CN113564570B - Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities and application thereof - Google Patents

Abstract

The invention relates to a preparation method of plating solution, in particular to Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities and application thereof, and belongs to the technical field of surface treatment. A Ni-Sn-P pinhole-free ternary plating solution for marine facilities, the plating solution comprising: nickel salt: 7-9 g/L, tin salt: tin tetrachloride 1g/L, reducing agent: 18-22g/L complexing agent: 5-10 g/L, stabilizer: 0.5-2.0 mg/L, surfactant: 0.3g/L of sodium dodecyl sulfate, and water as a solvent; the pH value is regulated to 4.5-5.5 by using 6-8g/L buffer. The Ni-Sn-P pinhole-free ternary plating layer plating solution has the advantages of simple formula and preparation process, low cost, environmental protection, high plating rate, smooth and smooth plating surface, excellent neutral salt fog resistance, meeting the requirement of corrosion resistance and having wider application prospect in the marine corrosion prevention field.

Description

Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities and application thereof

Technical Field

The invention relates to a preparation method of plating solution, in particular to Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities and application thereof, and belongs to the technical field of surface treatment.

Background

The electroless plating of Ni-P has been developed very rapidly as a novel material, and has been widely used in industrial fields due to its uniform thickness, high hardness and wear resistance, and excellent corrosion resistance. However, the nickel plating layer is easy to oxidize and darken in a humid atmosphere or in a sulfur-containing environment, so that the beauty is affected, the corrosion resistance and the welding performance of the film layer are reduced, and the Ni-P single-metal plating layer is difficult to adapt to the service environment in a specific field. The existing research shows that after a small amount of Sn is added into the Ni-P coating, the amorphous capability of the alloy coating is improved, the porosity of the coating is obviously reduced, the higher thermodynamic stability is shown, the corrosion resistance of the coating is greatly improved, and the excellent corrosion prevention effect is achieved.

In addition, researches on nickel-series Ni-Sn-P ternary plating layers show that the Ni-Sn-P ternary plating layers have better characteristics than Ni-P ternary plating layers in the application of industrial fields such as chemical industry, machinery, electronics, aerospace, energy and the like.

However, all the reducing agents currently used in Ni-Sn-P ternary plating are still based on hypophosphite, such as the one disclosed in patent publication No.: the invention patent of CN 104561960B discloses a high-stability nickel-tin-phosphorus chemical plating solution, which comprises the following components in parts by weight: each liter of plating solution contains 20 to 45g of nickel dichloride hexahydrate, 15 to 25g of sodium hypophosphite, and tin methane sulfonate microcapsule (Sn (CH) ₃ SO ₃ ) ₂ @SiO ₂ ) 5-35 g of sodium acetate, 6-35 ml of acetic acid, 3-10 g of complexing agent, 4-15 g of stabilizer, 2-6 g of surfactant and the balance of water. The pH of the solution is 4.0-5.0. The plating solution mainly comprising hypophosphite contains a large amount of substances which are difficult to treat, such as phosphoric acid, and the like, and the treatment of the waste solution is still difficult to develop around chemical plating, and the defects of poor stability, harsh operation conditions, low Sn and P content in the plating layer, low plating speed and the like exist in the plating solution.

When nickel chloride is used as nickel salt, in the chemical plating of certain workpieces which are easy to corrode, such as aluminum, aluminum alloy and iron alloy parts, corrosion can be formed on the workpieces due to the too high activity of chloride ions, and nickel chloride cannot be used as nickel salt because the plating object is alloy steel or carbon alloy steel for marine facilities; in addition, the tin methanesulfonate microcapsule (Sn (CH) ₃ SO ₃ ) ₂ @SiO ₂ ) The method is high in cost and is not suitable for surface treatment of large ocean facilities.

Therefore, a new Ni-Sn-P ternary pinhole-free green plating solution is needed to meet the corrosion resistance requirements of marine facilities.

Disclosure of Invention

The invention aims to provide Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities, which is used for plating alloy steel or carbon alloy steel of the marine facilities.

The invention also provides a method for applying the Ni-Sn-P pinhole-free ternary plating layer plating solution for the marine facilities to the surface of the carbon steel substrate for chemical plating.

The technical scheme adopted for solving the technical problems is as follows:

a Ni-Sn-P pinhole-free ternary plating solution for marine facilities, the plating solution comprising:

nickel salt: 7 to 9g/L of the total weight of the product,

tin salt: 1g/L of stannic chloride,

reducing agent: 18 to 22g/L of the total weight of the product,

complexing agent: 5 to 10g/L of the total weight of the mixture,

stabilizing agent: 0.5-2.0 mg/L,

and (2) a surfactant: sodium dodecyl sulfate 0.3g/L,

the solvent is water;

the pH value is adjusted to 4.5-5.5 by a buffering agent.

The Ni-Sn-P pinhole-free ternary plating layer plating solution has the advantages of simple formula and preparation process, low cost, environmental protection, high plating rate, smooth and smooth plating surface, excellent neutral salt fog resistance, meeting the requirement of corrosion resistance and having wider application prospect in the marine corrosion prevention field.

The invention uses tin tetrachloride as tin salt and sodium dodecyl sulfate as surface active agent, and uses orthorhombic method to prepare Ni-Sn-P ternary plating layer under the condition of 90 deg.C and pH=4.5-5.5 by controlling the dosage of nickel salt nickel sulfate, sodium hypophosphite as reducing agent, sodium acetate as buffering agent, sodium citrate as complexing agent and sodium thiosulfate as stabilizing agent, and optimizing the preparation process condition. The observation by a scanning electron microscope shows that the surface of the ternary plating layer is compact and has no pinholes. In addition, the ternary plating layer prepared by the method disclosed by the invention has excellent neutral salt fog resistance, and can be applied to the field of ocean corrosion prevention.

Preferably, the plating solution contains: 8g/L of nickel sulfate, 1g/L of stannic chloride, 22g/L of sodium hypophosphite, 10g/L of sodium citrate, 6g/L of sodium acetate, 1mg/L of sodium thiosulfate and 0.3g/L of sodium dodecyl sulfate.

Preferably, the nickel salt is selected from nickel sulfate, nickel acetate or nickel hypophosphite.

Preferably, the reducing agent is selected from hypophosphite (NaH ₂ PO ₂ ) Borohydride (NaBH) ₄ ) Ammonia borane ((CH) ₃ ) ₂ HNBH ₃ ) Pyridineboranes (C) ₅ H ₈ BN), hydrazine (N) ₂ H ₄ ) Formaldehyde (HCHO).

Preferably, the complexing agent is selected from one or more of lactic acid, sodium citrate, glycine, potassium sodium tartrate, ethylene glycol or succinic acid.

Preferably, the buffer is a strong alkali weak acid salt, such as sodium acetate, borax, potassium pyrophosphate, and the like. Further, the buffer is sodium acetate with a concentration of 6-8 g/L.

Preferably, the stabilizer is selected from potassium iodide, lead acetate, ethoxy-a-naphtholsulfonic acid (ENSA), thiourea, sodium thiosulfate, and the like.

The method for applying the plating solution to the surface of the carbon steel substrate to implement chemical plating comprises the following steps:

(1) And (3) rust removal: firstly, 260# abrasive paper is used for polishing to remove surface rust, and then 400# abrasive paper, 600# abrasive paper and 800# abrasive paper are used for polishing in sequence, so that the surface is too smooth and is not beneficial to plating;

(2) Deoiling: in order to avoid the problems of bursting sheets, foaming phenomena, pollution to the plating solution, premature decomposition of the plating solution and the like caused by influencing the binding force between the plating layer and the test piece, the greasy dirt on the test piece needs to be removed; ultrasonically cleaning the polished sample with acetone for 10min, and then cleaning the sample with absolute ethyl alcohol to remove greasy dirt on the surface;

(3) Alkali washing: the sample was immersed in a mixed solution containing NaOH20g/L, na at 90℃for 20 minutes ₃ CO ₃ 30g/L、Na ₃ PO ₄ 25g/L, then washing with distilled water at 90 ℃ and drying;

(4) Acid washing: immersing the deoiled sample in 15wt% sulfuric acid for ultrasonic treatment for 2 minutes to remove the surface oxide layer, and then flushing and drying the sample by distilled water;

(5) Activating: activating the pickled sample with 5wt% sulfuric acid solution for 1min at room temperature, and removing an ultrathin oxide film formed by oxidizing the sample in air to obtain a pure surface to be plated;

(6) Plating: placing the test piece into the Ni-Sn-P plating solution, plating for 1-1.5 hours, and stirring at 90+/-5 ℃; after plating, the test piece is washed by distilled water and dried.

Compared with the prior art, the invention has the beneficial effects that:

1. the Ni-Sn-P ternary plating layer prepared by adopting the Ni-Sn-P pinhole-free ternary plating layer plating solution has the characteristics of smooth and compact plating layer surface under low magnification, and the spherical particle size is distributed between 2 mu m and 10 mu m, so that the pinhole defects of the rod-shaped particles are fully filled, the coverage rate of a matrix is improved, and the corrosion resistance is enhanced;

2. the plating layer has no phenomena of chalking, cracking, foaming, mildew, rust spots and the like, after 30 days of neutral salt spray experiment, very slight discoloration and chalking occur, a small amount of foaming phenomenon is caused, but no phenomena of mildew, rust spots and peeling are observed, in addition, after 60 days of neutral salt spray experiment, the ternary plating layer still has no visible cracking and no mildew generation, which indicates that the ternary plating layer has stronger neutral salt spray resistance and can meet the requirement of corrosion resistance;

3. the Ni-Sn-P pinhole-free ternary plating layer plating solution for the marine facilities is designed for alloy steel or carbon alloy steel of the marine facilities, and has good applicability.

Drawings

FIG. 1 is a diagram of a Ni-Sn-P ternary plating apparatus of the present invention;

FIG. 2 is a graph showing the comparison of plating speed and thickness of Ni-Sn-P ternary plating layers under plating solutions of different formulations;

FIG. 3 is a graph showing the surface topography of a plated layer after plating under plating solutions of different formulations;

FIG. 4 is a scanning electron microscope image of the surface of the coating after plating with different formulations;

fig. 5 is a surface topography diagram of the neutral salt spray resistance experiment on the 0 th day, the 30 th day and the 60 th day.

Detailed Description

The technical scheme of the invention is further specifically described by the following specific examples. It should be understood that the practice of the invention is not limited to the following examples, but is intended to be within the scope of the invention in any form and/or modification thereof.

In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment, materials, etc. used are commercially available or are conventional in the art. The methods in the following examples are conventional in the art unless otherwise specified.

Example 1

Preparation of Ni-Sn-P ternary plating layer by 1 orthogonal method

1.1 design of plating solution formulation and orthogonal experiment

The formula of the experimental orthogonal Ni-Sn-P ternary plating solution adopts tin tetrachloride (1 g/L) as tin salt, nickel salt as nickel sulfate (6-14 g/L), sodium hypophosphite (16-24 g/L), sodium acetate as a buffer (6-8 g/L), sodium citrate as a complexing agent (5-10 g/L), sodium thiosulfate as a stabilizer with the optimal concentration not more than 2mg/L (0.5-2.0 mg/L), and sodium dodecyl sulfate (0.3 g/L) as a surfactant. The orthogonal experimental design is shown in table 1, and other parameters should be ensured besides the main components shown in the table: temperature 90 ℃, pH:4.5 to 5.5.

TABLE 1 orthogonal test formulation design

1.2 plating operation procedure

1) Pretreatment of plating samples:

(1) Sample polishing: selecting a plurality of steel plates with the dimensions of 150mm multiplied by 70mm multiplied by 1mm, firstly polishing by 260# abrasive paper to remove surface rust, and then sequentially polishing by 400# abrasive paper, 600# abrasive paper and 800# abrasive paper, wherein the surface is too smooth and is not beneficial to plating;

(2) Deoiling: ultrasonically cleaning the polished sample with acetone for about 10min, and then cleaning with absolute ethyl alcohol to remove greasy dirt on the surface;

(3) Alkali washing: immersing the sample in a mixed solution (NaOH (20 g/L), na) at 90 DEG C ₃ CO ₃ (30g/L)、Na ₃ PO ₄ (25 g/L)) for 20 minutes, washing with distilled water at 90 ℃ and drying;

(4) Acid washing: immersing the deoiled sample in sulfuric acid (15 wt%) for ultrasonic treatment for 2 min to remove the surface oxide layer, then flushing with distilled water and drying;

(5) Activating: placing the acid-washed sample in a sulfuric acid (5 wt%) solution for 1min at room temperature for activation, removing an ultrathin oxide film formed by oxidizing the sample in air, and obtaining a pure surface to be plated;

2) Plating:

according to the formula requirement of the orthogonal experiment on 16 groups of plating solutions, accurately weighing various reagents, sequentially putting the reagents into a beaker according to the sequence of nickel salt (nickel sulfate), reducing agent (sodium hypophosphite), buffering agent (sodium acetate), complexing agent (sodium citrate), stabilizing agent (sodium thiosulfate) and surfactant (sodium dodecyl sulfate) to dissolve the reagents with distilled water, pouring the solution into a plating container, adding distilled water to an accurate volume, and stirring at a constant speed. And measuring the pH value of the solution by using a pH meter, regulating the buffer amount to stabilize the pH value of the plating solution, and carrying out ultrasonic oscillation on the plating solution uniformly for later use. Plating is carried out in the prepared plating solution for about 1.5 hours, a certain rotating speed is provided by an electromagnetic stirrer, and the temperature is set at about 90 ℃; after plating, the sample is washed with distilled water and dried for standby. The Ni-Sn-P ternary plating device is shown in figure 1.

1.3 study of coating Performance

The plating solution is subjected to ultrasonic oscillation by a numerical control ultrasonic cleaner (KQ 3200 DE) to ensure that the oscillation is uniform, and the pH value of the plating solution is regulated and controlled by a precise pH meter (PHS-3C).

The surface microtopography of the Ni-Sn-P ternary plating layer was studied by a field emission scanning electron microscope (FE-SEM, carl Zeiss Supra 55).

The neutral salt spray resistance of the Ni-Sn-P ternary coating is characterized by a HW-90 type salt spray corrosion test box.

Plating completion the plated article was cooled at room temperature and the thickness of the plating layer was measured at 5 different positions using a MINITEST model 600 thickness gauge, and the deposition thickness was calculated using the following formula:

wherein D is _Thickness For the average thickness (um) of the coating, d1 are the thicknesses (um) of the coating at 5 different positions in sequence.

2 results and analysis

2.1 plating speed and thickness of the plating layer

The plating speed and thickness comparison chart of the Ni-Sn-P ternary plating layer under 16 groups of plating solutions with different formulas in the orthogonal experiment are shown in fig. 2 and 3 respectively. Electroless nickel plating involves two simultaneous reactions, the cathodic reaction: ni (Ni) ²⁺ 、H ⁺ And H ₂ PO ₂ ^- Namely, ni-P alloy deposition and hydrogen production reaction are shown in formulas (2) to (4), and anode reaction is carried out: h ₂ PO ₂ ^- Oxidation (hydrolysis process) is shown in formula (5). In the actual reaction, part of nascent atomic hydrogen is combined into hydrogen gas to be separated out in the deposition process due to self bonding effect, the formula (3) is shown, and the other part of atomic hydrogen and hypophosphite are subjected to secondary reaction to form P deposition, and the formula (4) is shown.

In the experiment, the reducing agent sodium hypophosphite is adopted, more atomic hydrogen is generated through hydrolysis, and the ion hydrolysis process of hypophosphite is inhibited, so that the reduction efficiency is improved. When all other components in the plating solution and plating conditions are unchanged, the number of free hydrogen atoms in the solution is increased along with the addition of the reducing agent, and the metal Ni ²⁺ 、Sn ²⁺ Ions are reduced into Ni and Sn by enough hydrogen atoms to be deposited on the surface of the plating layer, and hypophosphite ions are mainly used as a deposition source of P, and the deposition rate is greatly improved as shown in the formula (4). The plating rate and plating thickness of each set of plating solutions in fig. 2 are shown: in 16 groups of orthogonal experiments, the plating speed of 7# reaches a peak value of 36.5um/h, which is probably due to the fact that the hydrolysis process of hypophosphite ions (formula (5)) is excessively inhibited when the concentration of the reducing agent is too small (16-22 g/L) or too large (22-24 g/L)Nickel phosphate sediment with smaller solubility product is generated with nickel ions generated in the solution, and the solution is turbid, the plating layer is rough and matt, and the deposition rate is reduced as shown in the formula (6).

Ni ²⁺ +2e ^- ＝Ni (2)

2H ⁺ +2e ^- ＝H ₂ (3)

H ₂ PO ₂ ^- +2H ⁺ +e ^- ＝P+2H ₂ O (4)

H ₂ PO ₂ ^- +H ₂ O＝H ₂ PO ₃ ^- +H+H ⁺ +e ^- (5)

H ₂ PO ₂ ^- +N _i ⁺ ＝N _i H ₂ PO ₂ (6)

2.2 surface topography of the coating

FIG. 3 is a diagram showing the surface morphology of a Ni-Sn-P ternary plating layer under 16 sets of plating solutions of different formulations by an orthogonal method. As shown in the figure, the surfaces of the plating layers of # 3, # 5, # 6, # 7, # 13, # 14 and # 15 are smoother and smoother, no obvious rough feeling appears, and the experimental results show that the plating solution which is wanted to correspond can ensure the uniformity of the plating layer on the premise of high-efficiency plating by combining the thickness and the plating speed of the plating layer which are corresponding to those in figure 2, so that the surface of the plating layer is smooth and smooth. When the concentration of the reducing agent (sodium hypophosphite) is too small (16-22 g/L) or too large (22-24 g/L), the hydrolysis process of the hypophosphite ions (formula (5)) is excessively inhibited, and at the moment, the hypophosphite ions can generate nickel phosphite precipitates with smaller solubility products with the generated nickel ions in the solution, as shown in formula (6), so that the plating solution is turbid, the plating layer is rough and matt, and the deposition rate is reduced, such as No. 1, no. 2, no. 11 and the like. In addition, the stabilizer (sodium thiosulfate) in the formula of the No. 13 plating solution, the No. 14 plating solution and the No. 15 plating solution is relatively high, and the sodium thiosulfate is a strong reducing agent, and the too high content can further inhibit the ion hydrolysis process (formula (5)) of the hypophosphite, so that the plating rate is reduced, and the surface integrity of the plating layer is damaged. Therefore, the content of the stabilizer (sodium thiosulfate) in the plating solution formula is 1mg/L, and the plating efficiency is influenced by the excessively high content (1-2 mg/L) or the excessively low content (0.5-1 mg/L) so as to cause the phenomenon of reagent waste. Therefore, the 7# plating solution formulation is the optimal formulation.

2.3 microscopic morphology of the coating

FIG. 4 is a photograph of a scanning electron microscope of the surface of the Ni-Sn-P ternary plating layer under 16 groups of plating solutions of different formulations according to the orthogonal method in FIG. 3. The data show that the corrosion resistance of the amorphous alloy is better than that of the crystalline alloy, and the difference of the corrosion resistance of different alloy coatings is larger because of different crystal structures. When the content of the reducing agent is 16-18g/L (No. 1, no. 2, no. 5, no. 6, no. 9, no. 10, no. 13 and No. 14), the surface of the plating layer is flat under high magnification, the shape is regular, which indicates that the crystallization rate of the plating layer is higher, the crystal shape in the plating layer is more regular, in addition, the nickel salt content in the plating solution is low (6-8 g/L), and the pinhole defect size among grains is larger. When the content of the reducing agent is gradually increased from 18g/L, spherical particles and rod-shaped particles appear on the surface of the plating layer under low magnification, the sizes are different, partial spherical particles can be observed to be smaller under high magnification, pinhole defects of the rod-shaped particles can be filled, so that the coverage rate of a substrate is improved, the corrosion resistance is improved, and redundant tiny spherical particles are attached to the surface. When the content of the reducing agent is 18-22g/L, the alloy coating has the characteristics of smoothness and compactness under the amplification of the same multiple, and the spherical particles have wider particle size distribution between 2 and 10 mu m and optimal corrosion resistance. This phenomenon can be explained by the fact that the addition of the reducing agent changes the microstructure of the coating, promotes the formation of an amorphous state, compacts the coating, refines the crystals, and reduces the number of pinhole defects in the coating. When the content of the reducing agent is higher than 22g/L, the particle size in the coating is gradually increased, the spherical particles are mainly used in the visual field, the surface of the spherical particles is rough under high magnification, and pinhole defects with larger size and loose particle adhesion are generated. When the content is 24g/L, the surface is rough, the crystal particles are unevenly distributed, and large-area pinhole defects appear. This is related to the excessive content of the reducing agent affecting the positive reaction in the ni—sn-P alloy plating layer, thereby causing the overall decrease in corrosion resistance of the plating layer.

2.4 analysis of neutral salt spray resistance and corrosion resistance of coating after formula optimization

And combining the plating rate, the plating thickness, the plating surface topography map and the plating surface microscopic topography map, selecting the No. 7 as an optimal formula, and carrying out neutral salt spray resistance experimental analysis on the formula. The specific formula comprises the following components: main salt nickel sulfate: 8g/L, sodium hypophosphite as reducing agent: 22g/L complexing agent sodium citrate: 10g/L, buffer sodium acetate: 6g/L, stabilizer sodium thiosulfate: 1.0mg/L, surfactant sodium dodecyl sulfate: 0.30g/L. The neutral salt spray test of the coating panels was carried out according to GB/T1771-2007 determination of neutral salt spray resistance of paints and varnishes using a HW-90 salt spray corrosion test box. The panels were rated with reference to GB/T1766-2008. The surface of the test plate is observed regularly during the experiment, the plating layer cannot be damaged, the stop time of the salt spray box in any 24 hours is not more than 30 minutes, and the plating layer is inspected at the same time every day. At the end of the prescribed test period, the test solution residue on the surface of the test panel was removed by washing with warm water, and immediately thereafter the test panel was placed on a table surface and examined for surface damage phenomena such as foaming, rust and the extent of spread of rust from the scratch. Rating with reference to GB/T1766-2008 rating method for ageing of paint and varnish coatings, comprising: grade of degree of disruption, number and size of disruption. "0" means no damage and "5" means severe damage. To indicate the level of the size of the corruption, the brackets are noted and the letter "S" is added before the level.

TABLE 2 evaluation of comprehensive ageing Property ratings of protective paint films

Through testing and rating, the rating of the optimized ternary plating layer on the 0 th day is as follows: color change 0: no discoloration, powdering 0: no pulverization, cracking 0: no visible cracking, foam 0: bubble-free, long mould 1S2: mildew-free, rust 0: rust-free spot, peel 0: no flaking area; the rating on day 30 was color change 1: very slight discoloration, chalking 1: very slightly, trace pigment particles, crack 0 were observed on the test cloths: no visible cracking, foaming 1 (S1): few bubbles, long mold 1S2, were visible under a 10-fold magnification: mildew-free, rust 0: rust-free spot, peel 0: no flaking area; the rating on day 60 was color change 2: slight discoloration, chalking 2: slightly, a small amount of pigment particles are stained on the test cloth, and the crack is 0: no visible cracking, bubbling 2 (S2): there were a small number of blebs visible under normal vision, long mould 1S2: no mildew point, rust 1 (S1), few rust points visible under a 10-fold magnifying glass, flaking 1 (S1): the peeling area is less than or equal to 0.1 percent, and the peeling size is less than or equal to 1mm. According to the combination of an electron microscope graph and a grading result, the surface of the ternary coating prepared by the optimized formula is smooth and compact, the phenomena of chalking, cracking, foaming, mildew spots, rust spots and the like are avoided, after a 30-day neutral salt spray experiment, very slight color change and chalking occur, a small amount of foaming phenomena are caused, but the mildew spots, rust spots and flaking phenomena are not observed, in addition, after a 60-day neutral salt spray experiment, the ternary coating still does not generate visible cracking, no mildew spots are generated, and the ternary coating is strong in neutral salt spray resistance and can meet the requirement of corrosion resistance.

Example 2

A Ni-Sn-P pinhole-free ternary plating layer plating solution for marine facilities comprises the following components in percentage by weight:

8g/L of nickel sulfate, 1g/L of stannic chloride, 22g/L of sodium hypophosphite, 10g/L of sodium citrate, 6g/L of sodium acetate, 1mg/L of sodium thiosulfate and 0.3g/L of sodium dodecyl sulfate; the solvent is distilled water.

The specific configuration steps of the plating solution are as follows: according to the plating solution formula, accurately weighing the mass of each solid medicine by an electronic balance with the accuracy of 0.0001g, and sequentially putting the solid medicines into a beaker for dissolution by distilled water. Adding the dissolved solution into a plating container, adding distilled water to an accurate volume, and stirring at a constant speed to obtain Ni-Sn-P plating solution. And uniformly oscillating the Ni-Sn-P plating solution by ultrasonic vibration for standby.

The prepared plating solution is applied to the surface of a carbon steel substrate to implement electroless plating of Ni-Sn-P, and a test piece adopted is a cold-rolled steel plate, and the specific steps are as follows:

(1) And (3) rust removal: firstly, 260# abrasive paper is used for polishing to remove surface rust, and then 400# abrasive paper, 600# abrasive paper and 800# abrasive paper are used for polishing in sequence, so that the surface is too smooth and is not beneficial to plating;

(2) Deoiling: in order to avoid the problems of bursting sheets, foaming phenomena and pollution to the plating solution, premature decomposition of the plating solution and the like caused by influencing the binding force between the plating layer and the test piece, the greasy dirt on the test piece needs to be removed. Ultrasonically cleaning the polished sample with acetone for about 10min, and then cleaning with absolute ethyl alcohol to remove greasy dirt on the surface;

(3) Alkali washing: the sample was immersed in a mixed solution (the mixed solution contains NaOH20g/L, na) at 90 ℃ ₃ CO ₃ 30g/L、Na ₃ PO ₄ 25 g/L) for 20 minutes, and then washing with distilled water at 90 ℃ and drying;

(4) Acid washing: immersing the deoiled sample in a 15wt% sulfuric acid solution for 2 minutes by ultrasonic treatment to remove a surface oxide layer, and then flushing and drying the sample by distilled water;

(5) Activating: placing the acid-washed sample at room temperature, activating with 5wt% sulfuric acid solution for 1min, and removing an ultrathin oxide film formed by oxidizing the sample in air to obtain a pure surface to be plated;

(6) Plating: placing a test piece into the prepared Ni-Sn-P plating solution, plating for about 1.5 hours, providing a certain rotating speed by an electromagnetic stirrer, and setting the temperature at about 90 ℃; after plating, the test piece is washed by distilled water and dried for standby.

Through detection, the surface of the prepared ternary coating is smooth and compact, the phenomena of chalking, cracking, foaming, mildew spots, rust spots and the like are avoided, after a 30-day neutral salt spray experiment, very slight color change and chalking occur, a small amount of foaming phenomena are caused, but no mildew spots, rust spots and peeling phenomena are observed, in addition, after a 60-day neutral salt spray experiment, the ternary coating still does not generate visible cracking, no mildew spots are generated, and the ternary coating is strong in neutral salt spray resistance and can meet the requirement of corrosion resistance.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

The Ni-Sn-P pinhole-free ternary plating layer plating solution for the marine facilities and the preparation method thereof are described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims (2)

1. A Ni-Sn-P pinhole-free ternary plating solution for marine facilities is characterized by comprising the following components in percentage by weight:

8g/L of nickel sulfate, 1g/L of stannic chloride, 22g/L of sodium hypophosphite, 10g/L of sodium citrate, 6g/L of sodium acetate, 1mg/L of sodium thiosulfate, 0.3g/L of sodium dodecyl sulfate, water as a solvent and adjusting the pH value to 4.5-5.5 by using a buffering agent.

2. A method of electroless plating of a carbon steel substrate surface using the plating solution of claim 1, comprising the steps of:

(1) And (3) rust removal: removing the surface rust on the to-be-plated piece by using 260# abrasive paper, and then polishing by using 400# abrasive paper, 600# abrasive paper and 800# abrasive paper in sequence;

(2) Deoiling: removing greasy dirt on the test piece; ultrasonically cleaning the polished sample with acetone, and then cleaning the sample with absolute ethyl alcohol to remove greasy dirt on the surface;

(3) Alkali washing: the sample was immersed in a mixed solution containing NaOH20g/L, na at 90℃for 20 minutes ₃ CO ₃ 30g/L、Na ₃ PO ₄ 25g/L, then washing with distilled water at 90 ℃ and drying;

(4) Acid washing: immersing the deoiled sample in 15wt% sulfuric acid for ultrasonic treatment for 2 minutes to remove the surface oxide layer, and then flushing and drying the sample by distilled water;

(5) Activating: placing the acid-washed sample at room temperature, activating with 5wt% sulfuric acid solution for 1min, and removing an ultrathin oxide film formed by oxidizing the sample in air to obtain a pure surface to be plated;

(6) Plating: placing the test piece into the plating solution according to claim 1, plating for 1-1.5 hours while stirring, and setting the temperature at 90+/-5 ℃; after plating, the test piece is washed by distilled water and dried.

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