; (2) The hydrophilic film on the surface is eliminated and the defects in the coating are reduced by carrying out heat treatment in a vacuum environment, so that the Ni/P coating which is flat, bright, compact, uniform, firm and corrosion-resistant is prepared; (3) The method has the advantages of simple process, low energy consumption, low cost and great practical and popularization value.
Detailed Description
The invention will be further illustrated by the following examples.
Example 1.
(1) Preparing materials: the Al-Mg-Si alloy polar plate comprises the following elements in percentage by weight: the content of Mg element was 0.8wt.%, the content of Si element was 0.6wt.%, and the balance was Al and inevitable impurities.
(2) Removing oil and impurities from the polar plate: sequentially polishing the polar plates by using 400#, 1000#, 2000#, and 5000# abrasive paper, sequentially ultrasonically cleaning the aluminum alloy plates in ethanol and acetone for 10min, ultrasonically cleaning the aluminum alloy plates by using deionized water for 5min, finally corroding the aluminum alloy plates by using 10% NaOH solution at the temperature of 60 ℃ for 2min to remove surface oxidation films, and placing the aluminum alloy plates in a vacuum drying oven for later use.
(3) Solution preparation: 1) Hydrophilic membrane mixed solution: 1.5g/L of polyvinyl alcohol, 0.25g/L of glyoxal and the balance of deionized water. 2) Zinc dipping solution: 140g/L NaOH, 12g/L ZnO, 10g/L NiCl 2 1.3g/L FeCl 3 1.1g/L NaNO 2 A proper amount of complexing agent and the balance of deionized water. 3) Alkaline nickel leaching solution: 30g/L of nickel sulfate, 30g/L of sodium hypophosphite and 60g/L of ammonium citrate, and the pH value is adjusted to be 11. 4) Acid Ni/P plating solution: 300g/L of nickel sulfate, 40g/L of nickel chloride, 400g/L of sodium hypophosphite, 50g/L of citric acid, 1.5g/L of benzenesulfonic acid main brightener, a proper amount of organic phosphate complexing agent and the balance of deionized waterAdding water, and adjusting the pH value to be 4.8.
(4) Zinc dipping on the surface layer: and soaking the polar plate after deoiling and impurity removal in a hydrophilic film solution for 40s to generate a thin hydrophilic film on the surface of the polar plate. And (3) putting the polar plate with the hydrophilic film into a zinc dipping solution for 75s, depositing a uniform and fine zinc layer on the surface of the polar plate, washing the surface with deionized water at 85 ℃, and then washing with cold deionized water.
(5) Alkaline nickel leaching: and (3) soaking the plate subjected to zinc dipping in an alkaline nickel dipping solution for 3min, keeping the temperature at 40 ℃, then washing the surface with deionized water at 75 ℃, and then washing with cold deionized water.
(6) Chemical nickel plating: immersing the polar plate after being dipped with nickel in the hydrophilic film solution for 40min to generate a thin hydrophilic film on the surface of the polar plate, and then chemically plating nickel on the polar plate in the acid Ni/P plating solution for 80min at the temperature of 75 ℃.
(7) And (3) heat treatment: finally, the plate was annealed at 320 ℃ in vacuum for 160min to remove the hydrophilic film and reduce defects in the coating to produce an Al-Mg-Si alloy plate with a uniform bright Ni/P coating.
Under the conditions, the prepared coating is flat, bright, compact and uniform, the coating does not peel off, and the substrate is not corroded after being soaked in a 10-percent NaOH solution for 10 hours.
Example 2.
(1) Preparing materials: the Al-Mg-Si alloy polar plate comprises the following elements in percentage by weight: the content of Mg element is 1.0wt.%, the content of Si element is 0.6wt.%, and the balance is Al and unavoidable impurities.
(2) Removing oil and impurities from the polar plate: sequentially polishing the polar plate with 400#, 1000#, 2000#, and 5000# sandpaper, sequentially ultrasonically cleaning the aluminum alloy plate in ethanol and acetone for 8min, ultrasonically cleaning with deionized water for 6min, finally corroding with 10% NaOH solution at 65 ℃ for 1min to remove the surface oxidation film, and placing in a vacuum drying oven for later use.
(3) Solution preparation: 1) Hydrophilic membrane mixed solution: 1.2g/L of polyvinyl alcohol, 0.2g/L of glyoxal and the balance of deionized water. 2) Zinc dipping solution: 110g/L NaOH, 12g/L ZnO, 10g/L NiCl 2 、1.4g/L FeCl 3 1.0g/L of NaNO 2 A proper amount of complexing agent and the balance of deionized water. 3) Alkaline nickel leaching solution: 24g/L of nickel sulfate, 23g/L of sodium hypophosphite and 45g/L of ammonium citrate, and the pH value is adjusted to be 10. 4) Acid Ni/P plating solution: 270g/L of nickel sulfate, 35g/L of nickel chloride, 320g/L of sodium hypophosphite, 50g/L of citric acid, 2.0g/L of benzenesulfonic acid main brightener, a proper amount of organic phosphate complexing agent and the balance of deionized water, and the pH is adjusted to be 4.6.
(4) Zinc dipping on the surface layer: and soaking the polar plate after deoiling and impurity removal in a hydrophilic film solution for 45s to generate a thin hydrophilic film on the surface of the polar plate. And (3) placing the polar plate with the hydrophilic film into a zinc dipping solution for 80s to ensure that a uniform and fine zinc layer is deposited on the surface of the polar plate, and then washing the surface by using deionized water at the temperature of 80 ℃ and then washing by using cold deionized water.
(5) Alkaline nickel leaching: and (3) soaking the plate after zinc dipping in an alkaline nickel dipping solution for 4min, keeping the temperature at 40 ℃, then washing the surface with deionized water at 80 ℃, and then washing with cold deionized water.
(6) Chemical nickel plating: immersing the polar plate after being dipped with nickel in the hydrophilic film solution for 45min to generate a thin hydrophilic film on the surface of the polar plate, and then chemically plating nickel on the polar plate in the acidic Ni/P plating solution for 80min at the temperature of 85 ℃.
(7) And (3) heat treatment: finally, the plate is annealed at 350 ℃ for 120min in vacuum to remove the hydrophilic film and reduce the defects in the coating, so as to prepare the Al-Mg-Si alloy plate with the uniform bright Ni/P coating.
Under the conditions, the prepared coating is flat, bright, compact and uniform, the coating does not peel off, and the substrate is not corroded after being soaked in a 10-percent NaOH solution for 10 hours.
Example 3.
(1) Preparing materials: the Al-Mg-Si alloy polar plate comprises the following elements in percentage by weight: the content of Mg element was 1.2wt.%, the content of Si element was 0.8wt.%, and the balance was Al and inevitable impurities.
(2) Removing oil and impurities from the polar plate: sequentially polishing the polar plates by using 400#, 1000#, 2000#, and 5000# abrasive paper, sequentially ultrasonically cleaning the aluminum alloy plates in ethanol and acetone for 6min, ultrasonically cleaning the aluminum alloy plates by using deionized water for 8min, finally corroding the aluminum alloy plates by using 10% NaOH solution at the temperature of 65 ℃ for 1.5min to remove surface oxidation films, and placing the aluminum alloy plates in a vacuum drying oven for later use.
(3) Solution preparation: 1) Hydrophilic membrane mixed solution: 1.0g/L of polyvinyl alcohol, 0.15/L of glyoxal and the balance of deionized water. 2) Zinc dipping solution: 120g/L NaOH, 10g/L ZnO, 9g/L NiCl 2 1.2g/L FeCl 3 1.2g/L of NaNO 2 A proper amount of complexing agent and the balance of deionized water. 3) Alkaline nickel leaching solution: 25g/L of nickel sulfate, 26g/L of sodium hypophosphite and 52g/L of ammonium citrate, and the pH value is adjusted to be 11. 4) Acid Ni/P plating solution: the pH value is adjusted to 4.9 by using the following raw materials, wherein the raw materials comprise 280g/L of nickel sulfate, 35g/L of nickel chloride, 330g/L of sodium hypophosphite, 45g/L of citric acid, 1.8g/L of benzenesulfonic acid main brightener, a proper amount of organic phosphate complexing agent and the balance of deionized water.
(4) Zinc dipping on the surface layer: and soaking the polar plate after deoiling and impurity removal in a hydrophilic film solution for 50s to generate a thin hydrophilic film on the surface of the polar plate. And (3) putting the polar plate with the hydrophilic film into a zinc dipping solution for 90s, depositing a uniform and fine zinc layer on the surface of the polar plate, washing the surface with deionized water at 75 ℃, and then washing with cold deionized water.
(5) Alkaline nickel leaching: and (3) soaking the zinc-dipped pole plate in an alkaline nickel dipping solution for 5min, keeping the temperature at 30-50 ℃, then washing the surface with deionized water at 75 ℃, and then washing with cold deionized water.
(6) Chemical nickel plating: immersing the polar plate after being dipped with nickel in the hydrophilic film solution for 30min to generate a thin hydrophilic film on the surface of the polar plate, and then chemically plating nickel on the polar plate in the acidic Ni/P plating solution for 90min at the temperature of 80 ℃.
(7) And (3) heat treatment: finally, the plate is annealed in vacuum at 300 ℃ for 180min to remove the hydrophilic film and reduce the defects in the coating, so as to prepare the Al-Mg-Si alloy plate with the uniform bright Ni/P coating.
Under the conditions, the prepared coating is flat, bright, compact and uniform, the coating does not peel off, and the substrate is not corroded after being soaked in a 10-percent NaOH solution for 10 hours.
The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (1)
1. A method for preparing a Ni/P coating on the surface of an Al-Mg-Si alloy polar plate is characterized by comprising the following steps:
(1) Preparing materials: the Al-Mg-Si alloy polar plate comprises the following elements in percentage by weight: the percentage of Mg element is 0.8-1.2 wt.%, the percentage of Si element is 0.4-0.8 wt.%, and the balance is Al and inevitable impurities;
(2) Removing oil and impurities from the polar plate: sequentially polishing a polar plate by using sand paper of No. 400, no. 1000, no. 2000 and No. 5000, sequentially ultrasonically cleaning an aluminum alloy plate in ethanol and acetone for 5-10 min, ultrasonically cleaning the aluminum alloy plate by using deionized water for 5-10 min, finally corroding the aluminum alloy plate by using 10% NaOH solution at the temperature of 50-70 ℃ for 1-2 min to remove a surface oxidation film, and placing the aluminum alloy plate in a vacuum drying box for later use;
(3) Solution preparation: 1) Hydrophilic membrane mixed solution: 1.0-1.5 g/L of polyvinyl alcohol, 0.15-0.25 g/L of glyoxal and the balance of deionized water; 2) Zinc dipping solution: 100-150 g/L NaOH, 8-12 g/L ZnO, 8-12 g/L NiCl 2 1-1.5 g/L% FeCl 3 1-1.2 g/L of NaNO 2 A proper amount of complexing agent and the balance of deionized water; 3) Alkaline nickel leaching solution: 20-30 g/L of nickel sulfate, 20-30 g/L of sodium hypophosphite and 40-60 g/L of ammonium citrate, and the PH value is adjusted to 9-11; 4) Acid Ni/P plating solution: 250-300g/L of nickel sulfate, 30-40 g/L of nickel chloride, 300-400 g/L of sodium hypophosphite, 40-50 g/L of citric acid, 1.5-2.5 g/L of benzenesulfonic acid main brightener, a proper amount of organic phosphate complexing agent and the balance of deionized water, and the PH is adjusted to 4.5-5;
(4) Zinc dipping on the surface layer: soaking the polar plate after deoiling and impurity removal in a hydrophilic film solution for 30-60 s to generate a layer of hydrophilic film on the surface of the polar plate; placing the polar plate with the hydrophilic film into a zinc dipping solution for 60-90 s to deposit a uniform and fine zinc layer on the surface of the polar plate, then washing the surface with deionized water at 75-85 ℃, and then washing with cold deionized water;
(5) Alkaline nickel leaching: soaking the zinc-dipped polar plate in an alkaline nickel-dipping solution for 3-5 min at the temperature of 30-50 ℃, then washing the surface with deionized water at the temperature of 75-85 ℃, and then washing with cold deionized water;
(6) Chemical nickel plating: immersing the polar plate after being dipped with nickel in a hydrophilic film solution for 30-60 min to generate a thin hydrophilic film on the surface of the polar plate, and then chemically plating nickel on the polar plate in an acidic Ni/P plating solution for 60-90 min at the temperature of 75-85 ℃;
(7) And (3) heat treatment: finally, the pole plate is annealed for 120-180 min at 300-350 ℃ in vacuum to remove the hydrophilic film and reduce the defects in the coating, so as to prepare the Al-Mg-Si alloy pole plate with the uniform and bright Ni/P coating.
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