Liquid supplement for chemical nickel plating and long-period chemical nickel plating method

Abstract

The invention relates to the technical field of nickel plating, in particular to a liquid supplement for chemical nickel plating and a long-period chemical nickel plating method. The solution for chemical nickel plating provided by the invention comprises a C1 solution and a C2 solution, the liquid C1 comprises the following components: 200-500 g / L of first divalent nickel salt, 50-200 g / L of first accelerator, 0.01-5 g / L of first brightener and the balance of water; and the liquid C2 comprises the following components: 150-560 g / L of a first reducing agent, 50-200 g / L of a first complexing agent, 0.2-20 g / L of a first stabilizing agent, 5-50 g / L of a first buffering agent, 50-200 g / L of a second accelerating agent and the balance of water. In the chemical nickel plating process, the liquid C1 and the liquid C2 are supplemented in time, the purpose of adjusting the components of the plating solution is achieved by reasonably controlling the chemical components of the initial plating solution and the liquid supplementing solution, the nickel plating layer can be quickly and uniformly deposited, the service life of the plating solution is prolonged, and the plating layer with stable mechanical properties is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of nickel plating, and in particular to a replenishing solution for chemical nickel plating and a long-cycle chemical nickel plating method. Background Art

[0002] Chemical nickel plating refers to a reaction that relies on the autocatalytic effect of the substrate surface to reduce nickel ions and deposit them on the substrate through redox reaction.

[0003] In the traditional chemical nickel plating process, the stability and service life of the plating solution are affected by many factors, including pH fluctuations, improper temperature control, impurity contamination, oxygen introduced by air stirring, and natural decomposition of active ingredients in the plating solution. These problems not only increase production costs, but may also lead to a decline in the quality of the coating, affecting the consistency and reliability of the product.

[0004] Although researchers are committed to developing new chemical nickel plating solution formulas with long service life in order to improve the overall performance of the plating solution, the service life of traditional chemical nickel plating solutions is still difficult to reach more than 15 cycles. Therefore, the industry urgently needs a formula that can significantly extend the service life of chemical nickel plating solutions. In addition, the formula should also be able to provide consistent plating quality and performance in different industrial applications. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a replenishing solution for chemical nickel plating and a long-cycle chemical nickel plating method. The replenishing solution of the present invention is used for chemical nickel plating to increase the service life of the plating solution and obtain a coating with stable mechanical properties.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a replenishing solution for chemical nickel plating, comprising a C1 solution and a C2 solution;

[0008] The composition of the C1 liquid is: 200-500 g / L of the first divalent nickel salt, 50-200 g / L of the first accelerator, 0.01-5 g / L of the first brightener, and the balance is water;

[0009] The C2 liquid is composed of: 150-560 g / L of a first reducing agent, 50-200 g / L of a first complexing agent, 0.2-20 g / L of a first stabilizer, 5-50 g / L of a first buffer, 50-200 g / L of a second accelerator, and the balance is water.

[0010] Preferably, the first divalent nickel salt is nickel sulfate and / or nickel chloride;

[0011] The first accelerator and the second accelerator are independently at least one of succinic acid and lactic acid.

[0012] Preferably, the first complexing agent is at least one of adipic acid, tartaric acid, malic acid, citric acid, citrate and propionic acid.

[0013] Preferably, the first reducing agent is at least one of sodium hypophosphite, sodium borohydride and hydrazine hydrate.

[0014] Preferably, the first stabilizer is at least one of molybdenum oxide, sodium thiosulfate, thiourea and potassium iodate.

[0015] Preferably, the first buffer is at least one of acetic acid, acetate, phosphate, amino acid, amino acid salt, lactic acid and boric acid;

[0016] The first brightener is at least one of butynediol, propargyl alcohol and ethoxypropargyl alcohol.

[0017] The present invention provides a method for long-cycle chemical nickel plating using the replenishing solution described in the above scheme, comprising the following steps:

[0018] Placing the workpiece in an initial plating solution for chemical nickel plating; the initial plating solution comprises: 20-60 g / L of a second divalent nickel salt, 10-50 g / L of a second complexing agent, 15-45 g / L of a second reducing agent, 0.01-10 g / L of a second stabilizer, 0.01-2 g / L of a second brightener, 0.1-30 g / L of a third accelerator, 10-50 g / L of a second buffer, and the balance is water;

[0019] Ni in the plating solution during the plating process 2+ The concentration is reduced, and C1 solution and C2 solution are added to the Ni in the plating solution. 2+ The initial mass concentration reaches 98-102%; the volume ratio of the added C1 liquid and C2 liquid is 1:1.

[0020] Preferably, when Ni 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is below 10%, add C1 liquid and C2 liquid in a volume ratio of 1:1.

[0021] Preferably, the pH value of the chemical nickel plating is 4.5-5.0, and the temperature is 82-90°C.

[0022] Preferably, the loading capacity of the workpiece is 1.0 to 1.5 dm 2 / L.

[0023] The present invention provides a replenishing solution for chemical nickel plating, comprising a C1 solution and a C2 solution; the C1 solution is composed of: 200-500 g / L of a first divalent nickel salt, 50-200 g / L of a first accelerator, 0.01-5 g / L of a first brightener, and the balance is water; the C2 solution is composed of: 150-560 g / L of a first reducing agent, 50-200 g / L of a first complexing agent, 0.2-20 g / L of a first stabilizer, 5-50 g / L of a first buffer, 50-200 g / L of a second accelerator, and the balance is water. In the process of chemical nickel plating, the present invention timely replenishes the C1 solution and the C2 solution, and achieves the purpose of adjusting the composition of the plating solution by reasonably controlling the chemical composition of the initial plating solution and the replenishing solution, so that the nickel plating layer can be deposited quickly and evenly, the service life of the plating solution can be extended, and a plating layer with stable mechanical properties can be obtained. DETAILED DESCRIPTION

[0024] The present invention provides a replenishing solution for chemical nickel plating, comprising a C1 solution and a C2 solution;

[0025] The composition of the C1 liquid is: 200-500 g / L of the first divalent nickel salt, 50-200 g / L of the first accelerator, 0.01-5 g / L of the first brightener, and the balance is water;

[0026] The C2 liquid is composed of: 150-560 g / L of a first reducing agent, 50-200 g / L of a first complexing agent, 0.2-20 g / L of a first stabilizer, 5-50 g / L of a first buffer, 50-200 g / L of a second accelerator, and the balance is water.

[0027] The following first describes the C1 liquid.

[0028] In the present invention, the C1 solution includes 200-500 g / L of the first divalent nickel salt, and in a specific embodiment, it can be 200, 250, 300, 330, 350, 400, 450 or 500 g / L. In the present invention, the first divalent nickel salt is preferably nickel sulfate and / or nickel chloride; the first divalent nickel salt is used to supplement the Ni in the plating solution. 2+ .

[0029] In the present invention, the C1 solution includes 50 to 200 g / L of the first accelerator, and in a specific embodiment, it can be 50, 100, 120, 150 or 200 g / L. In the present invention, the first accelerator is preferably at least one of succinic acid and lactic acid. In the present invention, the function of the first accelerator is to increase the Ni content in the plating solution. 2+ Deposition rate on the workpiece surface.

[0030] In the present invention, the C1 liquid includes 0.01-5 g / L of the first brightener, and in specific embodiments, it can be 0.01, 0.1, 0.5, 1, 1.25, 3, 4 or 5 g / L. In the present invention, the first brightener is preferably at least one of butynediol, propargyl alcohol and ethoxypropargyl alcohol.

[0031] In the present invention, the C1 liquid includes a balance of water, and the water is preferably ultrapure water.

[0032] Next, the C2 liquid will be described.

[0033] In the present invention, the C2 liquid includes 150-560 g / L of the first reducing agent, and in a specific embodiment, it can be 150, 200, 250, 300, 350, 400, 450, 500 or 560 g / L. In the present invention, the first reducing agent is preferably at least one of sodium hypophosphite, sodium borohydride and hydrazine hydrate.

[0034] In the present invention, the C2 solution includes 50 to 200 g / L of the first complexing agent, and in a specific embodiment, it can be 50, 100, 115, 125, 150, 175 or 200 g / L. In the present invention, the first complexing agent is preferably at least one of adipic acid, tartaric acid, malic acid, citric acid, citrate and propionic acid. In the present invention, the citrate preferably includes sodium citrate. In the present invention, the function of the first complexing agent is to complex the Ni in the plating solution. 2+ , promoting Ni 2+ Uniform deposition.

[0035] In the present invention, the C2 solution includes 0.2-20 g / L of the first stabilizer, and in a specific embodiment, it can be 0.2, 1.5, 2, 5, 6.5, 10, 15 or 20 g / L. In the present invention, the first stabilizer is preferably at least one of molybdenum oxide, sodium thiosulfate, thiourea and potassium iodate. In the present invention, the function of the first stabilizer is to control the plating speed and maintain the stability of the plating solution.

[0036] In the present invention, the C2 liquid includes 5 to 50 g / L of the first buffer, and in a specific embodiment, it can be 5, 10, 15, 20, 30, 40 or 50 g / L. In the present invention, the first buffer is preferably at least one of acetic acid, acetate, phosphate, amino acid, amino acid salt, lactic acid and boric acid. In the present invention, the acetate preferably includes sodium acetate; the phosphate preferably includes sodium phosphate; the amino acid salt preferably includes sodium amino acid.

[0037] In the present invention, the C2 solution includes 50 to 200 g / L of a second accelerator, and in a specific embodiment, it can be 50, 80, 100, 120, 130, 150, 180 or 200 g / L. In the present invention, the optional type of the second accelerator is the same as the first accelerator, and more preferably the same as the first accelerator. In the present invention, the function of the second accelerator is to increase the Ni content in the plating solution. 2+ Deposition rate on the workpiece surface.

[0038] In the present invention, the C2 liquid includes a balance of water, and the water is preferably ultrapure water.

[0039] The present invention has no special requirements for the preparation method of the replenishing solution. Each component can be directly dissolved in water according to the composition to obtain C1 solution and C2 solution.

[0040] The present invention provides a method for long-cycle chemical nickel plating using the replenishing solution described in the above scheme, comprising the following steps:

[0041] Placing the workpiece in an initial plating solution for chemical nickel plating; the initial plating solution comprises: 20-60 g / L of a second divalent nickel salt, 10-50 g / L of a second complexing agent, 15-45 g / L of a second reducing agent, 0.01-10 g / L of a second stabilizer, 0.01-2 g / L of a second brightener, 0.1-30 g / L of a third accelerator, 10-50 g / L of a second buffer, and the balance is water;

[0042] Ni in the plating solution during the plating process 2+ The concentration will decrease, and C1 and C2 solutions will be added to the Ni 2+ The initial mass concentration reaches 98-102%; the volume ratio of the added C1 liquid and C2 liquid is 1:1.

[0043] The initial plating solution will first be described below.

[0044] In the present invention, the initial plating solution includes 20 to 60 g / L of the second divalent nickel salt, and in a specific embodiment, it can be 20, 25, 30, 33, 35, 40, 45, 50, 55 or 60 g / L. In the present invention, the optional range of the second divalent nickel salt is preferably the same as the first divalent nickel salt, and more preferably the same as the first divalent nickel salt.

[0045] In the present invention, the initial plating solution includes 10 to 50 g / L of the second complexing agent, and in a specific embodiment, it can be 10, 15, 20, 25, 30, 35, 40, 45 or 50 g / L. In the present invention, the type of the second complexing agent is preferably the same as the type of the first complexing agent, which will not be repeated here.

[0046] In the present invention, the initial plating solution includes 15 to 45 g / L of the second reducing agent, and in a specific embodiment, it can be 15, 20, 25, 30, 35, 40 or 45 g / L. In the present invention, the optional range of the second reducing agent is preferably the same as the first reducing agent, and more preferably the same type as the first reducing agent.

[0047] In the present invention, the initial plating solution includes 0.01 to 10 g / L of the second stabilizer, and in specific embodiments, it can be 0.01, 0.1, 1, 3, 5, 7, 9 or 10 g / L. In the present invention, the optional range of the second stabilizer is preferably the same as the first stabilizer, and more preferably the same type as the first stabilizer.

[0048] In the present invention, the initial plating solution includes 0.01-2 g / L of the second brightener, and in a specific embodiment, it can be 0.01, 0.1, 0.5, 1.0, 1.3, 1.5, 1.7 or 2 g / L. In the present invention, the optional range of the second brightener is preferably the same as the first brightener, and more preferably the same as the first brightener.

[0049] In the present invention, the initial plating solution includes a third accelerator of 0.1 to 30 g / L, and in a specific embodiment, it can be 0.1, 1, 5, 10, 15, 20, 25 or 30 g / L. In the present invention, the optional range of the third accelerator is preferably the same as the first accelerator, and more preferably the same type as the first accelerator. In the present invention, the third accelerator is used to control the plating speed within a suitable range.

[0050] In the present invention, the initial plating solution includes 10 to 50 g / L of the second buffer, and in a specific embodiment, it can be 10, 15, 20, 25, 30, 35, 40, 45 or 50 g / L. In the present invention, the optional range of the second buffer is preferably the same as the first buffer, and more preferably the same as the first buffer.

[0051] In the present invention, the initial plating solution includes a balance of water, and the water is preferably ultrapure water.

[0052] The present invention has no special requirements on the preparation process of the initial plating solution, and the preparation process well known in the art can be adopted.

[0053] In the present invention, when the pH value of the initial plating solution cannot meet the plating conditions (pH value is 4.5-5.0), the present invention preferably adjusts the pH value of the initial plating solution to the required pH value range before chemical nickel plating. The present invention preferably uses dilute ammonia or dilute sulfuric acid to adjust the pH value.

[0054] In the present invention, the pH value of the chemical nickel plating is preferably 4.5-5.0, and in a specific embodiment, the pH value of the chemical nickel plating can be 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0; the temperature of the chemical nickel plating is preferably 82-90° C., and in a specific embodiment, the temperature of the chemical nickel plating can be 82, 84, 86, 88 or 90° C. Compared with traditional chemical nickel plating, the present invention can achieve low-temperature, fast and uniform deposition of nickel plating by reasonably adjusting the initial plating solution composition and the replenishing solution composition.

[0055] In the present invention, the loading amount of the workpiece is preferably 1.0 to 1.5 dm 2 / L, in a specific embodiment, the loading amount of the workpiece can be 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5 dm 2 / L. The present invention can effectively avoid excessive consumption of the plating solution by loading the workpieces reasonably, which is beneficial to increasing the service life of the plating solution.

[0056] During the plating process, Ni in the plating solution 2+ The concentration is reduced, and the present invention adds C1 solution and C2 solution to the Ni in the plating solution. 2+ After reaching 98-102% of the initial mass concentration, the plating is continued. In a specific embodiment, Ni 2+ Reach 98%, 99%, 100%, 101% or 102% of the initial mass concentration.

[0057] The present invention preferably contains Ni 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is below 10%, add C1 liquid and C2 liquid.

[0058] In the present invention, the volume ratio of the added C1 liquid and the C2 liquid is 1:1.

[0059] The present invention preferably tests the Ni content in the plating solution once every half an hour. 2+ Content, use C1 liquid and C2 liquid to adjust the composition of the plating solution in time.

[0060] In the plating process, the present invention preferably filters and removes solid particles and other impurities in the plating solution in a timely manner. The present invention is conducive to the stable deposition of the nickel plating layer by filtering and removing solid particles and other impurities in the plating solution in a timely manner.

[0061] The chemical nickel plating replenishing solution and the chemical nickel plating method provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0062] Example 1

[0063] The composition of the chemical nickel plating solution is: nickel sulfate 33g / L, lactic acid 10mL / L, sodium acetate 5g / L, sodium hypophosphite 20g / L, sodium citrate 15g / L, oxalic acid 5g / L, tartaric acid 10g / L, molybdenum oxide 50mg / L, thiourea 10mg / L, butynediol 10mg / L, and the balance is ultrapure water.

[0064] S1: preparing a chemical nickel plating solution according to a chemical nickel plating solution formula.

[0065] S2: According to the formula of chemical nickel plating solution, supplementary solutions C1 and C2 are prepared. C1 contains 330g / L nickel sulfate, 100mL / L lactic acid (equivalent to 120g / L), 500mg / L butynediol, and the balance is ultrapure water; C2 contains 250g / L sodium hypophosphite, 75g / L sodium citrate, 20g / L adipic acid, 30g / L tartaric acid, 5000mg / L molybdenum oxide, 1000mg / L thiourea, 100mL / L lactic acid, 20g / L sodium acetate, and the balance is ultrapure water.

[0066] S3: Strictly control the temperature at 88°C, pH between 4.5 and 5.0, and test the Ni content in the plating solution every half an hour 2+ Content, when Ni in the plating solution 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is less than 10%, add C1 liquid and C2 liquid in a volume ratio of 1:1 to replenish the solution to extend the service life. Use C1 liquid and C2 liquid to adjust the Ni content in the plating solution. 2+ The mass concentration reaches 100% of the cylinder opening concentration, and the amount of C1 liquid added reaches 10L / 100L, which is a cycle. During the nickel plating process, solid particles and other impurities in the plating solution are filtered and removed in time. The workpiece loading capacity is 1.25dm 2 / L, to avoid affecting the stability of the plating solution.

[0067] Table 1 Performance evaluation table of Example 1

[0068] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 > 1 12.8 8.6％ 784 2 13.0 8.4％ 716 3 12.5 8.9％ 752 4 12.6 8.3％ 745 5 12.8 8.7％ 762 6 13.0 8.4％ 743 7 12.1 8.1％ 706 8 11.8 9.3％ 719 9 11.2 9.5％ 683 10 10.5 10.2％ 645 11 9.3 11.2％ 619 12 7.3 13.2％ 584

[0069] Example 2

[0070] The composition of the chemical nickel plating solution is: nickel sulfate 33g / L, lactic acid 10mL / L, sodium acetate 5g / L, sodium hypophosphite 30g / L, sodium citrate 15g / L, oxalic acid 5g / L, malic acid 5g / L, molybdenum oxide 50mg / L, thiourea 5mg / L, potassium iodate 10mg / L, butynediol 10mg / L, propargyl alcohol 10mg / L, and the balance is ultrapure water.

[0071] S1: preparing a chemical nickel plating solution according to a chemical nickel plating solution formula.

[0072] S2: According to the formula of chemical nickel plating solution, supplementary solutions C1 and C2 are prepared. C1 contains 330g / L nickel sulfate, 100mL / L lactic acid, 500mg / L butynediol, 500mg / L propargyl alcohol, and the balance is ultrapure water; C2 contains 350g / L sodium hypophosphite, 75g / L sodium citrate, 20g / L adipic acid, 20g / L malic acid, 5000mg / L molybdenum oxide, 500mg / L thiourea, 1000mg / L potassium iodate, 100mL / L lactic acid, 20g / L sodium acetate, and the balance is ultrapure water.

[0073] S3: Strictly control the temperature at 88°C, pH between 4.5 and 5.0, and test the Ni content in the plating solution every half an hour 2+ Content, when Ni in the plating solution 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is less than 10%, add C1 liquid and C2 liquid in a volume ratio of 1:1 to replenish the solution to extend the service life. Use C1 liquid and C2 liquid to adjust the Ni content in the plating solution. 2+ The mass concentration reaches 100% of the opening concentration, and the amount of C1 liquid added reaches 10L / 100L, which is a cycle. During the nickel plating process, solid particles and other impurities in the plating solution are filtered out in time, and the workpiece loading is controlled at 1.25dm 2 / L, to avoid affecting the stability of the plating solution.

[0074] Table 2 Performance evaluation table of Example 2

[0075] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 <!-- 5 -->]]> 1 14.6 8.1％ 715 2 13.2 8.3％ 745 3 12.7 8.6％ 762 4 12.6 8.7％ 785 5 12.5 8.5％ 746 6 13.0 8.9％ 786 7 12.4 8.4％ 734 8 12.7 8.6％ 762 9 12.5 8.2％ 716 10 12.3 8.7％ 728 11 11.8 8.9％ 734 12 11.9 8.6％ 764 13 11.6 9.4％ 710 14 10.8 9.5％ 719 15 9.5 10.3％ 703

[0076] Example 3

[0077] The composition of the chemical nickel plating solution is: nickel sulfate 33g / L, lactic acid 10mL / L, sodium acetate 5g / L, sodium hypophosphite 20g / L, sodium citrate 15g / L, malic acid 1g / L, adipic acid 10g / L, succinic acid 1g / L, tartaric acid 3g / L, thiourea 10mg / L, potassium iodate 20mg / L, butynediol 10mg / L, ethoxypropargyl alcohol 15mg / L, and the balance is ultrapure water.

[0078] S1: preparing a chemical nickel plating solution according to a chemical nickel plating solution formula.

[0079] S2: According to the formula of chemical nickel plating solution, supplementary solutions C1 and C2 are prepared. C1 contains 330g / L nickel sulfate, 100mL / L lactic acid, 500mg / L butynediol, 750mg / L ethoxypropargyl alcohol, and the balance is ultrapure water; C2 contains 350g / L sodium hypophosphite, 75g / L sodium citrate, 2g / L malic acid, 20g / L adipic acid, 10g / L tartaric acid, 500mg / L thiourea, 1000mg / L potassium iodate, 5g / L succinic acid, 100mL / L lactic acid, 20g / L sodium acetate, and the balance is ultrapure water.

[0080] S3: Strictly control the temperature at 88°C, pH between 4.5 and 5.0, and test the Ni content in the plating solution every half an hour 2+ Content, when Ni in the plating solution 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is less than 10%, add C1 liquid and C2 liquid in a volume ratio of 1:1 to replenish the solution to extend the service life. Use C1 liquid and C2 liquid to adjust the Ni content in the plating solution. 2+ The mass concentration reaches 100% of the opening concentration, and the amount of C1 liquid added reaches 10L / 100L, which is a cycle. During the nickel plating process, solid particles and other impurities in the plating solution are filtered out in time, and the workpiece loading is controlled at 1.25dm 2 / L, to avoid affecting the stability of the plating solution.

[0081] Table 3 Performance evaluation of Example 3

[0082] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 > 1 13.2 8.5％ 761 2 12.7 8.4％ 784 3 12.5 8.7％ 732 4 12.9 8.6％ 719 5 13.1 9.1％ 765 6 11.5 8.7％ 703 7 11.3 9.2％ 698 8 10.8 9.3％ 675 9 9.4 10.2％ 610 10 7.1 12.4％ 588

[0083] Comparative Example 1

[0084] The specific implementation method of this comparative example is the same as that of Example 1, except that the C2 liquid does not contain the buffer sodium acetate. Specifically: the C2 liquid contains 250 g / L sodium hypophosphite, 75 g / L sodium citrate, 20 g / L adipic acid, 30 g / L tartaric acid, 5000 mg / L molybdenum oxide, 1000 mg / L thiourea, 100 mL / L lactic acid, and the balance is ultrapure water.

[0085] Table 4 Performance evaluation of comparative example 1

[0086] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 > 1 12.7 8.4％ 746 2 12.1 8.6％ 759 3 12.3 9.1％ 724 4 11.7 9.7％ 732 5 11.3 9.8％ 709 6 10.5 10.2％ 694 7 9.3 10.8％ 652 8 7.2 12.4％ 613

[0087] Comparative Example 2

[0088] The specific implementation method of this comparative example is the same as that of Example 1, except that the C2 liquid does not contain a buffer (sodium acetate) and a complexing agent (sodium citrate, oxalic acid and tartaric acid). Specifically: the C2 liquid contains 250 g / L of sodium hypophosphite, 5000 mg / L of molybdenum oxide, 1000 mg / L of thiourea, 100 mL / L of lactic acid, and the remainder is ultrapure water.

[0089] Table 5 Performance evaluation of comparative example 2

[0090] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 > 1 12.3 8.7％ 745 2 11.5 8.5％ 712 3 10.2 9.2％ 682 4 9.1 10.9％ 617 5 8.3 12.3％ 543 6 6.5 14.8％ 515

[0091] Comparative Example 3

[0092] The specific implementation of this comparative example is the same as that of Example 1, except that the C2 liquid does not contain a buffer, a chelating agent, and a stabilizer. Specifically, the C2 liquid contains 250 g / L of sodium hypophosphite, 10 mL / L of lactic acid, and the remainder is ultrapure water.

[0093] Table 6 Performance evaluation of comparative example 3

[0094] Number of cycles Coating thickness μm / h Phosphorus content of coating <![CDATA[Coating hardness / HV 0.1 > 1 12.5 8.5％ 714 2 10.3 9.7％ 687 3 9.5 10.8％ 692 4 8.1 12.1％ 521 5 6.1 15.2％ 431

[0095] It can be seen from Tables 1 to 6 that the present invention can extend the service life of the plating solution by reasonably regulating the components of C1 liquid and C2 liquid (the stable thickness of the coating per unit time and the stable phosphorus content in the coating indicate that the plating solution is not scrapped and can continue to be used, and the service life can be extended), and the mechanical properties of the coating are stable (the hardness of the coating can reflect the mechanical properties).

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A replenishing solution for chemical nickel plating, characterized in that Including C1 liquid and C2 liquid; The composition of the C1 liquid is: 200-500 g / L of the first divalent nickel salt, 50-200 g / L of the first accelerator, 0.01-5 g / L of the first brightener, and the balance is water; The C2 liquid is composed of: 150-560 g / L of a first reducing agent, 50-200 g / L of a first complexing agent, 0.2-20 g / L of a first stabilizer, 5-50 g / L of a first buffer, 50-200 g / L of a second accelerator, and the balance is water.

2. The fluid replacement according to claim 1, characterized in that: The first divalent nickel salt is nickel sulfate and / or nickel chloride; The first accelerator and the second accelerator are independently at least one of succinic acid and lactic acid.

3. The fluid replacement according to claim 1, characterized in that: The first complexing agent is at least one of adipic acid, tartaric acid, malic acid, citric acid, citrate and propionic acid.

4. The fluid replacement according to claim 1, characterized in that: The first reducing agent is at least one of sodium hypophosphite, sodium borohydride and hydrazine hydrate.

5. The fluid replacement according to claim 1, characterized in that: The first stabilizer is at least one of molybdenum oxide, sodium thiosulfate, thiourea and potassium iodate.

6. The fluid replacement according to claim 1, characterized in that: The first buffer is at least one of acetic acid, acetate, phosphate, amino acid, amino acid salt, lactic acid and boric acid; The first brightener is at least one of butynediol, propargyl alcohol and ethoxypropargyl alcohol.

7. A method for long-term chemical nickel plating using the replenishing solution according to any one of claims 1 to 6, characterized in that: The following steps are involved: Placing the workpiece in an initial plating solution for chemical nickel plating; the initial plating solution comprises: 20-60 g / L of a second divalent nickel salt, 10-50 g / L of a second complexing agent, 15-45 g / L of a second reducing agent, 0.01-10 g / L of a second stabilizer, 0.01-2 g / L of a second brightener, 0.1-30 g / L of a third accelerator, 10-50 g / L of a second buffer, and the balance is water; Ni in the plating solution during the plating process 2+ The concentration is reduced, and C1 solution and C2 solution are added to the Ni in the plating solution. 2+ The initial mass concentration reaches 98-102%; the volume ratio of the added C1 liquid and C2 liquid is 1:

1.

8. The method according to claim 7, characterized in that When Ni in the plating solution 2+ The mass concentration of Ni in the initial plating solution is reduced to 2+ When the mass concentration is below 10%, add C1 liquid and C2 liquid in a volume ratio of 1:

1.

9. The method according to claim 7, characterized in that: The pH value of the chemical nickel plating is 4.5-5.0, and the temperature is 82-90°C.

10. The method according to claim 7, characterized in that The loading capacity of the workpiece is 1.0 to 1.5 dm 2 / L.