阅读说明：本技术 一种在镁合金表面制备致密电泳涂层的方法 (Method for preparing compact electrophoretic coating on surface of magnesium alloy ) 是由 张萌 闫大帅 王艳力 陈俐蔓 王迪 刘一博 于 2019-11-08 设计创作，主要内容包括：本发明公开一种在镁合金表面制备致密电泳涂层的方法,属于金属材料表面处理领域。具体包括以下步骤：对镁合金进行前处理；对镁合金表面离子液体电镀铝；制备电泳涂料；涂装电泳涂料。在涂装电泳涂层前,利用离子液体电镀的方式在镁合金表面沉积一层铝镀层,在制备的铝镀层上进行电泳涂装,该铝镀层可有效解决镁合金表面电位不均匀以及镁合金在电泳液中容易腐蚀的问题,使得制备的电泳涂层更致密。本发明制作过程简单、高效,对整个实验过程要求不高,且制备出的镁合金表面电泳涂层均匀、致密、平整,可有效的保护镁合金免受腐蚀的危害。进行中性盐雾试验的结果表明,在中性盐雾环境中500h后镁合金表面并没有出现腐蚀,电泳涂层完整无破坏。(The invention discloses a method for preparing a compact electrophoretic coating on the surface of a magnesium alloy, and belongs to the field of surface treatment of metal materials. The method specifically comprises the following steps: pretreating the magnesium alloy; electroplating aluminum on the ionic liquid on the surface of the magnesium alloy; preparing an electrophoretic coating; and (5) coating electrophoretic paint. Before the electrophoretic coating is coated, an aluminum coating is deposited on the surface of the magnesium alloy in an ionic liquid electroplating mode, and electrophoretic coating is carried out on the prepared aluminum coating, so that the problems of uneven surface potential of the magnesium alloy and easy corrosion of the magnesium alloy in an electrophoretic solution can be effectively solved by the aluminum coating, and the prepared electrophoretic coating is more compact. The preparation method disclosed by the invention is simple and efficient in manufacturing process, has low requirements on the whole experimental process, and the prepared electrophoretic coating on the surface of the magnesium alloy is uniform, compact and flat, so that the magnesium alloy can be effectively protected from being damaged by corrosion. The result of the neutral salt spray test shows that the surface of the magnesium alloy is not corroded after 500 hours in a neutral salt spray environment, and the electrophoretic coating is complete and is not damaged.)

1. A method for preparing a compact electrophoretic coating on the surface of a magnesium alloy is characterized by comprising the following steps:

step 1: pretreating the magnesium alloy;

step 2: electroplating aluminum on the ionic liquid on the surface of the magnesium alloy;

and step 3: preparing an electrophoretic coating;

and 4, step 4: and (5) coating electrophoretic paint.

2. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy according to claim 1, wherein the specific steps of the step 1 are as follows:

step (1.1) polishing the magnesium alloy by using 150-mesh, 400-mesh, 800-mesh and 1200-mesh abrasive paper respectively, washing the magnesium alloy by using deionized water, and putting the magnesium alloy into acetone for ultrasonic treatment for 10 minutes;

and (1.2) putting the magnesium alloy into an alkali liquor prepared from sodium hydroxide, anhydrous sodium carbonate and sodium dodecyl benzene sulfonate, and carrying out alkali washing in a water bath environment at 60 ℃.

3. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein the step 2 comprises the following specific steps: preparing AlCl with the molar ratio of 2:1₃A 1-butyl-3-methylimidazole (BMIC) solution, which takes magnesium alloy as a cathode and an aluminum sheet with the purity of 99.99 percent as an anode and adoptsAnd electroplating aluminum by constant current electrodeposition.

4. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein the specific steps of step 3 are as follows: the FY-0216 electrophoresis raw material is continuously stirred at room temperature for 48 hours to finish curing.

5. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein the specific steps of step 4 are as follows:

step (4.1) washing the prepared magnesium alloy covered with the aluminum coating with deionized water and taking the magnesium alloy as a cathode and a graphite electrode as an anode for electrophoretic coating;

and (4.2) washing the magnesium alloy subjected to electrophoresis with deionized water, drying, and curing at the temperature of 170-180 ℃ for 20-25 minutes.

6. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein the concentrations of the sodium hydroxide, the anhydrous sodium carbonate and the sodium dodecyl benzene sulfonate in the step 1 are 50g/L, 15g/L and 2g/L respectively.

7. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein in the step 2, AlCl is prepared₃AlCl when in solution in-1-butyl-3-methylimidazole (BMIC)₃Slowly adding into BMIC and stirring, and performing all operations in a glove box under argon protective atmosphere at room temperature; the distance between the cathode and the anode is 1-2cm, and the current density is 10-15mA/cm²And the deposition time is 30-35 minutes, and after the electroplating is finished, the sample is washed clean by dichloromethane and deionized water and is naturally air-dried.

8. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein the electrophoretic material is stirred by magnetic stirring in step 3.

9. The method for preparing the compact electrophoretic coating on the surface of the magnesium alloy as claimed in claim 1, wherein in the step 4, the area of the graphite electrode is 1/4 of the magnesium alloy electrode, the working voltage is 70-100V, the electrophoresis time is 2-3 minutes, the distance between the cathode and the anode is 4-5cm, the solution temperature is 25-30 ℃, and the baking temperature and the baking time are adjusted according to the electrophoresis parameters.

Technical Field

The invention belongs to the field of surface treatment of metal materials, and particularly relates to a method for preparing a compact electrophoretic coating on the surface of a magnesium alloy.

Background

Magnesium alloys have been widely used in the fields of aerospace, weaponry, engineering materials, biomaterials, etc. due to their characteristics of small density, high strength and specific stiffness, and excellent electrical and thermal conductivity. However, magnesium is relatively active in chemical property, and the magnesium alloy is extremely easy to corrode due to the lower standard electrode potential. Therefore, how to improve the corrosion resistance of magnesium alloy products has become a hot spot of research in recent years.

The electrophoretic coating is an effective means for preventing metal corrosion, and deposits charged coating particles on the surface of a metal workpiece under the action of an electric field force to form a uniform protective film, thereby achieving excellent corrosion resistance. Theoretically, the electrophoretic coating is coated on the surface of the magnesium alloy, so that the magnesium alloy can be well protected from being damaged by corrosion. However, the electrophoretic coating directly coated on the surface of the magnesium alloy is very loose and has many holes due to the reasons that the surface potential of the magnesium alloy is not uniform, the electrophoretic liquid is easy to cause magnesium alloy corrosion and the like, and the magnesium alloy is difficult to be effectively protected.

Therefore, how to solve the problem of compactness of the electrophoretic coating coated on the surface of the magnesium alloy is the key for realizing that the electrophoretic coating protects the magnesium alloy from corrosion. The present invention has been made to solve the above problems.

Disclosure of Invention

The invention aims to provide a method for preparing a compact electrophoretic coating on the surface of a magnesium alloy, which has simple and efficient manufacturing process.

The purpose of the invention is realized by the following technical scheme:

the invention provides a method for depositing an aluminum coating on the surface of a magnesium alloy by using an ionic liquid electroplating mode before coating an electrophoretic coating, and performing electrophoretic coating on the prepared aluminum coating, wherein the aluminum coating can effectively solve the problems of uneven surface potential of the magnesium alloy and easy corrosion of the magnesium alloy in an electrophoretic solution, so that the prepared electrophoretic coating is uniform and compact, and the magnesium alloy is protected from being damaged by corrosion.

A method for preparing a compact electrophoretic coating on the surface of a magnesium alloy specifically comprises the following steps:

step 1, pretreating magnesium alloy. The magnesium alloy is respectively polished by sand paper of 150 meshes, 400 meshes, 800 meshes and 1200 meshes, is washed clean by deionized water and is put into acetone for 10 minutes by ultrasound. Then, the magnesium alloy is put into an alkali solution prepared from sodium hydroxide, anhydrous sodium carbonate and sodium dodecyl benzene sulfonate, and alkali washing is carried out in a water bath environment at the temperature of 60 ℃.

And 2, electroplating aluminum on the surface of the magnesium alloy by using the ionic liquid. Preparing AlCl with the molar ratio of 2:1₃The 1-butyl-3-methylimidazole (BMIC) solution takes magnesium alloy as a cathode, an aluminum sheet with the purity of 99.99 percent as an anode, and the distance between the cathode and the anode is 1-2 cm. Adopting constant current electrodeposition with current density of 10-15mA/cm²And electroplating aluminum for 30-35 min.

And 3, preparing the electrophoretic paint. The FY-0216 electrophoresis raw material is continuously stirred at room temperature for 48 hours to finish curing.

And 4, coating the electrophoretic paint. Washing the prepared magnesium alloy covered with the aluminum plating layer by using deionized water, and using the magnesium alloy as a cathode, a graphite electrode as an anode, working voltage of 70-100V, electrophoresis time of 2-3 minutes, a distance between the cathode and the anode of 4-5cm, and electrophoretic coating at a solution temperature of 25-30 ℃. The magnesium alloy after electrophoresis is washed clean by deionized water, dried and cured for 20-25 minutes at the temperature of 170-180 ℃.

In step 1, the concentrations of sodium hydroxide, anhydrous sodium carbonate and sodium dodecylbenzenesulfonate were 50g/L, 15g/L and 2g/L, respectively.

In step 2, AlCl is prepared₃AlCl when in solution in-1-butyl-3-methylimidazole (BMIC)₃Add slowly to BMIC and stir well, all operations were performed at room temperature in a glove box under an argon atmosphere. And after the electroplating is finished, washing the sample with dichloromethane and deionized water, and naturally drying.

In step 3, the electrophoretic material is stirred by magnetic stirring, and the evaporation of water in the material is noted.

In step 4, the area of the graphite electrode is 1/4 of the magnesium alloy electrode, and the electrophoretic solution attached to the surface of the magnesium alloy after electrophoresis must be washed clean by deionized water.

The invention has the beneficial effects that:

the preparation method is simple and efficient in manufacturing process, has low requirements on the whole experimental process, and the prepared magnesium alloy surface electrophoretic coating is uniform, compact and flat. The experimental data were evaluated as follows:

the electrophoretic coating prepared by the method is compared with the electrophoretic coating prepared by directly carrying out electrophoretic coating on the magnesium alloy for observation. The comparison shows that the electrophoretic coating prepared by directly carrying out electrophoretic coating on the magnesium alloy is very loose and has more holes, and the surface of the magnesium alloy-aluminum plating layer-electrophoretic coating prepared by the method is very compact, uniform and flat.

The neutral salt spray test is carried out on the prepared magnesium alloy-aluminum plating layer-electrophoretic coating, and the result shows that the surface of the magnesium alloy is not corroded after 500 hours in a neutral salt spray environment, and the electrophoretic coating is complete and is not damaged.

Drawings

FIG. 1 shows the surface morphology of a magnesium alloy-aluminum plating-electrophoretic coating (a) (taking example 1 as an example) prepared by the method of the present invention and an electrophoretic coating (b) prepared by direct electrophoretic coating of a magnesium alloy;

FIG. 2 is a surface morphology of a magnesium alloy-aluminum plating-electrophoretic coating after 500 hours in a neutral salt spray environment.

Detailed Description

The following further describes embodiments of the present invention with reference to the accompanying drawings:

the magnesium alloy is AZ 91D; acetone, sodium hydroxide, anhydrous sodium carbonate and sodium dodecylbenzenesulfonate were produced by shinko technology development ltd, Tianjin; AlCl₃Manufactured by the national drug group chemical reagents limited; 1-butyl-3-methylimidazole (BMIC) ionic liquids are manufactured by Linzhoueneng, Inc.; FY-0216 electrophoretic paint is produced by Feiyang paint Co.

A method for preparing a compact electrophoretic coating on the surface of a magnesium alloy specifically comprises the following steps:

step 1: pretreating the magnesium alloy;

step 2: electroplating aluminum on the ionic liquid on the surface of the magnesium alloy;

and step 3: preparing an electrophoretic coating;

and 4, step 4: and (5) coating electrophoretic paint.

The specific steps of the step 1 are as follows:

step (1.1) polishing the magnesium alloy by using 150-mesh, 400-mesh, 800-mesh and 1200-mesh abrasive paper respectively, washing the magnesium alloy by using deionized water, and putting the magnesium alloy into acetone for ultrasonic treatment for 10 minutes;

and (1.2) putting the magnesium alloy into an alkali liquor prepared from sodium hydroxide, anhydrous sodium carbonate and sodium dodecyl benzene sulfonate, and carrying out alkali washing in a water bath environment at 60 ℃.

The specific steps of the step 2 are as follows: preparing AlCl with the molar ratio of 2:1₃The 1-butyl-3-methylimidazole (BMIC) solution is prepared by electroplating aluminum by using a magnesium alloy as a cathode and an aluminum sheet with the purity of 99.99% as an anode through constant-current electrodeposition.

The specific steps of the step 3 are as follows: the FY-0216 electrophoresis raw material is continuously stirred at room temperature for 48 hours to finish curing.

The specific steps of the step 4 are as follows:

step (4.1) washing the prepared magnesium alloy covered with the aluminum coating with deionized water and taking the magnesium alloy as a cathode and a graphite electrode as an anode for electrophoretic coating;

and (4.2) washing the magnesium alloy subjected to electrophoresis with deionized water, drying, and curing at the temperature of 170-180 ℃ for 20-25 minutes.

In step 1, the concentrations of sodium hydroxide, anhydrous sodium carbonate and sodium dodecylbenzenesulfonate were 50g/L, 15g/L and 2g/L, respectively.

In step 2, AlCl is prepared₃AlCl when in solution in-1-butyl-3-methylimidazole (BMIC)₃Slowly adding into BMIC and stirring, and performing all operations in a glove box under argon protective atmosphere at room temperature; the distance between the cathode and the anode is 1-2cm, and the current density is 10-15mA/cm²And the deposition time is 30-35 minutes, and after the electroplating is finished, the sample is washed clean by dichloromethane and deionized water and is naturally air-dried.

In step 3, the electrophoretic raw material is stirred by magnetic stirring.

In step 4, the area of the graphite electrode is 1/4 of the magnesium alloy electrode, the working voltage is 70-100V, the electrophoresis time is 2-3 minutes, the distance between the cathode and the anode is 4-5cm, the solution temperature is 25-30 ℃, and the baking temperature and time are adjusted along with the electrophoresis parameters.