Plating solution for preparing Ni-P coating and preparation method of Ni-P coating

Abstract

The invention relates to the technical field of preparation of Ni-P coatings, in particular to a plating solution for preparing a Ni-P coating and a preparation method of the Ni-P coating. The invention provides a plating solution for preparing a Ni-P plating layer. The plating solution comprises 30-35 g / L of nickel sulfate, 25-30 g / L of sodium hypophosphite, 15 g / L of sodium acetate, 20 g / L of trisodium citrate, 10 g / L of lactic acid, 5 g / L of propionic acid, 2 g / L of dicarboxylic acid, 2 mg / L of thiourea, 0.1 g / L of an anionic surfactant, 20-80 mL / L of an additive and water. The additive comprises a rare earth metal salt solution, and the concentration of the rare earth metal salt solution is 120 g / L. According to the plating solution, a Ni-P plating layer can have excellent corrosion resistance, impact resistance and wear resistance at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of Ni-P coatings, and particularly relates to a plating solution for preparing Ni-P coatings and a method for preparing Ni-P coatings. Background Art

[0002] The chemically deposited Ni-P coating has the characteristics of high hardness, good toughness and strong impact resistance, and at the same time has good corrosion resistance in different environmental media, and is widely used in the fields of engineering machinery and aerospace. The traditional Ni-P coating has good mechanical properties but poor corrosion resistance, or good corrosion resistance but poor mechanical properties, and it cannot have both good corrosion resistance and mechanical properties at the same time. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a plating solution for preparing Ni-P coatings and a method for preparing Ni-P coatings. The plating solution can enable the Ni-P coating to have excellent corrosion resistance and impact and abrasion resistance at the same time.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a plating solution for preparing Ni-P coatings, which includes nickel sulfate 30-35 g / L, sodium hypophosphite 20-30 g / L, sodium acetate 15 g / L, trisodium citrate 20 g / L, lactic acid 10 g / L, propionic acid 5 g / L, dicarboxylic acid 2 g / L, thiourea 2 mg / L, anionic surfactant 0.1 g / L, additive 20-80 ml / L and water;

[0006] The additive includes a rare earth metal salt solution, and the concentration of the rare earth metal salt solution is 120 g / L.

[0007] Preferably, the concentration of the additive in the plating solution is 40-60 mL / L.

[0008] Preferably, the rare earth metal salt in the rare earth metal salt solution includes one or more of lanthanum sulfate, yttrium sulfate, rubidium sulfate and ytterbium sulfate.

[0009] Preferably, the dicarboxylic acid includes succinic acid and / or malic acid.

[0010] Preferably, the anionic surfactant includes sodium dodecyl sulfate and / or sodium dodecyl sulfonate.

[0011] The present invention also provides a method for preparing a Ni-P coating, which includes the following steps:

[0012] After placing the substrate in the plating solution for plating, perform heat treatment to obtain the Ni-P coating;

[0013] The plating solution is the plating solution described in the above technical solution.

[0014] Preferably, during the plating process, the temperature of the plating solution is 85-90 °C, and the plating time is 90 min;

[0015] Before the plating, the pH value of the plating solution is also adjusted, and the adjusted pH value is 4.8-5.0.

[0016] Preferably, before the plating, the substrate is successively degreased, pickled and activated.

[0017] Preferably, the temperature of the heat treatment is 400 °C, and the heat preservation time is 1 h.

[0018] Preferably, heat preservation is also included before the heat treatment;

[0019] The temperature of the heat preservation is 190-350 °C, and the time is 1-2 h.

[0020] The present invention provides a plating solution for preparing a Ni-P coating, including nickel sulfate 30-35 g / L, sodium hypophosphite 25-30 g / L, sodium acetate 15 g / L, trisodium citrate 20 g / L, lactic acid 10 g / L, propionic acid 5 g / L, dicarboxylic acid 2 g / L, thiourea 2 mg / L, anionic surfactant 0.1 g / L, additive 20-80 mL / L and water; the additive includes a rare earth metal salt solution, and the concentration of the rare earth metal salt solution is 120 g / L. In the plating solution of the present invention, the addition of propionic acid and dicarboxylic acid can accelerate the reduction reaction between nickel and phosphorus in the plating solution, improve the reduction rate of nickel ions and thus increase the plating rate. The anionic surfactant can promote crystallization and improve the flatness of the coating, and the addition of the additive can increase the bonding force between the coating and the substrate material, thereby increasing the toughness. Description of the Drawings

[0021] Figure 1 Cross-sectional SEM image of the Ni-P coating described in Comparative Example 1;

[0022] Figure 2 Cross-sectional SEM image of the Ni-P coating described in Example 1;

[0023] Figure 3 Cross-sectional SEM image of the Ni-P coating described in Example 2;

[0024] Figure 4 Cross-sectional SEM image of the Ni-P coating described in Example 3;

[0025] Figure 5 Cross-sectional SEM image of the Ni-P coating described in Example 4. Detailed Description of the Invention

[0026] The invention provides a plating solution for preparing a Ni-P plating layer, comprising 30-35 g / L of nickel sulfate, 25-30 g / L of sodium hypophosphite, 15 g / L of sodium acetate, 20 g / L of trisodium citrate, 10 g / L of lactic acid, 5 g / L of propionic acid, 2 g / L of dicarboxylic acid, 2 mg / L of thiourea, 0.1 g / L of anionic surfactant, 20-80 mL / L of additives and water;

[0027] The additive includes a rare earth metal salt solution, and the concentration of the rare earth metal salt solution is 120 g / L.

[0028] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0029] In the present invention, the concentration of nickel sulfate in the plating solution is 30-35 g / L, preferably 35 g / L. In an embodiment of the present invention, the concentration of nickel sulfate in the plating solution may be 35 g / L.

[0030] In the present invention, the role of the nickel sulfate is to provide nickel ions in the plating solution, and the role of controlling the concentration of the nickel sulfate within the above range is to maintain the Ni 2+ The concentration is between 5.3 and 6.5 g / L. 2+ Concentration reduces the plating speed, too high Ni 2+ Concentration has no effect on the growth of the coating.

[0031] In the present invention, the concentration of sodium hypophosphite in the plating solution is 20 to 30 g / L, preferably 25 to 30 g / L. In the present invention, the concentration of sodium hypophosphite in the plating solution may be 25 g / L.

[0032] In the present invention, the role of the sodium hypophosphite is to act as a reducing agent to reduce the Ni 2+ Reduction, the effect of controlling the concentration of the sodium hypophosphite within the above range is that too much sodium hypophosphite will lead to intensified reaction and accelerated aging of the plating solution.

[0033] In the present invention, the concentration of sodium acetate in the plating solution is 15 g / L.

[0034] In the present invention, the sodium acetate acts as a buffer, and the concentration of the sodium acetate is controlled within the above range to maintain the pH in the plating solution stable.

[0035] In the present invention, the concentration of trisodium citrate in the plating solution is 20 g / L.

[0036] In the present invention, the trisodium citrate acts as a complexing agent, and the concentration of the trisodium citrate is controlled within the above range to reduce the Ni 2+Prevent the complexation reaction from proceeding too rapidly.

[0037] In the present invention, the concentration of lactic acid in the plating solution is 10 g / L.

[0038] In the present invention, the role of lactic acid is an accelerator, and controlling the concentration of lactic acid within the above range serves to increase the plating rate.

[0039] In the present invention, the concentration of propionic acid in the plating solution is 5 g / L.

[0040] In the present invention, the role of propionic acid is to increase the plating rate, and controlling the concentration of propionic acid within the above range serves to stabilize the plating rate at 18 - 20 μm / h.

[0041] In the present invention, the concentration of dicarboxylic acid in the plating solution is 2 g / L.

[0042] In the present invention, the dicarboxylic acid preferably includes succinic acid and / or malic acid, more preferably includes succinic acid; when there are two or more of the above specific substances as the dicarboxylic acid, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the examples of the present invention, the dicarboxylic acid can be succinic acid.

[0043] In the present invention, the role of the dicarboxylic acid is to regulate the plating rate of the plating solution and reduce the porosity of the coating. Controlling the concentration of the dicarboxylic acid within the above range serves to control the plating rate within the optimal range and ensure denser crystallization.

[0044] In the present invention, the concentration of thiourea in the plating solution is 2 mg / L.

[0045] In the present invention, the role of thiourea is that thiourea is a stabilizer to prevent the plating solution from undergoing self - reaction and affecting the coating quality. Controlling the concentration of thiourea within the above range serves to prevent the self - reaction of the plating solution, while an excessive amount of stabilizer will cause the coating to stop growing.

[0046] In the present invention, the concentration of anionic surfactant in the plating solution is 0.1 g / L.

[0047] In the present invention, the anionic surfactant preferably includes sodium dodecyl sulfate and / or sodium dodecylbenzenesulfonate, more preferably includes sodium dodecyl sulfate; when there are two or more of the above specific substances as the anionic surfactant, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio. In the examples of the present invention, the anionic surfactant can be sodium dodecyl sulfate.

[0048] In the present invention, the function of the anionic surfactant is to improve the flatness of the coating, reduce the surface roughness, increase the brightness, and thus improve the salt spray resistance. Controlling the type and dosage of the anionic surfactant within the above ranges is to prevent excessive anionic surfactant from causing a decrease in the stability of the plating solution and affecting the coating quality.

[0049] In the present invention, the concentration of the additive in the plating solution is 20 - 80 mL / L, preferably 40 - 60 mL / L. In the examples of the present invention, the concentration of the additive in the plating solution can be 20 mL / L, 40 mL / L, 60 mL / L, and 80 g / L.

[0050] In the present invention, the additive preferably includes a rare earth metal salt solution. In the present invention, the concentration of the rare earth metal salt in the rare earth metal salt solution is preferably 120 g / L. In the present invention, the rare earth metal salt in the rare earth metal salt solution preferably includes one or more of lanthanum sulfate, yttrium sulfate, rubidium sulfate, and ytterbium sulfate, more preferably includes lanthanum sulfate and yttrium sulfate; the mass ratio of lanthanum sulfate to yttrium sulfate is preferably 1:2. In the examples of the present invention, the rare earth metal solution can be a mixed solution of lanthanum sulfate and yttrium sulfate; the concentration of lanthanum sulfate in the mixed solution of lanthanum sulfate and yttrium sulfate can be 40 g / L. The concentration of yttrium sulfate in the mixed solution of lanthanum sulfate and yttrium sulfate can be 80 g / L.

[0051] In the present invention, the function of the additive is to increase the adhesion between the coating and the substrate, and improve the toughness and hardness of the coating. Controlling the type and dosage of the additive within the above ranges is to prevent excessive additive from having little improvement on the coating performance and increasing the use cost.

[0052] The present invention also provides a method for preparing a Ni - P coating, comprising the following steps:

[0053] After placing the substrate in the plating solution for plating, perform heat treatment to obtain the Ni - P coating;

[0054] The plating solution is the plating solution described in the above technical solution.

[0055] Before performing the plating, the present invention preferably degreases, pickles, and activates the substrate in sequence. In the present invention, the degreasing process is preferably soaking in an alkaline degreasing solution for 10 min. In the present invention, the alkaline degreasing solution preferably includes 60 g / L of sodium hydroxide, 40 g / L of sodium carbonate, and 10 g / L of sodium silicate. In the present invention, the pickling process is preferably soaking in a hydrochloric acid solution with a mass concentration of 50% for 1 min. In the present invention, the activation process is preferably soaking in a sulfuric acid solution with a mass concentration of 25% for 30 s.

[0056] In the present invention, during the plating process, the temperature of the plating solution is preferably 85 - 90 °C, more preferably 90 °C; the plating time is preferably 90 min. In the embodiments of the present invention, the temperature of the plating solution can be 90 °C and the plating time can be 90 min. In the present invention, before the plating, it is also preferably to adjust the pH value of the plating solution, and the adjusted pH value is preferably 4.8 - 5.0.

[0057] In the present invention, the temperature of the heat treatment is preferably 400 °C; the heat preservation time is preferably 1 h. Before the heat treatment, the present invention also preferably includes heat preservation, the temperature of the heat preservation is preferably 190 - 350 °C, more preferably 290 - 350 °C, and the heat preservation time is preferably 1 - 2 h. In the embodiments of the present invention, the heat treatment process can be to first heat preserve at 350 °C for 1 h and then heat preserve at 400 °C for 1 h. In the present invention, 350 °C can cause the amorphous Ni - P alloy to undergo recrystallization and transform into crystalline Ni 3 P, and then heat preserving at 400 °C for 1 h can improve the compactness of the coating, and improve the toughness and hardness of the coating.

[0058] In the present invention, during the plating process, the plating solution is acidic and its pH is controlled between 4.8 - 5.0, which is likely to cause relatively high hydrogen brittleness of the coating. After first heat preserving at 190 °C for 2 h and then heat preserving at 400 °C for 1 h, the hydrogen in the coating can be removed first to reduce hydrogen embrittlement; and then the compactness can be improved.

[0059] In the present invention, the mass percentage content of P in the Ni - P coating prepared by the above preparation method is preferably 10% - 12%, more preferably 12% - 15%.

[0060] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0061] Example 1

[0062] Formulation of the plating solution: nickel sulfate 35 g / L, sodium hypophosphite 25 g / L, sodium acetate 15 g / L, trisodium citrate 20 g / L, lactic acid 10 g / L, propionic acid 5 g / L, succinic acid 2 g / L, thiourea 2 g / L, sodium dodecyl sulfate 0.1 g / L, additive (the type of the additive is a mixed solution of 40 g / L lanthanum oxide + 80 g / L yttrium oxide) 20 mL / L, and the water is deionized water;

[0063] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), and then heat treatment was carried out (the process of heat treatment was: first, keep it at 350 °C for 1 h, and then keep it at 400 °C for 1 h), obtaining the Ni-P coating (with a thickness of 20 microns).

[0064] Example 2

[0065] Formulation of plating solution: 35 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 g / L succinic acid, 2 g / L thiourea, 0.1 g / L sodium dodecyl sulfate, additive (the type of the additive was a mixed solution of 40 g / L lanthanum oxide + 80 g / L yttrium oxide) 40 mL / L, and the water was deionized water;

[0066] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), and then heat treatment was carried out (the process of heat treatment was: first, keep it at 350 °C for 1 h, and then keep it at 400 °C for 1 h), obtaining the Ni-P coating (with a thickness of 21 microns).

[0067] Example 3

[0068] Formulation of plating solution: 35 g / L nickel sulfate, 30 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 g / L succinic acid, 2 g / L thiourea, 0.1 g / L sodium dodecyl sulfate, additive (the type of the additive was a mixed solution of 40 g / L lanthanum oxide + 80 g / L yttrium oxide) 60 mL / L, and the water was deionized water;

[0069] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min). Then, heat treatment was carried out (the process of heat treatment was: first, keep it at 350 °C for 1 h, and then keep it at 400 °C for 1 h), and the Ni-P coating (with a thickness of 22 microns) was obtained.

[0070] Example 4

[0071] Formulation of plating solution: 35 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 g / L succinic acid, 2 g / L thiourea, 0.1 g / L sodium dodecyl sulfate, additive (the type of additive was a mixture of 40 g / L lanthanum oxide + 80 g / L yttrium oxide) 80 mL / L, and deionized water was used as water;

[0072] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min). Then, heat treatment was carried out (the process of heat treatment was: first, keep it at 350 °C for 1 h, and then keep it at 400 °C for 1 h), and the Ni-P coating (with a thickness of 24 microns) was obtained.

[0073] Comparative Example 1

[0074] Formulation of plating solution: 35 g / L nickel sulfate, 20 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as water;

[0075] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), and then heat treatment was carried out (the process of heat treatment was: holding at 400 °C for 1 h), obtaining the Ni-P coating (with a thickness of 15 microns).

[0076] Comparative Example 2

[0077] Formulation of plating solution: 35 g / L nickel sulfate, 20 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as water;

[0078] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. After that, the pretreated iron-based metal sheet was immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), and then heat treatment was carried out (the process of heat treatment was: holding at 400 °C for 1 h), obtaining the Ni-P coating (with a thickness of 19 microns).

[0079] Comparative Example 3

[0080] Formulation of plating solution: 35 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 g / L succinic acid, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as water;

[0081] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. The pretreated iron-based metal sheet was then immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), followed by heat treatment (the process of heat treatment was: first, keep it at 350 °C for 1 h, and then keep it at 400 °C for 1 h), to obtain the Ni-P coating (with a thickness of 18 microns).

[0082] Comparative Example 4

[0083] Formulation of the plating solution: 35 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as the water;

[0084] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. The pretreated iron-based metal sheet was then immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min), followed by heat treatment (the process of heat treatment was: keep it at 400 °C for 1 h), to obtain the Ni-P coating (with a thickness of 20 microns).

[0085] Comparative Example 5

[0086] Formulation of the plating solution: 32 g / L nickel sulfate, 30 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as the water;

[0087] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. The pretreated iron-based metal sheet was then immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min). After that, heat treatment was carried out (the process of heat treatment was: first, keep it at 190 °C for 2 h, and then keep it at 400 °C for 1 h) to obtain the Ni-P coating (with a thickness of 18 microns).

[0088] Comparative Example 6

[0089] Formulation of plating solution: 30 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L sodium acetate, 20 g / L trisodium citrate, 10 g / L lactic acid, 5 g / L propionic acid, 2 mg / L thiourea, 0.1 g / L sodium dodecyl sulfate, and deionized water was used as water;

[0090] Preparation of Ni-P coating: A 10 cm × 10 cm iron-based metal sheet was immersed in an alkaline degreasing solution (including 60 g / L sodium hydroxide, 40 g / L sodium carbonate, and 10 g / L sodium silicate) for 10 min for degreasing. Then, it was successively immersed in a hydrochloric acid solution with a mass concentration of 50% for 1 min and in a sulfuric acid solution with a mass concentration of 25% for 30 s. The pretreated iron-based metal sheet was then immersed in the plating solution (the temperature of the plating solution was 90 °C, and ammonia water was used to adjust the pH to 4.8 - 5.0) for plating (the plating time was 90 min). After that, heat treatment was carried out (the process of heat treatment was: first, keep it at 190 °C for 2 h, and then keep it at 400 °C for 1 h) to obtain the Ni-P coating (with a thickness of 19 microns).

[0091] Refer to GB / T4340.1 - 2009 "Metallic materials - Vickers hardness test - Part 1: Test method" to test the hardness of the Ni-P coatings described in Test Examples 1 - 4 and Comparative Examples 1 - 6;

[0092] Refer to GB / T 232 - 2024 "Metallic materials - Bend test" standard to test the toughness of the Ni-P coatings described in Test Examples 1 - 4 and Comparative Examples 1 - 6;

[0093] Refer to GB6458 - 86 "Metallic coatings - Neutral salt spray test (NSS test)" standard to test the corrosion resistance of the Ni-P coatings described in Test Examples 1 - 4 and Comparative Examples 1 - 6;

[0094] Refer to the thickness of the Ni-P coating described in Test Examples 1-4 and Comparative Examples 1-6 of the standard GB / T 42674-2023 "Test Method for Microstructure Thickness of Optical Functional Films".

[0095] Refer to GB / T 30707-2014 "Scratch Method for Testing the Adhesion of Fine Ceramic Coatings". The adhesion of the Ni-P coating described in Test Examples 1-4 and Comparative Examples 1-6 of the standard.

[0096] Table 1 shows the performance parameters of the Ni-P coatings described in Examples 1-4 and Comparative Examples 1-6:

[0097] Table 1 Performance parameters of the Ni-P coatings described in Examples 1-4 and Comparative Examples 1-6

[0098]

[0099] As can be seen from Table 1, adding additives to the plating solution can effectively improve the toughness and adhesion of the coating. The contents of the additives added in Examples 1, 2, 3, and 4 are 20 mL / L, 40 mL / L, 60 mL / L, and 80 mL / L in sequence. As the addition amount increases, the toughness of the coating increases and the adhesion is enhanced; when the addition amount reaches 80 mL / L, the hardness of the coating decreases. The heat treatment process uses the method of keeping warm at 350 °C for 1 h and then at 400 °C for 1 h, which can promote the transformation of the coating from the amorphous state to the crystalline state, improve the compactness of the coating, and improve the corrosion resistance; and the improvement of the adhesion also has a promoting effect on the corrosion resistance.

[0100] Figure 1 It is the cross-sectional SEM image of the Ni-P coating described in Comparative Example 1. Figure 2 It is the cross-sectional SEM image of the Ni-P coating described in Example 1. Figure 3 It is the cross-sectional SEM image of the Ni-P coating described in Example 2. Figure 4 It is the cross-sectional SEM image of the Ni-P coating described in Example 3. Figure 5 It is the cross-sectional SEM image of the Ni-P coating described in Example 4. As Figures 1 to 5 can be seen, as the concentration of the additive increases continuously, the interfacial bonding compactness of the coating gradually improves, improving the toughness of the coating. At the same time, by adjusting the content of sodium hypophosphite in the plating solution, the phosphorus content in the coating can be increased, thereby improving the corrosion resistance. At the same time, in order to avoid the decrease in hardness, the heat treatment function can be adjusted to achieve a hardness above 1000 HV, and finally a high-performance coating with high hardness, good toughness, and corrosion resistance is formed.

[0101] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A plating solution for preparing a Ni-P plating layer, characterized in that: Including nickel sulfate 30-35g / L, sodium hypophosphite 25-30g / L, sodium acetate 15g / L, trisodium citrate 20g / L, lactic acid 10g / L, propionic acid 5g / L, dicarboxylic acid 2g / L, thiourea 2mg / L, anionic surfactant 0.1g / L, additives 20-80mL / L and water; The additive includes a rare earth metal salt solution, and the concentration of the rare earth metal salt solution is 120 g / L.

2. The plating solution according to claim 1, characterized in that The concentration of the additive in the plating solution is 40-60 mL / L.

3. The plating solution according to claim 1 or 2, characterized in that The rare earth metal salt in the rare earth metal salt solution includes one or more of lanthanum sulfate, yttrium sulfate, rubidium sulfate and ytterbium sulfate.

4. The plating solution according to claim 1, characterized in that The dicarboxylic acid includes succinic acid and / or malic acid.

5. The plating solution according to claim 1, characterized in that The anionic surfactant includes sodium lauryl sulfate and / or sodium lauryl sulfonate.

6. A method for preparing a Ni-P coating, characterized in that: The following steps are involved: Plating the substrate in a plating solution and then performing a heat treatment to obtain the Ni-P plating layer; The plating solution is the plating solution according to any one of claims 1 to 5.

7. The preparation method according to claim 6, characterized in that: During the plating process, the temperature of the plating solution is 85-90° C., and the plating time is 90 minutes; Before the plating, the method further comprises adjusting the pH value of the plating solution, and the adjusted pH value is 4.8-5.

0.

8. The preparation method according to claim 6 or 7, characterized in that: Before the plating, the substrate is degreased, pickled and activated in sequence.

9. The preparation method according to claim 6, characterized in that The heat treatment temperature is 400° C. and the heat preservation time is 1 hour.

10. The preparation method according to claim 6, characterized in that: The heat treatment also includes heat preservation; The temperature of the insulation is 190-350° C., and the time is 1-2 hours.

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