Barrel plating process for metal part machining

Abstract

The invention relates to a barrel plating process for metal part machining, and relates to the technical field of metal surface treatment.The barrel plating process comprises the following steps that (1) a metal part is subjected to oil removal and acid pickling, and the cleaned metal part is obtained; (2) the cleaned metal part is pretreated, and the pretreated metal part is obtained; (3) carrying out barrel plating on the pretreated metal piece in a plating bath to obtain a barrel-plated metal piece; and (4) carrying out passivation post-treatment on the barrel-plated metal piece to obtain a product. The plating bath includes a primary salt, sodium citrate, a leveling agent, and a grain refiner. The method has the effect of improving the corrosion resistance and hardness of the metal part, and the obtained plating layer is uniform and fine.

Description

Technical Field

[0001] The present application relates to the technical field of metal surface treatment, and in particular to a roller plating process for metal parts processing. Background Art

[0002] In the field of metal parts processing, the barrel plating process is an important coating technology and is widely used to improve the corrosion resistance, decorativeness and wear resistance of metal parts. With the development of the manufacturing industry, the requirements for coating quality are constantly increasing, especially in the fields of automobiles, aerospace, electronics, etc., which require higher uniformity and bonding strength of the coating. Therefore, new barrel plating processes are constantly being developed to meet market demand.

[0003] In the prior art, the coating is prone to burnt or poor gloss during the coating process in the barrel plating process. Especially when processing objects with complex shapes, the uniformity and tightness of the coating are difficult to ensure. These problems directly affect the quality of the coating, limit the application scope and development of the barrel plating process, and therefore need to be improved. Summary of the invention

[0004] In order to improve the uniformity and tightness of the coating, the present application provides a roller plating process for metal parts processing.

[0005] The present application provides a barrel plating process for metal parts processing using the following technical solution: A barrel plating process for metal parts processing comprises the following steps: (1) Degreasing and pickling the metal parts to obtain clean metal parts; (2) pre-treating the cleaned metal part to obtain a pre-treated metal part; (3) Roll-plating the pretreated metal part in a plating bath to obtain a roll-plated metal part (4) performing a passivation post-treatment on the metal parts after the barrel plating to obtain a product; The plating bath includes a main salt, sodium citrate, a leveler and a grain refiner.

[0006] By degreasing and pickling the metal parts, impurities such as oil and oxides on the surface of the metal parts can be removed, the surface of the metal parts can be cleaned, and the bonding force between the coating and the metal substrate can be improved; pretreatment can further activate the surface of the metal parts, improve its surface activity, and prepare for the subsequent bath deposition process; during the roller plating process, metal ions react with the surface of the metal parts to form a coating, and sodium citrate, as a chelating agent, can form a stable complex with the metal ions, control the release rate of the metal ions, and make the coating more uniform and dense, and the leveling agent makes the coating smoother, thereby reducing the accumulation of corrosive media, and the grain refiner can refine the grain structure of the coating, reduce the defects and pores at the grain boundaries, and prevent the penetration of corrosive media. The leveling agent and the grain refiner work synergistically, thereby significantly improving the corrosion resistance of the metal parts; the passivation treatment can form a dense oxide film on the surface of the metal parts, further improving the corrosion resistance of the metal parts.

[0007] Preferably, the degreasing and pickling comprises the following steps: The metal parts are placed in a degreasing solution, subjected to ultrasonic degreasing treatment, and then rinsed with deionized water to obtain degreasing metal parts; the degreasing metal parts are immersed in a pickling solution, and then rinsed with deionized water to obtain cleaned metal parts.

[0008] The metal parts are placed in a degreasing solution and subjected to ultrasonic degreasing treatment. The effect of ultrasound can make the degreasing more thorough and effectively remove impurities such as oil stains on the surface of the metal parts, providing a clean base for subsequent coating deposition; after degreasing, they are washed with deionized water to remove the residual degreasing solution; the degreased metal parts are soaked in a pickling solution, which can remove oxides and other undesirable substances on the surface of the metal parts and further activate the metal surface. After soaking, they are washed with deionized water again to obtain clean metal parts; a clean metal surface is conducive to the uniform adhesion and close bonding of the coating. Through thorough degreasing and pickling, the corrosion resistance of the metal parts can be greatly improved and the attachment points of the corrosive medium on the metal surface can be reduced. At the same time, good surface cleanliness also helps to form a more uniform and dense coating during the roll plating process, thereby improving the surface hardness of the metal parts, so that the metal parts can maintain excellent performance and appearance under various usage environments.

[0009] Preferably, the pretreatment comprises the following steps: The cleaned metal parts are immersed in an activation solution for activation treatment, and the activated metal parts are immersed in a pretreatment solution. After the immersion is completed, the metal parts are washed with deionized water to obtain pretreated metal parts.

[0010] Immersing the cleaned metal parts in the activation solution for activation treatment can further activate the surface of the metal parts, making them more receptive to subsequent coating treatment. The surface activity of the activated metal parts is enhanced, creating conditions for a good combination of the coating and the metal substrate; the components in the pretreatment solution can react with the surface of the metal parts to form a transition layer that is conducive to the adhesion of the coating; the pretreated metal parts can deposit the coating more evenly in the subsequent roll plating process, and the formed coating is denser and stronger, which can effectively block the invasion of external corrosive media, thereby significantly improving the corrosion resistance of the metal parts. At the same time, good coating bonding strength also helps to improve the surface hardness of the metal parts, making them more wear-resistant and durable, and able to maintain stable performance and good appearance in various complex usage environments.

[0011] Preferably, the pretreatment solution comprises dopamine hydrochloride and colloidal titanium salt.

[0012] Dopamine hydrochloride can self-polymerize on the surface of metal parts to form a polydopamine coating. The coating has good adhesion and biocompatibility, can adhere tightly to the metal surface, and provides an excellent base for subsequent coating treatment. The polydopamine coating also has certain antioxidant and corrosion resistance, and can protect metal parts from corrosion by corrosive media. Colloidal titanium salts can react chemically with the surface of metal parts to form a titanium-rich compound layer, which can not only enhance the surface hardness of the metal parts and make them more wear-resistant, but also cooperate with the polydopamine coating to further improve the corrosion resistance of the metal parts. In the pretreatment process, dopamine hydrochloride and colloidal titanium salts work together to form a strong and corrosion-resistant composite layer structure on the surface of the metal parts. In the subsequent roller plating process, this composite layer structure can better combine with the coating, so that the metal parts have better corrosion resistance and surface hardness.

[0013] Preferably, the main salt includes zinc sulfate and nickel sulfamate.

[0014] Nickel sulfamate can provide nickel ions more stably in the plating bath, making the nickel distribution in the coating more uniform, thereby forming a denser coating. At the same time, the coating formed with the participation of nickel sulfamate has a higher surface hardness, making the metal parts more wear-resistant and durable. During the roller plating process, zinc sulfate and nickel sulfamate work synergistically to form a coating with excellent corrosion resistance and high surface hardness, enabling metal parts to maintain stable performance and good appearance in various complex use environments.

[0015] Preferably, the mass ratio of zinc sulfate to nickel sulfamate is (9-11):1.

[0016] The coating prepared according to the above mass ratio has good corrosion resistance and high hardness.

[0017] Preferably, the leveler comprises benzyltrimethylammonium chloride.

[0018] Benzyltrimethylammonium chloride can be preferentially adsorbed on the microscopic protrusions with high surface energy on the surface of metal parts, thereby changing the electric field distribution on the electrode surface, making the electric field strength at the microscopic recesses relatively high, which is conducive to the deposition of metal ions there, while the electric field strength at the microscopic protrusions is weakened due to the presence of benzyltrimethylammonium chloride, and the deposition rate of metal ions is slowed down; benzyltrimethylammonium chloride promotes the preferential deposition of metal ions in the microscopic recesses, thereby making the coating on the surface of the metal parts more uniform and smooth, thereby improving the corrosion resistance and surface hardness of the metal parts.

[0019] Preferably, the grain refiner is 2-mercaptobenzothiazole, cerium sulfate and lanthanum sulfate.

[0020] 2-Mercaptobenzothiazole can adsorb on the active sites of metal crystals and inhibit the growth of crystals, thereby making the grains of the coating finer; cerium sulfate and lanthanum sulfate change the growth pattern of crystals and further refine the grains through interaction with metal ions; the fine grain structure makes the coating more dense and uniform, which can effectively prevent the penetration of corrosive media and improve the corrosion resistance of metal parts; at the same time, the dense grain structure also enhances the hardness and strength of the coating, improves the surface hardness of metal parts, and makes them more wear-resistant and durable.

[0021] Preferably, the post-passivation treatment comprises the following steps: after degreasing and cleaning the metal parts after roller plating, passivation treatment is performed in a passivation solution, the passivation temperature is 20-40° C., and the passivation time is 30-60 s.

[0022] The metal parts after roller plating are degreased and cleaned to remove impurities that may remain on the surface, creating good conditions for passivation treatment; passivation treatment is carried out in a passivation solution. Within a limited temperature and time range, the passivation solution can fully react with the surface of the metal parts to form a dense passivation film. This passivation film can effectively prevent the external corrosive medium from contacting the metal parts, greatly improving the corrosion resistance of the metal parts. At the same time, the passivation film can also enhance the hardness of the metal part surface, making it more wear-resistant and durable.

[0023] Preferably, the passivation solution comprises chromium trichloride, humic acid and ammonium fluoride.

[0024] During the passivation process, chromium trichloride can react with the surface of metal parts to form a chromium-containing passivation film; humic acid contains a variety of functional groups and can form complexes with metal ions to enhance the stability and density of the passivation film. At the same time, humic acid can also improve the color and uniformity of the passivation film, further improving the appearance quality of metal parts; ammonium fluoride can react with oxides on the metal surface to remove undesirable substances on the surface, so that the passivation film can be more evenly covered on the surface of the metal parts. In addition, ammonium fluoride can also improve the hardness and wear resistance of the passivation film, thereby improving the surface hardness of the metal parts; during the passivation treatment process, chromium trichloride, humic acid and ammonium fluoride work synergistically to further improve the corrosion resistance and hardness of metal parts.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. By degreasing and pickling the metal parts, impurities such as oil and oxides on the surface of the metal parts can be removed, the surface of the metal parts can be cleaned, and the bonding force between the coating and the metal substrate can be improved; pretreatment can further activate the surface of the metal parts, improve its surface activity, and prepare for the subsequent bath deposition process; during the roll plating process, metal ions react with the surface of the metal parts to form a coating. Sodium citrate, as a chelating agent, can form a stable complex with the metal ions, control the release rate of metal ions, and make the coating more uniform and dense. The leveling agent makes the coating smoother and smoother, thereby reducing the accumulation of corrosive media. The grain refiner can refine the grain structure of the coating, reduce the defects and pores at the grain boundaries, and prevent the penetration of corrosive media. The leveling agent and the grain refiner work synergistically, thereby significantly improving the corrosion resistance of the metal parts; the passivation treatment can form a dense oxide film on the surface of the metal parts, further improving the corrosion resistance of the metal parts.

[0026] 2. Dopamine hydrochloride can self-polymerize on the surface of metal parts to form a polydopamine coating. The coating has good adhesion and biocompatibility, can adhere tightly to the metal surface, and provides an excellent base for subsequent coating treatment. The polydopamine coating also has certain antioxidant and corrosion resistance, which can protect metal parts from corrosion by corrosive media. Colloidal titanium salts can react chemically with the surface of metal parts to form a titanium-rich compound layer, which can enhance the surface hardness of metal parts and make them more wear-resistant. It can also cooperate with the polydopamine coating to further improve the corrosion resistance of metal parts. In the pretreatment process, dopamine hydrochloride and colloidal titanium salts work together to form a strong and corrosion-resistant composite layer structure on the surface of metal parts. In the subsequent roller plating process, this composite layer structure can better combine with the coating, so that the metal parts have better corrosion resistance and surface hardness.

[0027] 3. Benzyltrimethylammonium chloride can be preferentially adsorbed on the microscopic protrusions with high surface energy on the surface of metal parts, thereby changing the electric field distribution on the electrode surface, making the electric field strength at the microscopic concave parts relatively high, which is conducive to the deposition of metal ions there, while the electric field strength at the microscopic protrusions is weakened due to the presence of benzyltrimethylammonium chloride, and the deposition rate of metal ions is slowed down; benzyltrimethylammonium chloride promotes the preferential deposition of metal ions in the microscopic concave parts, thereby making the coating on the surface of the metal parts more uniform and smooth, thereby improving the corrosion resistance and surface hardness of the metal parts.

[0028] 4.2-Mercaptobenzothiazole can adsorb on the active sites of metal crystals and inhibit the growth of crystals, thereby making the grains of the coating finer; cerium sulfate and lanthanum sulfate change the growth mode of crystals and further refine the grains through interaction with metal ions; the fine grain structure makes the coating more dense and uniform, which can effectively prevent the penetration of corrosive media and greatly improve the corrosion resistance of metal parts; at the same time, the dense grain structure also enhances the hardness and strength of the coating, improves the surface hardness of metal parts, and makes them more wear-resistant and durable. DETAILED DESCRIPTION

[0029] The present application embodiment discloses a barrel plating process for metal parts processing. The raw materials used in the present application can be obtained from commercially available raw materials unless otherwise specified. The present application is further described in detail below in conjunction with the embodiments: Description of raw materials: dopamine hydrochloride (CAS No.: 62-31-7), colloidal titanium salt model CD-101, purchased from Shengzhou Chunkai New Materials Co., Ltd., nickel sulfamate (CAS No.: 13770-89-3), benzyltrimethylammonium chloride (CAS No.: 56-93-9), 2-mercaptobenzothiazole (CAS No.: 149-30-4), humic acid (CAS No.: 1415-93-6), ammonium fluoride (CAS No.: 12125-01-8).

[0030] Example 1 (1) placing the metal parts in a degreasing solution and degreasing them by ultrasonic wave of 40 Hz, wherein the degreasing solution is an aqueous solution, wherein the concentration of sodium hydroxide is 25 g / L, the concentration of sodium carbonate is 20 g / L, and the concentration of sodium bicarbonate is 40 g / L, and the metal parts are immersed at 60° C. for 20 min, and then washed with deionized water after degreasing to obtain the degreasing metal parts; soaking the degreasing metal parts in an acid cleaning solution for 30 s, wherein the acid cleaning solution is an aqueous solution, wherein the volume concentration of hydrochloric acid is 5%, and the volume concentration of nitric acid is 1%, and then washed with deionized water after soaking in the acid cleaning solution to obtain the cleaned metal parts; (2) soaking the cleaned metal part in an activation solution for 5 minutes to perform activation treatment, wherein the activation solution is an aqueous solution, and the mass concentration of sodium bisulfate in the activation solution is 3%, and immersing the activated metal part in a pretreatment solution, which is an aqueous solution and contains 2 g / L dopamine hydrochloride and 1 g / L colloidal titanium salt, for 10 minutes, and washing with deionized water to obtain a pretreated metal part; (3) The pretreated metal parts are subjected to roller plating in a plating bath, wherein the plating bath is an aqueous solution, the plating bath contains 108 g / L zinc sulfate, 12 g / L nickel sulfamate, 10 g / L benzyltrimethylammonium chloride, 2 g / L 2-mercaptobenzothiazole, 1 g / L cerium sulfate and 1 g / L lanthanum sulfate, the plating bath pH is 5, the electroplating temperature is 40°C, the anode is a nickel plate, the roller speed is 5 rpm, the mechanical stirring speed of the plating bath is 40 rpm, and the current density is 1.5 A / dm 2 After 1 hour of barrel plating, the plated parts are obtained; (4) The plated parts after roller plating are degreased and cleaned with ethanol, and then passivated in a passivation solution at 20° C. for 60 seconds. The passivation solution is an aqueous solution containing 10 g / L chromium trichloride, 5 g / L humic acid and 3 g / L ammonium fluoride. The pH value of the passivation solution is 3. After passivation, the parts are washed three times with deionized water, and then dried at 60° C. to obtain the product.

[0031] Example 2 (1) placing the metal parts in a degreasing solution and degreasing them by ultrasonic wave of 40 Hz, wherein the degreasing solution is an aqueous solution, wherein the concentration of sodium hydroxide is 25 g / L, the concentration of sodium carbonate is 20 g / L, and the concentration of sodium bicarbonate is 40 g / L, and the metal parts are immersed at 60° C. for 20 min, and then washed with deionized water after degreasing to obtain the degreasing metal parts; soaking the degreasing metal parts in an acid cleaning solution for 30 s, wherein the acid cleaning solution is an aqueous solution, wherein the volume concentration of hydrochloric acid is 5%, and the volume concentration of nitric acid is 1%, and then washed with deionized water after soaking in the acid cleaning solution to obtain the cleaned metal parts; (2) soaking the cleaned metal part in an activation solution for 5 minutes to perform activation treatment, wherein the activation solution is an aqueous solution, and the mass concentration of sodium bisulfate in the activation solution is 3%, and immersing the activated metal part in a pretreatment solution, which is an aqueous solution and contains 2 g / L dopamine hydrochloride and 1 g / L colloidal titanium salt, for 10 minutes, and washing with deionized water to obtain a pretreated metal part; (3) The pretreated metal parts are subjected to roller plating in a plating bath, wherein the plating bath is an aqueous solution, the plating bath contains 110 g / L zinc sulfate, 10 g / L nickel sulfamate, 10 g / L benzyltrimethylammonium chloride, 2 g / L 2-mercaptobenzothiazole, 1 g / L cerium sulfate and 1 g / L lanthanum sulfate, the plating bath pH is 5, the electroplating temperature is 40°C, the anode is a nickel plate, the roller speed is 5 rpm, the mechanical stirring speed of the plating bath is 40 rpm, and the current density is 1.5 A / dm 2 After 1 hour of barrel plating, the plated parts are obtained; (4) The plated parts after roller plating are degreased and cleaned with ethanol, and then passivated in a passivation solution at 40° C. for 30 seconds. The passivation solution is an aqueous solution containing 10 g / L chromium trichloride, 5 g / L humic acid and 3 g / L ammonium fluoride. The pH value of the passivation solution is 3. After passivation, the parts are washed three times with deionized water, and then dried at 60° C. to obtain the product.

[0032] Example 3 (1) placing the metal parts in a degreasing solution and degreasing them by ultrasonic wave of 40 Hz, wherein the degreasing solution is an aqueous solution, wherein the concentration of sodium hydroxide is 25 g / L, the concentration of sodium carbonate is 20 g / L, and the concentration of sodium bicarbonate is 40 g / L, and the metal parts are immersed at 60° C. for 20 min, and then washed with deionized water after degreasing to obtain the degreasing metal parts; soaking the degreasing metal parts in an acid cleaning solution for 30 s, wherein the acid cleaning solution is an aqueous solution, wherein the volume concentration of hydrochloric acid is 5%, and the volume concentration of nitric acid is 1%, and then washed with deionized water after soaking in the acid cleaning solution to obtain the cleaned metal parts; (2) soaking the cleaned metal part in an activation solution for 5 minutes to perform activation treatment, wherein the activation solution is an aqueous solution, and the mass concentration of sodium bisulfate in the activation solution is 3%, and immersing the activated metal part in a pretreatment solution, which is an aqueous solution and contains 2 g / L dopamine hydrochloride and 1 g / L colloidal titanium salt, for 10 minutes, and washing with deionized water to obtain a pretreated metal part; (3) The pretreated metal parts are subjected to roller plating in a plating bath, wherein the plating bath is an aqueous solution, the plating bath contains 109.1 g / L zinc sulfate, 10.9 g / L nickel sulfamate, 10 g / L benzyltrimethylammonium chloride, 2 g / L 2-mercaptobenzothiazole, 1 g / L cerium sulfate and 1 g / L lanthanum sulfate, the plating bath pH is 5, the electroplating temperature is 40°C, the anode is a nickel plate, the roller speed is 5 rpm, the mechanical stirring speed of the plating bath is 40 rpm, and the current density is 1.5 A / dm 2 After 1 hour of barrel plating, the plated parts are obtained; (4) The plated parts after roller plating are degreased and cleaned with ethanol, and then passivated in a passivation solution at 30° C. for 45 seconds. The passivation solution is an aqueous solution containing 10 g / L chromium trichloride, 5 g / L humic acid and 3 g / L ammonium fluoride. The pH value of the passivation solution is 3. After passivation, the parts are washed three times with deionized water, and then dried at 60° C. to obtain the product.

[0033] Example 4 Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that in Example 4, dopamine hydrochloride is not added to the pretreatment solution.

[0034] Example 5 Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that in Example 5, the amount of zinc sulfate is 105 g / L and the amount of nickel sulfamate is 15 g / L.

[0035] Example 6 Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that in Example 6, the amount of zinc sulfate used is 111.4 g / L, and the amount of nickel sulfamate used is 8.6 g / L.

[0036] Example 7 Example 7 is based on Example 3, and the only difference between Example 7 and Example 3 is that nickel sulfamate is replaced by nickel sulfate in Example 7.

[0037] Example 8 Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that in Example 8, no 2-mercaptobenzothiazole is added to the grain refiner.

[0038] Example 9 Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that in Example 9, cerium sulfate and 2-mercaptobenzothiazole are not added to the grain refiner.

[0039] Example 10 Example 10 is based on Example 3, and the only difference between Example 10 and Example 3 is that ammonium fluoride is not added to the passivation solution in Example 10.

[0040] Embodiment 11 Example 11 is based on Example 3. The only difference between Example 11 and Example 3 is that in Example 11, the passivation temperature is 60° C. and the passivation time is 10 s.

[0041] Example 12 Example 12 is based on Example 3. The only difference between Example 12 and Example 3 is that in Example 12, the passivation temperature is 10° C. and the passivation time is 90 s.

[0042] Comparative Example 1 Comparative Example 1 is based on Example 3, and the only difference between Comparative Example 1 and Example 3 is that no leveling agent is added to the plating bath of Comparative Example 1.

[0043] Comparative Example 2 Comparative Example 2 is based on Example 3, and the only difference between Comparative Example 2 and Example 3 is that in Comparative Example 2, no grain refiner is added to the plating bath.

[0044] Performance testing (1) GB / T19746-2018 Metal and Alloy Corrosion Salt Solution Immersion Test was selected as the standard to prepare the test specimens. The specimens were immersed in a simulated humid atmospheric environment. The test solution contained an aqueous solution of 1 g / L acetic acid and 1 g / L sodium chloride. After immersion for 3 weeks, the corrosion depth of the specimens was tested, the corrosion rate was calculated, and the corrosion conditions of the specimens were observed and recorded. The results are recorded in Table 1.

[0045] (2) Select GB / T 4340.1-2009 Metallic Materials Vickers Hardness Test Part 1: Test Method as the standard to test the Vickers hardness of the sample. Each sample is tested three times and the average value is taken after measurement. The results are recorded in Table 1.

[0046] (3) Status of metal parts after barrel plating: Observe the metal parts after barrel plating to see whether the coating is uniform and fine, and whether there is any expansion or peeling. The results are recorded in Table 1. Table 1 Test results Test results Corrosion rate (mm / a) Hardness (HV) Workpiece appearance Example 1 0.003 532 Uniform and fine, no expansion or peeling Example 2 0.002 535 Uniform and fine, no expansion or peeling Example 3 0.002 541 Uniform and fine, no expansion or peeling Example 4 0.008 513 Uniform and fine, no expansion or peeling Example 5 0.007 554 Uniform and fine, no expansion or peeling Example 6 0.009 507 Uniform and fine, no expansion or peeling Example 7 0.007 522 Uniform and fine, no expansion or peeling Example 8 0.009 516 Uniform and fine, no expansion or peeling Example 9 0.011 505 Uniform and fine, no expansion or peeling Example 10 0.006 523 Uniform and fine, no expansion or peeling Embodiment 11 0.009 518 Uniform and fine, no expansion or peeling Example 12 0.012 510 Uniform and fine, no expansion or peeling Comparative Example 1 0.025 506 There is expansion and peeling phenomenon Comparative Example 2 0.028 501 There is expansion and peeling phenomenon It can be seen from Table 1 that the corrosion rate of Examples 1-3 is less than 0.003 mm / a, the hardness is greater than 532 HV, the workpiece appearance is uniform and delicate, and there is no expansion or peeling phenomenon. It can be seen that the product prepared by the process of the present application has good corrosion resistance, high hardness, and the appearance of the product is good.

[0047] It can be seen from Table 1 that the only difference between Example 4 and Example 3 is that dopamine hydrochloride is not added to the pretreatment solution in Example 4, and compared with Example 3, the corrosion resistance and hardness of Example 4 are reduced; this is because no dopamine hydrochloride is added, the synergistic effect of polydopamine and colloidal titanium salt is lacking, the surface adhesion of the coating to the metal part is reduced, and thus the corrosion resistance and hardness are reduced.

[0048] It can be seen from Table 1 that the only difference between Examples 5 and 6 and Example 3 is that the mass ratio of zinc sulfate to nickel sulfamate in Example 5 is 7:1, and the mass ratio of zinc sulfate to nickel sulfamate in Example 6 is 13:1. Compared with Example 3, the performance of Examples 5 and 6 is reduced. This is because excessive nickel content will increase the surface hardness, but the surface adhesion between the coating and the metal part will decrease, and the corrosion resistance will deteriorate. Low nickel content will directly affect the corrosion resistance and hardness.

[0049] As can be seen from Table 1, the only difference between Examples 7, 8, and 9 and Example 3 is that nickel sulfamate is replaced by nickel sulfate in Example 7, 2-mercaptobenzothiazole is not added to the grain refiner in Example 8, and cerium sulfate and 2-mercaptobenzothiazole are not added to the grain refiner in Example 9. Compared with Example 3, the corrosion resistance and hardness of Examples 7, 8, and 9 are reduced; this is because if nickel sulfamate is replaced by nickel sulfate, the distribution uniformity of nickel in the coating is reduced, the uniform density of the coating is reduced, and thus the corrosion resistance and hardness are reduced; and changing the components in the grain refiner will affect the synergistic effect between the components, the grains of the coating become larger, the density of the coating is reduced, and thus the corrosion resistance and hardness are reduced.

[0050] As can be seen from Table 1, the only difference between Examples 10, 11, and 12 and Example 3 is that: in Example 10, ammonium fluoride is not added to the passivation solution, in Example 11, the passivation temperature is 60°C, the passivation time is 10s, and in Example 12, the passivation temperature is 10°C, and the passivation time is 90s. Compared with Example 3, Examples 10, 11, and 12 have decreased corrosion resistance and hardness; this is because without adding ammonium fluoride, the conformability of the passivation film decreases; by changing the parameters of the electroplating, the thickness and stability of the coating are affected, so that the corrosion resistance and hardness are decreased.

[0051] As can be seen from Table 1, the only difference between Comparative Examples 1 and 2 and Example 3 is that: in Comparative Example 1, no leveling agent is added to the plating bath, and in Comparative Example 2, no grain refiner is added to the plating bath. Compared with Example 3, the corrosion resistance, hardness and workpiece appearance of Comparative Examples 1 and 2 are significantly deteriorated; this is because without adding a leveling agent or a grain refiner, the uniformity and density of the coating decrease, the grains become coarser, and the number of grain boundary defects and pores increases, so the corrosion resistance, hardness and workpiece appearance are significantly deteriorated.

[0052] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of ​​the present application. The technical scope of the present application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A barrel plating process for metal parts processing, characterized in that: The steps include: (1) Degreasing and pickling the metal parts to obtain clean metal parts; (2) pre-treating the cleaned metal parts to obtain pre-treated metal parts; (3) Roll-plating the pre-treated metal parts in a plating bath to obtain roll-plated metal parts (4) performing a passivation post-treatment on the metal parts after the barrel plating to obtain the product; The plating bath includes a main salt, sodium citrate, a leveler and a grain refiner.

2. A barrel plating process for metal parts processing according to claim 1, characterized in that: The degreasing and pickling comprises the following steps: The metal parts are placed in a degreasing solution, subjected to ultrasonic degreasing treatment, and then rinsed with deionized water to obtain degreasing metal parts; the degreasing metal parts are immersed in a pickling solution, and then rinsed with deionized water to obtain cleaned metal parts.

3. The barrel plating process for metal parts processing according to claim 1, characterized in that: The pre-processing comprises the following steps: The cleaned metal parts are immersed in an activation solution for activation treatment, and the activated metal parts are immersed in a pretreatment solution. After the immersion is completed, the metal parts are washed with deionized water to obtain pretreated metal parts.

4. The barrel plating process for metal parts processing according to claim 3, characterized in that: The pretreatment solution includes dopamine hydrochloride and colloidal titanium salt.

5. The barrel plating process for metal parts processing according to claim 1, characterized in that: The main salts include zinc sulfate and nickel sulfamate.

6. The barrel plating process for metal parts processing according to claim 5, characterized in that: The mass ratio of the zinc sulfate to nickel sulfamate is (9-11):

1.

7. The barrel plating process for metal parts processing according to claim 6, characterized in that: The leveler includes benzyltrimethylammonium chloride.

8. The barrel plating process for metal parts processing according to claim 7, characterized in that: The grain refiners are 2-mercaptobenzothiazole, cerium sulfate and lanthanum sulfate.

9. The barrel plating process for metal parts processing according to claim 1, characterized in that: The post-passivation treatment comprises the following steps: after degreasing and cleaning the metal parts after the roll plating, passivation treatment is performed in a passivation solution, the passivation temperature is 20-40° C., and the passivation time is 30-60s.

10. The barrel plating process for metal parts processing according to claim 9, characterized in that: The passivation solution comprises chromium trichloride, humic acid and ammonium fluoride.