A zinc-nickel alloy passivator and its preparation method

Abstract

This application relates to the technical field of metal surface treatment and protection. This application discloses a zinc-nickel alloy passivator and a preparation method thereof. A zinc-nickel alloy passivator includes the following raw materials in parts by weight: 50-80 parts of trivalent chromium compound, 10-25 parts of acidic solution, 8-15 parts of hydroxy graphene, 12-20 parts of esterified polytetrafluoroethylene, and 1-3 parts of allylbenzene. The zinc-nickel alloy passivator prepared in this application has excellent comprehensive performance, with excellent corrosion resistance and mechanical strength.

Description

Technical Field

[0001] The present application relates to the technical field of metal surface treatment and protection, and particularly to a zinc-nickel alloy passivator and a preparation method thereof. Background Art

[0002] Metal surface passivation treatment is one of the important processes in metal surface treatment. After passivation treatment, the metal surface is transformed into a state that is not easily oxidized, delaying the corrosion rate of the metal surface and having high hardness and wear resistance, and is widely used in the electronics and electrical industry, the automotive industry, the aerospace industry, etc.

[0003] Hexavalent chromium zinc-nickel alloy passivator is a chemical substance commonly used in anti-corrosion treatment, forming a dense oxide layer on the surface of the zinc-nickel alloy to prevent the metal from contacting the external environment, thereby achieving the anti-corrosion effect. However, due to the potential environmental and health risks of hexavalent chromium zinc-nickel alloy passivator, attention should be paid to environmental protection and occupational health and safety during anti-corrosion treatment to avoid potential hazards to the environment and human health.

[0004] Trivalent chromium zinc-nickel alloy passivator is a new type of anti-corrosion treatment chemical substance. Compared with hexavalent chromium passivator, it has lower potential risks in terms of environment and human health. It does not contain hexavalent chromium, can reduce the pollution of the water environment, and complies with more stringent environmental regulations and standards, being more environmentally friendly.

[0005] However, the currently used trivalent chromium zinc-nickel alloy passivator has poorer anti-corrosion performance, anti-wear performance and self-repair performance compared with hexavalent chromium zinc-nickel alloy passivator.

[0006] Therefore, there is an urgent need to develop a passivator with excellent anti-corrosion performance, anti-wear performance and self-repair performance. Summary of the Invention

[0007] In order to solve at least one of the above technical problems and develop a passivator with excellent anti-corrosion performance, anti-wear performance and self-repair performance, the present application provides a zinc-nickel alloy passivator and a preparation method thereof.

[0008] On the one hand, a zinc-nickel alloy passivator provided by the present application includes the following raw materials in parts by weight: 50-80 parts of trivalent chromium compound, 10-25 parts of acidic solution, 8-15 parts of hydroxy graphene, 12-20 parts of esterified polytetrafluoroethylene, and 1-3 parts of allylbenzene.

[0009] By adopting the above technical solutions, the zinc-nickel alloy passivator prepared in this application has excellent comprehensive performance, with excellent corrosion resistance and self-healing performance; the passivator prepared with a specific content of esterified polytetrafluoroethylene can reconnect the molecular chains when damaged by the outside world, thereby repairing and restoring the integrity of the material surface; the passivator prepared with a specific content of hydroxy graphene and esterified polytetrafluoroethylene will form a dense spatial network structure, with higher dispersion performance, improving the corrosion resistance of the passivator and having higher strength, and the performance is more stable.

[0010] Optionally, the weight ratio of the hydroxy graphene to the esterified polytetrafluoroethylene is (0.8-1):1.

[0011] By adopting the above technical solutions, this application uses a compounding system of hydroxy graphene and esterified polytetrafluoroethylene with a specific ratio, and the cross-linked spatial network structure formed is denser, and the comprehensive performance is more excellent.

[0012] Optionally, the particle size of the hydroxy graphene is nanoscale and micron-scale.

[0013] By adopting the above technical solutions, this application compounded nanoscale and micron-scale hydroxy graphene. Nanoscale hydroxy graphene has a high specific surface area, good dispersibility and high activity, and can provide more active groups and reaction sites; micron-scale hydroxy graphene has a larger particle size and higher mechanical strength, and can provide better physical properties and processing properties; the prepared passivator has excellent corrosion resistance and strong mechanical properties;

[0014] Optionally, the weight ratio of the nanoscale hydroxy graphene to the micron-scale hydroxy graphene is (0.8-1.2):1.

[0015] By adopting the above technical solutions, this application controls the weight ratio of nanoscale hydroxy graphene and micron-scale hydroxy graphene, so that the prepared passivator has high mechanical strength and high specific surface area, and has excellent corrosion resistance.

[0016] Optionally, the particle size difference between the nanoscale hydroxy graphene and the micron-scale hydroxy graphene is not more than 400μm.

[0017] By adopting the above technical solutions, this application controls the particle size difference between the nanoscale hydroxy graphene and the micron-scale hydroxy graphene to be not more than 400μm. An appropriate particle difference can increase the interfacial contact area between particles and maintain the uniformity and dispersibility of the composite system.

[0018] Optionally, the esterified polytetrafluoroethylene includes the following raw materials in weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1:(0.3-0.6):(0.2-0.5).

[0019] By adopting the above technical solution, the esterified polytetrafluoroethylene prepared in this application introduces ester groups onto the polytetrafluoroethylene, improving the dispersion performance and wetting performance of the polytetrafluoroethylene, and endowing the polytetrafluoroethylene with a certain self-healing ability.

[0020] Optionally, the acid anhydride is 1,3-acetonedicarboxylic anhydride; the acidic catalyst is phosphoric acid.

[0021] Optionally, the trivalent chromium compound is one or more of chromium hydroxide or chromium sulfate.

[0022] Optionally, the acidic solution is one or more of citric acid, oxalic acid, acetic acid, phosphoric acid or carbonic acid.

[0023] On the other hand, a preparation method of a zinc-nickel alloy passivator includes the following steps:

[0024] S1. Heat the polytetrafluoroethylene, acid anhydride and acidic catalyst to 100-130 °C, mix and stir to prepare esterified polytetrafluoroethylene; S2. Add the trivalent chromium compound, acidic solution, hydroxy graphene, the esterified polytetrafluoroethylene prepared in S1 and allylbenzene into a container, mix and stir to prepare the passivator.

[0025] By adopting the above technical solution, the method for preparing the zinc-nickel alloy passivator in this application is simple, safe, low-cost, and the prepared zinc-nickel alloy passivator has excellent comprehensive performance, good corrosion resistance and high mechanical properties.

[0026] In summary, the present invention includes at least one of the following beneficial technical effects:

[0027] 1. The zinc-nickel alloy passivator prepared in this application has excellent comprehensive performance, excellent corrosion resistance and mechanical strength;

[0028] 2. The passivator prepared by this application using specific contents of hydroxy graphene and esterified polytetrafluoroethylene will form a dense spatial network structure, with higher dispersion performance, improved corrosion resistance of the passivator and higher strength, and more stable performance; 3. This application combines nano-scale and micro-scale hydroxy graphene, and the prepared passivator has a high specific surface area, good dispersibility and excellent mechanical strength;

[0029] 4. The method for preparing the zinc-nickel alloy passivator in this application is simple, low-cost, and the prepared zinc-nickel alloy passivator has excellent comprehensive performance, good corrosion resistance and high mechanical properties. Specific Embodiments

[0030] The following further elaborates on this application in conjunction with embodiments.

[0031] The present application designs a zinc-nickel alloy passivator, which comprises the following raw materials in parts by weight: 50-80 parts of trivalent chromium compound, 10-25 parts of acidic solution, 8-15 parts of hydroxy graphene, 12-20 parts of esterified polytetrafluoroethylene, and 1-3 parts of allylbenzene.

[0032] A preparation method of the zinc-nickel alloy passivator of the present application comprises the following steps:

[0033] S1. Heat polytetrafluoroethylene, acid anhydride and acidic catalyst to 100-130 °C, mix and stir to prepare esterified polytetrafluoroethylene; S2. Add the trivalent chromium compound, acidic solution, hydroxy graphene, esterified polytetrafluoroethylene prepared in S1 and allylbenzene into a container, mix and stir to prepare a passivator. Metal surface passivation treatment is one of the important processes in metal surface treatment. After passivation treatment, the metal surface is converted into a state that is not easily oxidized, delaying the corrosion rate of the metal surface and having high hardness and wear resistance, and is widely used in the electronic and electrical industries, the automotive industry, the aerospace industry, etc.

[0034] Trivalent chromium zinc-nickel alloy passivator is a new type of anti-corrosion treatment chemical substance. Compared with hexavalent chromium passivator, it has lower potential risks in terms of environment and human health. It does not contain hexavalent chromium, can reduce the pollution of water environment, and complies with more stringent environmental regulations and standards, being more environmentally friendly.

[0035] However, the currently used trivalent chromium zinc-nickel alloy passivator has poorer anti-corrosion performance, anti-wear performance and self-repair performance compared with the hexavalent chromium zinc-nickel alloy passivator.

[0036] In view of the above technical problems, the inventors of the present application designed the technical solution of the present application. First, the passivator prepared with specific contents of hydroxy graphene and esterified polytetrafluoroethylene will form a dense spatial network structure, with higher dispersion performance, improving the corrosion resistance of the passivator and having higher strength, and the performance is more stable.

[0037] Secondly, the present application compounded nano-scale and micro-scale hydroxy graphene. Nano-scale hydroxy graphene has a high specific surface area, good dispersion and high activity, and can provide more active groups and reaction sites; micro-scale hydroxy graphene has a larger particle size and higher mechanical strength, and can provide better physical properties and processing properties; and by controlling the weight ratio of nano-scale hydroxy graphene and micro-scale hydroxy graphene, the prepared passivator has high mechanical strength and high specific surface area, and thus has excellent corrosion resistance.

[0038] Finally, the present application controls the particle size difference between nano-hydroxy graphene and micro-hydroxy graphene to be no more than 400 nm. An appropriate particle difference can increase the interfacial contact area between particles and maintain the uniformity and dispersibility of the composite system.

[0039] Therefore, the zinc-nickel alloy passivator prepared in the present application has excellent comprehensive performance, excellent corrosion resistance, mechanical strength and self-healing performance.

[0040] The raw materials used in the present application are as follows. Unless otherwise specified, the raw materials in the present application are all commercially available:

[0041] Hydroxy graphene: Brand: Kermel;

[0042] Allyl benzene: Purity 99%;

[0043] Polytetrafluoroethylene: Purity BR;

[0044] 1,3-Acetonedicarboxylic anhydride: Purity 99%;

[0045] Phosphoric acid: Purity 85%;

[0046] Chromium hydroxide: Purity 99%;

[0047] Chromium sulfate: Purity 98%;

[0048] Citric acid: Purity 99.5%;

[0049] Oxalic acid: Purity 99%;

[0050] Acetic acid: Purity 99%;

[0051] Carbonic acid: Purity 99%.

[0052] Detection items and detection methods

[0053] Salt spray corrosion test: According to the salt spray test in GB / T6461-2002, check whether white rust appears after 360 hours of testing. If white rust appears, it is "yes", otherwise it is "no"; check whether red rust appears after 960 hours. If red rust appears, it is "yes", otherwise it is "no".

[0054] Adhesion test: Determine according to the national standard GB-9791-88, that is, use white paper and sand-free rubber to rub the surface of the passivation film back and forth 10 times under normal pressure. If there is no black substance on the white paper or the rubber, it is qualified.

[0055] Pencil hardness test: Detect the hardness of the passivation layer according to GB / T6739-1996. Specific embodiments

[0057] Examples 1-4

[0058] For the zinc-nickel alloy passivator in Examples 1-4, the specific raw material contents are shown in Table 1.

[0059] Table 1 Specific Raw Material Contents of Zinc-Nickel Alloy Passivator in Examples 1-4

[0060]

[0061]

[0062] Among them, the particle size of hydroxy graphene is 500 nm;

[0063] A preparation method of a zinc-nickel alloy passivator includes the following steps:

[0064] S1. Heat polytetrafluoroethylene, acid anhydride and acidic catalyst to 100-130 °C, mix and stir to prepare esterified polytetrafluoroethylene; S2. Add trivalent chromium compound, acidic solution, hydroxy graphene, the esterified polytetrafluoroethylene prepared in S1 and diisopropylbenzene peroxide into a container, mix and stir to prepare the passivator.

[0065] Example 1

[0066] The esterified polytetrafluoroethylene includes the following raw materials by weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1:0.6:0.5;

[0067] The trivalent chromium compound is chromium hydroxide;

[0068] The acidic solution is citric acid.

[0069] Example 2

[0070] The esterified polytetrafluoroethylene includes the following raw materials by weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1:0.4:0.3;

[0071] The trivalent chromium compound is chromium hydroxide and chromium sulfate, and the weight ratio of chromium hydroxide to chromium sulfate is 1:1.

[0072] The acidic solution is citric acid and oxalic acid, and the weight ratio of citric acid to oxalic acid is 1:1.

[0073] Example 3

[0074] The esterified polytetrafluoroethylene includes the following raw materials by weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1:0.6:0.5;

[0075] The trivalent chromium compound is chromium sulfate;

[0076] The acidic solution is citric acid, oxalic acid, acetic acid and phosphoric acid, and the weight ratio of citric acid, oxalic acid, acetic acid and phosphoric acid is 0.3:0.2:0.2:0.3.

[0077] Example 4

[0078] The esterified polytetrafluoroethylene comprises raw materials in the following weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1: 0.3: 0.5;

[0079] The trivalent chromium compound is chromium hydroxide;

[0080] The acidic solution is citric acid, oxalic acid, acetic acid, phosphoric acid and carbonic acid, and the weight ratio of citric acid, oxalic acid, acetic acid, phosphoric acid and carbonic acid is 0.2: 0.2: 0.1: 0.3: 0.2.

[0081] Comparative Examples 1-2

[0082] Comparative Example 1

[0083] Based on Example 1, except that an equal amount of esterified polytetrafluoroethylene is used to replace hydroxy graphene, the other components and preparation methods are the same as those in Example 1.

[0084] Comparative Example 2

[0085] Based on Example 1, except that an equal amount of hydroxy graphene is used to replace esterified polytetrafluoroethylene, the other components and preparation methods are the same as those in Example 1.

[0086] Comparative Example 3

[0087] Based on Example 1, except that an equal amount of polytetrafluoroethylene is used to replace an equal amount of esterified polytetrafluoroethylene, the other components and preparation methods are the same as those in Example 1.

[0088] The passivation films formed by the passivators prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to performance testing, and the test results are shown in Table 2.

[0089] Table 2 Performance test results of the passivation films formed by the passivators prepared in Examples 1-4 and Comparative Examples 1-3

[0090]

[0091] It can be seen from Examples 1-4, Comparative Examples 1-3 and Table 2 that the passivator prepared in this application has excellent comprehensive performance, strong corrosion resistance, qualified bonding strength after bonding strength testing, and high hardness;

[0092] It can be seen from Comparative Examples 1-2 and Table 2 that the passivators prepared by adding esterified polytetrafluoroethylene or hydroxy graphene alone have poor comprehensive performance, extremely poor wettability and dispersibility, and poor corrosion resistance;

[0093] It can be seen from Comparative Example 3 and Table 2 that the unesterified polytetrafluoroethylene has poor dispersion performance and extremely poor self-healing performance, red rust appears after salt spray testing, and the bonding strength testing is unqualified.

[0094] Examples 5 - 7

[0095] Based on Example 1, the total weight of hydroxy graphene and esterified polytetrafluoroethylene is 24 kg. Except for the different weight ratios of hydroxy graphene and esterified polytetrafluoroethylene, the other components and preparation methods are the same as those in Example 1.

[0096] Example 5

[0097] The weight ratio of hydroxy graphene to esterified polytetrafluoroethylene is 0.8:1.

[0098] Example 6

[0099] The weight ratio of hydroxy graphene to esterified polytetrafluoroethylene is 0.9:1.

[0100] Example 7

[0101] The weight ratio of hydroxy graphene to esterified polytetrafluoroethylene is 1:1.

[0102] Perform performance tests on the passivation films formed by the passivators prepared in Examples 5 - 7, and the test results are shown in Table 3.

[0103] Table 3 Performance test results of the passivation films formed by the passivators prepared in Examples 5 - 7

[0104]

[0105] It can be seen from Examples 5 - 7 and Table 3 that the present application uses the preferred ratio of hydroxy graphene and esterified polytetrafluoroethylene, and the passivator prepared has more excellent comprehensive performance and higher strength.

[0106] Examples 8 - 10

[0107] Based on Example 6, except that the particle sizes of hydroxy graphene are 500 nm and 500 μm, and the weight ratio of 500 nm and 500 μm of hydroxy graphene is different, the other components and preparation methods are the same as those in Example 6.

[0108] Example 8

[0109] The weight ratio of 500 nm and 500 μm of hydroxy graphene is 0.8:1.

[0110] Example 9

[0111] The weight ratio of 500 nm and 500 μm of hydroxy graphene is 1:1.

[0112] Example 10

[0113] The weight ratio of 500 nm and 500 μm of hydroxy graphene is 1.2:1.

[0114] The passivation films formed by the passivators prepared in Examples 8-10 were subjected to performance testing, and the test results are shown in Table 4.

[0115] Table 4 Performance Testing of Passivation Films Formed by Passivators Prepared in Examples 8-10

[0116]

[0117] As can be seen from Example 8-10 and Table 4, in this application, hydroxygraphene with particle sizes of 500 nm and 500 μm was compounded, and the prepared passivator has excellent comprehensive performance and high hardness.

[0118] Examples 11-15

[0119] Based on Example 9, except that the nano-size and micro-size of hydroxygraphene are different, the other components and preparation methods are the same as those in Example 9.

[0120] Example 11

[0121] The nano-size of hydroxygraphene is 50 nm, and the micro-size of hydroxygraphene is 100 μm.

[0122] Example 12

[0123] The nano-size of hydroxygraphene is 200 nm, and the micro-size of hydroxygraphene is 100 μm.

[0124] Example 13

[0125] The nano-size of hydroxygraphene is 400 nm, and the micro-size of hydroxygraphene is 100 μm.

[0126] Example 14

[0127] The nano-size of hydroxygraphene is 400 nm, and the micro-size of hydroxygraphene is 200 μm.

[0128] Example 15

[0129] The nano-size of hydroxygraphene is 400 nm, and the micro-size of hydroxygraphene is 400 μm.

[0130] The passivation films formed by the passivators prepared in Examples 11-15 were subjected to performance testing, and the test results are shown in Table 5.

[0131] Table 5 Performance Testing of Passivation Films Formed by Passivators Prepared in Examples 11-15

[0132]

[0133] As can be seen from Examples 9, 11-15 and Table 5, when the difference between the nano-particle size and the micro-particle size of the hydroxy graphene of the present application is not more than 400 μm, the prepared passivator has a better dispersion effect, higher strength and better comprehensive performance.

[0134] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A zinc-nickel alloy passivator, characterized in that, It comprises the following raw materials in parts by weight: 50 - 80 parts of trivalent chromium compound, 10 - 25 parts of acidic solution, 8 - 15 parts of hydroxy graphene, 12 - 20 parts of esterified polytetrafluoroethylene, and 1 - 3 parts of allylbenzene; The esterified polytetrafluoroethylene comprises the following raw materials in weight ratio: polytetrafluoroethylene: acid anhydride: acidic catalyst = 1:(0.3 - 0.6):(0.2 - 0.5), the acid anhydride is 1,3 - acetonedicarboxylic anhydride; the acidic catalyst is phosphoric acid; The preparation method of the esterified polytetrafluoroethylene is: heating polytetrafluoroethylene, acid anhydride and acidic catalyst to 100 - 130 °C, mixing and stirring to prepare esterified polytetrafluoroethylene.

2. The passivating agent for zinc-nickel alloy according to claim 1, wherein The weight ratio of the hydroxy graphene to the esterified polytetrafluoroethylene is (0.8 - 1):

1.

3. The passivating agent for zinc-nickel alloy according to claim 1, characterized in that The particle size of the hydroxy graphene is in nanoscale and microscale.

4. The passivating agent for zinc-nickel alloy according to claim 3, characterized in that, The weight ratio of the nanoscale hydroxy graphene to the microscale hydroxy graphene is (0.8 - 1.2):

1.

5. A zinc-nickel alloy passivator according to claim 3, wherein, The difference in particle size between the nanoscale hydroxy graphene and the microscale hydroxy graphene is not more than 400 μm.

6. The passivating agent for zinc-nickel alloy according to claim 1, characterized in that, The trivalent chromium compound is one or more of chromium hydroxide or chromium sulfate.

7. The passivator for zinc-nickel alloy according to claim 1, characterized in that The acidic solution is one or more of citric acid, oxalic acid, acetic acid, phosphoric acid or carbonic acid.

8. A method for preparing the zinc-nickel alloy passivator according to claim 1, characterized in that, It comprises the following steps: S1. Heating polytetrafluoroethylene, acid anhydride and acidic catalyst to 100 - 130 °C, mixing and stirring to prepare esterified polytetrafluoroethylene; S2. Adding the trivalent chromium compound, acidic solution, hydroxy graphene, the esterified polytetrafluoroethylene prepared in S1 and allylbenzene into a container, mixing and stirring to prepare a passivator.

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