Anti-corrosion blue-white passivation solution and preparation method thereof

Abstract

The invention discloses an anti-corrosion blue-white passivation solution and a preparation method thereof, and belongs to the technical field of metal surface treatment and corrosion prevention. The anti-corrosion blue and white passivation solution is prepared from the following components according to the content: 80 to 110 g / L of chromium chloride, 0.1 to 1 g / L of cobalt nitrate, 0.1 to 1.2 g / L of diethylene glycol dimethyl ether, 0.06 to 0.08 g / L of benzotriazole, 2 to 4 g / L of organosilane and 0.9 to 1.2 g / L of PAMAM (Polyamidoamine) modified graphene oxide. By optimizing the component content of the blue-white passivation solution and further adopting a step-by-step component adding mode, the prepared blue-white passivation solution has a remarkable corrosion resisting effect on a galvanized sheet, organosilane provides a supporting framework for a passivation film, PAMAM modified graphene oxide further improves the supporting force of the supporting framework, the corrosion path is prolonged, and the corrosion resistance of the galvanized sheet is improved. Benzotriazole plays a synergistic role in corrosion resistance through physical adsorption under a vacuum condition.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment and anti-corrosion, and particularly relates to an anti-corrosion blue-white passivation liquid and a preparation method thereof. Background Art

[0002] Common active metals are very easy to oxidize and rust when placed in the air, especially in the presence of water vapor, salt spray, exposure to the sun, etc. Many metals, such as the most common copper and iron, are easily oxidized and rusted after oxidation, which destroys the original structure of the metal surface. Generally, the galvanizing process is used for the easily corroded metal surface, and the anode is used to protect the cathode by sacrificial protection, so as to achieve the protection of the active metal. Metallic zinc in dry air hardly reacts chemically with air, but in most actual use environments, the galvanized layer will be exposed to high humidity atmosphere, soil or seawater for a long time, and affected by its own active chemical properties. In these easily corrosive use environments, the surface of the galvanized layer will easily corrode to generate white thin and dense corrosion products, basic zinc carbonate, which is also called "white rust", thereby destroying the original protective function of the city for centralized procurement, and seriously affecting the appearance quality and service life of the product. In order to solve the above problems, the galvanized layer is generally further passivated during production, and the chemical reaction is used to convert the active metal on the surface of the metal material into a state that is not easily corroded, so that the metal material can be exempted from rust or slow down the corrosion rate.

[0003] The blue-white passivation has a simple and elegant appearance and excellent performance, and is deeply favored by the market. After treatment, the galvanized parts are light blue and bright in appearance. It can not only maintain the metal color of the galvanized parts, but also improve the corrosion resistance of the products. Therefore, the blue-white passivation process is widely used in various metal protection industries. Traditional blue-white passivation treatment mostly uses hexavalent chromium compounds such as chromic acid and chromate as treatment agents. The chromate conversion film formed on the metal surface after passivation treatment has good corrosion resistance for the base metal. However, hexavalent chromium is recognized as a highly toxic carcinogen and one of the heavy metals that seriously pollutes the environment. It is very toxic and cannot be naturally degraded in nature; it is easy to accumulate in organisms and the human body, which can cause long-term harm. In addition, the blue-white passivation film obtained by the existing passivation liquid technology is thin and unevenly distributed, and the long-term corrosion resistance effect is unsatisfactory, and the passivation layer is also prone to color. Summary of the invention

[0004] One of the purposes of the present invention is to provide an anti-corrosion blue-white passivation solution to solve the problem of poor corrosion resistance of the zinc coating surface;

[0005] A second object of the present invention is to provide a method for preparing a corrosion-resistant blue-white passivation solution.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In the first aspect, an anti-corrosion blue-white passivation solution comprises the following components and contents:

[0008] Chromium chloride 80-110g / L, cobalt nitrate 0.1-1g / L, diethylene glycol dimethyl ether 0.1-1.2g / L, benzotriazole (BTA) 0.06-0.08g / L, organosilane 2-4g / L, PAMAM modified graphene oxide 0.9-1.2g / L, pH = 1.5-3.0.

[0009] As a further solution of the present invention, the preparation method of the PAMAM modified graphene oxide comprises the following steps:

[0010] S1. Add thionyl chloride (SOC l2) and N,N-dimethylformamide (DMF) to graphene oxide (GO), reflux and stir to react for 12-16 hours, and then filter and collect GO-COOH;

[0011] S2. GO-COOOH is dispersed in a mixed alcohol solvent, and then a dendritic polymer polyamide-amine (PAMAM) is added. The mixture is stirred at room temperature (25-30° C.) for 2-6 hours, and then filtered, washed, and dried to obtain PAMAM-modified graphene oxide.

[0012] The carboxyl groups on the surface of graphene oxide are activated by thionyl chloride, thereby further promoting the nucleophilic substitution reaction between graphene oxide and the amino group of PAMAM, and preparing PAMAM-modified graphene oxide.

[0013] As a further solution of the present invention, the usage ratio of GO, SOC l2 and DMF in S1 is 0.5-0.8 g: 200 mL: 6-8 mL.

[0014] As a further solution of the present invention, the reflux temperature in S1 is 75-85°C.

[0015] As a further solution of the present invention, the mixed alcohol solvent in S2 is a mixture of methanol and ethanol in a volume ratio of 1:3.

[0016] As a further solution of the present invention, the usage ratio of GO-COOOH, PAMAM and mixed alcohol solvent in S2 is 0.5-0.8 g: 5 mL: 200 mL.

[0017] As a further solution of the present invention, the stirring speed is 100-300 rpm.

[0018] As a further embodiment of the present invention, the organosilane is γ-aminopropyltriethoxysilane (KH550).

[0019] In a second aspect, a method for preparing an anti-corrosion blue-white passivation solution comprises the following steps:

[0020] Step 1, dissolving diethylene glycol dimethyl ether in deionized water, adding chromium chloride and cobalt nitrate, and then adding organosilane, and ultrasonically mixing for 1-2 hours to obtain a mixed solution A;

[0021] Step 2, adding PAMAM modified graphene oxide to the mixed solution A, stirring and reacting in a gradient heating manner to obtain a mixed solution B;

[0022] Step 3: Add benzotriazole to the mixed solution B, react in vacuum at 38-45° C. for 10-18 hours, adjust the pH to 1.5-3.0 with dilute hydrochloric acid, and obtain a corrosion-resistant blue-white passivation solution.

[0023] As a further solution of the present invention, the gradient temperature increase in step 2 is specifically to first increase the temperature to 45-55°C at a heating rate of 2-4°C / min and keep the reaction for 1-2 hours, and then increase the temperature to 75-85°C at a heating rate of 4-6°C / min and keep the reaction for 0.5-1.5 hours.

[0024] As a further solution of the present invention, the stirring speed in step 2 is 200-400 rpm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The invention provides an anti-corrosion blue-white passivation solution, wherein chromium chloride is used as a main film-forming salt, free trivalent chromium reacts with zinc ions and hydroxide ions to form an insoluble compound that is precipitated on the surface of a zinc-plated layer, and chloride ions have the ability to promote film formation, accelerate the dissolution of the zinc layer, shorten the film-forming time, and will not cause excessive harm to the environment; cobalt nitrate is used as a metal additive to accelerate the formation rate of the passivation film on the one hand, and adhere to the surface of the zinc-plated layer to further improve the color of the passivation film on the other hand; diethylene glycol dimethyl ether is used as a coordination stabilizer, and benzotriazole (corrosion inhibitor), organosilane and PAMAM modified graphene oxide are added to obtain a blue-white passivation solution that has excellent anti-corrosion effect on galvanized materials.

[0027] 2. The present invention provides a method for preparing a corrosion-resistant blue-white passivation solution. In the process of passivating galvanized parts with the blue-white passivation solution, water is volatilized by heating and curing, and the organosilane forms metal silicon-oxygen-zinc bonds with Zn ions on the zinc surface through covalent bonds, thereby building a skeleton structure for the passivation layer; graphene oxide is modified by PAMAM to form a condensation structure of PAMAM and GO, thereby reducing the penetration of corrosive media into the interface of the galvanized layer; in addition, in the gradient temperature increase reaction with the organosilane in the system, the hydroxyl groups in the graphene oxide are further effectively cross-linked with the organosilane, thereby further improving the supporting force of the passivation layer skeleton, making the passivation layer tighter and increasing the invasion path of the corrosive medium; finally, the corrosion inhibitor benzotriazole is adsorbed on the surface of the skeleton structure through physical adsorption under vacuum conditions, thereby achieving long-term corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 The present invention is a schematic diagram of the preparation process of the anti-corrosion blue-white passivation solution. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The preparation method of PAMAM modified graphene oxide comprises the following steps:

[0032] S1. Add SOC l2 and DMF to GO, reflux and stir at 75-85°C and 100-300 rpm for 12-16 hours, then filter and collect GO-COOH; the dosage ratio of GO, SOC l2, and DMF is 0.5-0.8 g: 200 mL: 6-8 mL;

[0033] S2. GO-COOOH is dispersed in a mixed alcohol solvent of methanol and ethanol in a volume ratio of 1:3, and PAMAM is added. The mixture is stirred at 100-300 rpm for 2-6 hours at room temperature, and then filtered, washed, and dried to obtain polyamidoamine-modified graphene oxide; the dosage ratio of GO-COOOH, PAMAM, and mixed alcohol solvent is 0.5-0.8 g: 5 mL: 200 mL.

[0034] A corrosion-resistant blue-white passivation solution, comprising the following components and contents:

[0035] Chromium chloride 80-110g / L, cobalt nitrate 0.1-1g / L, diethylene glycol dimethyl ether 0.1-1.2g / L, benzotriazole 0.06-0.08g / L, organosilane 2-4g / L, PAMAM modified graphene oxide 0.9-1.2g / L, pH = 1.5-3.0;

[0036] The preparation method of the anti-corrosion blue-white passivation solution, please refer to Figure 1 , including the following steps:

[0037] Step 1, according to the above formula, dissolve diethylene glycol dimethyl ether in deionized water, add chromium chloride and cobalt nitrate, and then add organosilane, and mix by ultrasonication for 1-2h to obtain a mixed solution A;

[0038] Step 2, adding PAMAM modified graphene oxide to the mixed solution A, and heating the mixture to 45-55° C. at a heating rate of 2-4° C. / min for 1-2 h, and then heating the mixture to 75-85° C. at a heating rate of 4-6° C. / min for 0.5-1.5 h, under stirring at a speed of 200-400 rpm, to obtain a mixed solution B;

[0039] Step 3: Add benzotriazole to the mixed solution B, react in vacuum at 38-45° C. for 10-18 hours, adjust the pH to 1.5-3.0 with dilute hydrochloric acid, and obtain a corrosion-resistant blue-white passivation solution.

[0040] Example 1

[0041] The preparation method of PAMAM modified graphene oxide comprises the following steps:

[0042] S1. Add 200 mL of SOC l2 and 7 mL of DMF to 0.65 g of GO, stir under reflux at 80 ° C and 200 rpm for 15 h, and then filter and collect GO-COOH;

[0043] S2. 0.65 g GO-COOOH was dispersed in 200 mL of a mixed alcohol solvent of methanol and ethanol in a volume ratio of 1:3, and 5 mL of PAMAM was added. The mixture was stirred at room temperature at 200 rpm for 4 h, then filtered, washed with deionized water, and dried at 60 °C to obtain polyamidoamine-modified graphene oxide.

[0044] Example 2

[0045] A corrosion-resistant blue-white passivation solution, comprising the following components and contents:

[0046] Chromium chloride 90 g / L, cobalt nitrate 0.5 g / L, diethylene glycol dimethyl ether 0.8 g / L, benzotriazole 0.07 g / L, organosilane 3 g / L, PAMAM modified graphene oxide 1 g / L (prepared in Example 1), pH = 2;

[0047] The preparation method of the anti-corrosion blue-white passivation solution, please refer to Figure 1 , including the following steps:

[0048] Step 1, according to the above formula, diethylene glycol dimethyl ether was dissolved in deionized water, chromium chloride and cobalt nitrate were added, and then γ-aminopropyltriethoxysilane (KH550) was added, and ultrasonic mixing was performed for 1.5 hours to obtain a mixed solution A;

[0049] Step 2, adding the PAMAM modified graphene oxide prepared in Example 1 to the mixed solution A, and heating the mixture to 50° C. at a heating rate of 3° C. / min for 1.5 h, and then heating the mixture to 80° C. at a heating rate of 5° C. / min for 1 h, to obtain a mixed solution B;

[0050] Step 3: Add benzotriazole to the mixed solution B, react in vacuum at 42° C. for 15 h, adjust the pH to 2 with 1 mol / L dilute hydrochloric acid, and obtain a corrosion-resistant blue-white passivation solution.

[0051] Example 3

[0052] A corrosion-resistant blue-white passivation solution, comprising the following components and contents:

[0053] Chromium chloride 80 g / L, cobalt nitrate 1 g / L, diethylene glycol dimethyl ether 0.2 g / L, benzotriazole 0.08 g / L, organosilane 2 g / L, PAMAM modified graphene oxide (prepared in Example 1) 1.2 g / L, pH = 2;

[0054] The preparation method of the anti-corrosion blue-white passivation solution is the same as that of Example 2.

[0055] Example 4

[0056] A corrosion-resistant blue-white passivation solution, comprising the following components and contents:

[0057] Chromium chloride 110 g / L, cobalt nitrate 0.1 g / L, diethylene glycol dimethyl ether 1.2 g / L, benzotriazole 0.06 g / L, organosilane 4 g / L, PAMAM modified graphene oxide (prepared in Example 1) 0.9 g / L, pH = 2;

[0058] The preparation method of the anti-corrosion blue-white passivation solution is the same as that of Example 2.

[0059] Comparative Example 1

[0060] A blue-white passivation solution, comprising the following components and contents:

[0061] Chromium chloride 90g / L, cobalt nitrate 0.5g / L, diethylene glycol dimethyl ether 0.8g / L, benzotriazole 0.07g / L, organosilane 3g / L, PAMAM 0.5g / L, graphene oxide 0.5g / L, pH = 2;

[0062] The preparation method of the blue-white passivation solution comprises the following steps:

[0063] Step 1 is the same as in Example 2;

[0064] Step 2, PAMAM and graphene oxide were added to the mixed solution A, and the mixture was heated to 50°C at a heating rate of 3°C / min for 1.5 h, and then heated to 80°C at a heating rate of 5°C / min for 1 h, to obtain a mixed solution B;

[0065] Step 3 is the same as in Example 2.

[0066] Comparative Example 2

[0067] A blue-white passivation solution, the components and contents of which are different from those of Example 2 in that the PAMAM-modified graphene oxide prepared in Example 1 is not added;

[0068] The preparation method of the blue-white passivation solution comprises the following steps:

[0069] Step 1 is the same as in Example 2;

[0070] Step 2, the mixed solution A was stirred at a speed of 300 rpm, first heated to 50°C at a heating rate of 3°C / min for 1.5 h, and then heated to 80°C at a heating rate of 5°C / min for 1 h;

[0071] Step 3: Add benzotriazole to the mixed solution A, react in vacuum at 42°C for 15h, adjust the pH to 2 with 1 mol / L dilute hydrochloric acid, and obtain a blue-white passivation solution.

[0072] Comparative Example 3

[0073] A blue-white passivation solution, comprising the following components and contents:

[0074] Chromium chloride 90g / L, cobalt nitrate 0.5g / L, diethylene glycol dimethyl ether 0.8g / L, benzotriazole 0.07g / L, organosilane 3g / L, graphene oxide 1g / L, pH = 2;

[0075] The preparation method of the blue-white passivation solution comprises the following steps:

[0076] Step 1 is the same as in Example 2;

[0077] Step 2, adding graphene oxide to the mixed solution A, and heating the mixture to 50° C. at a heating rate of 3° C. / min for 1.5 h, and then heating the mixture to 80° C. at a heating rate of 5° C. / min for 1 h, to obtain a mixed solution B;

[0078] Step 3 is the same as in Example 2.

[0079] Comparative Example 4

[0080] A blue-white passivation solution, comprising the following components and contents:

[0081] Chromium chloride 90g / L, cobalt nitrate 0.5g / L, diethylene glycol dimethyl ether 0.8g / L, benzotriazole 0.07g / L, organosilane 3g / L, PMAMA 1g / L, pH = 2;

[0082] The preparation method of the blue-white passivation solution comprises the following steps:

[0083] Step 1 is the same as in Example 2;

[0084] Step 2, PMAMA was added to the mixed solution A, and the mixture was heated to 50°C at a heating rate of 3°C / min for 1.5 h, and then heated to 80°C at a heating rate of 5°C / min for 1 h, to obtain a mixed solution B;

[0085] Step 3 is the same as in Example 2.

[0086] Comparative Example 5

[0087] A blue-white passivation solution, comprising the following components and contents:

[0088] Chromium chloride 90 g / L, cobalt nitrate 0.5 g / L, diethylene glycol dimethyl ether 0.8 g / L, organosilane 3 g / L, PAMAM modified graphene oxide 1 g / L (prepared in Example 1), pH = 2;

[0089] The preparation method of the blue-white passivation solution comprises the following steps:

[0090] Step 1 and step 2 are the same as in Example 2;

[0091] Step 3: Adjust the pH of the mixed solution B to 2 with 1 mol / L dilute hydrochloric acid to obtain a blue-white passivation solution.

[0092] Comparative Example 6

[0093] An anti-corrosion blue-white passivation solution, whose components and contents are the same as those in Example 2;

[0094] The method for preparing the anti-corrosion blue-white passivation solution is different from that of Example 2 in that a constant temperature reaction is adopted in step 2, and specifically comprises the following steps:

[0095] Step 1 is the same as in Example 2;

[0096] Step 2, adding the PAMAM modified graphene oxide prepared in Example 1 to the mixed solution A, heating to 80° C. at a heating rate of 3° C. / min and keeping the temperature for 2.5 h under stirring at a speed of 300 rpm to obtain a mixed solution B;

[0097] Step 3 is the same as in Example 2.

[0098] Performance Test:

[0099] At room temperature, the electro-galvanized sheets were immersed in the blue-white passivation solutions prepared in Examples 2-4 and Comparative Examples 1-6, respectively, for a passivation time of 45 seconds, followed by a 10-second idle time, and then rinsed with deionized water three times, air-dried, and dried in an oven at 65°C.

[0100] (I) Salt water immersion corrosion test:

[0101] The surface corrosion resistance of the passivated galvanized sheet was evaluated using a NaCl solution with a pH of 6.8 and a mass concentration of 5%. The time from the start of immersion to the corrosion area reaching the point where rust spots began to appear was used as the basis for judging the corrosion resistance.

[0102] (II) Neutral salt spray corrosion test:

[0103] The test was carried out using the method specified in GB / T 10125-2012 “Artificial atmosphere corrosion test salt spray test”.

[0104] The test results are shown in Table 1:

[0105] Table 1

[0106]

[0107] It can be seen from Table 1 that the blue-white passivating solution prepared by the present invention by optimizing the component content of the blue-white passivating solution and further adopting the method of adding components in steps has a significant anti-corrosion effect on the galvanized sheet, wherein the organosilane provides a supporting skeleton for the passivation film, the PAMAM-modified graphene oxide further enhances the supporting force of the supporting skeleton and prolongs the corrosion path, and benzotriazole plays a synergistic anti-corrosion role through physical adsorption under vacuum conditions.

[0108] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0109] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A corrosion-resistant blue-white passivation solution, characterized in that: Includes the following components and contents: Chromium chloride 80-110g / L, cobalt nitrate 0.1-1g / L, diethylene glycol dimethyl ether 0.1-1.2g / L, benzotriazole 0.06-0.08g / L, organosilane 2-4g / L, PAMAM modified graphene oxide 0.9-1.2g / L.

2. The anti-corrosion blue-white passivation liquid according to claim 1, characterized in that: The preparation method of the PAMAM modified graphene oxide comprises the following steps: S1. Add SOCl2 and DMF to GO, reflux and stir for 12-16h, then filter and collect GO-COOH; S2. GO-COOOH is dispersed in a mixed alcohol solvent, and PAMAM is added. The mixture is stirred at room temperature for 2-6 hours, and then filtered, washed, and dried to obtain PAMAM-modified graphene oxide.

3. The anti-corrosion blue-white passivation liquid according to claim 2, characterized in that: The usage ratio of GO, SOCl2 and DMF in S1 is 0.5-0.8 g: 200 mL: 6-8 mL.

4. The anti-corrosion blue-white passivation liquid according to claim 2, characterized in that: The reflux temperature in S1 is 75-85°C.

5. The anti-corrosion blue-white passivation liquid according to claim 2, characterized in that: The mixed alcohol solvent in S2 is prepared by mixing methanol and ethanol in a volume ratio of 1:

3.

6. The anti-corrosion blue-white passivation liquid according to claim 2, characterized in that: The dosage ratio of GO-COOOH, PAMAM and mixed alcohol solvent in S2 is 0.5-0.8 g: 5 mL: 200 mL.

7. The anti-corrosion blue-white passivation liquid according to claim 1, characterized in that: The organosilane is γ-aminopropyltriethoxysilane.

8. A method for preparing the anti-corrosion blue-white passivation solution as claimed in claim 1, characterized in that: The following steps are involved: Step 1, dissolving diethylene glycol dimethyl ether in deionized water, adding chromium chloride and cobalt nitrate, and then adding organosilane, and ultrasonically mixing for 1-2 hours to obtain a mixed solution A; Step 2, adding PAMAM modified graphene oxide to the mixed solution A, stirring and reacting in a gradient heating manner to obtain a mixed solution B; Step 3: Add benzotriazole to the mixed solution B, react in vacuum at 38-45° C. for 10-18 hours, adjust the pH to 1.5-3.0 with dilute hydrochloric acid, and obtain a corrosion-resistant blue-white passivation solution.

9. The method for preparing a corrosion-resistant blue-white passivation solution according to claim 8, characterized in that: The gradient temperature increase in step 2 is specifically to first increase the temperature to 45-55°C at a heating rate of 2-4°C / min and keep the temperature for reaction for 1-2h, and then increase the temperature to 75-85°C at a heating rate of 4-6°C / min and keep the temperature for reaction for 0.5-1.5h.

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