A method of phosphating a metal part

Abstract

The application relates to the technical field of metal surface treatment, and discloses a phosphating method for metal parts, which comprises the following steps: immersing the metal parts into a treatment liquid for phosphating, washing with water, drying, and obtaining the phosphated metal parts; the raw materials of the treatment liquid comprise the following components in mass parts: 5-10 parts of dihydrogen phosphate, 6-12 parts of nitrate, 1-3 parts of phosphoric acid, 0.1-0.5 parts of graphene oxide, 0.5-1 part of a surfactant, 0.5-1.2 parts of a diglycidyl ether compound, 100-140 parts of water, and a pH buffer for adjusting the pH of the treatment liquid to 2-3. Through the technical scheme, the problems of poor corrosion resistance and poor adhesion of the phosphating film to the surface of the metal parts in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and more specifically, to a phosphating method for metal parts. Background Technology

[0002] Phosphating is a process in which metal parts such as steel, zinc, and aluminum are chemically treated in a solution containing zinc, manganese, calcium, iron, or alkali metal phosphates to form a water-insoluble phosphate film on their surface. The resulting phosphate film is called a phosphate coating.

[0003] Phosphating films have a wide range of applications. Due to their porous structure and excellent adsorption, lubrication, corrosion resistance, and high electrical insulation properties, they can be used as a protective coating for metals or as a pretreatment to improve the adhesion between organic films and metals. The corrosion resistance and adhesion of phosphating films to the surface of metal parts are crucial characteristics, significantly impacting the service life of these parts. Therefore, improving the corrosion resistance and adhesion of phosphating films to the surface of metal parts is a technical challenge that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0004] This invention proposes a phosphating method for metal parts, which solves the problems of poor corrosion resistance and poor adhesion of phosphating films to the surface of metal parts in related technologies.

[0005] The technical solution of the present invention is as follows: A method for phosphating metal parts includes the following steps: immersing the metal parts in a treatment solution for phosphating, washing with water, and drying to obtain phosphated metal parts. The raw materials of the treatment solution include the following components in parts by weight: 5-10 parts of dihydrogen phosphate, 6-12 parts of nitrate, 1-3 parts of phosphoric acid, 0.1-0.5 parts of graphene oxide, 0.5-1 part of surfactant, 0.5-1.2 parts of diglycidyl ether compound, and 100-140 parts of water, and also include a pH buffer solution to adjust the pH of the treatment solution to 2-3.

[0006] As a further technical solution, the mass ratio of the dihydrogen phosphate, nitrate, and phosphoric acid to the diglycidyl ether compound is 10:0.4~0.5.

[0007] As a further technical solution, the diglycidyl ether compound includes one or more of 1,4-butanediol diglycidyl ether, bisphenol A diglycidyl ether, and resorcinol diglycidyl ether.

[0008] As a further technical solution, the diglycidyl ether compound includes one of bisphenol A diglycidyl ether, resorcinol diglycidyl ether and 1,4-butanediol diglycidyl ether in a mass ratio of 2:8 to 4:6.

[0009] As a further technical solution, the diglycidyl ether compound is resorcinol diglycidyl ether and 1,4-butanediol diglycidyl ether in a mass ratio of 3:7.

[0010] As a further technical solution, the preparation method of the treatment solution includes the following steps: mixing the components in the specified mass fractions, adding a pH buffer to adjust the pH, and continuing to mix until homogeneous to obtain the treatment solution.

[0011] As a further technical solution, the dihydrogen phosphate salt includes one or more of manganese dihydrogen phosphate, zinc dihydrogen phosphate, and calcium dihydrogen phosphate.

[0012] As a further technical solution, the nitrate includes one or more of manganese nitrate tetrahydrate, zinc nitrate hexahydrate, and calcium nitrate tetrahydrate.

[0013] As a further technical solution, the surfactant includes one or more of OP-10, AEO-9, and PVP.

[0014] As a further technical solution, the phosphating temperature is 30~40℃ and the time is 10~20min.

[0015] The working principle and beneficial effects of this invention are as follows: 1. This invention improves the corrosion resistance and adhesion of the phosphating film to the surface of metal parts by adding diglycidyl ether compounds to the treatment solution. The reason may be that the epoxy groups in the molecular structure of diglycidyl ether compounds can react with the surface of metal materials, thereby producing strong adhesion and improving the tightness of the phosphating film, thus enhancing corrosion resistance.

[0016] 2. In this invention, the mass ratio of dihydrogen phosphate, nitrate, and phosphoric acid to diglycidyl ether compounds is limited to 10:0.4~0.5, which further improves the corrosion resistance of the phosphate film and its adhesion to the surface of metal parts.

[0017] 3. The present invention limits the diglycidyl ether compounds to one of bisphenol A diglycidyl ether, resorcinol diglycidyl ether and 1,4-butanediol diglycidyl ether in a mass ratio of 2:8 to 4:6, which further improves the corrosion resistance of the phosphating film and its adhesion to the surface of metal parts. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] The raw material parameters in the following examples and comparative examples are as follows: Graphene oxide is graphene oxide powder with a thickness of 0.8~1.2 nm, a particle size of 1~10 μm, and an oxygen content of 45 wt%. The pH buffer solution is Sodium Borate Buffer, 0.5M, pH 8.5; The metal parts are 15×10×1 (length×width×thickness mm) Grade A Q235 steel samples (Grade A Q235 steel contains C≤0.22wt%, Mn≤1.4wt%, Si≤0.35wt%, S≤0.050wt%, P≤0.045wt%).

[0020] Example 1 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.5 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0021] Example 2 S1. Preparation of treatment solution: Mix 5 parts of calcium dihydrogen phosphate, 6 parts of manganese nitrate tetrahydrate, 1 part of phosphoric acid, 0.1 parts of graphene oxide, 0.5 parts of PVP, 0.5 parts of bisphenol A diglycidyl ether, and 100 parts of water. Add pH buffer to adjust the pH to 2, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 30°C treatment solution for phosphating for 20 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0022] Example 3 S1. Preparation of treatment solution: Mix 5 parts calcium dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 12 parts calcium nitrate tetrahydrate, 3 parts phosphoric acid, 0.5 parts graphene oxide, 0.5 parts PVP, 0.5 parts AEO-9, 0.5 parts resorcinol diglycidyl ether, and 140 parts water. Add pH buffer to adjust the pH to 3, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 40℃ treatment solution for phosphating for 10 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0023] Example 4 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.8 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0024] Example 5 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 1 part 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0025] Example 6 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 1.2 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0026] Example 7 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.2 parts bisphenol A diglycidyl ether, 0.8 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0027] Example 8 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.3 parts bisphenol A diglycidyl ether, 0.7 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0028] Example 9 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.4 parts bisphenol A diglycidyl ether, 0.6 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0029] Example 10 S1. Preparation of treatment solution: Mix 3 parts manganese dihydrogen phosphate, 5 parts zinc dihydrogen phosphate, 10 parts zinc nitrate hexahydrate, 2 parts phosphoric acid, 0.3 parts graphene oxide, 0.8 parts OP-10, 0.3 parts resorcinol diglycidyl ether, 0.7 parts 1,4-butanediol diglycidyl ether, and 120 parts water. Add pH buffer to adjust the pH to 2.5, and stir at 30℃ and 300r / min for 40min until homogeneous to obtain the treatment solution. S2. Immerse the metal parts in a 35°C treatment solution for phosphating for 15 minutes, wash with water, and dry to obtain the phosphated metal parts.

[0030] Comparative Example 1 The only difference from Example 1 is that 1,4-butanediol diglycidyl ether is not added.

[0031] The phosphated metal parts obtained in Examples 1-10 and Comparative Example 1 were subjected to corrosion resistance tests according to the methods in GB / T 6807-2001 "Technical Conditions for Phosphating Treatment of Steel Workpieces Before Coating". Specifically, the phosphated metal parts were immersed in a 5wt% sodium chloride aqueous solution at 20°C, and the time for rust to appear on the phosphated surface was recorded. The adhesion was tested according to the methods in GB / T 31586.2-2015 "Evaluation and Acceptance Criteria for Adhesion / Cohesion (Breaking Strength) of Protective Coating Systems for Corrosion Protection of Steel Structures Part 2: Cross-cut Test and Cross-cut Test". The test results are recorded in Table 1.

[0032] Table 1. Corrosion resistance and adhesion of phosphating film to metal parts surface

[0033] As can be seen from Table 1, the phosphating method for metal parts provided by the present invention results in metal parts with a corrosion resistance of more than 339 min after phosphating, and the adhesion between the phosphating film and the surface of the metal parts is above level 2, indicating good corrosion resistance and adhesion.

[0034] Compared with Comparative Example 1, Example 1 added diglycidyl ether compounds, while Comparative Example 1 did not add diglycidyl ether compounds. The phosphating film obtained in Example 1 had better corrosion resistance and adhesion than that in Comparative Example 1, indicating that adding diglycidyl ether compounds can improve the corrosion resistance of the phosphating film and its adhesion to the surface of metal parts.

[0035] Compared to Examples 4-6, in Example 1, the mass ratio of dihydrogen phosphate, nitrate, and phosphoric acid to diglycidyl ether compounds was 10:0.25; in Example 4, it was 10:0.4; in Example 5, it was 10:0.5; and in Example 6, it was 10:0.6. The phosphate films obtained in Examples 4 and 5 showed better corrosion resistance and adhesion than those in Examples 1 and 6. This indicates that a mass ratio of dihydrogen phosphate, nitrate, and phosphoric acid to diglycidyl ether compounds of 10:0.4-0.5 can further improve the corrosion resistance of the phosphate film and its adhesion to the surface of metal parts.

[0036] The phosphating films obtained in Examples 7-10 have better corrosion resistance and adhesion than those in Example 5, indicating that the diglycidyl ether compounds, specifically one of bisphenol A diglycidyl ether, resorcinol diglycidyl ether, and 1,4-butanediol diglycidyl ether in a mass ratio of 2:8 to 4:6, can further improve the corrosion resistance and adhesion of the phosphating film to the surface of metal parts.

[0037] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for phosphating metal parts, characterized in that, Includes the following steps: The metal parts are immersed in a treatment solution for phosphating, washed with water, and dried to obtain phosphated metal parts. The raw materials of the treatment solution include the following components in parts by weight: 5-10 parts of dihydrogen phosphate, 6-12 parts of nitrate, 1-3 parts of phosphoric acid, 0.1-0.5 parts of graphene oxide, 0.5-1 part of surfactant, 0.5-1.2 parts of diglycidyl ether compound, and 100-140 parts of water. It also includes a pH buffer solution to adjust the pH of the treatment solution to 2-3. The mass ratio of the dihydrogen phosphate, nitrate, and phosphoric acid to the diglycidyl ether compound is 10:0.4-0.

5. The diglycidyl ether compound is resorcinol diglycidyl ether and 1,4-butanediol diglycidyl ether in a mass ratio of 3:

7.

2. The phosphating method for metal parts according to claim 1, characterized in that, The preparation method of the treatment solution includes the following steps: mixing the components in the specified mass fractions, adding pH buffer to adjust the pH, and continuing to mix until homogeneous to obtain the treatment solution.

3. The phosphating method for metal parts according to claim 1, characterized in that, The dihydrogen phosphate includes one or more of manganese dihydrogen phosphate, zinc dihydrogen phosphate, and calcium dihydrogen phosphate.

4. The phosphating method for metal parts according to claim 1, characterized in that, The nitrates include one or more of manganese nitrate tetrahydrate, zinc nitrate hexahydrate, and calcium nitrate tetrahydrate.

5. The phosphating method for metal parts according to claim 1, characterized in that, The surfactant includes one or more of OP-10, AEO-9, and PVP.

6. The phosphating method for metal parts according to claim 1, characterized in that, The phosphating temperature is 30~40℃ and the time is 10~20min.

Images