Magnesium alloy surface treatment method and treated magnesium alloy
阅读说明：本技术 一种镁合金表面处理方法和处理后的镁合金 (Magnesium alloy surface treatment method and treated magnesium alloy ) 是由 周红欣 梁栋科 郭庆放 林森 蒋佳宝 徐闻龙 于 2021-10-22 设计创作，主要内容包括：本发明公开一种镁合金表面处理方法,包括如下步骤：首先对镁合金表面进行碱洗；然后将碱洗后的镁合金浸入电解液中进行阳极氧化；最后将阳极氧化后的镁合金进行超疏水处理；所述电解液中包含F～(-)、OH～(-)、PO-(4)～(3-)。本发明还公开了使用上述表面处理方法处理的镁合金。本发明通过阳极氧化,在镁合金表面形成MgF-(2)、Mg-(3)(PO4)-(2)、MgO、Mg(OH)-(2)复合涂层,提高了对镁合金基体的保护,并且对其进行超疏水处理,使其表面形成疏水涂层,降低了镁合金基体与腐蚀介质的接触,进一步提高了镁合金耐蚀性。(The invention discloses a magnesium alloy surface treatment method, which comprises the following steps: firstly, performing alkali washing on the surface of the magnesium alloy; then, immersing the magnesium alloy subjected to alkali washing into electrolyte for anodic oxidation; finally, performing super-hydrophobic treatment on the magnesium alloy after anodic oxidation; the electrolyte contains F ‑ 、OH ‑ 、PO 4 3‑ . The invention also discloses a magnesium alloy treated by the surface treatment method. The invention forms MgF on the surface of the magnesium alloy by anodic oxidation 2 、Mg 3 (PO4) 2 、MgO、Mg(OH) 2 The composite coating improves the protection of the magnesium alloy matrix, and carries out super-hydrophobic treatment on the magnesium alloy matrix to form a hydrophobic coating on the surface of the magnesium alloy matrix, thereby reducing the contact between the magnesium alloy matrix and a corrosive medium and further improving the corrosion resistance of the magnesium alloy.)
1. A magnesium alloy surface treatment method is characterized by comprising the following steps:
s1: performing alkali washing on the surface of the magnesium alloy;
s2: immersing the magnesium alloy subjected to alkali washing into electrolyte for anodic oxidation;
s3: carrying out super-hydrophobic treatment on the magnesium alloy after anodic oxidation;
the electrolyte contains F-、OH-、PO4 3-。
2. The surface treatment method according to claim 1, wherein the electrolyte is prepared by adding a fluorine salt, a phosphate, an alkali, and an inhibitor into deionized water, and performing electromagnetic stirring to obtain a colloidal solution;
the fluorine salt comprises NaF, KF or NH4At least one of HF and the phosphate is Na3PO4、K3PO4Or (NH)4)3PO4And CaHPO4The alkali is at least one of NaOH or KOH, and the inhibitor is at least one of triethanolamine, ethylene glycol or glycerol.
3. The surface treatment method according to claim 2, wherein the fluoride salt is 10 to 30g/L of NaF and the phosphate salt is 10 to 15g/L of Na in the electrolyte3PO4And 3-4.5g/L of CaHPO4The alkali is NaOH with the concentration of 20-30g/L, and the inhibitor is triethanolamine with the concentration of 10-20 ml/L.
4. The surface treatment method as claimed in any one of claims 1 to 3, wherein in step S2, the voltage is 180-220V and the current density is 2-4mA/mm in the anodic oxidation2The frequency is 1-2.5kHz, the duty cycle is 10-20%, and the time is 10-20 s.
5. The surface treatment method according to any one of claims 1 to 4, wherein the superhydrophobic treatment is treatment with a 1-2.82 wt% stearic acid solution at a treatment temperature of 50-80 ℃ for 20-50min in step S3.
6. The surface treatment method according to claim 5, wherein before the super-hydrophobic treatment, the magnesium alloy is soaked in a 5% -10% NaOH solution for 30-60min at a temperature of 50-80 ℃.
7. The surface treatment method according to any one of claims 1 to 6, wherein in step S1, the magnesium alloy is subjected to electrochemical polishing before alkaline washing, is washed by immersing in alcohol after alkaline washing, and is finally dried.
8. A magnesium alloy, characterized in that it is treated by the surface treatment method according to any one of claims 1 to 7.
Technical Field
The invention relates to the field of magnesium alloy materials, in particular to a magnesium alloy surface treatment method and a treated magnesium alloy.
Background
Magnesium alloy is known as a green engineering material in the 21 st century, and is widely applied to aviation, aerospace, transportation, chemical engineering, rocket and other industrial departments due to the characteristics of high specific strength, strong creep resistance, large elastic modulus, good heat dissipation, good shock absorption and the like. And because the magnesium element is one of the essential elements of the human body, the density of the magnesium alloy is similar to that of human bones (the density of the magnesium alloy is 1.74 g/cm)3Human bone density of 1.75g/cm3) The stress shielding effect can be effectively avoided, tissue inflammation is reduced, and magnesium alloy medical products such as magnesium alloy bone nails, bone plates and the like are favored in recent years; because of good degradability and tissue compatibility, the magnesium alloy has wide application prospect in the field of degradable supports. However, compared with traditional metals such as stainless steel, copper alloy, aluminum alloy and the like, the magnesium alloy has more active chemical properties and very negative standard equilibrium potential (-2.36V), so that the magnesium alloy is implanted to generate hydrogen too fast and a large amount of H2The problem of corrosion caused by local tissue edema becomes a major bottleneck restricting the wide application of magnesium alloy, so how to improve the corrosion resistance of magnesium alloy and control the corrosion rate of magnesium alloy becomes the focus of research at present.
At present, main approaches for improving the corrosion resistance of magnesium alloy include alloying, surface treatment, tissue regulation, laser cladding, ion spraying, chemical deposition and the like, but the surface treatment of the magnesium alloy is the most effective corrosion resistance method, and the method is mainly characterized in that a layer of inorganic or organic polymer protective film is covered on the surface of the magnesium alloy to isolate the contact of a magnesium alloy matrix and the external environment and prevent corrosive media from entering, so that the aim of protecting the magnesium alloy is fulfilled. Currently, the major studied magnesium alloy surface treatment technologies include micro-arc oxidation (anodic oxidation), chemical conversion, metal plating, organic coatings, and the like. The anodic oxidation technology has the advantages of simple production process, large primary film forming area, low production equipment investment, low processing cost and the like, and is the most widely applied treatment technology for treating the surface of the magnesium alloy, but the obtained magnesium alloy surface has the problems of large aperture and high porosity, and the corrosion resistance of the magnesium alloy is influenced.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to solve the existing problem of anodizing the magnesium alloy, thereby providing a magnesium alloy surface treatment method and a treated magnesium alloy.
Therefore, the invention adopts the following technical scheme:
the invention provides a magnesium alloy surface treatment method, which comprises the following steps:
s1: performing alkali washing on the surface of the magnesium alloy;
s2: immersing the magnesium alloy subjected to alkali washing into electrolyte for anodic oxidation;
s3: carrying out super-hydrophobic treatment on the magnesium alloy after anodic oxidation;
the electrolyte contains F-、OH-、PO4 3-。
Further, the electrolyte is prepared by adding villiaumite, phosphate, alkali and an inhibitor into deionized water, and performing electromagnetic stirring to obtain a colloidal solution;
the fluorine salt comprises NaF, KF or NH4At least one of HF and the phosphate is Na3PO4、K3PO4Or (NH)4)3PO4And CaHPO4The alkali is at least one of NaOH or KOH, and the inhibitor is at least one of triethanolamine, ethylene glycol or glycerol.
Preferably, in the electrolyte, the fluoride salt is 10-30g/L NaF, and the phosphate salt is 10-15g/L Na3PO4And 3-4.5g/L of CaHPO4The alkali is NaOH with the concentration of 20-30g/L, and the inhibitor is triethanolamine with the concentration of 10-20 ml/L.
Further, in step S2, in the anodic oxidation, the voltage is 180-220V, and the current density is 2-4mA/mm2The frequency is 1-2.5kHz, the duty cycle is 10-20%, and the time is 10-20 s.
In step S3, the super-hydrophobic treatment is treatment with 1-2.82 wt% stearic acid solution for 20-50min at 50-80 deg.C.
Before the super-hydrophobic treatment, the magnesium alloy is soaked in a 5-10% NaOH solution for 30-60min at the temperature of 50-80 ℃.
In step S1, the magnesium alloy is electrochemically polished before alkaline cleaning, and is immersed in alcohol for cleaning after alkaline cleaning, and finally dried.
The invention also provides a magnesium alloy which is treated by the surface treatment method.
The technical scheme of the invention has the following advantages:
(1) the invention forms MgF on the surface of the magnesium alloy by anodic oxidation2、Mg3(PO4)2、MgO、Mg(OH)2The composite coating improves the protection of the magnesium alloy matrix, and the magnesium alloy is subjected to super-hydrophobic treatment after being subjected to anodic oxidation, so that a hydrophobic coating is formed on the surface of the magnesium alloy, the contact between the magnesium alloy matrix and a corrosive medium is reduced, and the corrosion resistance of the magnesium alloy is further improved.
(2) According to the invention, the inhibitor is added into the electrolyte to inhibit spark discharge in the anodic oxidation process, so that the discharge intensity is reduced, and the purposes of reducing the pore diameter and reducing the porosity are achieved.
(3) The invention forms colloidal solution by regulating and controlling the proportion of the components of the electrolyte, and charged colloid can enter the discharge channel to realize self-sealing in the process of anodic oxidation under the adsorption of a magnetic field, thereby greatly reducing the porosity of anodic oxidation and overcoming the ion aggregation and the non-uniformity of ion distribution in the process of electrodeposition.
(4) CaHPO added into electrolyte of the invention4Is slightly soluble, is added in proportion and is stirred to form charged colloidal particles suspended in electrolyte, and the charged colloidal particles CaHPO are used for anodic oxidation4Is absorbed into an anodic oxidation discharge channel under the action of electrostatic attraction, can effectively form self-sealing holes, reduce the porosity and simultaneously reduce Ca on the surface of the magnesium alloy2+、PO4 3-Easily form hydroxyl phosphorus after being implanted into human bodyThe apatite has an effect of further improving corrosion resistance, has good biocompatibility, does not cause tissue inflammatory reaction, and accelerates tissue endothelialization.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is an electron micrograph of a magnesium alloy after treatment in example 1 of the present invention;
FIG. 2 is an electron micrograph of a magnesium alloy after treatment in comparative example 1 of the present invention.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field.
The magnesium alloy to be treated used in the embodiment of the present invention is a self-grinding magnesium alloy material.
Example 1
The embodiment provides a magnesium alloy surface treatment method, which comprises the following specific steps:
(1) after the magnesium alloy to be treated is subjected to electrochemical polishing treatment, cleaning treatment is carried out by using alkali liquor, and finally cleaning and drying treatment is carried out in alcohol immersion;
(2) mixing 10g of NaF, 20g of NaOH and 10g of Na3PO410ml triethanolamine and 3g CaHPO4Adding 1L of deionized waterPerforming electromagnetic stirring in water until a colloidal solution is obtained by stirring, and obtaining an electrolyte;
(3) putting the magnesium alloy into electrolyte, and then adjusting the parameters to 200V of voltage and 2mA/mm of current density2Frequency 1kHz, duty ratio 10%, anodizing for 10 s;
(4) soaking the magnesium alloy after anodic oxidation in 10 wt% NaOH solution at 80 ℃ for 30min, and then soaking in 1 wt% stearic acid solution at 50 ℃ for 30min to obtain the treated magnesium alloy product.
The electron microscope photo of the magnesium alloy is shown in figure 1, the magnesium alloy bracket obtained by adopting the technical scheme has the microscopic surface porosity of less than 2 percent and the anodic oxidation pore diameter of less than 1 um; the macroscopic surface is smooth, and no coarse lamellar appears. The corrosion resistance test is carried out by soaking hanks liquid, the surface is still intact when the magnesium alloy is soaked for 20 days, and the technical scheme of the application greatly improves the corrosion resistance of the magnesium alloy.
Example 2
The embodiment provides a magnesium alloy surface treatment method, which comprises the following specific steps:
(1) after the magnesium alloy to be treated is subjected to electrochemical polishing treatment, cleaning treatment is carried out by using alkali liquor, and finally cleaning and drying treatment is carried out in alcohol immersion;
(2) mixing 20g of NaF, 30g of NaOH and 15g of Na3PO420ml triethanolamine and 4.5g CaHPO4Adding the mixture into 1L of deionized water, and performing electromagnetic stirring until a colloidal solution is obtained by stirring, thus obtaining an electrolyte;
(3) putting the magnesium alloy into electrolyte, and then adjusting the parameters to be 220V of voltage and 4mA/mm of current density2The frequency is 2KHZ, the duty ratio is 20 percent, and the anode is oxidized for 20 s;
(4) soaking the magnesium alloy after anodic oxidation in 8 wt% NaOH solution at 70 ℃ for 50min, and then soaking in 1.5 wt% stearic acid solution at 70 ℃ for 40min to obtain the treated magnesium alloy product.
The magnesium alloy bracket obtained by adopting the technical scheme has the microscopic upper surface porosity of less than 2 percent and the anodic oxidation pore diameter of less than 1 um; the macroscopic surface is smooth, and no coarse lamellar appears. The corrosion resistance test is carried out by soaking hanks liquid, the surface is still intact when the magnesium alloy is soaked for 20 days, and the technical scheme of the application greatly improves the corrosion resistance of the magnesium alloy.
Example 3
The embodiment provides a magnesium alloy surface treatment method, which comprises the following specific steps:
(1) after the magnesium alloy to be treated is subjected to electrochemical polishing treatment, cleaning treatment is carried out by using alkali liquor, and finally cleaning and drying treatment is carried out in alcohol immersion;
(2) mixing 30g of NaF, 24g of NaOH and 13g of Na3PO420ml triethanolamine and 3.6g CaHPO4Adding the mixture into 1L of deionized water, and performing electromagnetic stirring until a colloidal solution is obtained by stirring, thus obtaining an electrolyte;
(3) putting the magnesium alloy into electrolyte, and then adjusting the parameters to 180V of voltage and 3mA/mm of current density2The frequency is 2.5KHZ, the duty ratio is 15 percent, and the anode is oxidized for 15 s;
(4) soaking the magnesium alloy after anodic oxidation in 7 wt% NaOH solution at 60 ℃ for 40min, and then soaking in 2 wt% stearic acid solution at 60 ℃ for 50min to obtain the treated magnesium alloy product.
The magnesium alloy bracket obtained by adopting the technical scheme has the microscopic upper surface porosity of less than 2 percent and the anodic oxidation pore diameter of less than 1 um; the macroscopic surface is smooth, and no coarse lamellar appears. The corrosion resistance test is carried out by soaking hanks liquid, the surface is still intact when the magnesium alloy is soaked for 20 days, and the technical scheme of the application greatly improves the corrosion resistance of the magnesium alloy.
Example 4
The embodiment provides a magnesium alloy surface treatment method, which comprises the following specific steps:
(1) after the magnesium alloy to be treated is subjected to electrochemical polishing treatment, cleaning treatment is carried out by using alkali liquor, and finally cleaning and drying treatment is carried out in alcohol immersion;
(2) mixing 20g of NaF, 30g of NaOH and 10g of Na3PO410ml triethanolamine and 4.5g CaHPO4Adding the mixture into 1L of deionized water, and performing electromagnetic stirring until a colloidal solution is obtained by stirring, thus obtaining an electrolyte;
(3) putting the magnesium alloy into electrolyte, and then adjusting the parameters to 210V of voltage and currentDensity 2mA/mm2The frequency is 1.7KHZ, the duty ratio is 16 percent, and the anodic oxidation is carried out for 14 s;
(4) soaking the magnesium alloy after anodic oxidation in 5 wt% NaOH solution at 80 ℃ for 20min, and then soaking in 2.82 wt% stearic acid solution at 80 ℃ for 60min to obtain the treated magnesium alloy product.
The magnesium alloy bracket obtained by adopting the technical scheme has the microscopic upper surface porosity of less than 2 percent and the anodic oxidation pore diameter of less than 1 um; the macroscopic surface is smooth, and no coarse lamellar appears. The corrosion resistance test is carried out by soaking hanks liquid, the surface is still intact when the magnesium alloy is soaked for 20 days, and the technical scheme of the application greatly improves the corrosion resistance of the magnesium alloy.
Comparative example 1
The comparative example provides a surface treatment method of a traditional anodic magnesium oxide alloy, which comprises the following specific steps:
(1) after the magnesium alloy to be treated is subjected to electrochemical polishing treatment, cleaning treatment is carried out by using alkali liquor, and finally cleaning and drying treatment is carried out in alcohol immersion;
(2) adding 10g of sodium silicate, 20g of NaOH, 10g of glycerol and 10mL of triethanolamine into 100mL of deionized water, and performing electromagnetic stirring until a colloidal solution is obtained by stirring, thus obtaining an electrolyte;
(3) putting the magnesium alloy into electrolyte, and then adjusting the parameters to 250V of voltage and 1.8mA/mm of current density2The frequency is 1.0KHZ, the duty ratio is 16 percent, and the anodic oxidation is carried out for 14 s;
the magnesium alloy electron microscope photo is shown in figure 2, and the magnesium alloy bracket obtained by adopting the technical scheme has the advantages of rough bracket surface, porosity of more than 10 percent and aperture minimum size of about 3 um. The corrosion resistance experiment is carried out by soaking hanks liquid, and the surface is cracked when the hanks liquid is soaked for 5 days, which indicates that the corrosion resistance of the magnesium alloy in the technical scheme is far lower than that of the embodiment of the application.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
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