CN113684480A - Process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating - Google Patents
Process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating Download PDFInfo
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- C25D3/00—Electroplating: Baths therefor
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- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/10—Electroplating with more than one layer of the same or of different metals
- C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
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- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
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Abstract
The invention discloses a process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating, which comprises the steps of pretreating neodymium iron boron, then carrying out electro-coppering treatment on the surface of the neodymium iron boron, and then carrying out activation treatment; carrying out flash plating and nickel electroplating treatment on the outer surface of the copper plating layer of the neodymium iron boron, and then carrying out activation treatment again; preparing chemical nickel plating solution in a plating bath, firstly measuring the stability of the chemical nickel plating solution, if the stability is qualified, normally using the solution, if the stability is unqualified, adding a stabilizer, and after the regulation and control stability is qualified, normally using the solution; and finally, carrying out chemical nickel plating treatment in the chemical nickel plating solution after the stability of testing or regulation and control to form a chemical nickel plating layer, namely finishing the treatment. The method can adjust the chemical nickel plating solution with poor stability in time, and if the measured result shows that the chemical nickel is unqualified in stability, the stability of the chemical nickel plating solution is improved by adding the stabilizer, the service life of the chemical nickel plating solution is prolonged, and the cost is saved.
Description
Technical Field
The invention belongs to the technical field of metal surface treatment, and particularly relates to a process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating.
Background
At present, the neodymium iron boron permanent magnet material is used as a magnetic material with high magnetic performance and high cost performance, and is widely applied to a plurality of fields such as electronic machinery, medical equipment and the like. However, because of some characteristics of the ndfeb substrate, such as easy oxidation of the substrate, porous and loose substrate, etc., the surface treatment of the ndfeb substrate has been a difficulty.
The novel neodymium iron boron magnet is a third-generation rare earth material, is a magnetic functional material, has poor corrosion resistance and is easy to be affected by temperature. By adopting the composite plating process, a plating layer with excellent corrosion resistance and small thermal demagnetization scene response on the magnet can be formed on the surface of the neodymium iron boron magnet.
In the prior art, in the surface treatment process of the neodymium iron boron, copper plating treatment and chemical nickel plating treatment are generally required to be performed on the surface of a neodymium iron boron substrate, and a nickel plating solution is adopted in the chemical nickel plating process. However, the stability of the chemical nickel plating solution affects the plating effect of the plating layer, the service life of the bath solution and other problems, and adverse factors such as too high local temperature, too high pH, too high nickel salt concentration and the like of the chemical nickel plating solution are all easy to generate particle precipitates such as nickel phosphite or nickel hydroxide and the like in the chemical nickel plating solution, and the particle precipitates have a certain autocatalysis effect, and when a certain amount is reached, the plating solution is caused to self-decompose, so that the chemical nickel plating solution is invalid, and therefore, the monitoring process of the stability of the chemical nickel plating solution is of great importance. In the chemical nickel treatment process, technical information of poor stability or insufficient stability of a chemical nickel plating solution needs to be monitored in time so as to replace or maintain the electroplating bath solution in time, and then a qualified electroplated product is obtained.
Disclosure of Invention
Aiming at the technical problems in the prior art, the application aims to provide a process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating.
The process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating is characterized by comprising the following steps of:
1) pretreating neodymium iron boron;
2) performing electro-coppering treatment on the surface of the pretreated neodymium iron boron to form a copper plating layer, and then performing activation treatment;
3) carrying out flash plating and nickel electroplating treatment on the outer surface of the neodymium iron boron copper plating layer to form an electroplated nickel plating layer, and then carrying out activation treatment again;
4) preparing chemical nickel plating solution in a plating bath, firstly measuring the stability of the chemical nickel plating solution, normally using the solution if the stability is qualified, adding a stabilizer if the stability is unqualified, and normally using the solution after the regulation and control stability is qualified; and (3) putting the product subjected to the activation treatment in the step 3) into chemical nickel plating solution subjected to testing or regulation and control stabilization to perform chemical nickel plating treatment to form a chemical nickel plating layer, namely finishing the treatment.
The process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating is characterized in that in the step 1), the process for pretreating neodymium iron boron is as follows: firstly, washing and degreasing the neodymium iron boron by using a surfactant solution, then fully washing the neodymium iron boron by using clear water, pickling the neodymium iron boron by using dilute nitric acid with the concentration of 3-5% for 3-5 minutes, and then washing the neodymium iron boron by using the clear water for 2-3 times.
The process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating is characterized in that the step 2) of electroplating copper treatment comprises two electroplating processes which are sequentially carried out, and the two electroplating processes are respectively as follows:
the first step is pre-copper plating treatment, and the plating solution for the pre-copper plating treatment comprises the following components: 3-5g/L, HEDP 100 g/140 g/L of copper carbonate, 60-80g/L of potassium carbonate, 0.02-0.04g/L of bismuth nitrate and 0.003-0.006g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 18-22 ℃, the pH value is 9.3-9.9, the current density is 0.3-0.5ASD, and the electroplating time is 40-60 min;
the second step is the treatment of electroplating thickened copper layer, and the plating solution comprises the following components: 13-15g/L, HEDP 140g/L of copper carbonate, 60-80g/L of potassium carbonate, 0.02-0.04g/L of bismuth nitrate and 0.003-0.006g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 50-60 ℃, the pH value is 9.3-9.9, the current density is 0.2-0.4ASD, and the electroplating time is 50-70 min.
The process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating is characterized in that in the pre-copper plating treatment or the treatment of electroplating a thickened copper layer, the polycation quaternary ammonium salt is polyquaternium-7, polyquaternium-10 or polyquaternium-22.
The process for regulating and controlling the stability of the chemical nickel in the neodymium iron boron electroplating is characterized in that in the step 2) or the step 3), the activation treatment step is as follows: and (3) washing and activating for 30-60 s by using a citric acid solution with the mass concentration of 2-3%, and then fully washing by using clear water.
The process for regulating and controlling the stability of chemical nickel in neodymium iron boron electroplating is characterized in that in the step 3), the plating solution for flash plating nickel electroplating treatment comprises 300-350 g/L of nickel sulfate, 40-50 g/L of nickel chloride and 40-50 g/L of boric acid; the flash plating nickel electroplating treatment process comprises the following steps: the pH value is 3.8-4.4, the temperature is 50-60 ℃, the current density is 0.2-0.4ASD, and the time is 8-15 min.
The process for regulating and controlling the stability of the chemical nickel in the neodymium iron boron electroplating is characterized in that in the step 4), the chemical nickel plating solution comprises the following components: 20-25 g/L of nickel sulfate, 18-23 g/L of sodium hypophosphite, 10-15 g/L of citric acid, 8-12 g/L of malic acid, 16-24 g/L, PPS-OH 0.005-0.01 g/L of sodium hydroxide, 0.002-0.007 g/L of allyl iodide and 3-4 mg/L of stabilizer; the chemical nickel plating treatment process comprises the following steps: the temperature is 80-90 ℃, the pH value is 4.3-4.9, and the treatment time is 25-35 min.
In the formula composition of the chemical nickel plating solution, the stabilizer has the action principle that the stabilizer is adsorbed on the surfaces of colloidal particles in the plating solution and occupies active centers on the surfaces of the colloidal particles, so that nickel is prevented from being deposited on the particles, and therefore, a certain amount of the stabilizer needs to be added into the formula composition of the chemical nickel plating solution. However, the content of the chemical nickel plating solution is not too high, otherwise, the chemical nickel deposition rate is inhibited during the chemical nickel plating treatment, even the chemical nickel plating solution does not start plating, and a stable chemical nickel plating layer cannot be formed on the surface of the neodymium iron boron.
The process for regulating and controlling the stability of the chemical nickel in the neodymium iron boron electroplating is characterized in that the stabilizer is thiourea.
The process for regulating and controlling the stability of the chemical nickel in the neodymium iron boron electroplating is characterized in that the method for measuring the stability of the chemical nickel plating solution comprises the following steps: adding 100ml of chemical nickel plating solution into a beaker, heating to 80-90 ℃, dropwise adding a palladium chloride solution with the Pd concentration of 20ppm into the beaker by using a dropper while stirring until the chemical nickel plating solution becomes turbid due to self-reaction, and recording the volume of the consumed palladium chloride solution; if the volume of the consumed palladium chloride solution is more than or equal to 1.5ml, the content of free thiourea in the chemical nickel plating solution is more than 3mg/L, the chemical nickel plating solution is determined to be qualified in stability, otherwise, the chemical nickel plating solution is determined to be unqualified in stability, then the stabilizer is added into the chemical nickel plating solution for stability regulation and control until the measured stability is qualified, and then the subsequent chemical nickel plating treatment operation is carried out.
The principle of the invention for determining the stability of the chemical nickel plating solution is as follows: when the palladium chloride solution is dropped into the electroless nickel plating solution in the case where the free stabilizer (thiourea) in the electroless nickel plating solution is sufficient, the colloidal palladium is adsorbed by the stabilizer (thiourea) in the plating solution, thereby preventing the spontaneous reaction of the plating solution. With the continuous dropping of the palladium chloride solution, the addition of the colloidal palladium enables the free thiourea to be continuously adsorbed and combined with the colloidal palladium, the free thiourea in the plating solution is consumed, and after the consumption of the free thiourea is finished, the plating solution starts to decompose automatically under the catalytic action of the palladium, so that the chemical nickel plating solution becomes turbid through self reaction. The method of the invention can calculate the content of free stabilizer (thiourea) in the plating solution by measuring and dropping the palladium chloride solution, thereby judging the stability of the chemical nickel plating solution.
Compared with the prior art, the technical effect that this application gained is:
the stability of the nickel plating solution in the chemical nickel plating process affects the plating effect of the plating layer, the service life of the bath solution and the like, and the poor stability of the chemical nickel plating solution easily causes the precipitation of nickel metal in the plating bath, so that the chemical nickel plating solution is ineffective. The method can quickly determine the stability of the chemical nickel plating solution in neodymium iron boron electroplating, can adjust the chemical nickel plating solution with poor stability in time, and can improve the stability of the chemical nickel plating solution in a mode of adding a stabilizer if the measured result shows that the chemical nickel is unqualified in stability, prolong the service life of the chemical nickel plating solution and save the cost.
Detailed Description
The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.
Example 1:
a process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating comprises the following steps:
1) pre-treating neodymium iron boron
Firstly, washing neodymium iron boron by using a soap solution with the mass concentration of 2%, then ultrasonically cleaning the neodymium iron boron twice by using clear water, then pickling the neodymium iron boron for 3 minutes by using dilute nitric acid with the concentration of 4%, and ultrasonically cleaning the neodymium iron boron twice by using the clear water;
2) electrolytic copper plating treatment
Carrying out electro-coppering treatment on the surface of the pretreated neodymium iron boron, comprising two electroplating processes which are carried out in sequence, wherein the two electroplating processes are respectively as follows:
the first step is pre-copper plating treatment, and the plating solution for the pre-copper plating treatment comprises the following components: 4g/L, HEDP 120g/L of copper carbonate, 70g/L of potassium carbonate, 0.03g/L of bismuth nitrate and 0.005g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 20 ℃, the pH value is about 9.6, the current density is 0.4ASD, and the electroplating time is 50 min;
the second step is the treatment of electroplating thickened copper layer, and the plating solution comprises the following components: 14g/L, HEDP 150g/L of copper carbonate, 70g/L of potassium carbonate, 0.03g/L of bismuth nitrate and 0.005g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 55 ℃, the pH value is about 9.6, the current density is 0.3ASD, and the electroplating time is 60 min;
the polycation quaternary ammonium salt adopts polyquaternium-7.
After the copper electroplating treatment is carried out in two steps, the activation treatment is carried out, and the process comprises the following steps: washing and activating with 3% citric acid solution for 50s, and washing with clear water.
3) Flash nickel electroplating
Carrying out flash plating nickel electroplating treatment on the outer surface of the copper plating layer of the neodymium iron boron, wherein the plating solution of the flash plating nickel electroplating treatment comprises 320g/L of nickel sulfate, 45g/L of nickel chloride and 45g/L of boric acid; the flash plating nickel electroplating treatment process comprises the following steps: the pH value is 4.0-4.2, the temperature is 55 ℃, the current density is 0.3ASD, and the electroplating time is 10 min;
after the flash plating nickel electroplating treatment, the activation treatment is carried out, and the process is as follows: washing and activating with 3% citric acid solution for 50s, and washing with clear water.
4) Chemical nickel treatment
Preparing an electroless nickel plating solution in a plating tank, wherein the electroless nickel plating solution comprises the following components: 23g/L of nickel sulfate, 20g/L of sodium hypophosphite, 12g/L of citric acid, 10g/L of malic acid, 20g/L, PPS-OH 0.008g/L of sodium hydroxide, 0.005g/L of allyl iodide and 3.0mg/L of thiourea as a stabilizer. And then carrying out chemical nickel treatment on the neodymium iron boron treated in the step 3) by using a chemical nickel plating solution in a plating bath, wherein the treatment process conditions are as follows: the temperature is 85 ℃, the pH value is 4.5-4.7, and the treatment time is 30 min; and after the treatment is finished, the final surface-treated neodymium iron boron product is obtained, and the appearance of the product is bright silver and the surface of the product is smooth.
And then measuring the stability of the chemical nickel plating solution in the plating tank, wherein the measuring method comprises the following steps: 100ml of chemical nickel plating solution is taken into a beaker, the chemical nickel plating solution is heated to the required temperature of 85 ℃, a palladium chloride aqueous solution with 20ppm of Pd concentration is dripped into the beaker by a dropper with stirring until the chemical nickel plating solution becomes turbid due to self-reaction, the volume of the used palladium chloride solution is recorded to be 1.5ml (1.5 ml of the palladium chloride solution with 20ppm of Pd concentration is consumed, namely 0.03mg of colloid-containing palladium, free thiourea in the chemical nickel plating solution is obtained by calculation =3 mg/L), and the stability result is qualified.
The cross section of the final surface-treated neodymium iron boron product obtained in example 1 is observed through a scanning electron microscope, and the thicknesses of the pre-copper plating layer, the thickened copper layer, the electroplated nickel plating layer and the chemical nickel plating layer plated on the surface of the neodymium iron boron substrate are respectively 1 μm, 2 μm, 0.3 μm and 2.7 μm.
The final surface treated nd fe-b product obtained in example 1 was subjected to a neutral salt spray test (NSS) according to section 8 of standard GBT 10125-. The test specimen was left in 10 portions and observed every 24 hours. The test result shows that the surface of the neodymium iron boron magnet obtained by the neodymium iron boron surface treatment method of the embodiment 1 has no white rust after the salt spray test is carried out for 80 hours, and the salt spray test can reach more than 80 hours. After 100 hours, the color of each sample is unchanged, the surface of the coating is still good, after 120 hours, the surface of the coating has no white rust, and after 180 hours, the surface of the coating begins to have a little white rust.
Comparative example 1:
the neodymium iron boron permanent magnet sample is plated, the process steps are repeated in the embodiment 1, the difference is only that the process of the step 4) of the comparative example 1 is different from that of the embodiment 1, and the other conditions are the same as the embodiment 1.
Comparative example 1, step 4) the procedure of the chemical nickel treatment was as follows:
preparing an electroless nickel plating solution in a plating tank, wherein the electroless nickel plating solution comprises the following components: 23g/L of nickel sulfate, 20g/L of sodium hypophosphite, 12g/L of citric acid, 10g/L of malic acid, 20g/L, PPS-OH 0.008g/L of sodium hydroxide, 0.005g/L of allyl iodide and 1.0mg/L of thiourea as a stabilizer. And then carrying out chemical nickel treatment on the neodymium iron boron subjected to the flash plating nickel electroplating treatment by using a chemical nickel plating solution in a plating tank, wherein the treatment process conditions are as follows: the temperature is 95 ℃, and the pH value is 4.5-4.7. Because the stability of the chemical nickel plating solution is reduced, the plating speed is accelerated, and the plating time required for obtaining the chemical nickel plating layer with the same thickness is reduced from 30min to 18 min. The stability of the electroless nickel plating solution in the plating tank is measured at this time by the following method: 100ml of chemical nickel plating solution is taken into a beaker, the chemical nickel plating solution is heated to the required temperature of 95 ℃, a palladium chloride aqueous solution with 20ppm of Pd concentration is dripped into the beaker by a dropper while stirring until the chemical nickel plating solution becomes turbid due to self-reaction, the volume of the used palladium chloride solution is recorded as 1.1ml, and the chemical nickel plating solution is judged to be unqualified in stability.
The final surface treated nd fe-b product obtained in example 1 was subjected to a neutral salt spray test (NSS) according to section 8 of standard GBT 10125-. The test specimen was left in 10 portions and observed every 24 hours. The test result shows that:
the neodymium iron boron magnet obtained by the neodymium iron boron surface treatment method of the comparative example 1 has no white rust on the surface after 24 hours of salt spray test, and the salt spray test can reach more than 48 hours. After 48 hours, the surface of the plating layer had no white rust, and after 72 hours, a little white rust began to appear on the surface of the plating layer.
The statements in this specification merely set forth a list of implementations of the inventive concept and the scope of the present invention should not be construed as limited to the particular forms set forth in the examples.
Claims (8)
1. A process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating is characterized by comprising the following steps:
1) pretreating neodymium iron boron;
2) performing electro-coppering treatment on the surface of the pretreated neodymium iron boron to form a copper plating layer, and then performing activation treatment;
carrying out flash plating and nickel electroplating treatment on the outer surface of the neodymium iron boron copper plating layer to form an electroplated nickel plating layer, and then carrying out activation treatment again;
4) preparing chemical nickel plating solution in a plating bath, firstly measuring the stability of the chemical nickel plating solution, normally using the solution if the stability is qualified, adding a stabilizer if the stability is unqualified, and normally using the solution after the regulation and control stability is qualified; and (3) putting the product subjected to the activation treatment in the step 3) into chemical nickel plating solution subjected to testing or regulation and control stabilization to perform chemical nickel plating treatment to form a chemical nickel plating layer, namely finishing the treatment.
2. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 1, wherein in the step 1), the process for pretreating neodymium iron boron comprises the following steps: firstly, washing and degreasing the neodymium iron boron by using a surfactant solution, then fully washing the neodymium iron boron by using clear water, pickling the neodymium iron boron by using dilute nitric acid with the concentration of 3-5% for 3-5 minutes, and then washing the neodymium iron boron by using the clear water for 2-3 times.
3. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 1, wherein the step 2) of electro-coppering treatment comprises two electroplating processes performed in sequence, respectively as follows:
the first step is pre-copper plating treatment, and the plating solution for the pre-copper plating treatment comprises the following components: 3-5g/L, HEDP 100 g/140 g/L of copper carbonate, 60-80g/L of potassium carbonate, 0.02-0.04g/L of bismuth nitrate and 0.003-0.006g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 18-22 ℃, the pH value is 9.3-9.9, the current density is 0.3-0.5ASD, and the electroplating time is 40-60 min;
the second step is the treatment of electroplating thickened copper layer, and the plating solution comprises the following components: 13-15g/L, HEDP 140g/L of copper carbonate, 60-80g/L of potassium carbonate, 0.02-0.04g/L of bismuth nitrate and 0.003-0.006g/L of polycation quaternary ammonium salt; the electroplating process comprises the following steps: the temperature is 50-60 ℃, the pH value is 9.3-9.9, the current density is 0.2-0.4ASD, and the electroplating time is 50-70 min.
4. The process of claim 3, wherein in the pre-copper plating treatment or the treatment of plating the thickened copper layer, the polycationic quaternary ammonium salt is polyquaternium-7, polyquaternium-10 or polyquaternium-22.
5. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 1, wherein in the step 2) or the step 3), the step of activation treatment is as follows: and (3) washing and activating for 30-60 s by using a citric acid solution with the mass concentration of 2-3%, and then fully washing by using clear water.
6. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 1, wherein in the step 3), the plating solution composition of the flash plating nickel electroplating treatment comprises 300-350 g/L of nickel sulfate, 40-50 g/L of nickel chloride and 40-50 g/L of boric acid; the flash plating nickel electroplating treatment process comprises the following steps: the pH value is 3.8-4.4, the temperature is 50-60 ℃, the current density is 0.2-0.4ASD, and the time is 8-15 min.
7. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 1, wherein in the step 4), the chemical nickel plating solution comprises the following components: 20-25 g/L of nickel sulfate, 18-23 g/L of sodium hypophosphite, 10-15 g/L of citric acid, 8-12 g/L of malic acid, 16-24 g/L, PPS-OH 0.005-0.01 g/L of sodium hydroxide, 0.002-0.007 g/L of allyl iodide and 3-4 mg/L of thiourea as a stabilizer; the chemical nickel plating treatment process comprises the following steps: the temperature is 80-90 ℃, the pH value is 4.3-4.9, and the treatment time is 25-35 min.
8. The process for regulating and controlling chemical nickel stability in neodymium iron boron electroplating according to claim 6, wherein the method for measuring the stability of the chemical nickel plating solution comprises the following steps: adding 100ml of chemical nickel plating solution into a beaker, heating to 80-90 ℃, dropwise adding a palladium chloride solution with the Pd concentration of 20ppm into the beaker by using a dropper while stirring until the chemical nickel plating solution becomes turbid due to self-reaction, and recording the volume of the consumed palladium chloride solution; if the volume of the consumed palladium chloride solution is more than or equal to 1.5ml, the content of free thiourea in the chemical nickel plating solution is more than 3mg/L, the chemical nickel plating solution is determined to be qualified in stability, otherwise, the chemical nickel plating solution is determined to be unqualified in stability, then the stabilizer is added into the chemical nickel plating solution for stability regulation and control until the measured stability is qualified, and then the subsequent chemical nickel plating treatment operation is carried out.
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