CN105803431A - Magnesium alloy chemical nickel plating solution and preparation method thereof, and nickel plating method - Google Patents

Abstract

The invention provides a magnesium alloy electroless nickel plating solution, which contains soluble nickel salt, complexing agent, buffer, resist, reducing agent, stabilizer and salicylaldehyde. The invention also provides a preparation method of the nickel plating solution and a nickel plating method on the surface of the magnesium alloy. The nickel plating solution of the present invention contains salicylaldehyde, which can effectively reduce the corrosion of the magnesium alloy galvanized layer in the electroless nickel plating solution, promote the smooth progress of the reaction, and facilitate the deposition of the nickel layer, thereby improving the density and pinhole of the coating , Missing plating problem. At the same time, the added salicylaldehyde can further prolong the use times of the nickel plating solution.

Description

A kind of electroless nickel plating liquid for magnesium alloy, preparation method and nickel plating method thereof

technical field

The invention relates to the technical field of electroplating, in particular to an electroless nickel plating solution for the surface of a magnesium alloy, a preparation method and a nickel plating method thereof.

Background technique

Magnesium alloy has been widely concerned because of its unique properties and abundant resources, and it is highly respected as an environmentally friendly material in this century. However, due to the immature electroplating process of magnesium alloy, the problem of poor corrosion resistance has become the main obstacle to exert its superiority, thus limiting its wider application to a large extent.

Therefore, it is particularly important to effectively decorate and prevent the surface of magnesium alloys. The commonly used treatment technology is electroplating, but magnesium alloys are not stable in conventional electroplating baths, and the surface needs to be pretreated to adapt to conventional electroplating environments. . At present, there are two kinds of pretreatment processes applicable to industrial production: zinc-precipitation method and direct electroless nickel plating method. These two methods were first introduced by Dow Chemical Company in the United States. Later, in the actual trial process, various manufacturers used this method as a basis for improvement to varying degrees, and developed into a variety of methods that are similar to each other. The NorskHydro process and the WCM process have been reported.

The purpose of the zinc precipitation method is to dissolve the oxide of magnesium; at the same time, a thin layer of hydroxide is formed on the surface of the magnesium alloy to prevent further oxidation of magnesium. In this application document, the technological process is improved based on the zinc precipitation method. The common process flow of the zinc precipitation method is: degreasing and descaling→activation→precipitating zinc→electroless nickel plating→electroplating copper/nickel/chromium, etc.

Normally, magnesium alloys will react violently with the acid/alkaline solution in the process, and the same violent reaction will also occur in the nickel plating solution, but this is not conducive to the deposition of the nickel layer on the surface of the substrate, often resulting in Pinholes and missing plating are present, and at the same time, the bonding force of the coating cannot be guaranteed, and problems such as bubbles and shedding are prone to occur.

Contents of the invention

The invention provides an electroless nickel plating solution for magnesium alloys, which can ease the reaction of magnesium alloy substrates in the nickel plating solution, make the reaction progress smoothly, achieve better nickel plating effect, and further solve the phenomena of pinholes and missed plating. At the same time, the nickel plating solution provided by the invention has a longer service life.

A magnesium alloy electroless nickel plating solution of the present invention comprises the following components: soluble nickel salt, complexing agent, buffer, resist, reducing agent, stabilizer, and salicylaldehyde.

The present invention also provides a preparation method of electroless nickel plating solution for magnesium alloy, said method is to add complexing agent, stabilizer, buffer and reducing agent in the aqueous solution of soluble nickel salt; then add resist and salicylic acid aldehyde.

The present invention also provides a method for electroless nickel plating on the surface of a magnesium alloy, comprising contacting the pretreated magnesium alloy with a nickel plating solution to obtain a magnesium alloy substrate with a nickel layer on the surface; wherein the nickel plating solution is based on The magnesium alloy nickel plating solution described in the invention.

The magnesium alloy electroless nickel plating solution of the present invention contains salicylaldehyde. Because the magnesium alloy galvanized layer will react violently in the electroless nickel plating, which will lead to problems such as uneven or missing plating of the nickel plating layer. The salicylaldehyde contained in the nickel plating solution of the present invention can effectively reduce the corrosion of the magnesium alloy galvanized layer in the electroless nickel plating solution, promote the smooth progress of the reaction, thereby ensuring the density of the coating and preventing pinholes and missed plating. At the same time, the added salicylaldehyde can further prolong the service life of the nickel plating solution.

detailed description

The technical solution of the present invention relates to a magnesium alloy electroless nickel plating solution, which contains the following components: soluble nickel salt, complexing agent, buffer, resist, reducing agent, stabilizer, and salicylaldehyde.

According to the electroless nickel plating solution provided by the present invention, preferably, soluble nickel salt 15-25g/L, complexing agent 20-65g/L, buffering agent 10-20g/L, resist 10-30g/L, reducing Agent 20-30g/L, stabilizer 0.001-0.003g/L, and salicylaldehyde 2-7g/L.

According to the electroless nickel plating solution provided by the present invention, preferably, the soluble nickel salt is one or more of nickel sulfate and nickel chloride; the complexing agent is ammonium citrate, ethylenediamine, sodium acetate , one or more of lactic acid, malic acid, citric acid, succinic acid, propionic acid; the buffer is boric acid; the resist is hydrofluoric acid, ammonium bifluoride, sodium fluoride, potassium fluoride One or more of them, when an appropriate amount of fluoride resist is added to the nickel plating solution, it can protect the surface of the magnesium alloy substrate during the electroless nickel plating process and prevent excessive corrosion, especially synergistic effect with salicylaldehyde , to further reduce the corrosion of the magnesium alloy galvanized layer in chemical nickel, ensure the binding force of the coating, reduce the chance of blistering and shedding of the coating; the reducing agent is sodium hypophosphite, sodium borohydride, borane, hydrazine One or more; the stabilizer is one or more of thiourea, potassium thiocyanate, and urea.

According to the electroless nickel plating solution provided by the present invention, preferably, the complexing agent is one or more of ammonium citrate, ethylenediamine, sodium acetate, and lactic acid.

According to the electroless nickel plating solution provided by the present invention, preferably, the pH value of the nickel plating solution is 8-9.

The present invention also provides a preparation method of magnesium alloy electroless nickel plating solution, the method described in the method is to add complexing agent, stabilizer, buffering agent and reducing agent in the aqueous solution of soluble nickel salt; then add anti-corrosion agent and salicylaldehyde.

According to the preparation method provided by the present invention, preferably, the soluble nickel salt 15-25g/L, complexing agent 20-65g/L, buffering agent 10-20g/L, resist 10-30g/L, reducing Agent 20-30g/L, stabilizer 0.001-0.003g/L and salicylaldehyde 2-7g/L.

According to the preparation method provided by the present invention, preferably, the soluble nickel salt is one or more of nickel sulfate and nickel chloride; the complexing agent is ammonium citrate, ethylenediamine, sodium acetate, lactic acid , malic acid, citric acid, succinic acid, propionic acid or one or more; the buffer is boric acid; the resist is hydrofluoric acid, ammonium bifluoride, sodium fluoride, potassium fluoride One or more; the reducing agent is one or more of sodium hypophosphite, sodium borohydride, borane, hydrazine; the stabilizer is one of thiourea, potassium thiocyanate, urea or more.

According to the preparation method provided by the present invention, preferably, ammonia water is used to adjust the pH value between 8-9.

The present invention also provides a method for electroless nickel plating on the surface of a magnesium alloy, comprising contacting the pretreated magnesium alloy with a nickel plating solution to obtain a magnesium alloy substrate with a nickel layer on the surface; it is characterized in that the nickel plating solution It is the magnesium alloy nickel plating solution described in the present invention.

The present invention will be further described in detail below in conjunction with the examples, but not limited thereto.

All raw materials in the examples described in the present invention are commercially available unless otherwise specified.

Example 1

1. Preparation of magnesium alloy electroless nickel plating solution

Add ammonium citrate, ethylenediamine, sodium acetate, lactic acid, thiourea, boric acid and sodium hypophosphite to the aqueous solution of nickel sulfate and stir well; then add hydrofluoric acid, ammonium bifluoride and salicylaldehyde, and finally use ammonia water to adjust The pH value is 8, and the nickel plating solution A1 can be obtained. Among them, nickel sulfate 20g/L, ammonium citrate 25g/L, ethylenediamine 3g/L, sodium acetate 7g/L, lactic acid 10g/L, thiourea 0.002g/L, boric acid 15g/L, sodium hypophosphite 25g /L, hydrofluoric acid 8g/L, ammonium bifluoride 10g/L and salicylaldehyde 4g/L.

2. Nickel plating on the surface of magnesium alloy

1) Substrate pretreatment: select magnesium alloy with brand AZ91D as the substrate, put the substrate into the degreasing solution (recipe: sodium carbonate 20g/L, sodium phosphate 20g/L, sodium citrate 10g/L, ten Dialkyl sodium sulfate 1g/L), soak for 10 minutes at 20-30°C, take it out, wash it with tap water, and then wash it with 300g/L phosphoric acid.

2) Activation: Immerse the magnesium alloy substrate treated in step 1 in the activation solution (recipe: phosphoric acid 180g/L, ammonium bifluoride 90g/L), dip for 60 seconds at 20-30°C, take it out and wash it with tap water.

3) Zinc precipitation: immerse the magnesium alloy substrate obtained in step 2 into the zinc precipitation solution (recipe: zinc sulfate 30g/l, sodium pyrophosphate 120g/L, sodium carbonate 6g/L, potassium fluoride 2g/L, nickel sulfate 0.5g/L), soak at 50°C for 10 minutes, take it out and wash it with tap water.

4) Electroless nickel plating: Put the magnesium alloy substrate treated in steps 1-3 into nickel plating solution A1, the temperature of the nickel plating solution is 40°C, take it out after soaking for 20 minutes, wash it with tap water, and get the plated piece Y1 .

Example 2

Add ammonium citrate, ethylenediamine, sodium acetate, lactic acid, thiourea, boric acid and sodium hypophosphite to the aqueous solution of nickel sulfate and stir well; then add hydrofluoric acid, ammonium bifluoride and salicylaldehyde, and finally use ammonia water to adjust The pH value is 8.5, and the nickel plating solution A2 can be obtained. Among them, nickel sulfate 18g/L, ammonium citrate 22g/L, ethylenediamine 2g/L, sodium acetate 6g/L, lactic acid 8g/L, thiourea 0.001g/L, boric acid 12g/L, sodium hypophosphite 22g /L, hydrofluoric acid 7g/L, ammonium bifluoride 9g/L and salicylaldehyde 4g/L.

According to the method of Example 1, the magnesium alloy was plated with nickel using the nickel plating solution A2 to obtain the plated piece Y2.

Example 3

The nickel plating solution A3 was configured according to the method of Example 1, the difference being: ammonium citrate was 35 g/L, and ethylenediamine, sodium acetate and lactic acid were not contained.

According to the method of Example 1, the magnesium alloy was plated with nickel using the nickel plating solution A3 to obtain the plated piece Y3.

Example 4

Configure nickel plating solution A4 according to the method of embodiment 1, difference is: replace ethylenediamine, sodium acetate, lactic acid in A1 with the malic acid of 10g/L, the succinic acid of 15g/L.

According to the method of Example 1, the magnesium alloy was plated with nickel using the nickel plating solution A4 to obtain the plated piece Y4.

Example 5

Nickel plating solution A5 was configured according to the method of Example 1, with the difference that: 10 g/L of sodium fluoride was used to replace the ammonium bifluoride solution in A1.

According to the method of Example 1, the magnesium alloy was plated with nickel using the nickel plating solution A5 to obtain the plated piece Y5.

Comparative example 1

Except not containing salicylaldehyde, all the other are identical with embodiment 1.

Performance Tests and Results

1. Enter the slow reaction time

Observe how long it takes for the substrate to enter a gentle reaction after it is put into the nickel plating solution.

2. Service life of nickel plating solution

Observe whether there is precipitation in the nickel plating solution after use.

3. Nickel-plated appearance

Observe whether the appearance of the nickel-plated magnesium alloy substrate is uniform, whether there are pinholes, missing plating, etc.

4. Test results

Test items Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Time to enter the bland reaction Within 60S Within 60S Within 60S Within 60S Within 60S Greater than 120S Appearance after nickel plating Flat and dense appearance, no pinholes, missing plating, Flat and dense appearance, no pinholes, missing plating, The appearance is relatively flat, no pinholes, missing plating, Flat and dense appearance, no pinholes, missing plating, Flat and dense appearance, no pinholes, missing plating, The appearance is relatively flat, with occasional pinholes and missing plating Nickel plating bath life No precipitation after 10 times of use, no nickel deposits No precipitation after 10 times of use, no nickel deposits No precipitation after 10 times of use, but nickel deposits No precipitation after 10 times of use, no nickel deposits No precipitation after 10 times of use, no nickel deposits Precipitation occurs after 6 uses, nickel deposits

From the above test results, it can be seen that salicylaldehyde can effectively prevent violent reaction, improve the density of the coating, and prevent pinholes and missed plating. At the same time, the added salicylaldehyde absorbs the impurity ions dissolved in the nickel-plating solution by the magnesium alloy, which can further prolong the service life of the nickel-plating solution.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to list all the implementation modes here, and the obvious changes or changes derived therefrom are still within the protection scope of the claims of the present invention.

Claims (10)

1. a chemically coating nickel by magnesium-alloy liquid, it is characterised in that containing, for example lower component in described nickel-plating liquid: soluble nickel salt, chelating agent, buffer agent, resist, reducing agent, stabilizer and salicylide.

2. chemical nickel-plating liquid according to claim 1, it is characterized in that, described soluble nickel salt 15-25g/L, chelating agent 20-65g/L, buffer agent 10-20g/L, resist 10-30g/L, reducing agent 20-30g/L, stabilizer 0.001-0.003g/L and salicylide 2-7g/L.

3. chemical nickel-plating liquid according to claim 1, it is characterised in that described soluble nickel salt is one or more in nickel sulfate, Nickel dichloride.；

Described chelating agent is one or more in ammonium citrate, ethylenediamine, sodium acetate, lactic acid, malic acid, citric acid, succinic acid, propanoic acid；

Described buffer agent is boric acid；

Described resist is one or more in Fluohydric acid., ammonium acid fluoride, sodium fluoride, potassium fluoride；

Described reducing agent is one or more in hypophosphite, sodium borohydride, borine, hydrazine；

Described stabilizer is one or more in thiourea, potassium thiocyanate, carbamide.

4. chemical nickel-plating liquid according to claim 3, it is characterised in that described chelating agent is one or more in ammonium citrate, ethylenediamine, sodium acetate, lactic acid.

5. chemical nickel-plating liquid according to claim 1, it is characterised in that the pH value of described nickel-plating liquid is 8-9.

6. the preparation method of a chemically coating nickel by magnesium-alloy liquid, it is characterised in that described method is add chelating agent, stabilizer, buffer agent and reducing agent in the aqueous solution of soluble nickel salt；Add resist and salicylide.

7. preparation method according to claim 6, it is characterised in that the pH value of described nickel-plating liquid is at 8-9.

8. preparation method according to claim 6, it is characterized in that, described soluble nickel salt 15-25g/L, chelating agent 20-65g/L, buffer agent 10-20g/L, resist 10-30g/L, reducing agent 20-30g/L, stabilizer 0.001-0.003g/L and salicylide 2-7g/L.

9. preparation method according to claim 6, it is characterised in that described soluble nickel salt is one or more in nickel sulfate, Nickel dichloride.；

Described chelating agent is one or more in ammonium citrate, ethylenediamine, sodium acetate, lactic acid, malic acid, citric acid, succinic acid, propanoic acid；

Described buffer agent is boric acid；

Described resist is one or more in Fluohydric acid., ammonium acid fluoride, sodium fluoride, potassium fluoride；

Described reducing agent is one or more in sodium hypophosphite, sodium borohydride, borine, hydrazine；

Described stabilizer is one or more in thiourea, potassium thiocyanate, carbamide.

10. a method for magnesium alloy surface chemical nickel plating, contacts with nickel-plating liquid including by the magnesium alloy through pre-treatment, must arrive surface and have the magnesium alloy substrates of nickel dam；It is characterized in that, described nickel-plating liquid is the magnesium alloy nickel-plating liquid described in any one of claim 1-5.