A manganese-zirconium series surface conditioner and its preparation method and application

Abstract

The present invention provides a manganese-zirconium surface conditioner composed, by weight, of the following ingredients: 15-19% manganese fluoride, 13-16% manganese nitride, 6-8% manganese dihydrogen phosphate, 7-12% zirconium boride, 5-9% zirconium carbide, 15-20% sodium polycarboxylate, 5-10% polyethylene glycol, and the balance sodium hydride. Due to the presence of zirconium, the manganese-zirconium surface conditioner significantly improves the hardness and acid and alkali resistance of the manganese phosphate film. Scanning electron microscopy reveals crystal sizes of 1-3 microns and virtually zero porosity.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface treatment, and in particular to a manganese-zirconium series surface conditioner, a preparation method and an application thereof. Background Art

[0002] Manganese-zirconium surface conditioner is a powdered metal surface conditioner used in the surface conditioning process prior to manganese phosphating. It is specifically designed for manganese phosphating of iron, steel, and alloys. At room or low temperatures, zinc phosphating processes for steel, aluminum, and aluminum alloys, and zinc and zinc alloys generally use colloidal titanium surface conditioner. Medium-temperature zinc phosphating processes for steel also often use colloidal titanium surface conditioner. However, high-temperature manganese phosphating processes generally use manganese-zirconium surface conditioner. Using manganese-zirconium surface conditioner ensures the phosphate film's film thickness and its desired wear and corrosion resistance. Fatigue testing has proven that manganese phosphating films offer a strong ability to prevent wear, with the wear resistance and fatigue life of workpieces treated with manganese phosphating three to four times that of zinc phosphating films.

[0003] The surface treatment of workpieces prior to manganese phosphating significantly impacts the quality of the phosphate film, especially after pickling or high-temperature, strong-alkali cleaning, which has the most significant impact on thin-layer phosphating. For workpieces treated with high-temperature or strong-alkali cleaning, the active sites on the steel surface transform into oxides or hydroxides, which form the crystal nuclei of the phosphate film. This reduces the number of crystals that form sparse, coarse crystals, which affects the phosphate film quality. Without surface conditioning, it is difficult to form a high-quality phosphate film. To overcome the adverse effects of surface pretreatment, organic or inorganic compounds are often added before the phosphating process to enable surface conditioning. This is the basic function of metal surface conditioners.

[0004] Currently, manganese-based surface conditioners on the market are mainly composed of manganese phosphate and sodium carbonate. For example, Chinese patent CN202210327930.2 discloses a new and efficient manganese-based surface conditioner, its preparation method, and application. The manganese-based surface conditioner is composed of the following components in weight ratio: manganese salt: 20-40%, organic salt complex: 3%-5%, fluoride: 10%-25%, sodium carbonate: 15%-35% and dispersion promoter: 2-15%. This invention can form a phosphate coating on the surface of a metal workpiece in a short time and at a relatively low temperature. The coating can change the microscopic state of the metal workpiece surface, overcome the phenomenon of coarsening of the metal workpiece film, and eliminate the uneven corrosion defects caused by strong alkaline degreasing or strong acid rust removal. At the same time, it can enhance the corrosion resistance of the metal workpiece surface, improve the adhesion of the coating, reduce the amount of residue in the phosphating solution, and reduce the consumption of the phosphating solution. It also has the advantages of removing impurities introduced by the workpiece, preventing bath aging, extending the service life of the bath, increasing the phosphating speed, and shortening the treatment time. However, the phosphate coating formed on the workpiece surface by manganese-based surface conditioners made from current commercial formulas generally suffers from coarse crystals, coarsened film, slow film formation speed, and poor stability, making it difficult to form a high-quality phosphate coating, resulting in poor adhesion and corrosion resistance. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a manganese-zirconium surface conditioner, which forms phosphate crystals on the surface of a workpiece in the form of granular crystals, has an ultra-fine film, a thick film, a fast film formation speed, good stability, etc., and has good adhesion and corrosion resistance.

[0006] The second object of the present invention is to provide a method for preparing the manganese-zirconium surface conditioner.

[0007] The third object of the present invention is to provide an application of the manganese-zirconium series surface conditioner.

[0008] A manganese-zirconium surface conditioner is made of the following ingredients by weight:

[0009] Manganese fluoride 15-19%,

[0010] Manganese nitride 13-16%,

[0011] Manganese dihydrogen phosphate 6-8%,

[0012] Zirconium boride 7-12%,

[0013] Zirconium carbide 5-9%,

[0014] Sodium polycarboxylate 15-20%,

[0015] Polyethylene glycol 5-10%,

[0016] Sodium hydride residue.

[0017] Among them, manganese fluoride, manganese nitride, manganese dihydrogen phosphate, zirconium boride, and zirconium carbide are the main active ion components of the manganese-zirconium series surface conditioner. Manganese fluoride can thicken the phosphate film, manganese nitride can enhance the hardness or rigidity of the phosphate film, manganese dihydrogen phosphate can improve the crystal density, zirconium boride can improve the high temperature resistance of the phosphate film, and zirconium carbide can improve the hardness and high temperature resistance of the phosphate film; sodium polycarboxylate is an organic dispersant, which prevents the aggregation of colloidal microparticle molecules and the formation of precipitation, thereby reducing the surface conditioner activity; polyethylene glycol is a phosphate crystallization regulator, which can make the crystals granular or spherical; sodium hydride is a pH regulator and promoter component.

[0018] In the manganese-zirconium series surface conditioning agent of the present invention, the amount of manganese fluoride and manganese nitride is greater than that of zirconium salt for the following reasons:

[0019] The weight ratio of manganese nitride to zirconium carbide is 1.5-2.5. If the ratio is too small, that is, the amount of manganese nitride is too small, it is difficult to form a continuous phosphating film; if the ratio is too large, that is, the amount of manganese nitride is too large, the phosphating film is easy to be brittle, easy to powder, and the hardness is insufficient.

[0020] The polyethylene glycol is PEG200, and the molecular weight is 180-220. If the molecular weight is too large, the crystal gap will be large when the phosphating crystals are formed, and the phosphating film will have many pores.

[0021] The preparation method of the manganese-zirconium series surface conditioner is as follows:

[0022] Manganese fluoride, manganese nitride, manganese dihydrogen phosphate, zirconium boride, zirconium carbide, sodium polycarboxylate, polyethylene glycol and sodium hydride are sequentially added into a grinder, crushed for 3-6 hours, and then ground using a solid powder grinder for 4-6 hours to obtain a manganese-zirconium series surface conditioner.

[0023] The pulverizer is an ultrafine powder airflow pulverizer.

[0024] The colloidal particle size range of the manganese-zirconium surface conditioner after being dissolved in water is 10-50 nm.

[0025] The method of using the manganese-zirconium series surface regulator is as follows:

[0026] The manganese-zirconium surface conditioner is diluted with water at a ratio of 0.1-0.4% (weight concentration), that is, a solution with a mass concentration of 0.1-0.4% of the manganese-zirconium surface conditioner is prepared. The degreased and rusted iron-based workpiece is immersed in the solution for 1-5 minutes, then removed and placed in a manganese-based phosphating bath (manganese-based phosphating solution diluted with water in a ratio of 1:4, free acid value: 13.5-15pt, total acid value: 80-85pt) until the phosphating film is completely formed.

[0027] The 1L manganese phosphating solution is composed of the following components:

[0028] 85-90 wt% H3PO4 40-60 mL,

[0029] Mn(H2PO4)2·2H2O 12-18g,

[0030] Zn(NO3)21-3g,

[0031] Ni(NO3)21-3g,

[0032] Accelerator 4-6g,

[0033] Ca(NO3)20.8-3g,

[0034] Water balance.

[0035] The accelerators are: citric acid, salicylic acid, EDTA, sodium nitrite, sodium nitrobenzenesulfonate, and Schiff base, and the weight ratio of the six is 1: (1-1.5): (1-2): (1-1.5): (1-1.5): (1-1.5).

[0036] The free acid value of the manganese phosphating bath solution is 13.5-15, the total acid value is 80-85, the treatment temperature is 92-95° C., and the treatment time is 10 minutes.

[0037] The beneficial effects of the present invention are as follows:

[0038] The manganese-zirconium surface conditioner of this invention differs from other manganese-based surface conditioners on the market. The presence of zirconium significantly improves the hardness and acid and alkali resistance of the manganese-based phosphate film. Scanning electron microscopy reveals that the crystal size is 1-3 microns and the porosity is almost zero. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an electron scanning microscope image of Example 1.

[0040] Figure 2 This is an electron scanning microscope image of Example 3.

[0041] Figure 3 This is an electron scanning microscope image of Example 5.

[0042] Figure 4 This is a scanning electron microscope image of Comparative Example 9. Implementation Method

[0043] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0044] The brand and manufacturer of polyethylene glycol in the examples and comparative examples are: Jiangsu Haian Petrochemical Plant, PEG200.

[0045] The brand and manufacturer of the sodium polycarboxylate in the examples and comparative examples are: Nantong Yongle Chemical Co., Ltd., HLB value: 17-18.

[0046] Table 1 is the formula of Examples 1-5, Table 2 is the formula of Comparative Examples 1-6, and Table 3 is the formula of Comparative Examples 7-10, which are as follows:

[0047] Table 1 (preparation 1 kg)

[0048] Example 1 Example 2 Example 3 Example 4 Example 5 Manganese fluoride 150g 160g 170g 180g 190g Manganese nitride 130g 140g 145g 150g 90g Manganese dihydrogen phosphate 60g 65g 70g 75g 80g Zirconium boride 70g 80g 100g 110g 120g Zirconium carbide 50g 60g 70g 80g 160g Sodium polycarboxylate 150g 160g 180g 190g 200g polyethylene glycol 50g 60g 80g 90g 100g Sodium hydride margin margin margin margin margin

[0049] Table 2 (preparation 1 kg)

[0050] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Manganese fluoride - 160g 170g 180g 190g 190g Manganese nitride 130g - 145g 150g 160g 160g Manganese dihydrogen phosphate 60g 65g - 75g 80g 80g Zirconium boride 70g 80g 100g - 120g 120g Zirconium carbide 50g 60g 70g 80g - 90g Sodium polycarboxylate 150g 160g 180g 190g 200g - polyethylene glycol 50g 60g 80g 90g 100g 100g Sodium hydride margin margin margin margin margin margin

[0051] The preparation method of the manganese-zirconium series surface conditioner is as follows:

[0052] Manganese fluoride, manganese nitride, manganese dihydrogen phosphate, zirconium boride, zirconium carbide, sodium polycarboxylate, polyethylene glycol, and sodium hydride were sequentially added to a grinder, pulverized for 4 hours, and ground using a solid powder grinder for 5 hours to obtain a manganese-zirconium surface conditioner.

[0053] During use, dilute the manganese-zirconium surface conditioner with water at a ratio of 0.2%. Immerse the degreased and rust-free iron-based workpiece in it for 1 minute, then remove it and place it in a manganese-based phosphating bath until the phosphate film is fully formed. The formula for 1L of manganese-based phosphating solution is: 50mL of 85wt% H₃PO₄, 15g of Mn(H₂PO₄)₂·2H₂O, 22g of Zn(NO₃), 22g of Ni(NO₃), 4-6g of accelerator, 0.8-3g of Ca(NO₃), and the balance of water. The accelerators are citric acid, salicylic acid, EDTA, sodium nitrite, sodium nitrobenzenesulfonate, and Schiff base, in a weight ratio of 1:1.5:2:1:1:1.

[0054] The manganese phosphating solution has a free acid value of 14.2 points, a total acid value of 82 points, a treatment temperature of 92-95° C., and a treatment time of 10 minutes.

[0055] The active ingredients in the manganese-zirconium surface-adjusted emulsion serve as crystal nuclei during the growth of the phosphating film, and the phosphating solution provides manganese phosphate as a crystal coat to wrap the nuclei until the entire phosphating film is completely formed.

[0056] Table 3 (preparation 1 kg)

[0057] Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Manganese fluoride 150g 150g 70g 150g Manganese nitride 0 180g 50g 130g Manganese dihydrogen phosphate 60g 60g 60g 60g Zirconium boride 70g 70g 150g 70g Zirconium carbide 180g 0 130g 50g Sodium polycarboxylate 150g 150g 150g 150g polyethylene glycol 50g 50g 50g 50g Sodium hydride margin margin margin margin

[0058] In Comparative Example 7 in Table 3, manganese nitride is removed from Example 1, and the amount of zirconium carbide is the total amount of manganese nitride and zirconium carbide in Example 1, and the other aspects are the same as in Example 1; Comparative Example 8 is removed from Example 1, and the amount of manganese nitride is the total amount of manganese nitride and zirconium carbide in Example 1, and the other aspects are the same as in Example 1; Comparative Example 9 is based on Example 1, but the amount of manganese fluoride is exchanged with the amount of zirconium boride, and the amount of manganese nitride is exchanged with the amount of zirconium carbide, and the other aspects are the same as in Example 1; Comparative Example 10 is based on Example 1, but the amount of manganese nitride is exchanged with the amount of zirconium boride, and the other aspects are the same as in Example 1.

[0059] Comparative Example 11

[0060] The iron-based workpiece that has been degreased and rusted is directly immersed in the manganese phosphating solution without surface conditioning, and waits for the phosphating film to be completely formed.

[0061] The test results of Examples 1-5 are shown in Table 4, the test results of Comparative Examples 1-6 are shown in Table 5, and the test results of Comparative Examples 7-11 are shown in Table 6.

[0062] Table 4

[0063] Performance requirements Example 1 Example 2 Example 3 Example 4 Example 5 Phosphate crystal shape spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals Phosphate crystal size 1-3 microns 1-3 microns 1-3 microns 1-3 microns 1-3 microns 1-3 microns Phosphate film thickness 10-20 microns 10-20 microns 10-20 microns 10-20 microns 10-20 microns 10-20 microns Phosphate coating neutral salt spray 72 hrs 72 hrs 72 hrs 72 hrs 72 hrs 72 hrs Copper sulfate drip test More than 10 minutes More than 10 minutes More than 10 minutes More than 10 minutes More than 10 minutes More than 10 minutes Phosphate film impact resistance 50kg·cm, no shedding 50kg·cm, no shedding 50kg·cm, no shedding 50kg·cm, no shedding 50kg·cm, no shedding 50kg·cm, no shedding Adhesion Level 0 Level 0 Level 0 Level 0 Level 0 Level 0 Phosphate film flexibility 3mm column, no shedding 3mm column, no shedding 3mm column, no shedding 3mm column, no shedding 3mm column, no shedding 3mm column, no shedding Phosphate film hardness 4H 4H 4H 4H 4H 4H Phosphate film high temperature resistance 500℃, no powdering 500℃, no powdering 500℃, no powdering 500℃, no powdering 500℃, no powdering 500℃, no powdering

[0064] Table 5

[0065] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Phosphate crystal shape spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals Phosphate crystal size 10-20 microns 10-20 microns 10-20 microns 10-20 microns 10-20 microns 10-20 microns Phosphate film thickness 5-10 microns 5-10 microns 5-10 microns 5-10 microns 5-10 microns 5-10 microns Phosphate coating neutral salt spray 4 hrs 4 hrs 4 hrs 4 hrs 4 hrs 4 hrs Copper sulfate drip test 1min 1min 1min 1min 1min 1min Phosphate film impact resistance 30kg·cm, no shedding 30kg·cm, no shedding 30kg·cm, no shedding 30kg·cm, no shedding 30kg·cm, no shedding 30kg·cm, no shedding Adhesion Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Phosphate film flexibility 6mm column, no falling off 6mm column, no falling off 6mm column, no falling off 6mm column, no falling off 6mm column, no shedding 6mm column, no falling off Phosphate film hardness B B B B B B Phosphate film high temperature resistance 500℃, powderization 500℃, powderization 500℃, powderization 500℃, powderization 500℃, powderization 500℃, powderization

[0066] Table 6

[0067] Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Phosphate crystal shape spherical granular crystals spherical granular crystals spherical granular crystals spherical granular crystals needle-shaped crystals Phosphate crystal size 10-20 microns 10-20 microns 10-20 microns 10-20 microns 100-200 microns Phosphate film thickness 5-10 microns 5-10 microns 3-6 microns 5-10 microns 0.5-1.0 microns Phosphate coating neutral salt spray 8 hours 8 hours 8 hours 8 hours 0.5hrs Copper sulfate drip test 5min 5min 5min 5min 3s Phosphate film impact resistance 30kg·cm, falling off 50kg·cm, falling off 30kg·cm, falling off 50kg·cm, falling off 20kg·cm, falling off Adhesion Level 2 Level 1 Level 2 Level 2 Level 4 Phosphate film flexibility 6mm column, falling off 3mm column, no shedding 6mm column, falling off 6mm column, falling off 6mm column, falling off Phosphate film hardness B 4H 2H B B Phosphate film high temperature resistance 500℃, no powdering 300℃, powderization 500℃, no powdering 500℃, powderization 500℃, powderization

[0068] It can be seen from the test data of Example 1 in Table 4 and the test data of Comparative Examples 7-8 in Table 6 that manganese nitride and zirconium carbide have a synergistic effect.

[0069] The test methods for each item in Table 4-Table 6 are as follows:

[0070] Phosphate crystal shape: Scanning electron microscope SEM photo,

[0071] Phosphate crystal size: Scanning electron microscope SEM photo,

[0072] Phosphate film thickness: film thickness meter,

[0073] Phosphate coating neutral salt spray: GB / T 6458,

[0074] Copper sulfate drip test: GB 5936,

[0075] Impact resistance of phosphate film: Impact tester GB / T 1732-1993 "Determination of impact resistance of paint film",

[0076] Adhesion: Cross-cut test method GB / T 9286-1998 "Cross-cut test for paint and varnish films",

[0077] Phosphate film flexibility: GB 6742 "Paint film bending test (cylindrical shaft)",

[0078] Phosphate coating hardness: Brinell hardness tester,

[0079] Phosphate film high temperature resistance: ultra-high temperature test oven 500 ℃,

[0080] The manganese-zirconium surface conditioner of the present invention is different from the manganese-based surface conditioners on the market. Due to the presence of zirconium element, the hardness and acid and alkali resistance of the manganese-based phosphate film are greatly improved.

Claims

1. A manganese-zirconium surface conditioner, characterized in that: The invention is made of the following ingredients by weight percentage: 15-19% manganese fluoride, 13-16% manganese nitride, 6-8% manganese dihydrogen phosphate, 7-12% zirconium boride, 5-9% zirconium carbide, 15-20% sodium polycarboxylate, 5-10% polyethylene glycol, and the balance is sodium hydride; The weight ratio of manganese nitride to zirconium carbide is 1.5-2.5; The polyethylene glycol is PEG200, and the molecular weight is 180-220.

2. The method for preparing the manganese-zirconium surface conditioning agent according to claim 1, characterized in that: The method comprises the following steps: adding manganese fluoride, manganese nitride, manganese dihydrogen phosphate, zirconium boride, zirconium carbide, sodium polycarboxylate, polyethylene glycol and sodium hydride into a grinder in sequence, grinding for 3-6 hours, and grinding for 4-6 hours using a solid powder grinder to obtain a manganese-zirconium surface conditioner.

3. The method for preparing the manganese-zirconium surface conditioning agent according to claim 2, characterized in that: The pulverizer is an ultrafine powder airflow pulverizer.

4. The method for using the manganese-zirconium surface conditioning agent according to claim 1, characterized in that: The method comprises the following steps: adding water to a manganese-zirconium surface conditioner at a ratio of 0.1-0.4%, immersing the iron-based workpiece that has been degreased and derusted for 1-5 minutes, taking it out, and placing it in a manganese-zirconium phosphating liquid tank to wait for the phosphating film to be completely formed.

5. The method for using the manganese-zirconium surface conditioning agent according to claim 4, characterized in that: The manganese phosphating solution is composed of the following components per liter: 40-60 mL of phosphoric acid, 12-18 g of Mn(H2PO4)2·2H2O, 1-3 g of Zn(NO3)2, 1-3 g of Ni(NO3)2, 4-6 g of accelerator, 0.8-3 g of Ca(NO3)2, and the balance is water.

6. The method for using the manganese-zirconium series surface conditioner according to claim 5, characterized in that: The accelerators in the manganese phosphating solution are: citric acid, salicylic acid, EDTA, sodium nitrite, sodium nitrobenzene sulfonate, and Schiff base, and the weight ratio of the six is 1: (1-1.5): (1-2): (1-1.5): (1-1.5): (1-1.5).

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