阅读说明：本技术 一种羟基化纳米封闭处理液及其制备方法和应用 (Hydroxylated nano sealing treatment fluid and preparation method and application thereof ) 是由 肖革 向可友 蓝玉良 杨晓波 朱立群 于 2019-11-22 设计创作，主要内容包括：本发明涉及一种羟基化纳米封闭处理液及其制备方法和应用,该羟基化纳米封闭处理液由浓度为5-30wt％的无机碱性组分溶液、浓度为3-20wt％的纳米溶胶液、浓度为0.1-5wt％的羟基表面活性剂溶液及浓度为10-40wt％的有机酸溶液按照一定体积比混合而成。本发明在化学镀与电镀锌镍镀层之间,采取羟基化纳米封闭处理,提高了化学镀镍层的耐腐蚀性能,以及与后续锌镍合金镀层结合力,使得电镀产品的合格率由70-80％提高到98％以上。再提高汽车零件的耐腐蚀性能方面,由过去的盐雾腐蚀实验48小时提高到360小时,耐腐蚀性能得到大幅度提高。(The invention relates to a hydroxylated nano sealing treatment fluid and a preparation method and application thereof, wherein the hydroxylated nano sealing treatment fluid is prepared by mixing an inorganic alkaline component solution with the concentration of 5-30 wt%, a nano sol solution with the concentration of 3-20 wt%, a hydroxyl surfactant solution with the concentration of 0.1-5 wt% and an organic acid solution with the concentration of 10-40 wt% according to a certain volume ratio. According to the invention, hydroxylation nano sealing treatment is adopted between chemical plating and zinc-nickel plating, so that the corrosion resistance of a chemical nickel plating layer is improved, and the binding force with a subsequent zinc-nickel alloy plating layer is improved, so that the qualification rate of an electroplating product is improved to more than 98% from 70-80%. And in the aspect of improving the corrosion resistance of the automobile parts, the corrosion resistance is greatly improved from 48 hours to 360 hours in the traditional salt spray corrosion experiment.)

1. A hydroxylated nano sealing treatment fluid is characterized by comprising the following components: inorganic alkaline components, nano sol, hydroxyl surfactant and organic acid; the preparation steps are as follows: dissolving inorganic alkaline components into inorganic alkaline solution with the concentration of 5-30 wt% by using deionized water, preparing nano sol liquid with the concentration of 3-20 wt%, then preparing hydroxyl surfactant solution with the concentration of 0.1-5 wt% by using deionized water, preparing organic acid solution with the concentration of 10-40 wt% by using deionized water, and then dissolving the four liquids according to the volume ratio of 1 (0.5-1.5): (0.05-0.5): (0.5-3) mixing to obtain the hydroxylated nano sealing treatment fluid.

2. The hydroxylated nano-blocking treatment fluid of claim 1, wherein the inorganic alkaline component is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, or sodium phosphate; the mixing ratio of the inorganic alkali solution to the nano sol liquid to the hydroxyl surfactant solution to the organic acid solution is 1:1: 0.2: 1.2.

3. the hydroxylated nano-blocking treatment fluid of claim 1, wherein the nanosol is selected from at least one of a nano-aluminum sol, a nano-titanium sol, a nano-zirconium sol, or a nano-silicon sol.

4. The hydroxylated nano-blocking treatment fluid of claim 1, wherein the hydroxyl surfactant is selected from at least one of a fatty alcohol hydroxyl surfactant, a sorbitol hydroxyl surfactant, or a hydroxy phosphate ester surfactant.

5. The hydroxylated nano-blocking treatment fluid of claim 1, wherein the organic acid is at least one of chemically pure citric acid, tartaric acid, ascorbic acid, gluconic acid, phytic acid, or malic acid.

6. A method of corrosion protection of a metal part, comprising the steps of:

1) after the parts are subjected to pretreatment, chemical nickel plating is carried out, and a chemical nickel plating layer is formed on the surface;

2) soaking the part subjected to the chemical nickel plating treatment in the hydroxylated nano sealing solution according to any one of claims 1 to 5;

3) electroplating the metal parts treated in the step 2) to form an electroplated layer.

7. The method for preventing corrosion of a metal part according to claim 6, wherein the electroless plating treatment in step 1) is an electroless nickel-phosphorus plating process treatment; the electroplating treatment in the step 3) is electroplating zinc-nickel alloy process treatment.

8. The method for preventing corrosion of a metal part according to claim 6, wherein in the step 2), the temperature for soaking in the hydroxylated nano confining liquid is 20-40 ℃ and the soaking time is 10-60 seconds; a water washing step is also included between steps 2) and 3), and preferably twice.

9. The method of preventing corrosion of a metal part according to claim 6, wherein the metal part is an automotive water oil capillary.

10. An anti-corrosion coating produced on the surface of a part by the method of any of claims 6 to 9.

Technical Field

The invention belongs to the technical field of electroplating, and particularly relates to a hydroxylated nano sealing treatment fluid and a preparation method and application thereof.

Background

Under the trend of light weight of automobiles, a lot of high-strength steel sheets and thin-wall parts are applied, the weight of the automobile parts is reduced, but high corrosion resistance is required. The plating of protective coatings on the surfaces of parts is a common rust-proof mode, such as electroplating corrosion-resistant coatings. However, for some parts with narrow and complex cavities, it is very difficult to uniformly form a coating with sufficient thickness by electroplating. For example, some high-strength oil supply tubules have narrow and complex interior and need complete protective coating coverage, and the tubules can be known from the basic theory of electrodeposition and the distribution of electric lines of force (for example

About 100mm or more) or the like, and the inner surface of a narrow or complex cavity cannot be uniformly and entirely covered with the plating layer, and the inner surface of the cavity with a thin plating layer or without the plating layer is easily corroded. Some documents have used a method of immersing the inside of the pipe with rust preventive water after plating, but the corrosion resistance is low and the pipe is corroded after a salt spray test for several hours. There are also reports of water repellent impregnation, but the corrosion resistance is not satisfactory, and the salt spray test has been successful for over ten hours. The method of chemical plating nickel-phosphorus alloy can completely cover the surface of the coating, but the plating layer is only a few micrometers, the plating time can be up to 1 hour, and the chemical plating nickel-phosphorus alloy layer has a large number of pinholes (caused by hydrogen gas generated by chemical plating reaction), so that the corrosion resistance can not meet the requirement. The subsequent electroplating of zinc-nickel alloy can partially thicken the coating, but because the distribution of the power lines at the deep inside of the thin tube is not in place, the pinholes on the nickel-phosphorus alloy plating layer are difficult to uniformly and completely cover, and the anti-corrosion effect is poor. More importantly, after the chemical nickel-phosphorus alloy plating layer is plated, and before the electroplating of the zinc-nickel alloy is performed, the chemical nickel-phosphorus plating layer is easy to passivate, so that the binding force of the chemical nickel-phosphorus plating layer and the zinc-nickel plating layer is influenced. This results in a yield of plated parts onlyCan reach 70-80%. There is also a method in which after the electroless plating of nickel-phosphorus alloy, an activation treatment is performed using an acid (hydrochloric acid, sulfuric acid, etc.), and then a plating layer required for electroplating, such as a zinc-nickel alloy plating layer, is performed. However, the bonding force between the coatings obtained in this way is unstable, and the coatings can be passivated quickly after being placed in the air after acid activation, so that the process control is difficult. After the activating solution is used for a period of time, the activating effect is deteriorated, and the bonding force between the surface chemical plating layer and the electroplated layer of the part is deteriorated.

In summary, two important problems exist in the chemical plating and electroplating of the tubules: 1. the interior of the tubule is only provided with a chemical plating layer with pores, and the corrosion resistance can not meet the requirement of more than 360 hours (the dissected tubule is tested according to the national standard GB/T24195 for 96 hours); 2. the bonding force reject ratio of the zinc-nickel alloy coating which can be electroplated on the surface of the chemical coating in the thin tube is high and reaches about 20%.

Therefore, it is urgent to solve the above problems in the field of electroplating technology for lightweight steel parts for automobiles.

Disclosure of Invention

In view of the above, the present invention aims to provide a hydroxylated nano-sealing treatment fluid, and a preparation method and an application thereof.

In order to achieve the above object, the present invention provides a hydroxylated nano-blocking treatment fluid, comprising the following components: inorganic alkaline component, nano sol, hydroxyl surfactant and organic acid. The preparation method comprises the following steps of dissolving an inorganic alkaline component into a solution with the concentration of 5-30 wt% by using deionized water, preparing a nano sol liquid with the concentration of 3-20 wt%, preparing a hydroxyl surfactant solution with the concentration of 0.1-5 wt% by using deionized water, preparing an organic acid solution with the concentration of 10-40 wt% by using deionized water, and mixing the four liquids according to the volume ratio of 1 (0.5-1.5): (0.05-0.5): (0.5-3) to obtain the hydroxylated nano sealing treatment fluid.

Further wherein the strong base is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate or sodium phosphate.

Further, the nano sol is at least one selected from nano aluminum sol, nano titanium sol, nano zirconium sol and nano silicon sol.

Further, the hydroxyl surfactant is selected from at least one of fatty alcohol hydroxyl surfactant, sorbitol hydroxyl surfactant or hydroxyl phosphate surfactant, such as sucrose fatty acid ester, sorbitol fatty acid ester, etc.

Further, the organic acid is selected from at least one of chemically pure citric acid, tartaric acid, ascorbic acid, gluconic acid, phytic acid or malic acid, etc.

The inorganic alkaline component, partial hydroxyl surfactant and organic acid have the effects of utilizing the hydroxyl groups generated by the solution components on the surface of the chemical nickel plating layer, avoiding the passivation of the chemical nickel plating and improving the binding force of the subsequent zinc-nickel alloy plating layer.

In order to achieve the above object, another aspect of the present invention provides a method for preparing a hydroxylated nano-blocking treatment solution, comprising the following steps:

dissolving inorganic alkaline components into 5-30 wt% solution by using deionized water, preparing 3-20 wt% nano sol liquid, preparing 0.1-5 wt% hydroxyl surfactant by using deionized water, preparing 10-40 wt% organic acid by using deionized water, and respectively preparing the following components according to the weight ratio of 1 (0.5-1.5) to 0.05-0.5): (0.5-3), preferably in a mixing ratio of 1:1: 0.2: 1.2, obtaining the hydroxylated nano sealing treatment fluid.

In order to achieve the above objects, another aspect of the present invention provides a method for using the hydroxylated nano-sealing treatment liquid in an automobile water-oil capillary (e.g., water-oil capillary)

Left and right, length 100mm or more).

Wherein the application comprises the steps of:

1) after the pre-treatment, the steel part is subjected to chemical nickel plating treatment to form a chemical nickel plating layer on the surface;

2) soaking the part subjected to chemical plating treatment in a hydroxylated nano sealing liquid;

3) electroplating the metal parts treated in the step 2) to form an electroplated layer.

Further, in the step 1), the pretreatment comprises oil removal, acid washing and the like; the chemical plating treatment is a conventional chemical nickel-phosphorus plating process.

Further, in the step 2), the temperature for soaking in the hydroxylated nano confining liquid is 20-40 ℃, and the soaking time is 10-60 seconds.

Further, in the step 3), the electroplating treatment is a conventional zinc-nickel alloy electroplating process.

Further, a water washing step is also included between the steps 2) and 3), and preferably, the water washing step is carried out twice.

The invention mainly replaces the acid activation of the prior art with the hydroxylation nano sealing treatment, because the acid activation is carried out after the chemical plating of the electroplated parts, the parts are quickly and easily passivated in the air after coming out of the acid activation tank and washed by water, and the binding force of the subsequent electroplated zinc-nickel alloy coating is influenced; and the hydroxylation nano sealing treatment is adopted, so that the surface of the part cannot be passivated after being washed by water, and good binding force with a subsequent zinc-nickel electroplating coating is kept.

The invention has the following beneficial effects:

the invention can well solve the problem of corrosion prevention in the complex pipe fitting, and is based on the following steps:

on one hand, the hydroxylation nano sealing treatment is carried out between the chemical nickel plating process and the zinc-nickel electroplating process, so that the passivation of the surface of a plating layer after the chemical nickel plating is finished can be prevented, and the binding force between a chemical nickel plating layer and a subsequent zinc-nickel electroplating layer is improved. The surface of the chemical nickel plating layer after surface hydroxylation can not be passivated again in the air, and the control difficulty of the whole process is also reduced. In the process, the alkaline component and the hydroxyl surfactant in the hydroxylated nano confining liquid play an important role together.

On the other hand, the invention utilizes the nanometer sol particles to seal the pinholes of the chemical plating layer (metallic nickel plating layer) (the pinholes of the chemical nickel plating layer are sealed by the synergistic action of the nanometer sol, the hydroxyl surfactant and the organic acid in the hydroxylation nanometer sealing treatment solution).

The above is also the innovative focus of the present invention.

According to the invention, the hydroxylation nano sealing treatment is adopted between the chemical nickel plating and the zinc-nickel plating layer, so that the corrosion resistance of the chemical nickel plating layer and the binding force with the subsequent zinc-nickel alloy plating layer are improved, and the qualification rate of the electroplated product is improved from 70-80% to more than 98%; in the aspect of improving the corrosion resistance of automobile parts, the corrosion resistance is greatly improved from 48 hours to 360 hours in the traditional salt spray corrosion experiment.

In addition, other metal coatings which are easy to passivate and have pinholes, such as nickel plating, copper plating, tin plating and the like, can be treated by the hydroxylated nano sealing liquid, so that the qualification rate of electroplated products and the corrosion resistance and other performances of the products are improved.

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.

The complete process flow of the following examples is as follows: the conventional pretreatment process of the high-strength steel part (oil removal, water washing, hydrochloric acid pickling, water washing and water washing), the conventional chemical nickel and phosphorus plating process, the water washing, the hydroxylation nano sealing treatment, the water washing, the conventional zinc-nickel alloy electroplating process, the water washing, the passivation, the water washing and the drying.