CN105586580A - Method for medium-low temperature quick chemical plating of Ni-P based on copper leaching and plating pretreatment - Google Patents

Abstract

The invention relates to a method for rapid electroless plating of Ni-P at low temperature on the surface of an aluminum alloy based on copper immersion pretreatment. The method comprises the following steps: 1) The plating solution is composed of choline chloride-ethylene glycol ionic liquid, copper salt and thiourea; 2) After grinding and cleaning the aluminum alloy, place it in an alkali solution and an acid solution in turn, and then wash; 3) Put the treated aluminum alloy into the plating solution described in step 1), and put it in 20~30 ?C at 1~6? h, then sequentially washed with choline chloride-ethylene glycol ionic liquid, water and ethanol, and dried; 4) Ni-P plating solution is alkaline or acidic plating solution; The alloy is placed in the Ni-P plating solution, and placed at 30~60?C for 0.5~5? h, washed with water and dried. The invention performs electroless Ni-P plating in a conventional plating solution without inputting external energy and without adding any catalyst and accelerator, so as to realize a rapid electroless plating process at a relatively low temperature.

Description

A method for rapid electroless plating of Ni-P on the surface of aluminum alloy based on immersion copper pretreatment at low temperature

technical field

The invention relates to a method for rapid electroless Ni-P plating at low temperature on the surface of an aluminum alloy based on immersion copper pretreatment, and belongs to the technical field of metal surface treatment.

Background technique

Aluminum and aluminum alloys are an important class of light metal materials, which have the advantages of low price, low density, high plasticity, good formability, and no low-temperature brittleness. They are widely used in aerospace, shipbuilding, integrated circuits, and daily necessities decoration industries. However, the chemical properties of aluminum are lively, the standard potential is low, and the corrosion resistance is poor. At the same time, the surface hardness of aluminum and aluminum alloys is low, and the wear resistance is poor. In order to overcome the above shortcomings, surface treatment of aluminum and aluminum alloys is a very important link. At present, a variety of surface treatment methods have been developed, among which electroless Ni-P alloy plating has the advantages of high hardness, good corrosion resistance and good weldability, and is an important way to improve the surface properties of aluminum alloys.

At present, the most widely used electroless Ni-P plating process is generally carried out at a relatively high temperature (80~95°C). Although the rate of coating at high temperature is fast, the energy consumption of the process is high, the control is difficult, the equipment loss is serious, and the plating solution is volatile at high temperature, and the service life is short; in addition, for some materials that are easily deformed at high temperature, high temperature may The deformation and modification of the substrate are caused, which limits the further popularization and application of the electroless Ni-P plating process. Reducing the temperature of electroless plating is one of the effective ways to solve the above problems. It can not only improve the stability of the plating solution, reduce the cost, but also facilitate on-site operation. However, the reduction of the temperature of the plating solution will greatly reduce the deposition rate, and even make it impossible to apply plating. Therefore, improving the deposition rate under medium and low temperature conditions is the current chemical plating Ni- An important research direction in the field of P.

In recent years, researchers at home and abroad have developed a variety of methods such as ultrasonic method, pulse chemical plating method, photochemical method, accelerated catalysis method, electron carrier method and organic acid complexing agent method to improve the electroless Ni-P plating efficiency under medium and low temperature conditions. deposition rate. Among them, the ultrasonic method, the pulse chemical plating method and the photochemical method realize the improvement of the electroless plating speed by inputting external energy, while the accelerated catalytic method, the electronic carrier method and the organic acid complexing agent method are achieved by adding accelerators, catalysts or coordination agents. Agents, etc. accelerate the oxidation of hypophosphite or reduce the reduction activation energy of nickel ions to increase the deposition rate. Although the above-mentioned methods can all play a role in improving the deposition rate of electroless Ni-P, they also have problems such as easy decomposition of the plating solution, difficult operation, complex composition of the plating solution and high production cost, and the deposition rate is still relatively low.

Contents of the invention

The object of the present invention is to provide a method for rapid electroless Ni-P plating at low temperature on the surface of an aluminum alloy based on immersion copper pretreatment.

In the present invention, the aluminum alloy is pretreated by immersion copper plating in choline chloride-ethylene glycol ionic liquid to obtain a layer of copper coating, which is then used as the pre-plating layer of the aluminum alloy substrate without inputting external energy and without adding any The electroless Ni-P plating is carried out in the conventional plating solution of the catalyst and the accelerator, and a rapid electroless plating process at a lower temperature can be realized. By comparing with electroless Ni-P plating on aluminum alloy after galvanizing treatment and direct electroless Ni-P plating on aluminum alloy without immersion plating treatment, it is found that carrying out immersion copper plating treatment on aluminum alloy with the method of the present invention can significantly improve the alkalinity. Or the deposition rate of electroless Ni-P in acid plating solution provides a new technical approach for the further popularization and application of electroless plating process in aluminum alloy surface treatment.

A kind of method based on immersion plating copper pretreated aluminum alloy surface low-temperature fast electroless plating Ni-P method, it is characterized in that the method comprises the following steps:

1) Preparation of copper immersion plating solution: the plating solution is composed of choline chloride-ethylene glycol ionic liquid, copper salt and thiourea;

2) Sample pretreatment: After grinding and cleaning the aluminum alloy, place it in an alkaline solution at 65~75˚C, wash it with water after 5~10 min; then place it in an acid solution at room temperature for 0.5~3 min, and finally washed with acetone;

3) Immersion copper plating treatment: put the treated aluminum alloy into the plating solution described in step 1), and let it stand at 20~30˚C for 1~6 h, and then a layer of copper plating can be obtained on the surface of the aluminum alloy. Then successively wash with choline chloride-ethylene glycol ionic liquid, water and ethanol, then dry;

4) Preparation of electroless Ni-P plating solution: Ni-P plating solution is alkaline plating solution or acidic plating solution, alkaline plating solution is composed of NiSO ₄ 6H ₂ O, Na ₃ C ₆ H ₅ O ₇ 2H ₂ O and NaH ₂ PO ₂ ·H ₂ O, adding ammonia water to adjust the pH of the plating solution between 8.0 and 11.0; the acidic plating solution is composed of NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ ·H ₂ O and CH ₃ COONa·3H ₂ O, adding lactic acid to adjust the pH of the plating solution between 4.0 and 7.0;

5) Electroless Ni-P plating: Place the aluminum alloy that has been dipped in copper in the electroless Ni-P plating solution, and place it at 30~60˚C for 0.5~5 h to get the Ni-P coating, wash with water ,dry.

The molar ratio of choline chloride to ethylene glycol in the choline chloride-ethylene glycol ionic liquid is 1:2, the concentration of copper salt is 0.01~0.50 mol/L, and the concentration of thiourea is 0.01~0.40 mol/L.

The copper salt is copper chloride.

Step 2) The composition of the alkaline solution is: 20 g/L Na ₂ CO ₃ , 10 g/L NaOH, 5 g/L Na ₃ PO ₄ ·12H ₂ O, and the composition of the acid solution is: HF 0.07mL/mL.

The concentrations of NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ ·H ₂ O in the Ni-P alkaline plating solution are 10.5~16.0 g/L, 10.0~24.0 g/L, 17.5~40.0 g/L.

The concentrations of NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ ·H ₂ O, CH ₃ COONa·3H ₂ O in the Ni-P acidic plating solution are 10.5~16.0 g/L, 10.0~24.0 g/L, 17.5~40.0 g/L, 15~25 g/L.

Compared with the prior art, the present invention has the following advantages:

1) In the present invention, the aluminum alloy is pretreated by immersion copper plating and then electroless Ni-P plating, and a uniform and dense Ni-P coating can be obtained under medium and low temperature conditions in a short period of time.

2) The rapid electroless Ni-P plating method of the present invention does not need to input additional energy, nor does it need to add any catalysts and accelerators under the medium and low temperature conditions of the surface of the aluminum alloy pretreated by immersion plating.

3) The present invention uses the green and environment-friendly choline chloride-ethylene glycol ionic liquid as the solvent for aluminum alloy copper plating treatment, the treatment method is simple and easy to operate, and a uniform copper bottom layer can be obtained within a certain period of time.

4) In the present invention, after the aluminum alloy is dipped in copper, the deposition rate of electroless Ni-P is higher than that of the zinc dipped and untreated aluminum alloy under the medium and low temperature conditions of 30~60°C.

5) In the present invention, after the aluminum alloy is subjected to immersion copper plating treatment, the obtained Ni-P is uniform and dense, and has excellent corrosion resistance.

6) The method of the present invention expands the scope of application of electroless Ni-P plating in aluminum alloy surface treatment, and provides a new technical approach for further popularization and application of electroless plating process in aluminum alloy surface treatment.

Description of drawings

Fig. 1 is a comparison result diagram of the electroless Ni-P deposition rate of aluminum alloy pretreated by immersion plating of copper in the present invention and aluminum alloys treated by immersion zinc and without immersion plating treatment.

Fig. 2 is the microscopic morphology of the copper layer (a) and the Ni-P plating layer (b) obtained by immersion copper plating on the surface of the aluminum alloy according to the present invention.

detailed description

Example 1

The method for rapid electroless plating of Ni-P at low temperature on the surface of aluminum alloy based on immersion copper pretreatment, the specific process conditions and operation steps are as follows:

1) Preparation of copper immersion plating solution: Weigh 1.70 g of CuCl ₂ 2H ₂ O and 0.76 g of thiourea into the prepared choline chloride-ethylene glycol ionic liquid, stir and dissolve, and prepare a 100 mL solution;

2) Sample pretreatment: grind and clean the aluminum alloy; place it in an alkaline solution at 65~75˚C, wash it with water after 5~10 min; then place it in an acid solution at room temperature for 0.5~3 min, and finally washed with acetone;

3) Immersion copper plating treatment: immerse the treated aluminum alloy in the copper plating solution, place it at 30˚C for 4 h, take out the sample, wash it with choline chloride-ethylene glycol ionic liquid, water and ethanol in sequence, and then dry;

4) Preparation of electroless Ni-P plating solution: the concentration of each component of the plating solution is as follows: NiSO ₄ 6H ₂ O 10.5 g/L, Na ₃ C ₆ H ₅ O ₇ 2H ₂ O 23.5 g/L, NaH ₂ PO ₂ ·H ₂ O 17.5 g/L, add ammonia to adjust the pH between 9.1 and 9.4;

5) Electroless Ni-P plating: The aluminum alloy treated with immersion copper was placed in the Ni-P plating solution, and reacted at 40 °C for 0.5 h to obtain the Ni-P coating, washed with water, and dried.

Fig. 1 is the comparison result of Ni-P deposition rate of electroless plating of aluminum alloy pretreated by immersion copper plating in the present invention and aluminum alloy treated by immersion zinc and without immersion plating treatment. It can be seen from the figure that the deposition rate (5.36 g/dm ³ h) of electroless Ni-P on the aluminum alloy surface after immersion copper plating treatment at 40˚C is higher than that of zinc immersion treatment (3.04 g/dm 3 h) at the same temperature. dm ³ ·h) and the deposition rate of aluminum alloy without immersion treatment (2.84 g/dm ³ ·h).

Example 2

The method for rapid electroless plating of Ni-P at low temperature on the surface of aluminum alloy based on immersion copper pretreatment, the specific process conditions and operation steps are as follows:

1) Preparation of copper immersion plating solution: Weigh 2.56 g of CuCl ₂ 2H ₂ O and 1.14 g of thiourea into the prepared choline chloride-ethylene glycol ionic liquid, stir and dissolve, and prepare a 100 mL solution;

2) Sample pretreatment: same as Example 1;

3) Immersion copper plating treatment: immerse the treated aluminum alloy in the copper plating solution, place it at 30˚C for 3 h, take out the sample, wash it with choline chloride-ethylene glycol ionic liquid, water and ethanol in sequence, and then dry;

4) Preparation of electroless Ni-P plating solution: same as Example 1;

5) Electroless Ni-P plating: The aluminum alloy treated with immersion copper was placed in the prepared Ni-P plating solution, and reacted at 60 °C for 0.5 h to obtain a Ni-P coating, washed with water, and dried.

The deposition rate of electroless Ni-P plating was compared, and the results are shown in Figure 1. The deposition rate (14.9 g/dm ³ h) of electroless Ni-P plating on aluminum alloy was significantly higher after immersion copper plating at 60˚C Deposition rates of zinc-dipped (8.20 g/dm ³ ·h) and uncoated (6.32 g/dm ³ ·h) aluminum alloys under the same temperature conditions.

Example 3

The method for rapid electroless plating of Ni-P at low temperature on the surface of aluminum alloy based on immersion copper pretreatment, the specific process conditions and operation steps are as follows:

1) Preparation of copper immersion plating solution: Weigh 3.40 g of CuCl ₂ 2H ₂ O and 1.52 g of thiourea into the prepared choline chloride-ethylene glycol ionic liquid, stir and dissolve, and prepare a 100 mL solution;

2) Sample pretreatment: same as Example 1;

3) Immersion copper plating treatment: immerse the treated aluminum alloy in the copper plating solution, place it at 30˚C for 2 h, take out the sample, wash it with choline chloride-ethylene glycol ionic liquid, water and ethanol successively, and then dry;

4) Preparation of electroless Ni-P plating solution: same as Example 1;

5) Electroless Ni-P plating: The aluminum alloy treated with immersion copper was placed in the prepared Ni-P plating solution, and reacted at 30 °C for 0.5 h to obtain a Ni-P coating, washed with water, and dried.

Comparing the rate of electroless Ni-P plating, the deposition rate (2.61 g/dm ³ h) of immersion copper treatment aluminum alloy at 30˚C is higher than that of zinc immersion treatment (0.46 g/dm ³ h) at the same temperature. h) and the deposition rate of aluminum alloy without dipping treatment (1.82 g/dm ³ ·h).

Example 4

The method for rapid electroless plating of Ni-P at low temperature on the surface of aluminum alloy based on immersion copper pretreatment, the specific process conditions and operation steps are as follows:

1) Preparation of copper immersion plating solution: same as in Example 2;

2) Sample pretreatment: same as Example 1;

3) copper immersion plating treatment: same as embodiment 2;

4) Preparation of electroless Ni-P plating solution: the concentration of each component of the plating solution is as follows: NiSO ₄ 6H ₂ O 15.0 g/L, Na ₃ C ₆ H ₅ O ₇ 2H ₂ O 10.0 g/L, NaH ₂ PO ₂ H ₂ O 40.0 g/L, CH ₃ COONa·3H ₂ O 20.0 g/L, add lactic acid to adjust the pH between 4.0 and 6.0;

5) Electroless Ni-P plating: The aluminum alloy treated with immersion copper was placed in the prepared Ni-P plating solution, and reacted at 60 °C for 1.5 h to obtain a Ni-P coating, washed with water, and dried.

Comparing the rate of electroless Ni-P plating, the deposition rate (22.3 g/dm ³ h) of aluminum alloy treated by dipping copper at 60˚C is higher than that of zinc dipping (14.4 g/dm ³ h) at the same temperature. h) and the deposition rate of aluminum alloy without dipping treatment (17.7 g/dm ³ ·h). Fig. 2 is the microscopic morphology of the copper layer (a) and the Ni-P coating (b) obtained by immersion copper plating on the surface of the aluminum alloy according to the present invention. It can be seen from the figure that the obtained copper layer and the Ni-P coating are uniform and compact , with no obvious defects.

Claims (9)

1. a kind of method based on the aluminum alloy surface of immersion plating copper pretreatment low-temperature fast electroless plating Ni-P, it is characterized in that the method comprises the following steps: 1) Preparation of copper immersion plating solution: the plating solution is composed of choline chloride-ethylene glycol ionic liquid, copper salt and thiourea; 2) Sample pretreatment: After grinding and cleaning the aluminum alloy, place it in an alkaline solution at 65~75˚C, wash it with water for 5~10 minutes; then put it in an acid solution at room temperature for 0.5~3 minutes, and finally use Acetone washing; 3) Immersion copper plating treatment: Put the treated aluminum alloy into the plating solution described in step 1), let it stand at 20~30˚C for 1~6 h, and then use choline chloride-ethylene glycol ion successively Liquid, water and ethanol washes followed by drying; 4) Preparation of electroless Ni-P plating solution: Ni-P plating solution is alkaline plating solution or acidic plating solution, alkaline plating solution is composed of NiSO ₄ 6H ₂ O, Na ₃ C ₆ H ₅ O ₇ 2H ₂ O and NaH ₂ PO ₂ ·H ₂ O, adjust its pH between 8.0~11.0; the acidic plating solution is composed of NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ Composition of H ₂ O and CH ₃ COONa·3H ₂ O, adjust its pH between 4.0 and 7.0; 5) Electroless Ni-P plating: Place the aluminum alloy treated with immersion copper in the electroless Ni-P plating solution, place it at 30~60˚C for 0.5~5 h, wash with water, and dry to obtain the Ni-P coating . 2. The method according to claim 1, characterized in that: said step 1) in the choline chloride-ethylene glycol ionic liquid, the mol ratio of choline chloride and ethylene glycol is 1:2, the copper salt The concentration is 0.01~0.50 mol/L, the concentration of thiourea is 0.01~0.40 mol/L. 3. The method according to claim 1 or 2, characterized in that: the copper salt is copper chloride. 4. The method according to claim 1, characterized in that: the composition of the alkaline solution in step 2) is 20 g/L Na ₂ CO ₃ , 10 g/L NaOH, 5 g/L Na ₃ PO ₄ ·12H ₂ O. 5. The method according to claim 1, characterized in that: the composition of the acid solution in step 2) is 0.07mL/mL HF. 6. The method according to claim 1, characterized in that: NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ · The concentration of H ₂ O is 10.5~16.0 g/L, 10.0~24.0 g/L, 17.5~40.0 g/L in turn. 7. The method according to claim 1, characterized in that: NiSO ₄ ·6H ₂ O, Na ₃ C ₆ H ₅ O ₇ ·2H ₂ O, NaH ₂ PO ₂ ·H in the Ni-P acidic plating solution The concentrations of ₂ O and CH ₃ COONa·3H ₂ O were 10.5-16.0 g/L, 10.0-24.0 g/L, 17.5-40.0 g/L, 15-25 g/L. 8. The method according to claim 1, characterized in that: the pH of the alkaline plating solution is adjusted with ammonia water. 9. The method according to claim 1, characterized in that: the pH of the acidic plating solution is adjusted with lactic acid.