阅读说明：本技术 一种环保三价铬彩锌钝化液及其制备方法及钝化工艺 (Environment-friendly trivalent chromium color zinc passivation solution and preparation method and passivation process thereof ) 是由 汤建飞 于 2020-12-23 设计创作，主要内容包括：本申请涉及镀锌钝化液技术领域,具体公开了一种环保三价铬彩锌钝化液及其制备方法及钝化工艺。一种环保三价铬彩锌钝化液,每升钝化液中包含以下各组分原料：氯化铬5-10g,硫酸铬15-30 g,氧化剂25-40 g,配位剂20-50 g,辅助成膜剂2-5 g,添加剂3-8 g,余量为水；辅助成膜剂包括稀土金属盐,稀土金属盐为硫酸铈、氯化镧、硝酸钇中的至少一种,添加剂包括封闭剂和稳定剂,封闭剂包括硅烷偶联剂,稳定剂包括聚氧乙烯醚磺酸盐、烷基季铵盐中的至少一种。本申请的环保三价铬彩锌钝化液可用于镀锌工件钝化,其形成的钝化层具有耐腐蚀性能好的优点。(The application relates to the technical field of galvanizing passivation solution, and particularly discloses an environment-friendly trivalent chromium color zinc passivation solution, a preparation method thereof and a passivation process. An environment-friendly trivalent chromium color zinc passivation solution, wherein each liter of passivation solution comprises the following raw materials: 5-10g of chromium chloride, 15-30g of chromium sulfate, 25-40g of oxidant, 20-50g of complexing agent, 2-5g of auxiliary film-forming agent, 3-8g of additive and the balance of water; the auxiliary film forming agent comprises rare earth metal salt, the rare earth metal salt is at least one of cerium sulfate, lanthanum chloride and yttrium nitrate, the additive comprises a sealing agent and a stabilizing agent, the sealing agent comprises a silane coupling agent, and the stabilizing agent comprises at least one of polyoxyethylene ether sulfonate and alkyl quaternary ammonium salt. The environment-friendly trivalent chromium color zinc passivation solution can be used for passivation of galvanized workpieces, and a passivation layer formed by the passivation solution has the advantage of good corrosion resistance.)

1. An environment-friendly trivalent chromium color zinc passivation solution is characterized in that each liter of passivation solution comprises the following raw materials: 5-10g of chromium chloride, 15-30g of chromium sulfate, 25-40g of oxidant, 20-50g of complexing agent, 2-5g of auxiliary film-forming agent, 3-8g of additive and the balance of water; the auxiliary film-forming agent comprises rare earth metal salt, the additive comprises a sealing agent and a stabilizing agent, the sealing agent comprises a silane coupling agent, and the stabilizing agent comprises at least one of polyoxyethylene ether sulfonate and alkyl quaternary ammonium salt.

2. The environment-friendly trivalent chromium color zinc passivation solution as claimed in claim 1, wherein the auxiliary film forming agent further comprises an organic complexing agent, and the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene, and p-nitrophenol in a mass ratio of (1-2), (0.5-1.5), (0.1-0.5).

3. The environment-friendly trivalent chromium color zinc passivation solution according to claim 1, wherein the silane coupling agent is an aminosilane coupling agent.

4. The environment-friendly trivalent chromium color zinc passivation solution according to claim 1, wherein the polyoxyethylene ether sulfonate is fatty alcohol polyoxyethylene ether sulfonate, and the alkyl quaternary ammonium salt is octadecyl quaternary ammonium salt.

5. The environment-friendly trivalent chromium color zinc passivation solution according to claim 4, wherein the molecular number of the ethylene oxide added in the molecular chain of the fatty alcohol-polyoxyethylene ether sulfonate is 2-6.

6. The environmentally friendly trivalent chromium colored zinc passivating solution according to any one of claims 1-5, wherein the sealant further comprises silicon dioxide.

7. The environment-friendly trivalent chromium color zinc passivation solution as claimed in claim 6, wherein the raw materials further comprise a dispersant, and the dispersant is composed of dodecyl polyoxyethylene and sodium dodecyl sulfate in a mass ratio of (2-3) to (1-2).

8. The environment-friendly trivalent chromium color zinc passivation solution as claimed in claim 7, wherein the raw materials further comprise an impurity removal agent, and the impurity removal agent is composed of thiosemicarbazide, thiosemicarbazide and thiourea in a mass ratio of (0.5-0.8) to (0.1-0.2) to (0.2-0.3).

9. The preparation method of the environment-friendly trivalent chromium color zinc passivation solution as claimed in claim 1, characterized by comprising the following steps:

1) uniformly mixing an oxidant, a coordination agent and part of water to prepare a solution A;

2) uniformly mixing chromium chloride, chromium sulfate, an auxiliary film-forming agent and the solution A to prepare a solution B;

3) and (3) uniformly mixing the additive and the solution B to obtain the additive.

10. The passivation process of the environment-friendly trivalent chromium color zinc passivation solution according to claim 1, characterized in that: and (3) establishing a bath by using the passivation solution, adjusting the pH value of the passivation solution to 1-2, adjusting the passivation temperature to 40-70 ℃, and controlling the passivation time of the galvanized workpiece in the passivation solution to 20-40 s.

Technical Field

The application relates to the technical field of zinc plating passivation solution, in particular to environment-friendly trivalent chromium color zinc passivation solution and a preparation method and passivation process thereof.

Background

The zinc-nickel alloy coating has excellent corrosion resistance which is 3-6 times that of a zinc coating, has excellent performances of good brightness, strong tarnish resistance, high hardness, convenience in machining and the like, and is widely applied to industries such as automobiles, machining, aviation industry, instruments, electronics and the like. However, the mass fraction of nickel in the zinc-nickel alloy coating is usually about 8-15%, and the mass fraction of zinc is much larger than that of nickel, so that the zinc-nickel alloy coating is easily oxidized and corroded in a humid and high-salt environment to affect the performance of the zinc-nickel alloy, and therefore the zinc-nickel alloy coating needs to be passivated. The traditional passivation technology adopts a hexavalent chromium passivation process, and the hexavalent chromium has extremely strong toxicity and can cause serious harm to the ecological environment. Trivalent chromium has properties similar to hexavalent chromium, and toxicity is only 1% of hexavalent chromium, so hexavalent chromium passivation processes have been gradually replaced by trivalent chromium passivation processes.

Chinese patent with application publication number CN105401140A discloses a colorful passivation solution for galvanization and preparation thereofThe method comprises the following steps: 3-10ml/L of titanium trichloride; 5-15g/L of sodium nitrate; 1-8g/L of sodium gluconate; 1-3g/L of boric acid; h₂O₂10-20 mL/L; 3-5g/L of cerium nitrate; 1-3g/L of sodium acetate; the balance of water. The galvanized material treated by the passivating solution has good visual effect of uniformly doping various colors such as red, blue, yellow, purple, green and the like.

In view of the above, the inventors consider that the passivation layer formed by passivating the galvanized workpiece by the passivation solution has poor corrosion resistance.

Disclosure of Invention

In order to solve the problem of poor corrosion resistance of a passivation layer, the application provides an environment-friendly trivalent chromium color zinc passivation solution, a preparation method and a passivation process thereof.

In a first aspect, the application provides an environment-friendly trivalent chromium color zinc passivation solution, which adopts the following technical scheme:

an environment-friendly trivalent chromium color zinc passivation solution, wherein each liter of passivation solution comprises the following raw materials: 5-10g of chromium chloride, 15-30g of chromium sulfate, 25-40g of oxidant, 20-50g of complexing agent, 2-5g of auxiliary film-forming agent, 3-8g of additive and the balance of water; the auxiliary film-forming agent comprises rare earth metal salt, the additive comprises a sealing agent and a stabilizing agent, the sealing agent comprises a silane coupling agent, and the stabilizing agent comprises at least one of polyoxyethylene ether sulfonate and alkyl quaternary ammonium salt.

By adopting the technical scheme, the environment-friendly trivalent chromium color zinc passivation solution adopts rare earth metal salt, rare earth metal elements have larger ion radius, high coordination number and more active chemical property, the fineness of chromium grains in the passivation layer can be improved, the density of the passivation layer is increased, meanwhile, rare earth ions and chromium ions can be co-deposited on the surface of a zinc layer, the self-corrosion potential of the passivation layer is reduced, and the corrosion resistance of the passivation layer is improved; the silane coupling agent can form a three-dimensional network structure in the passivation layer, has the effects of hole sealing and sealing on the passivation layer, can delay the deposition speed of chromium ions to a certain extent, and increases the thickness and uniformity of the passivation layer; in addition, the polyoxyethylene ether sulfonate or the alkyl quaternary ammonium salt reduces the surface tension of the passivation solution, improves the dispersing capacity of the silane coupling agent and the rare earth metal salt in the passivation solution, increases the binding force between a three-dimensional network structure formed by the silane coupling agent and the passivation layer, further improves the uniformity of the passivation layer, and enables the passivation layer to have higher corrosion resistance and durability.

Preferably, the auxiliary film-forming agent also comprises an organic complexing agent, and the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of (1-2): (0.5-1.5): (0.1-0.5).

By adopting the technical scheme, gamma-pyrone-2, 6-dicarboxylic acid, hexafluorobenzene, tetrahydrofuran and rare earth metal ions are subjected to pi-type coordination to form an organic ligand, the content of the gamma-pyrone-2, 6-dicarboxylic acid and tetrahydrofuran is controlled, the concentration of the rare earth metal ions in a passivation layer and a solid-liquid interface layer of passivation solution is further controlled, the deposition speed of the rare earth metal ions is adjusted, and the rare earth elements in the passivation layer reach a proper mass ratio, so that the passivation layer obtains a better corrosion resistance.

Preferably, the silane coupling agent is an aminosilane coupling agent.

By adopting the technical scheme, the aminosilane coupling agent has better stability and high temperature resistance, can stably exist in the passivation solution for a longer time, prolongs the service life of the passivation solution, and reduces the maintenance procedures of the passivation solution.

Preferably, the polyoxyethylene ether sulfonate is fatty alcohol polyoxyethylene ether sulfonate, and the alkyl quaternary ammonium salt is octadecyl quaternary ammonium salt.

By adopting the technical scheme, the compatibility of the fatty alcohol-polyoxyethylene ether sulfonate and the octadecyl quaternary ammonium salt is good, ether bonds in molecules are not easily damaged by acid and alkali, and the stability in the passivation solution is good.

Preferably, the molecular weight of the ethylene oxide added in the molecular chain of the fatty alcohol-polyoxyethylene ether sulfonate is 2-6.

By adopting the technical scheme, when the number of ethylene oxide molecules added on the molecular chain of the polyoxyethylene ether sulfonate is 2-6, the critical micelle concentration of the polyoxyethylene ether sulfonate is more suitable, the passivation solution system is more stable, and the passivation solution has good wetting, penetrating and dispersing capabilities and is beneficial to improving the uniformity of a passivation layer.

Preferably, the blocking agent further comprises silica.

By adopting the technical scheme, the silicon dioxide and the silane coupling agent can generate a compounding synergistic effect, amino groups on the silane coupling agent can form a molecular bridge with hydroxyl groups of the silicon dioxide, the stability of a three-dimensional network structure of the silane coupling agent is improved, the brightness and the flatness of a passivation layer are improved, and the corrosion resistance of the passivation layer is further improved.

Preferably, the raw materials also comprise a dispersing agent, wherein the dispersing agent is composed of dodecyl polyoxyethylene and dodecyl sodium sulfate according to the mass ratio of (2-3) to (1-2).

By adopting the technical scheme, the surface tension of the passivation solution can be reduced by the dodecyl polyoxyethylene and the dodecyl sodium sulfate, the dispersion degree of each component in the raw materials in the passivation solution is improved, and the uniformity degree of the passivation solution is increased.

Preferably, the raw materials also comprise an impurity removing agent, wherein the impurity removing agent is composed of (0.5-0.8) of thiosemicarbazide, 0.1-0.2) of thiosemicarbazide and (0.2-0.3) of thiourea according to the mass ratio.

By adopting the technical scheme, the thiosemicarbazide, the guanyl thiourea and the thiourea have stronger electronegativity, lone electron pairs on molecules of the thiosemicarbazide, can be coordinated on an empty track of metal ions, and form a complex with impurity metal ions in passivation solution, so that the deposition amount of the impurity metal ions on a passivation layer is reduced, the purity of the passivation layer is improved, and the corrosion resistance of the passivation layer is improved.

In a second aspect, the application provides a preparation method of an environment-friendly trivalent chromium color zinc passivation solution, which adopts the following technical scheme:

a preparation method of an environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) uniformly mixing an oxidant, a coordination agent and part of water to prepare a solution A;

2) uniformly mixing chromium chloride, chromium sulfate, an auxiliary film-forming agent and the solution A to prepare a solution B;

3) and (3) uniformly mixing the additive and the solution B to obtain the additive.

By adopting the technical scheme, the oxidant, the complexing agent and part of water are uniformly mixed, the pH value of the solution A is reduced, then the chromium chloride, the chromium sulfate and the auxiliary film-forming agent are uniformly mixed with the solution A, the dispersion degree of the rare earth metal salt and the organic complexing agent is improved, the formation of organic ligands by rare earth metal elements is facilitated, the oxidation probability of trivalent chromium ions is reduced, finally the additive is uniformly mixed with the solution B, all components in the raw materials are uniformly dispersed in the passivation solution, and the prepared passivation solution is uniform and consistent and has good stability.

In a third aspect, the passivation process of the environment-friendly trivalent chromium color zinc passivation solution provided by the application adopts the following technical scheme:

a passivation process of an environment-friendly trivalent chromium color zinc passivation solution comprises the following specific steps: and (3) establishing a bath by using the passivation solution, adjusting the pH value of the passivation solution to 1-2, adjusting the passivation temperature to 40-70 ℃, and controlling the passivation time of the galvanized workpiece in the passivation solution to 20-40 s.

In summary, the present application has the following beneficial effects:

1. according to the environment-friendly trivalent chromium color zinc passivation solution, the rare earth metal salt and the organic coordination agent are adopted to generate the rare earth element organic ligand, so that the grain fineness of chromium in the passivation layer is improved, the density of the passivation layer is increased, the self-corrosion potential of the passivation layer is reduced, and the passivation layer has a good corrosion resistance effect.

2. The amino silane coupling agent and the silicon dioxide generate synergistic effect, the stability of a three-dimensional network structure of the silane coupling agent is improved, and the corrosion resistance of a passivation layer is further improved.

3. The environment-friendly trivalent chromium color zinc passivation solution is added with the dispersing agent, the surface tension of the passivation solution is reduced through the dispersing agent, and the uniformity of the passivation solution is improved.

Detailed Description

The present application will be described in further detail with reference to examples.

The application provides an environment-friendly trivalent chromium color zinc passivation solution, each liter of passivation solution comprises the following raw materials: 5-10g of chromium chloride, 15-30g of chromium sulfate, 25-40g of oxidant, 20-50g of complexing agent, 2-5g of auxiliary film-forming agent, 3-8g of additive and the balance of water; the auxiliary film-forming agent comprises rare earth metal salt, the additive comprises a sealing agent and a stabilizing agent, the sealing agent comprises a silane coupling agent, and the stabilizing agent comprises at least one of polyoxyethylene ether sulfonate and alkyl quaternary ammonium salt.

Preferably, the oxidizing agent is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5.

Preferably, the complexing agent is composed of malonic acid and sodium fluoride according to the mass ratio of (5-15) to (1-3). Further preferably, the complexing agent is composed of malonic acid and sodium fluoride according to a mass ratio of 10: 2.

More preferably, the rare earth metal salt is composed of (5-7) parts by mass, (1-2) parts by mass and (2-4) parts by mass of cerium sulfate, lanthanum chloride and yttrium nitrate.

Further preferably, the aminosilane coupling agent is gamma-aminopropyltriethoxysilane or modified gamma-aminopropyltriethoxysilane. Preferably, the modified gamma-aminopropyltriethoxysilane is obtained by reacting adipic acid with thionyl chloride in DMF to generate binary acyl chloride, and then performing amidation reaction on the binary acyl chloride and the gamma-aminopropyltriethoxysilane.

Preferably, the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of (1-2): (0.5-1.5): (0.5-1.5): 0.1-0.5. More preferably, the organic complexing agent is gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol which are mixed according to the mass ratio of 2:1:1: 0.5. Further preferably, the auxiliary film-forming agent is composed of an organic complexing agent and a rare earth metal salt according to the mass ratio of (2-5) to (0.5-1.5). Further preferably, the auxiliary film-forming agent is composed of an organic complexing agent and a rare earth metal salt according to the mass ratio of 3: 1.

Preferably, the additive is composed of a sealing agent and a stabilizing agent according to the mass ratio of (7-8.5) to (1.5-3). Further preferably, the additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8: 2.

Preferably, the stabilizer is composed of fatty alcohol polyoxyethylene ether sulfonate and octadecyl quaternary ammonium salt according to the mass ratio of (5-8) to (2-5). Preferably, the stabilizer is fatty alcohol polyoxyethylene ether sulfonate and octadecyl quaternary ammonium salt according to the mass ratio of 7: 3. Preferably, the fatty alcohol-polyoxyethylene ether sulfonate is sodium salt or potassium salt, and the octadecyl quaternary ammonium salt is fluorine salt or chlorine salt. More preferably, the quaternary ammonium salt of octadecyl is ammonium octadecyl chloride.

Preferably, the number of molecules of ethylene oxide added to the molecular chain in the fatty alcohol polyoxyethylene ether sulfonate is 4. Further preferably, the chain length of the carbon atoms of the fatty alcohol in the fatty alcohol polyoxyethylene ether sulfonate is C6-C12. Further preferably, the fatty alcohol-polyoxyethylene ether sulfonate is sodium n-octanol-polyoxyethylene ether sulfonate.

Preferably, the blocking agent further comprises silica. More preferably, the silica is nanosilica. Further preferably, the particle size of the nanosilica is in the range of 10-30 nm. More preferably, the particle size of the nanosilica is in the range of 15 nm. Further preferably, the mass ratio of the nano silicon dioxide to the gamma-aminopropyl triethoxy silicon or the modified gamma-aminopropyl triethoxy silicon is (10-15) to (0.5-1). Further preferably, the mass ratio of the nano silicon dioxide to the gamma-aminopropyl triethoxy silicon or the modified gamma-aminopropyl triethoxy silicon is 15: 1.

Preferably, the dispersing agent is composed of dodecyl polyoxyethylene and dodecyl sodium sulfate according to the mass ratio of (2-3) to (1-2). More preferably, the dispersant is composed of dodecyl polyoxyethylene and sodium dodecyl sulfate according to the mass ratio of 2:1. More preferably, the concentration of the dispersant in the passivating solution is (0.5-1) g/L. More preferably, the concentration of the dispersant in the passivating solution is 0.8 g/L.

Preferably, the impurity removing agent is composed of thiosemicarbazide, guanyl thiourea and thiourea according to the mass ratio of (0.5-0.8) to (0.1-0.2) to (0.2-0.3). Further preferably, the impurity removing agent is thiosemicarbazide, guanyl thiourea or thiourea, and the mass ratio of the thiosemicarbazide to the guanyl thiourea is 0.6: 0.15: 0.25. Further preferably, the concentration of the impurity removing agent in the passivation solution is (0.3-0.8) g/L. More preferably, the concentration of the dispersant in the passivating solution is 0.5 g/L.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) uniformly mixing an oxidant, a coordination agent and part of water to prepare a solution A;

2) uniformly mixing chromium chloride, chromium sulfate, an auxiliary film-forming agent and the solution A to prepare a solution B;

3) and (3) uniformly mixing the additive and the solution B to obtain the additive.

Preferably, in the step 1), the step of uniformly mixing the oxidant, the complexing agent and the part of water to prepare the solution A is to stir the oxidant, the complexing agent and the part of water at the rotation speed of 600-800rpm for 5-10 min.

Preferably, in the step 2), the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A are uniformly mixed to prepare the solution B, and the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A are stirred at the rotation speed of 800-.

Preferably, the step 3) of uniformly mixing the additive and the solution B is to stir the additive and the solution B at the rotation speed of 1200-1500rpm for 15-30 min.

A passivation process of an environment-friendly trivalent chromium color zinc passivation solution comprises the following specific steps: and (3) establishing a bath by using the passivation solution, adjusting the pH value of the passivation solution to 1-2, adjusting the passivation temperature to 40-70 ℃, and controlling the passivation time of the galvanized workpiece in the passivation solution to 20-40 s.

Preferably, the pH value of the passivation solution is adjusted to 1-2 by using phosphoric acid. Further preferably, the passivation temperature is 50 ℃. Further preferably, the galvanized workpiece is soaked in the passivation solution and passivated for 30 s.

The information on the main raw materials of the examples and comparative examples of the present application is shown in table 1.

TABLE 1 information on main raw materials of examples and comparative examples of the present application

Raw materials	Specification of	Source manufacturer
			Silicon dioxide		Hubeihuifu
Chromium chloride	Chemical purity	Tianjin Fu Chen
			Chromium sulfate	Chemical purity	Tianjin Fu Chen
Sodium fluoride	Chemical purity	Tianjin Fu Chen
			Cerium sulfate	Chemical purity	Tianjin Fu Chen
Lanthanum chloride	Chemical purity	Tianjin Fu Chen
			Yttrium nitrate	Chemical purity	Tianjin Fu Chen
Sodium nitrate	Chemical purity	Tianjin Fu Chen
			Nitric acid	Chemical purity	Tianjin Fu Chen
Oxalic acid	Chemical purity	Tianjin Fu Chen
			Malonic acid	Chemical purity	Tianjin Fu Chen
Sodium hypophosphite	Chemical purity	Tianjin Fu Chen
			Potassium persulfate	Chemical purity	Effersha
Adipic acid	Chemical purity	Effersha
			DMF	Chemical purity	Effersha
Gamma-pyrone-2, 6-dicarboxylic acid	Chemical purity	Effersha
			P-nitrophenol	Chemical purity	Effersha
Sodium n-octyl alcohol polyoxyethylene ether sulfonate	Chemical purity	Effersha
			Tetrahydrofuran (THF)	Chemical purity	Effersha
Amidinothioureas	Chemical purity	Effersha
			Hexafluorinated benzenes	Chemical purity	Effersha
Dodecyl polyoxyethylene	Chemical purity	Effersha
			Amino silane	Chemical purity	Reagent for river
Thiouranilides	Chemical purity	Tianjin Kemi Europe
			Thiourea	Chemical purity	Tianjin Kemi Europe
Octadecyl ammonium chloride	Chemical purity	Tianjin Kemi Europe
			Gamma-aminopropyl triethoxy silicon	Chemical purity	Tianjin Kemi Europe

Examples

Examples 1 to 3

The environment-friendly trivalent chromium color zinc passivation solution of the embodiments 1 to 3 is prepared from the following raw materials by weight: 500g of chromium chloride, 1.5kg of chromium sulfate, 2.5kg of oxidant, 2kg of complexing agent, 200g of auxiliary film-forming agent, 300g of additive and 100kg of water.

Wherein the oxidant consists of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is a rare earth metal salt, and the rare earth metal salt comprises cerium sulfate, lanthanum chloride and yttrium nitrate. The additive consists of a sealing agent and a stabilizing agent according to the mass ratio of 8:2, wherein the sealing agent is gamma-aminopropyl triethoxy silicon. The stabilizer is composed of fatty alcohol polyoxyethylene ether sodium sulfonate and octadecyl ammonium chloride according to the mass ratio of 7: 3.

In examples 1 to 3, the mass ratios of cerium sulfate, lanthanum chloride and yttrium nitrate in the rare earth metal salts are shown in Table 2.

TABLE 2 Mass ratios of cerium sulfate, lanthanum chloride and yttrium nitrate in rare earth metal salts of examples 1-3

Rare earth metal salt	Example 1	Example 2	Example 3
				Cerium sulfate	5	1	2
Lanthanum chloride	6	1.5	3
				Yttrium nitrate	7	2	4

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution of the embodiment 1 to 3 comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 5min at the rotating speed of 600rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 800rpm for 10min to prepare a solution B;

3) stirring the additive and the solution B at the rotation speed of 1200rpm for 15min to obtain the additive.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution of the embodiment 1-3 comprises the following specific steps:

adding the passivation solution into a passivation tank, adjusting the pH value of the passivation solution to 1-2 by using phosphoric acid, adjusting the passivation temperature to 50 ℃, soaking the galvanized workpiece in the passivation solution, passivating for 30s, taking out and drying.

Example 4

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 1kg of chromium chloride, 3kg of chromium sulfate, 4kg of oxidant, 5kg of complexing agent, 500g of auxiliary film-forming agent, 800g of additive and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, and the sealing agent is gamma-aminopropyl triethoxy silicon. The stabilizer is composed of fatty alcohol polyoxyethylene ether sodium sulfonate and octadecyl ammonium chloride according to the mass ratio of 7: 3.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water at the rotating speed of 800rpm for 10min to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 1200rpm for 20min to prepare a solution B;

3) stirring the additive and the solution B at the rotation speed of 1500rpm for 30min to obtain the final product.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution comprises the following specific steps:

adding the passivation solution into a passivation tank, adjusting the pH value of the passivation solution to 1-2 by using phosphoric acid, adjusting the passivation temperature to 50 ℃, soaking the galvanized workpiece in the passivation solution, passivating for 30s, taking out and drying.

Example 5

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, and the sealing agent is gamma-aminopropyl triethoxy silicon. The stabilizer is composed of fatty alcohol polyoxyethylene ether sodium sulfonate and octadecyl ammonium chloride according to the mass ratio of 7: 3.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 8min at the rotating speed of 700rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 1000rpm for 15min to prepare a solution B;

3) stirring the additive and the solution B at the rotating speed of 1300rpm for 20min to obtain the final product.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution comprises the following specific steps:

adding the passivation solution into a passivation tank, adjusting the pH value of the passivation solution to 1-2 by using phosphoric acid, adjusting the passivation temperature to 50 ℃, soaking the galvanized workpiece in the passivation solution, passivating for 30s, taking out and drying.

Example 6

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, and the sealing agent is modified gamma-aminopropyl triethoxy silicon. The stabilizer is composed of fatty alcohol polyoxyethylene ether sodium sulfonate and octadecyl ammonium chloride according to the mass ratio of 7: 3.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 5.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 1.

Example 7

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of an organic complexing agent and rare earth metal salt according to the mass ratio of 3:1, the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of 2:1:1:0.5, and the rare earth metal salt is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, and the sealing agent is modified gamma-aminopropyl triethoxy silicon. The stabilizer is composed of fatty alcohol polyoxyethylene ether sodium sulfonate and octadecyl ammonium chloride according to the mass ratio of 7: 3.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 5.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 1.

Example 8

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of an organic complexing agent and rare earth metal salt according to the mass ratio of 3:1, the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of 2:1:1:0.5, and the rare earth metal salt is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, the sealing agent is composed of nano silicon dioxide and modified gamma-aminopropyl triethoxy silicon according to a mass ratio of 15:1, and the stabilizing agent is composed of fatty alcohol polyoxyethylene ether sulfonate and octadecyl quaternary ammonium salt according to a mass ratio of 7: 3.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 5.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 1.

Example 9

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive, 80g of dispersing agent and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of an organic complexing agent and rare earth metal salt according to the mass ratio of 3:1, the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of 2:1:1:0.5, and the rare earth metal salt is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, the sealing agent is composed of nano silicon dioxide and modified gamma-aminopropyl triethoxy silicon according to a mass ratio of 15:1, and the stabilizing agent is composed of fatty alcohol polyoxyethylene ether sulfonate and octadecyl quaternary ammonium salt according to a mass ratio of 7: 3. The dispersing agent is composed of dodecyl polyoxyethylene and dodecyl sodium sulfate according to the mass ratio of 2:1.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 8min at the rotating speed of 700rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 1000rpm for 15min to prepare a solution B;

3) stirring the additive, the dispersant and the solution B at the rotating speed of 1300rpm for 20min to obtain the aqueous emulsion.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 1.

Example 10

The environment-friendly trivalent chromium color zinc passivation solution in the embodiment is prepared from the following raw materials in parts by weight: 800g of chromium chloride, 2kg of chromium sulfate, 3kg of oxidant, 3.5kg of complexing agent, 300g of auxiliary film-forming agent, 500g of additive, 80g of dispersing agent, 50g of impurity removing agent and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is composed of an organic complexing agent and rare earth metal salt according to the mass ratio of 3:1, the organic complexing agent is composed of gamma-pyrone-2, 6-dicarboxylic acid, tetrahydrofuran, hexafluorobenzene and p-nitrophenol according to the mass ratio of 2:1:1:0.5, and the rare earth metal salt is composed of cerium sulfate, lanthanum chloride and yttrium nitrate according to the mass ratio of 6:1.5: 3. The additive is composed of a sealing agent and a stabilizing agent according to a mass ratio of 8:2, the sealing agent is composed of nano silicon dioxide and modified gamma-aminopropyl triethoxy silicon according to a mass ratio of 15:1, and the stabilizing agent is composed of fatty alcohol polyoxyethylene ether sulfonate and octadecyl quaternary ammonium salt according to a mass ratio of 7: 3. The powder is composed of dodecyl polyoxyethylene and dodecyl sodium sulfate according to the mass ratio of 2:1. The impurity removing agent is thiosemicarbazide, guanyl thiourea or thiourea, and the mass ratio is 0.6: 0.15: 0.25.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 8min at the rotating speed of 700rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 1000rpm for 15min to prepare a solution B;

3) and stirring the additive, the dispersing agent, the impurity removing agent and the solution B at the rotating speed of 1300rpm for 20min to obtain the catalyst.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution is the same as that of the embodiment 1.

Comparative example

Comparative example 1

The environment-friendly trivalent chromium color zinc passivation solution of the comparative example is prepared from the following raw materials in parts by weight: 5kg of chromium chloride, 1.5kg of chromium sulfate, 2.5kg of oxidant, 2kg of complexing agent and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 8min at the rotating speed of 700rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate and the solution A for 15min at the rotating speed of 1000rpm to prepare a solution B;

3) stirring the additive and the solution B at the rotating speed of 1300rpm for 20min to obtain the final product.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution of the comparative example is the same as that of example 1.

Comparative example 2

The environment-friendly trivalent chromium color zinc passivation solution of the comparative example is prepared from the following raw materials in parts by weight: 5kg of chromium chloride, 1.5kg of chromium sulfate, 2.5kg of oxidant, 2kg of complexing agent, 200g of auxiliary film-forming agent and 100kg of water.

Wherein the oxidant is composed of sodium nitrate, nitric acid and potassium persulfate according to the mass ratio of 3:2: 1.5. The complexing agent consists of malonic acid and sodium fluoride according to the mass ratio of 10: 2. The auxiliary film-forming agent is a rare earth metal salt, and the rare earth metal salt comprises cerium sulfate, lanthanum chloride and yttrium nitrate.

The preparation method of the environment-friendly trivalent chromium color zinc passivation solution comprises the following steps:

1) stirring an oxidant, a coordination agent and part of water for 8min at the rotating speed of 700rpm to prepare a solution A;

2) stirring the chromium chloride, the chromium sulfate, the auxiliary film-forming agent and the solution A at the rotating speed of 1000rpm for 15min to prepare a solution B;

3) stirring the additive and the solution B at the rotating speed of 1300rpm for 20min to obtain the final product.

The passivation process of the environment-friendly trivalent chromium color zinc passivation solution of the comparative example is the same as that of example 1.

Performance test

(1) The environment-friendly trivalent chromium color zinc passivation solution of the examples 1 to 10 and the comparative examples 1 to 2 is used for passivating the galvanized workpiece according to the passivation process, the galvanized workpiece is tested according to the GB6458-86 metal covering layer neutral salt spray test standard, and the test results are shown in the table 3.

TABLE 3 comparison of neutral salt fog test data for galvanized workpieces of examples 1-10 and comparative examples 1-2

Serial number	Time h
		Example 1	1787
Example 2	1803
		Example 3	1773
Example 4	1812
		Example 5	1823
Example 6	1927
		Example 7	1993
Example 8	2015
		Example 9	2021
Example 10	2036
		Comparative example 1	1102
Comparative example 2	1305

It can be seen from comparative examples 1 to 3 and table 3 that the rare earth metal salt can improve the corrosion resistance of the passivation layer, and the effect is best when the mass ratio of cerium sulfate, lanthanum chloride and yttrium nitrate in the rare earth metal salt is 6:1.5: 3.

As can be seen by comparing examples 1 to 3, 4 and 5 and comparative examples 1 to 2 with Table 3, the corrosion resistance of the passivation layer is the best at a trivalent chromium salt concentration of 30 g/L.

As can be seen by comparing example 5, example 6 and comparative examples 1-2 with Table 3, the modified gamma-aminopropyl triethoxy silicon has better stability in the passivation solution and better corrosion resistance effect of the passivation layer.

By comparing the embodiment 6, the embodiment 7, the embodiment 8 and the comparative examples 1 to 2 with the table 3, it can be seen that the density of the passivation layer is further improved by the rare earth element organic ligand, and the corrosion resistance is better.

As can be seen by comparing examples 1-8, example 9 and comparative examples 1-2 with Table 3, the dispersant improves the uniformity of the passivation solution, and the passivation layer is more uniform.

Comparing examples 1-8, example 10 and comparative examples 1-2 with table 3, it can be seen that the passivation layer has a high purity, a low self-etching potential and a good corrosion resistance.

In summary, the passivation layer formed by passivating the galvanized workpiece by the environment-friendly trivalent chromium color zinc passivation solution has the effects of good brightness, high flatness and good corrosion resistance.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.