阅读说明：本技术 一种封闭处理液和透明耐腐蚀膜层及其制备方法 (Sealing treatment liquid, transparent corrosion-resistant film and preparation method thereof ) 是由 向可友 肖革 蓝玉良 杨晓波 朱立群 于 2019-11-13 设计创作，主要内容包括：本发明涉及一种封闭处理液及其制备方法,以及利用该封闭处理液制备的透明耐腐蚀膜层,该方法包括以下步骤：在含有有机溶剂与无机硫酸盐及表面活性剂的液体中,电解4-6小时,得到含石墨烯片的基础封闭溶液；将纳米铝锆溶胶水溶液在合成反应装置中搅拌后,与上述制备的基础封闭溶液混合,形成高度分散的纳米溶胶封闭水溶液,然后将钝化零件置于该水溶液中进行封闭处理,然后烘干。本发明所提供的制备方法,其可使得电镀锌(或者电镀锌镍合金)汽车零部件的表面重量基本没有增加(膜层厚度只有50-100纳米,透明),镀层外观均匀。(The invention relates to a sealing treatment fluid, a preparation method thereof and a transparent corrosion-resistant film prepared by using the sealing treatment fluid, wherein the method comprises the following steps: electrolyzing for 4-6 hours in liquid containing an organic solvent, inorganic sulfate and a surfactant to obtain a basic sealing solution containing graphene sheets; stirring the nano aluminum zirconium sol aqueous solution in a synthesis reaction device, mixing the nano aluminum zirconium sol aqueous solution with the prepared basic sealing solution to form a highly dispersed nano sol sealing aqueous solution, then placing the passivated part in the aqueous solution for sealing treatment, and then drying. The preparation method provided by the invention can ensure that the surface weight of the electrogalvanized (or electrogalvanized zinc-nickel alloy) automobile parts is not increased basically (the thickness of a film layer is only 50-100 nanometers, and the film layer is transparent), and the appearance of the coating is uniform.)

1. A preparation method of a sealing treatment fluid is characterized by comprising the following steps:

1) sequentially adding an organic solvent, an inorganic sulfate and a surfactant into deionized water, and uniformly mixing to form a solution;

2) preparing a basic sealing solution containing graphene sheets by an electrochemical method by taking a carbon rod as an anode and a platinum sheet or the carbon rod as a cathode in the solution;

3) preparing raw materials of aluminum sol and zirconium sol in a synthesis reaction device, and generating the aluminum sol and the zirconium sol in situ to obtain a nano aluminum zirconium sol aqueous solution;

4) mixing the nano aluminum zirconium sol aqueous solution prepared in the step 3) with the basic sealing solution prepared in the step 2) to obtain sealing treatment liquid.

2. The method according to claim 1, wherein the weight ratio of the organic solvent, the inorganic sulfate, and the surfactant in step 1) is 0.1: (15-30): (0.08-0.15); the concentration of the graphene sheet in the basic sealing solution obtained in the step 2) is 0.5 wt% to 10 wt%; the molar ratio of the aluminum sol to the zirconium sol generated in situ in the step 3) is (5-12) to 1, and the total molar concentration of the aluminum sol and the zirconium sol is as follows: 0.05-1.5mol/L, and the weight ratio of the nano aluminum zirconium sol aqueous solution to the basic sealing solution in the step 4) is (4-18): 1.

3. The method according to claim 1, wherein the surfactant in step 1) is a hydroxyl group-containing surfactant.

4. The production method according to claim 1 or 3, wherein the surfactant in step 1) is a fatty alcohol hydroxyl surfactant or a hydroxyl phosphate ester surfactant; the total concentration of the organic solvent, the inorganic sulfate and the surfactant in the basic sealing solution obtained in the step 2) is 3-8 wt%.

5. The method of claim 1 or 3, wherein the electrochemical process in step 2) comprises: controlling the voltage of a direct current power supply to be 15-35V, the temperature to be 20-40 ℃, and electrolyzing for 3-6 hours; the raw material for preparing the zirconium sol in the step 3) is fluozirconate or zirconium salt, the raw material for preparing the aluminum sol is aluminum salt, and the raw materials react and are stirred for 3.5 to 5 hours in the preparation process.

6. The method according to claim 1 or 3, wherein in the step 1), the weight ratio of the organic solvent, the inorganic sulfate, and the surfactant is 0.1: 20: 0.1; the molar concentration of the aluminum sol and the zirconium sol prepared in step 3) is preferably 0.2 to 1mol/L in total.

7. The method according to claim 1 or 3, wherein the organic solvent in step 1) is methanol or ethanol, the inorganic sulfate is nickel sulfate or zinc sulfate, and the surfactant is sucrose fatty acid ester or sorbitol fatty acid ester; the concentration of the graphene sheet in the basic sealing solution obtained in the step 2) is as follows: 5 wt% -7 wt%, the graphene sheet has a diameter of 1-5 μm and a thickness of less than 5 nm; the molar ratio of the aluminum sol to the zirconium sol generated in situ in the step 3) is (8-9): 1; the weight ratio of the nano aluminum zirconium sol aqueous solution to the basic sealing solution in the step 4) is (8-14): 1.

8. A sealing treatment fluid, characterized in that it is prepared by the method of any one of claims 1 to 7.

9. A transparent corrosion-resistant film, characterized in that the transparent corrosion-resistant film is subjected to sealing treatment by using the sealing treatment liquid according to claim 8, a passivated part is subjected to sealing treatment by being placed in the sealing treatment liquid, and then dried.

10. The transparent corrosion resistant film layer of claim 9, wherein the sealing process is performed at a temperature of 20 ℃ to 50 ℃; the sealing treatment time is 0.5-15 minutes; the drying temperature is 60-80 ℃; the drying time is 10-30 minutes.

Technical Field

The invention belongs to the technical field of electroplating, and particularly relates to a sealing treatment liquid and a preparation method thereof, as well as a transparent corrosion-resistant film layer with low surface energy and low friction coefficient and prepared by using the sealing treatment liquid and a preparation method thereof.

Background

After being galvanized and zinc-nickel alloy, the light-weight and high-strength steel parts of the automobile are generally subjected to trivalent chromium passivation (blue, colored and the like) treatment and then subjected to sealing treatment (products of America companies abroad and products of domestic markets). However, the surface of the plated layer of the part cannot maintain stable low surface energy (water contact angle of 110 ° or more) and low friction coefficient, and thus it is difficult to meet the requirements of the plated product of the automobile parts.

Some documents adopt methods of plating zinc or plating zinc and nickel, and then soaking molybdenum disulfide, polytetrafluoroethylene and the like on the passivated surface of a part coating to reduce the friction coefficient of the surface and improve the water contact angle of the surface. However, the molybdenum disulfide and polytetrafluoroethylene film layers dip-coated on the surfaces of the electroplated parts are thicker (4-10 mu m), and experimental results show that the film layers are low in bonding strength and easy to fall off, so that the service life of the surface film layer is shortened, and the service life of the parts is shortened; and the surface appearance quality (color, luster, uniformity and the like) of the original galvanized or galvanized nickel alloy passivated parts is influenced, and the uniformity of the film layer is difficult to control. The other data report that the aim of antifriction lubrication is realized by adopting a method of soaking silicon nano emulsion on the passivated surface of an electroplated part, but the surface antifriction performance of the electroplated part is unstable, different areas are different, the friction coefficient is often more than 0.2, and the water contact angle of the surface of the part does not meet the performance index requirement of 110 degrees.

While some patents or articles report that the corrosion resistance of the plating layer is improved by passivation sealing after electroplating, although certain requirements on wear resistance and lubricating performance are provided, quantitative data is not provided, the stability of different areas of the plating layer is not evaluated, and specific assessment indexes are not provided for other performances (surface contact angle, friction coefficient and the like) of the plating surface of the current automobile part. If the solution added with the powder nano-level hydroxyl graphene is mixed with silica sol, water-soluble silane polymer, organic silicon defoamer, organic silicon flatting agent and deionized water, a modified sealing agent solution is obtained. After the alkaline or acidic zinc-nickel alloy plating layer passivated by trivalent chromium natural color or blue is sealed by the alkaline or acidic zinc-nickel alloy plating layer, the neutral salt spray test is free from corrosion for 600 h. Here, only the improvement of the corrosion resistance of the plating layer is concerned, and other properties (surface contact angle, friction coefficient, etc.) of the plated surface of the automobile part are not concerned. In Jianjia faithfully in 2013 plating and coating No. 10 'sealing treatment of trivalent chromium passivation and passivation film of a zinc coating', the influence of the vinyl trimethylsilane sealing treatment on the surface appearance and the corrosion resistance of the passivation film is researched. Namely, graphene is not present, and only the purpose is to improve the corrosion resistance of the plating layer. In addition, in the aspect of coating sealing, for example, CN 106318200a discloses that graphene and silica sol are added into an aqueous composite sealing agent, and inorganic silica sol is added as an auxiliary film-forming substance, so as to form a dense film on the surface of the coating, thereby improving the corrosion resistance of the coating, wherein the redox graphene has a two-dimensional network structure and has a strong binding force with the coating, so that the coating can be isolated from the external environment, the coating can be protected from corrosion, and the stability of the sealing layer is also increased. CN 105670480A discloses a zinc-nickel alloy coating and zinc coating nanometer modified sealing agent, which comprises nanometer polytetrafluoroethylene and nanometer silica sol as fillers, realizes the sealing performance and improves the corrosion resistance. CN 108611631a discloses that silica sol and graphene are directly added into a passivation solution to form a passivation layer on the surface of a galvanized steel sheet. However, the graphene used in these patents is powder or slurry, and then is mixed with silica sol, but the problem of dispersion of graphene added with sol needs to be solved, because the problem of non-uniform dispersion is easily generated in the process of dispersing graphene, the effect of the sealing coating is not uniform due to non-uniform dispersion, and the corrosion resistance is not effectively improved.

Therefore, it is also very important to pay attention to the performances such as frictional wear, low surface energy and the like in addition to the corrosion resistance of the galvanized (or zinc-nickel alloy) surface, which are the application requirements of the light-weight plated parts for automobiles. The technical problem to be solved by the invention is to obtain a protective film layer on the surface of the galvanized (or galvanized nickel alloy) to improve the corrosion resistance, reduce the surface friction coefficient and reduce the surface energy.

Disclosure of Invention

In view of the above, the present invention is directed to a sealing treatment solution and a preparation method thereof, and a transparent corrosion-resistant film layer with low surface energy and low friction coefficient prepared by using the sealing treatment solution and a preparation method thereof, so as to obtain a protective film layer on a galvanized (or zinc-nickel alloy-plated) surface, improve corrosion resistance, reduce surface friction coefficient, and reduce surface energy.

In order to achieve the above object, the present invention provides a treating fluid for surface treatment of a zinc-plated or zinc-nickel alloy and a method for preparing the same. The transparent corrosion-resistant film with low surface energy and low friction coefficient is prepared by using the sealing treatment fluid.

The preparation method of the sealing treatment fluid comprises the following steps:

1) adding an organic solvent, inorganic sulfate and a surfactant into deionized water, and uniformly mixing to form a solution, wherein the weight ratio of the organic solvent to the inorganic sulfate to the surfactant is 0.1: (15-30): (0.08-0.15), preferably 0.1: 20: 0.1.

2) and preparing graphene in the solution by an electrochemical method by taking a carbon rod as an anode and a platinum sheet or a carbon rod as a cathode. And (3) controlling the voltage of a direct-current power supply to be 15-35V, the temperature to be 20-40 ℃, and electrolyzing for 3-6 hours to obtain the transparent light yellow basic sealing solution containing the graphene sheets. Wherein, the concentration of the graphene sheet in the basic sealing solution is 0.5 wt% to 10 wt%, and the total concentration of the organic solvent, the inorganic sulfate and the surfactant is 3 wt% to 8 wt%. The total concentration of the graphene, the organic solvent, the inorganic sulfate, and the surfactant in the base sealing solution may be preferably 4 to 15 wt%, more preferably 5 to 10 wt%.

3) Preparing the nano aluminum zirconium sol aqueous solution. Raw materials for preparing the aluminum sol and the zirconium sol are added into a synthesis reaction device, and the aluminum sol and the zirconium sol are generated in situ in water by a chemical method. After reacting and stirring for 3.5-5 hours, the nano aluminum zirconium sol aqueous solution is obtained. The zirconium sol can be prepared from the following raw materials: fluorozirconates or zirconium salts, such as potassium fluorozirconate, sodium fluorozirconate, zirconium oxychloride octahydrate, and the like. The raw material of the aluminum sol may be an aluminum salt such as aluminum nitrate or the like. The molar ratio of the in situ generated aluminium sol to zirconium sol may be (5-12) to 1, preferably (8-9): 1. the molar concentrations of the aluminum sol and the zirconium sol in total are: 0.05 to 1.5mol/L, preferably 0.2 to 1 mol/L. Wherein the molar ratio and the molar concentration are calculated by the amount of substances of two elements of aluminum and zirconium.

4) Mixing the nano aluminum zirconium sol aqueous solution prepared in the step 3) with the basic sealing solution prepared in the step 2) according to a certain proportion to obtain the sealing treatment solution, wherein the nano sol and the graphene are highly dispersed. The weight ratio of the nano aluminum zirconium sol aqueous solution to the basic sealing solution is (4-18):1, preferably (8-16): 1.

Further, the organic solvent may be an alcohol organic solvent such as ethanol or methanol. The presence of the organic solvent facilitates dispersion of graphene sheets during electrochemical preparation of graphene.

Further, the inorganic sulfate can be zinc sulfate or nickel sulfate, etc.

Further, the surfactant is a surfactant with hydroxyl, such as fatty alcohol hydroxyl surfactant, and hydroxyl phosphate ester surfactant. Fatty alcohol hydroxyl surfactants are preferred.

Further wherein the passivated component is an electrogalvanized or electrogalvanized nickel passivated component.

Further, the concentration of the graphene sheet in the basic sealing solution obtained in step 2) is 0.5 wt% to 10 wt%, and preferably: 5 to 7 weight percent. The graphene sheets have a diameter of 1-5 μm, a thickness of less than 5nm, and 5-10 layers. The total concentration of the organic solvent, the inorganic sulfate and the surfactant may be more preferably 4.9 to 6.5 wt%.

Further, in the step 4), the weight ratio of the nano aluminum zirconium sol aqueous solution to the base blocking solution is further preferably (9-12):1, such as 10: 1. The ratio of the nano aluminum zirconium sol to the basic sealing liquid influences the performance of the final coating. If the content of graphene in the basic sealing liquid obtained by electrochemical stripping is too high, the surface state of a coating is uneven, and the phenomenon is that the surface of an electroplated part is bloomed; if the content is too low, the sealing effect is not good, and the corrosion resistance is insufficient, and the surface contact angle is low.

Further, the fatty alcohol hydroxyl surfactant is a polyhydric alcohol type nonionic surfactant having hydroxyl groups, such as: sucrose fatty acid ester, and sorbitol fatty acid ester.

The invention also provides a sealing treatment fluid, which is prepared by the method.

The invention also provides a transparent corrosion-resistant film layer with low surface energy and low friction coefficient, which is prepared by the following steps: in addition to the sealing treatment liquid prepared by the steps 1) to 4), the method also comprises a step 5): and (4) placing the passivated part in the aqueous solution for sealing treatment, and then drying.

Further, in the step 5), the temperature of the sealing treatment is 20-50 ℃, preferably 25-40 ℃; the time of the sealing treatment is 0.5-15 minutes.

Further, in the step 5), the drying temperature is 60-80 ℃; the drying time is 10-30 minutes.

The invention has the following beneficial effects:

the preparation method provided by the invention can improve the corrosion resistance of a galvanized layer (the salt spray corrosion time is more than 360 hours) or a galvanized nickel alloy layer (the salt spray corrosion time is more than 1000 hours) on the surface of the electroplated automobile part; the improvement of the corrosion resistance has important value for light weight, energy conservation and emission reduction of automobile materials, for example, on the premise of the same corrosion resistance, the weight of the materials can be reduced by 5-8 times, and the energy conservation and emission reduction is 15-20%. The corrosion resistance effect comes from the contribution of sealing the surface of the electroplating film layer by using the aluminum oxide and zirconium oxide nano particles prepared by a chemical method and graphene to block the invasion of external corrosive substances, and also the low surface energy hydrophobic effect brought by the microstructure formed on the surfaces of the electroplating layer and the gold layer by the treatment solution disclosed by the invention reduces the chance of contact between a part and a water medium in the environment, and is beneficial to improving the corrosion resistance of the electroplating part.

The invention can keep the surface of the coating (zinc plating or zinc nickel alloy plating layer) of the automobile electroplating part with stable low surface energy and stable low friction coefficient, so as to meet the requirements of the electroplating products of the lightweight automobile parts; the low surface energy can be characterized by a water contact angle of 110 ° or more, and the low coefficient of friction can be characterized by a coefficient of friction stably less than 0.2. In the technical scheme of the invention, the surfactant with hydroxyl can further improve the dispersion effect of the graphene and the aluminum zirconium sol and ensure the dispersion uniformity of the graphene and the aluminum zirconium sol.

The stable low friction coefficient of the part surface means that the friction coefficient difference of different positions on the surface of the electroplated part subjected to sealing treatment is not large, the parts have low friction coefficients, and the friction coefficients are smaller than 0.2 at all positions on the surface in production practice. This is because the present invention focuses on the uniform dispersion of graphene in each process step. Compared with graphene or graphene oxide of the external reinforcement powder, the graphene in the basic sealing solution prepared by the electrochemical method is fewer in number of graphene layers and uniform in dispersion. The added graphene powder is dispersed by the dispersing agent to obtain a graphene solution, so that the high dispersion degree cannot be achieved, and the transparent graphene solution is difficult to form. Finally, graphene is unevenly distributed on the surface of the film layer, although some local friction coefficients can be lower than 0.2, the friction coefficient of a region with less graphene may reach 0.3, even 0.6 and 0.8, and the overall friction coefficient of the surface of the part is unstable. In addition, the organic solvent contained in the closed base solution prepared by electrochemistry can further promote the dispersion of graphene. The use of the surfactant having hydroxyl groups also helps the graphene to be uniformly dispersed and attached to the surface of the workpiece during immersion of the workpiece in the sealing treatment liquid. In the process, the hydroxyl groups contribute to the surface attachment and uniform dispersion effect of the graphene. This is best with a surfactant of the fatty alcohol type with hydroxyl groups. The method can stably obtain the effect of low friction coefficient in different areas of the surface of the film layer, and is the result of the combined action of the electrochemical graphene preparation process, the organic solvent and the surface activity with hydroxyl.

The preparation method provided by the invention can ensure that the surface weight of the electrogalvanized automobile parts is not increased basically (the thickness of the film layer is only 50-100 nanometers, and the film layer is transparent), and the appearance is uniform. To realize the sealing effect of the graphene, the transparency of the film layer on the sealing surface is ensured, the graphene sheet layer needs to be thin enough, and the dispersity of the graphene is high enough. In the prior art, the graphene which is directly added is difficult to achieve the uniform dispersion degree, and the formed film layer has good corrosion resistance, but the film layer is dark due to the aggregation of the graphene, so that a transparent coating cannot be formed.

In the technical scheme of the invention, the final realization of the stable low surface energy is a result of the combined action of the graphene base solution and the aluminum zirconium sol, and the graphene base solution and the aluminum zirconium sol have a synergistic effect. And forming a surface microstructure in the process that the aluminum zirconium sol and the graphene are attached to the surface of the workpiece to form a closed film layer. On one hand, the aluminum zirconium sol has low surface energy, and on the other hand, the surface microstructure also strengthens the hydrophobic effect. In order to achieve the above technical effects, the aluminum zirconium sol and the graphene need to be in a proper concentration ratio in the treatment solution (such as the concentration ratio relationship of the present invention), and the graphene sheet and the aluminum zirconium sol need to be dispersed at a high enough degree and adhered uniformly enough to achieve the above technical effects. Particularly, the dispersion uniformity of graphene in the sealing solution is very difficult in practice, and the graphene composite material is prepared by an electrochemical method, added with an organic solvent for facilitating the dispersion of the graphene composite material and surface activity for facilitating the uniform adhesion of the graphene composite material, and all the measures play a role in the high dispersion of the graphene in the sealing solution. It can be said that the low surface energy hydrophobic effect achieved by the present invention is generated by the mutual cooperation of the aluminum zirconium sol and the highly dispersed graphene. Zirconium alumina sol alone, or zirconium alumina sol with lower dispersion of graphene, is difficult to achieve.

The transparent corrosion-resistant film layer provided by the invention can be used on the surface of a metal plating part which needs corrosion resistance and antifriction requirements, and can improve the performances of corrosion resistance, antifriction and the like of an electroplating product part. In addition, the film layer is thin and transparent, so that the metallic luster of the surface of the electroplated metal can be well kept, and the electroplated metal has good metallic appearance. Therefore, the method has good application value in the fields of transportation, aerospace, mechanical equipment and the like.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

Materials, reagents and the like used in the following examples are commercially available.