阅读说明：本技术 一种高耐蚀镁合金轮毂表面处理方法 (high-corrosion-resistance magnesium alloy hub surface treatment method ) 是由 陈宏� 郝建民 丁健 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种高耐蚀镁合金轮毂表面处理方法,包括以下步骤：镁合金轮毂打磨—水洗—碱洗—水洗—氧化锆陶瓷膜微弧氧化—聚氟乙烯封孔处理。通过该方法处理后,可以使镁合金轮毂表面生成均匀的陶瓷膜,该陶瓷膜与镁合金基体结合良好,界面致密性好,镁合金轮毂的耐蚀性和耐磨性能显著提高,增加了汽车轮毂的服役寿命；且通过严格控制微弧氧化工艺过程的各个工艺参数,使陶瓷膜质量高,稳定性好,可操造性强。(The invention discloses a surface treatment method of a high-corrosion-resistance magnesium alloy hub, which comprises the following steps: polishing a magnesium alloy hub, washing with water, washing with alkali, washing with water, performing micro-arc oxidation on a zirconium oxide ceramic membrane, and sealing holes with polyvinyl fluoride. After the treatment by the method, a uniform ceramic membrane can be generated on the surface of the magnesium alloy hub, the ceramic membrane is well combined with a magnesium alloy matrix, the interface compactness is good, the corrosion resistance and the wear resistance of the magnesium alloy hub are obviously improved, and the service life of the automobile hub is prolonged; and each process parameter of the micro-arc oxidation process is strictly controlled, so that the ceramic membrane has high quality, good stability and strong operability.)

1. the surface treatment method of the high-corrosion-resistance magnesium alloy hub is characterized by comprising the following steps of:

Step 1, mechanically polishing a magnesium alloy hub, and cleaning with clear water to obtain the magnesium alloy hub with a smooth surface;

step 2, placing the magnesium alloy hub with a smooth surface in alkaline degreasing liquid, soaking, and cleaning with clear water to obtain a degreased magnesium alloy hub;

Step 3, preparing micro-arc oxidation treatment liquid, placing the deoiled magnesium alloy hub and the stainless steel plate in the micro-arc oxidation treatment liquid, performing micro-arc oxidation on the deoiled magnesium alloy hub, and growing a uniform ceramic membrane on the surface of the magnesium alloy hub in situ to obtain the magnesium alloy hub with the ceramic membrane; wherein, the magnesium alloy hub after deoiling is connected with the anode of the micro-arc oxidation power supply, and the stainless steel plate is connected with the cathode of the micro-arc oxidation power supply;

And 4, preparing a polyvinyl fluoride hole sealing solution, soaking the magnesium alloy hub with the ceramic membrane in the polyvinyl fluoride hole sealing solution, taking out the magnesium alloy hub, standing at normal temperature, and heating and curing.

2. The method for treating the surface of the high-corrosion-resistance magnesium alloy hub according to claim 1, wherein in the step 2, the alkaline degreasing liquid comprises potassium hydroxide, potassium carbonate, sodium phosphate, a surfactant and water.

3. the method for processing the surface of the high-corrosion-resistance magnesium alloy hub according to claim 2, wherein in the step 2, the surfactant is sodium dodecyl sulfate or/and perfluorooctyl sulfonic acid tetraethylene amine.

4. the method for treating the surface of the high-corrosion-resistance magnesium alloy hub according to claim 3, wherein in the step 2, in the alkaline degreasing liquid, the concentration of potassium hydroxide is 20-30g/L, the concentration of potassium carbonate is 25-45g/L, the concentration of sodium phosphate is 5-15g/L, and the concentration of a surfactant is 10-80 mg/L.

5. The method for treating the surface of the high-corrosion-resistance magnesium alloy hub according to claim 1, wherein in the step 2, the soaking temperature is 65-80 ℃, and the soaking time is 5-10 min.

6. The method for processing the surface of the high-corrosion-resistance magnesium alloy hub according to claim 1, wherein in the step 3, the micro-arc oxidation treatment solution is prepared by the following steps: adding 10-15g of dipotassium phosphate, 2-5g of ammonium citrate and 20-40g of ammonium bifluoride into 1L of water, and adjusting the pH value to 10-12 by using ammonia water to obtain a mixed solution; and adding 1L of hydrous zirconyl nitrate solution with the concentration of 40g/L into the mixed solution, and stirring and mixing uniformly to obtain the zirconium nitrate-zirconium mixed solution.

7. The surface treatment method for the high corrosion-resistant magnesium alloy hub according to claim 1, wherein in the step 3, the power source for the micro-arc oxidation is a direct current pulse power source, the pulse frequency of the power source is 500-600Hz, the duty ratio is 10-30%, and the voltage is 300-400V; the distance between the deoiled magnesium alloy hub and the stainless steel plate is 10-20 cm.

8. The method for treating the surface of the high-corrosion-resistance magnesium alloy hub according to claim 7, wherein in the step 3, the temperature of the micro-arc oxidation is 20-50 ℃, and the time of the micro-arc oxidation is 10-30 min.

9. the method for processing the surface of the high-corrosion-resistance magnesium alloy hub according to claim 1, wherein in the step 4, the polyvinyl fluoride hole sealing solution is prepared by the following steps: adding 1g of polyvinyl fluoride powder into 100mL of acetamide, continuously stirring for 25-35min at 40-60 ℃, and adding water for dilution to obtain a polyvinyl fluoride hole sealing solution with the polyvinyl fluoride concentration of 1-4 g/L.

10. The surface treatment method for the high-corrosion-resistance magnesium alloy hub according to claim 1, wherein in the step 4, the dipping time is 3-12min, and the standing time at normal temperature is 1-3 h; the temperature of the heating and curing is 150-160 ℃, and the time of the heating and curing is 10-15 min.

Technical Field

The invention relates to the field of metal surface treatment, in particular to a surface treatment method for a high-corrosion-resistance magnesium alloy wheel hub.

Background

The automobile hub is an important component part in an automobile, and the quality of the automobile hub directly influences the driving safety and long-term use reliability of the automobile. The magnesium alloy is an indispensable material in automobile parts due to the characteristics of small density, high specific strength and specific stiffness, good damping and shock absorption performance and the like. The magnesium alloy has excellent shock absorption performance, so that when elastic stress from the outside of the structure is transmitted to other structural parts through the magnesium alloy structural part, the stress is greatly attenuated in the magnesium alloy structural part, the actual load on the structural part adjacent to the structural part is reduced, the strength requirement of the structural part design is relieved, and the safety is improved. The automobile hub made of magnesium alloy material has the following advantages: the fuel oil has the advantages of obviously reducing the vehicle weight, reducing the oil consumption, reducing the exhaust emission and improving the overall economic index of the fuel oil. 60% of fuel used by the automobile is consumed by the dead weight of the automobile, and the fuel efficiency can be improved by more than 5% when the weight of the automobile is reduced by 10%. Meanwhile, the brake and acceleration performance is improved, and the magnesium alloy component can also improve the shock absorption performance of the automobile, reduce noise and improve safety performance. However, because magnesium alloy has high chemical reaction activity, an oxide film is easily formed in the air, the structure is loose, and the magnesium alloy is easily damaged by corrosion, so that the application of the magnesium alloy in the field of automobiles is severely limited.

The automobile hub is usually subjected to surface treatment by methods such as electroplating, vacuum coating technology, plasma spraying technology and the like. However, the electroplating solution often contains a large amount of toxic heavy metal ions, which easily causes environmental pollution; the vacuum coating technology and the plasma spraying technology have high requirements on the pretreatment of the wheel hub, the process is complex, and the usability of the wheel hub is greatly limited, so that the development of a high-corrosion-resistance magnesium alloy wheel hub surface treatment method is particularly important.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a surface treatment method for a high-corrosion-resistance magnesium alloy hub, which is characterized in that after the magnesium alloy hub is subjected to micro-arc oxidation surface treatment, a uniform ceramic film layer is generated on the surface of the magnesium alloy hub, and the ceramic film layer has the advantages of high hardness, high corrosion resistance, high wear resistance and the like, so that the corrosion resistance and wear resistance of the magnesium alloy hub are obviously improved, and the service life of the automobile hub is prolonged.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme.

A surface treatment method for a high-corrosion-resistance magnesium alloy hub comprises the following steps:

Step 1, mechanically polishing a magnesium alloy hub, and cleaning with clear water to obtain the magnesium alloy hub with a smooth surface;

Step 2, placing the magnesium alloy hub with a smooth surface in alkaline degreasing liquid, soaking, and cleaning with clear water to obtain a degreased magnesium alloy hub;

Step 3, preparing micro-arc oxidation treatment liquid, placing the deoiled magnesium alloy hub and the stainless steel plate in the micro-arc oxidation treatment liquid, performing micro-arc oxidation on the deoiled magnesium alloy hub, and growing a uniform ceramic membrane on the surface of the magnesium alloy hub in situ to obtain the magnesium alloy hub with the ceramic membrane; wherein, the magnesium alloy hub after deoiling is connected with the anode of the micro-arc oxidation power supply, and the stainless steel plate is connected with the cathode of the micro-arc oxidation power supply;

And 4, preparing a polyvinyl fluoride hole sealing solution, soaking the magnesium alloy hub with the ceramic membrane in the polyvinyl fluoride hole sealing solution, taking out the magnesium alloy hub, standing at normal temperature, and heating and curing.

Preferably, in the step 1, the cleaning is performed for 1-3min by using clean water.

preferably, in step 2, the alkaline deoiling liquid contains potassium hydroxide, potassium carbonate, sodium phosphate, a surfactant and water.

Further preferably, in step 2, the surfactant is sodium dodecyl sulfate or/and perfluorooctyl sulfonic acid tetraethylene amine.

Preferably, in the step 2, the concentration of potassium hydroxide is 20-30g/L, the concentration of potassium carbonate is 25-45g/L, the concentration of sodium phosphate is 5-15g/L, and the concentration of surfactant is 10-80 mg/L.

Preferably, in the step 2, the soaking temperature is 65-80 ℃, and the soaking time is 5-10 min.

Preferably, in the step 2, the cleaning is performed for 1-3min by using clean water.

Preferably, in step 3, the preparation method of the micro-arc oxidation treatment solution comprises the following steps: adding 10-15g of dipotassium phosphate, 2-5g of ammonium citrate and 20-40g of ammonium bifluoride into 1L of water, and adjusting the pH value to 10-12 by using ammonia water to obtain a mixed solution; and adding 1L of hydrous zirconyl nitrate solution with the concentration of 40g/L into the mixed solution, and stirring and mixing uniformly to obtain the zirconium nitrate-zirconium mixed solution.

Preferably, in the step 3, the power supply for micro-arc oxidation is a direct current pulse power supply, the pulse frequency of the power supply is 500-600Hz, the duty ratio is 10-30%, and the voltage is 300-400V; the distance between the deoiled magnesium alloy hub and the stainless steel plate is 10-20 cm.

Preferably, in the step 3, the temperature of the micro-arc oxidation is 20-50 ℃, and the time of the micro-arc oxidation is 10-30 min.

Preferably, in step 4, the preparation method of the polyvinyl fluoride sealing solution comprises: adding 1g of polyvinyl fluoride powder into 100mL of acetamide, continuously stirring for 25-35min at 40-60 ℃, and adding water for dilution to obtain a polyvinyl fluoride hole sealing solution with the polyvinyl fluoride concentration of 1-4 g/L.

Preferably, in the step 4, the dipping time is 3-12min, and the standing time at normal temperature is 1-3 h.

Preferably, in the step 4, the temperature for heating and curing is 150-.

Compared with the prior art, the invention has the beneficial effects that:

(1) The micro-arc oxidation treatment method has no special requirements on the material grade and the size of the magnesium alloy hub, and even ceramic film layers are obtained on the surfaces of the magnesium alloy soaked in the micro-arc oxidation solution after the micro-arc oxidation treatment, so the micro-arc oxidation treatment process has good universality.

(2) the process disclosed by the invention is simple and environment-friendly, has low requirements on the pretreatment of the hub, is easy to control, improves the corrosion resistance of the magnesium alloy hub substrate, and effectively controls the corrosion speed of the surface of the magnesium alloy hub substrate.

(3) The micro-arc oxidation solution and the preparation process parameters adopted by the invention can enable the surface of the magnesium alloy hub to generate a uniform ceramic membrane, the ceramic membrane is well combined with a matrix, the interface compactness is good, the corrosion resistance and the wear resistance of the magnesium alloy hub are obviously improved, and the micro-arc oxidation ceramic membrane has high quality, good stability and strong operability by strictly controlling each process parameter in the micro-arc oxidation process.

(4) After the hole sealing treatment is carried out on the ceramic membrane on the surface of the magnesium alloy hub, the polyvinyl fluoride covers the surface of the ceramic membrane to seal micropores of the ceramic membrane, and the ceramic membrane has the characteristics of oil repellency and hydrophobicity due to low free energy of the surface of the ceramic membrane, is strong in antifouling property, is difficult to attach dust, and can be cleaned as new after being washed by rainwater.

Drawings

the invention is described in further detail below with reference to the figures and specific embodiments.

FIG. 1 is a photograph of a magnesium alloy hub treated by the treatment method of example 1;

FIG. 2 shows the corrosion rate of the ceramic membrane after hole sealing in a 5% NaCl solution; wherein, the graph (a) shows the influence of the concentration of the polyvinyl fluoride hole sealing solution on the corrosion rate (the dipping time in the hole sealing solution is 9 min); the graph (b) shows the influence of the sealing time on the corrosion rate (the concentration of the polyvinyl fluoride sealing solution is 4 g/L);

FIG. 3 is a schematic diagram of a hole sealing process of a magnesium alloy micro-arc oxidation ceramic membrane;

FIG. 4 shows SEM micro-morphology of the magnesium alloy before and after micro-arc oxidation ceramic membrane sealing; wherein, the surface appearance of the ceramic membrane before hole sealing is shown in the figure (a), the section appearance of the ceramic membrane before hole sealing is shown in the figure (b), the surface appearance after hole sealing is shown in the figure (c), and the section appearance after hole sealing is shown in the figure (d);

FIG. 5 is a diagram showing contact angles of magnesium alloys with deionized water in different surface states; wherein, the magnesium alloy matrix in the graph (a) is 69.5 degrees, the graph (b) is 81.5 degrees after the fluorocarbon sealing hole, and the graph (c) is 35.0 degrees of the micro-arc oxidation ceramic layer;

FIG. 6 is a macroscopic surface topography diagram of a soaking experiment before and after hole sealing of a magnesium alloy; wherein, the picture (a) is a macroscopic surface topography picture after magnesium alloy and micro-arc oxidation; and (b) is a macroscopic surface topography diagram of magnesium alloy, micro-arc oxidation and polyvinyl fluoride.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention.