阅读说明：本技术 一种表面多孔镁合金及其制备方法 (Surface porous magnesium alloy and preparation method thereof ) 是由 陈厚文 孔德昊 于 2020-12-21 设计创作，主要内容包括：本发明提供了一种表面多孔镁合金制备方法,包括：将镁合金在处理液中进行处理,得到表面多孔镁合金；所述处理液包括碱金属化合物、螯合剂和水。本发明通过螯合剂-碱共处理法对镁合金的表面进行处理,在镁合金基底上直接制备出耐蚀性多孔结构的表面,提高镁合金表面涂层以及层合材料中的表面结合强度,抑制镁合金的腐蚀行为。本发明还提供了一种表面多孔镁合金。(The invention provides a preparation method of a surface porous magnesium alloy, which comprises the following steps: treating the magnesium alloy in a treatment solution to obtain a surface porous magnesium alloy; the treatment liquid includes an alkali metal compound, a chelating agent, and water. The surface of the magnesium alloy is treated by a chelating agent-alkali co-treatment method, the surface with a corrosion-resistant porous structure is directly prepared on a magnesium alloy substrate, the surface bonding strength of a magnesium alloy surface coating and a laminated material is improved, and the corrosion behavior of the magnesium alloy is inhibited. The invention also provides a surface porous magnesium alloy.)

1. A preparation method of a surface porous magnesium alloy comprises the following steps:

treating the magnesium alloy in a treatment solution to obtain a surface porous magnesium alloy;

the treatment liquid includes an alkali metal compound, a chelating agent, and water.

2. The method according to claim 1, wherein the alkali metal compound is a hydroxide.

3. The method according to claim 1, wherein the concentration of the alkali metal compound in the treatment solution is 2 to 120 g/L.

4. The method according to claim 1, wherein the chelating agent is selected from one or more of a carboxylic acid type chelating agent, an organic polyphosphoric acid, and a polyphosphate.

5. The method according to claim 4, wherein the carboxylic acid type chelating agent is one or more selected from the group consisting of ethylenediaminetetraacetic acid and its sodium salt, nitrilotriacetic acid, diethylenetriaminepentaacetic acid and its salt, citric acid, tartaric acid, gluconic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylglycine, and polycarboxylic acid.

6. The method according to claim 1, wherein the concentration of the chelating agent in the treatment solution is 6 to 530 g/L.

7. The method according to claim 1, wherein the temperature of the treatment is 35-95 ℃; the treatment time is 10-480 min.

8. The method of claim 1, further comprising, after the processing:

and cleaning and drying the treated product to obtain the magnesium alloy with porous surface.

9. The method according to claim 8, wherein the drying temperature is 50-70 ℃; the drying time is 50-70 min.

10. A surface-porous magnesium alloy prepared by the method of claim 1.

Technical Field

The invention belongs to the technical field of magnesium alloy, and particularly relates to a surface porous magnesium alloy and a preparation method thereof.

Background

The magnesium alloy is used as a light structural material, and has wide application prospects in the fields of automobile lightweight, 3C products, electronic communication, aerospace and the like. However, magnesium alloys have poor corrosion resistance, and are used as anodes in most environments to cause galvanic corrosion, which affects the wide application of magnesium alloys. In addition, since the carbon fiber-magnesium alloy laminate, which is a new-generation fiber metal laminate material, has a large potential difference (about 1.8V) between carbon fiber and magnesium alloy, interlayer electrochemical corrosion is easily generated during long-term use, thereby limiting the application thereof.

To solve these problems, the main treatment methods for the surface of magnesium alloy at present are: sand blasting, anodic oxidation, micro-arc oxidation and the like. The sand blasting treatment can improve the adhesion performance of the coating material and the laminated material with the surface of the magnesium alloy, but does not play an effective role in inhibiting the corrosion of the magnesium alloy in the use environment. The advantages of good surface bonding strength and corrosion resistance are considered in both anodic oxidation and micro-arc oxidation, but the methods have requirements on equipment, high energy consumption and environmental pollution; in addition, the bonding force between the oxide film and the substrate is low, and the film has the defects of hard brittleness, poor bending resistance and the like.

Disclosure of Invention

In view of the above, the present invention provides a surface porous magnesium alloy and a preparation method thereof, and the surface porous magnesium alloy prepared by the present invention has a porous structure and a better corrosion resistance.

The invention provides a preparation method of a surface porous magnesium alloy, which comprises the following steps:

treating the magnesium alloy in a treatment solution to obtain a surface porous magnesium alloy;

the treatment liquid includes an alkali metal compound, a chelating agent, and water.

Preferably, the alkali metal compound is a hydroxide.

Preferably, the concentration of the alkali metal compound in the treatment liquid is 2-120 g/L.

Preferably, the chelating agent is selected from one or more of carboxylic acid type chelating agent, organic polyphosphoric acid and polyphosphate.

Preferably, the carboxylic acid type chelating agent is one or more selected from ethylenediamine tetraacetic acid and sodium salts thereof, nitrilotriacetic acid, diethylenetriamine pentaacetic acid and salts thereof, citric acid, tartaric acid, gluconic acid, hydroxyethyl ethylenediamine triacetic acid, dihydroxyethyl glycine and polycarboxylic acids.

Preferably, the concentration of the chelating agent in the treatment liquid is 6-530 g/L.

Preferably, the treatment temperature is 35-95 ℃; the treatment time is 10-480 min.

Preferably, after the treatment, the method further comprises:

and cleaning and drying the treated product to obtain the magnesium alloy with porous surface.

Preferably, the drying temperature is 50-70 ℃; the drying time is 50-70 min.

The invention provides a surface porous magnesium alloy prepared by the method in the technical scheme.

The invention prepares the corrosion-resistant porous structure on the surface of the magnesium alloy by using a chelating agent-alkali co-treatment method, improves the bonding strength between the coating material and the laminated material and the surface of the magnesium alloy, has certain corrosion resistance and inhibits the corrosion behavior among the components. The method comprises the steps of carrying out alkali cleaning and oil removal on the surface of the magnesium alloy, then placing the magnesium alloy in a chelating agent-alkali co-treatment solution for treatment, and washing and drying to obtain the magnesium alloy with excellent corrosion resistance and porous structure surface. The method can directly carry out surface treatment on the magnesium alloy without removing the oxide film on the surface of the magnesium alloy in advance; for workpieces without greasy dirt on the surface, alkali washing and oil removal can be omitted, compared with the traditional magnesium alloy surface treatment mode, the preparation process is reduced, energy is saved, consumption is reduced, and the preparation cost is reduced. The method provided by the invention has the advantages of simple preparation process and low cost, the prepared magnesium alloy has uniform and compact surface pore structure, good corrosion resistance and the like, and the porous surface is obtained by etching on a magnesium alloy substrate, so that the problems of low bonding strength, hardness, brittleness and the like of a magnesium alloy chemical conversion film and the substrate are solved. The invention has practical value significance for the industrial application of the magnesium alloy.

The surface of the magnesium alloy is treated by a chelating agent-alkali co-treatment method, the surface with a corrosion-resistant porous structure is directly prepared on a magnesium alloy substrate, the surface bonding strength of a magnesium alloy surface coating and a laminated material is improved, and the corrosion behavior of the magnesium alloy is inhibited.

Drawings

FIG. 1 is a flow chart of a process for preparing a surface porous magnesium alloy according to an embodiment of the present invention;

FIG. 2 is a microstructure morphology diagram of a magnesium alloy with porous surface prepared by the embodiment of the invention;

FIG. 3 is an X-ray diffraction pattern of the surface porous magnesium alloy in example 1 of the present invention;

FIG. 4 is an electrochemical polarization curve of the surface porous magnesium alloy in example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.

The preparation method of the surface porous magnesium alloy provided by the embodiment of the invention is shown in figure 1, and the preparation method of the surface porous magnesium alloy provided by the invention comprises the following steps:

treating the magnesium alloy in a treatment solution to obtain a surface porous magnesium alloy;

the treatment liquid includes an alkali metal compound, a chelating agent, and water.

The shape of the magnesium alloy is not particularly limited, and a person skilled in the art can select the magnesium alloy with a required shape according to actual needs, for example, the magnesium alloy can be a plate, a bar, a pipe, a special-shaped member and other structural members.

The invention is not limited to the components of the magnesium alloy, and those skilled in the art can select a magnesium alloy with a suitable composition according to actual needs, for example, an AZ31 magnesium alloy can be used.

In the present invention, the magnesium alloy is preferably subjected to a pretreatment before being subjected to a treatment, and the pretreatment method preferably includes:

and (3) polishing the magnesium alloy by using sand paper and/or washing the magnesium alloy by using alkali to remove oil.

In the present invention, the water is preferably deionized water.

In the present invention, the alkali metal compound is preferably a hydroxide, more preferably sodium hydroxide and/or potassium hydroxide.

In the invention, the concentration of the alkali metal compound in the treatment liquid is preferably 2-120 g/L, more preferably 5-100 g/L, more preferably 10-80 g/L, more preferably 20-60 g/L, and most preferably 30-50 g/L.

In the invention, the chelating agent can be one or a mixture of several organic chelating agents, such as a carboxylic acid type chelating agent, specifically, ethylenediaminetetraacetic acid (EDTA) and sodium salt thereof, nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid and salt thereof; hydroxycarboxylic acid chelating agents such as Citric Acid (CA), Tartaric Acid (TA), Gluconic Acid (GA), and the like; hydroxylamino carboxylic acid chelating agents such as hydroxyethylethylenediaminetriacetic acid (HEDTA), and Dihydroxyethylglycine (DEG), and the like; chelating agents such as organic polyphosphonic acids and polycarboxylic acids; inorganic metal ion chelating agents such as polyphosphates and the like, preferably EDTA-2Na (disodium ethylenediaminetetraacetate), may also be used.

In the invention, the concentration of the chelating agent in the treatment liquid is preferably 6-530 g/L, more preferably 10-500 g/L, more preferably 50-400 g/L, more preferably 100-300 g/L, and most preferably 150-250 g/L.

Chelating agents, also known as complexing agents, contain two or more coordinating atoms and are capable of chelating metal ions to form stable water-soluble complexes, as exemplified by the commonly used EDTA: EDTA is a chelating agent for six ligands with chelating Mg²⁺The ability to plasma metal ions. Generally, EDTA is available in seven different forms in aqueous solutions of different pH values: h₆Y²⁺、H₅Y⁺、H₄Y、H₃Y^-、H₂Y^2-、HY^3-And Y^4-. Ion Y^4-Is a ligand and has the strongest complexation. The greater the ion concentration, the more stable the complex, and when the solution pH is greater than 10, the ion Y^4-Will dominate. In the present invention, the pH of the hot alkali solution is about 13.3, so that EDTA may be HY^3-And Y^4-In the form of (1), in which case EDTA will absorb and react with Mg²⁺Complexing to dissolve the magnesium matrix and generate a porous corrosion pit on the surface; at this point more Mg is present on the surface of the magnesium matrix and in the solution²⁺Promoting the formation of magnesium hydroxide on the surface of the substrate, wherein the chemical reaction formula is as follows:

Mg→Mg^2-+2e^- (1)

Mg²⁺+Y^4-→MgY^2- (2)

2H₂O+2e^-→2OH^-+H₂↑ (3)

Mg²⁺+2OH^-→Mg(OH)₂↓ (4)

EDTA is insoluble in water, and hydroxide is added to react with EDTA to promote the dissolution; EDTA vs. Mg on the other hand²⁺The addition of hydroxide can slow down the reaction rate; the study shows that EDTA and Mg²⁺The complexation of (A) takes place in the initial stage of the reaction, with the reaction time extending, Mg (OH)₂The layer will cover MgY^2-Layer, thereby forming Mg (OH) on the surface of the magnesium alloy₂The porous structure of the film further increases the surface roughness of the magnesium alloy and simultaneously has excellent corrosion resistance.

In the invention, the treatment temperature is preferably 35-95 ℃, more preferably 40-90 ℃, more preferably 50-80 ℃, and most preferably 60-70 ℃; the treatment time is preferably 10-480 min, more preferably 15-400 min, more preferably 20-150 min, and most preferably 30-90 min.

In the present invention, the method further comprises, after the treatment:

and cleaning and drying the treated product to obtain the magnesium alloy with porous surface.

In the present invention, the cleaning method is preferably ultrasonic cleaning.

In the invention, the drying is preferably carried out in an air drying box, and the drying temperature is preferably 50-70 ℃, more preferably 55-65 ℃, and most preferably 60 ℃; the drying time is preferably 50-70 min, more preferably 55-65 min, and most preferably 60 min.

The surface of the corrosion-resistant porous structure is prepared on the surface of the magnesium alloy by the alkali-chelating agent co-processing method, so that the bonding strength of the coating material and the laminated material with the surface of the magnesium alloy is effectively improved, the corrosion behavior of the magnesium alloy is inhibited, and the method has practical value significance for the industrial application of the magnesium alloy.

The invention provides a surface porous magnesium alloy prepared by the method in the technical scheme.

The corrosion-resistant surface with a porous structure is prepared on the surface of the magnesium alloy by a chelating agent-alkali co-treatment method, the porous structure is favorable for the infiltration of a coating material and an adhesive, and a meshing type mechanical bolt lock structure is formed on the surface of the magnesium alloy, so that better bonding strength is obtained, and the corrosion resistance of the corrosion-resistant surface is favorable for inhibiting the corrosion behavior of the magnesium alloy in a use environment. The method provided by the invention has the advantages of simple process and low cost, can improve the bonding performance of the magnesium alloy surface coating, inhibits the corrosion resistance behavior of the magnesium alloy, and has practical value significance for the industrial application of the magnesium alloy.

In the following examples of the present invention, the raw materials used were commercially available, and the magnesium alloy used was AZ31B commercial magnesium alloy.

Example 1

Pretreatment: washing the magnesium alloy with alkali to remove oil to obtain a pretreated magnesium alloy;

chelating agent-alkali co-treatment: weighing 4g of NaOH and 15g of EDTA-2Na, adding into 100mL of deionized water, and stirring for dissolving to obtain a treatment solution; then, the pretreated magnesium alloy is put into a treatment fluid for treatment, the treatment temperature is 80 ℃, and the treatment time is 60 min;

cleaning and drying: and (3) carrying out ultrasonic cleaning on the treated magnesium alloy, placing the magnesium alloy in an air drying box after cleaning, and drying for 60min at the temperature of 60 ℃ to obtain the surface porous magnesium alloy.

The surface morphology of the surface porous magnesium alloy in the embodiment 1 of the present invention is detected by a characterization method of a scanning electron microscope, and the detection result shows that the surface of the magnesium alloy is a porous structure, as shown in a in fig. 2.

Example 2

Pretreatment: washing the magnesium alloy with alkali to remove oil to obtain a pretreated magnesium alloy;

chelating agent-alkali co-treatment: weighing 0.2g of NaOH and 6g of EDTA-2Na, adding into 100mL of deionized water, and stirring for dissolving to obtain a treatment solution; then, the pretreated magnesium alloy is put into a treatment fluid for treatment, the treatment temperature is 90 ℃, and the treatment time is 30 min;

cleaning and drying: and (3) carrying out ultrasonic cleaning on the treated magnesium alloy, placing the magnesium alloy in an air drying box after cleaning, and drying for 60min at the temperature of 60 ℃ to obtain the surface porous magnesium alloy.

The surface morphology of the surface porous magnesium alloy prepared in example 2 of the present invention was detected by the method of example 1, and the detection result shows that the surface of the magnesium alloy is a porous structure, as shown in b in fig. 2.

Example 3

Pretreatment: carrying out alkali washing and oil removal on the magnesium alloy to obtain a pretreated magnesium alloy;

chelating agent-alkali co-treatment: weighing 18g of NaOH and 18.6g of EDTA-2Na, adding into 100mL of deionized water, and stirring for dissolving to obtain a treatment solution; then, the pretreated magnesium alloy is put into a treatment fluid for treatment, the treatment temperature is 60 ℃, and the treatment time is 210 min;

cleaning and drying: and (3) carrying out ultrasonic cleaning on the treated magnesium alloy, placing the magnesium alloy in an air drying box after cleaning, and drying for 60min at the temperature of 60 ℃ to obtain the surface porous magnesium alloy.

The surface morphology of the surface porous magnesium alloy prepared in example 3 of the present invention was detected by the method of example 1, and the detection result shows that the surface of the magnesium alloy is a porous structure, as shown in c in fig. 2.

Example 4

Pretreatment: washing the magnesium alloy with alkali to remove oil to obtain a pretreated magnesium alloy;

chelating agent-alkali co-treatment: weighing 0.4g of NaOH and 1g of EDTA-2Na, adding into 100mL of deionized water, and stirring for dissolving to obtain a treatment solution; then, the pretreated magnesium alloy is put into a treatment fluid for treatment, the treatment temperature is 80 ℃, and the treatment time is 60 min;

cleaning and drying: and (3) carrying out ultrasonic cleaning on the treated magnesium alloy, placing the magnesium alloy in an air drying box after cleaning, and drying for 60min at the temperature of 60 ℃ to obtain the surface porous magnesium alloy.

The surface topography of the surface porous magnesium alloy prepared in example 4 of the present invention was detected by the method of example 1, and the detection result shows that the surface of the magnesium alloy is a porous structure, as shown in d in fig. 2.

In order to verify the surface composition of the surface porous magnesium alloy of the present invention, the surface composition of the porous magnesium alloy of example 1 of the present invention was measured by XRD diffraction analysis, and the measurement results are shown in fig. 3. From FIG. 3, it can be seen thatMg (OH) appears in XRD diffraction peaks on the surface of the porous magnesium alloy₂Shows that Mg (OH) is generated in the process of preparing the surface porous magnesium alloy₂. The results show that: the surface of the surface porous magnesium alloy prepared by the invention forms a layer of Mg (OH)₂And (3) a film, which is beneficial to improving the corrosion resistance of the magnesium alloy. The results of the tests of examples 2 to 4 were similar to those of example 1.

In order to verify the corrosion resistance of the surface porous magnesium alloy, an electrochemical analysis method is adopted, and 1 mV.s is adopted in 3.5 wt.% NaCl solution at room temperature^-1The magnesium alloy and the porous magnesium alloy of example 1 of the present invention were subjected to polarization testing at a scan rate of from about-2000 to 500 mV/SCE; as shown in FIG. 4, it is understood from FIG. 4 that the corrosion current of the surface porous magnesium alloy is 3.95X 10 times that of the magnesium alloy^-6A is reduced to 16.43 multiplied by 10^-11A; the surface porous magnesium alloy prepared by the method improves the corrosion resistance of the magnesium alloy.

The invention prepares the corrosion-resistant porous structure on the surface of the magnesium alloy by using a chelating agent-alkali co-treatment method, improves the bonding strength between the coating material and the laminated material and the surface of the magnesium alloy, has certain corrosion resistance and inhibits the corrosion behavior among the components. The method comprises the steps of carrying out alkali cleaning and oil removal on the surface of the magnesium alloy, then placing the magnesium alloy in a chelating agent-alkali co-treatment solution for treatment, and washing and drying to obtain the magnesium alloy with excellent corrosion resistance and porous structure surface. The method provided by the invention has the advantages of simple preparation process and low cost, the prepared magnesium alloy has uniform and compact surface pore structure, good corrosion resistance and the like, and the porous surface is obtained by etching on a magnesium alloy substrate, so that the problems of low bonding strength, hardness, brittleness and the like of a magnesium alloy chemical conversion film and the substrate are solved. The invention has practical value significance for the industrial application of the magnesium alloy.

While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.