CN115807248A - Silver plating brightener and preparation method thereof - Google Patents

Abstract

The invention discloses a silver plating brightener and a preparation method thereof, the main components comprise deionized water, a metal compound, a surfactant, a complexing agent, ammonia water and an alkaline compound, and the brightener has the advantages of high silver plating speed, full bright surface, fine crystallization of a plating layer, high hardness of a silver plating layer up to 160-200HV, excellent conductivity, high binding degree and the like, and is excellent in conductivity, high in binding degree and the like; and the preparation process of the brightener is simple, easy to control and suitable for industrial production and application. The invention is suitable for preparing the silver plating brightener.

Description

Silver plating brightener and preparation method thereof

Technical Field

The invention belongs to the technical field of silver plating, and relates to a silver plating brightener and a preparation method thereof.

Background

Silver plating is the process of depositing metallic silver on the surface of an object. The surface state after silver plating has a large relationship with the silver plating solution, and only a plating layer with smooth and bright surface and firm combination with the surface of an object can be accepted by the market.

Theoretical research shows that the silver plating process can obtain ideal plating only under the control mechanism of brightener diffusion and can control the size of silver crystal on the surface of the sediment. In the presence of a brightener, the brightener (usually a surfactant) is capable of causing silver ions to first migrate to depressions in the surface of the object in relief, where the deposition levels the surface, and then the silver ions are uniformly deposited on the leveled surface again, theoretically leveling the surface. However, silver undergoes a series of nucleation-growth processes after surface deposition to form crystals, and if the crystal grains are too large, cracks and voids occur even in a flat surface. Therefore, when silver plating is performed by electroplating, the size of the silver grains must be controlled so that a smooth and bright plating can be formed.

Although scholars in various countries in the world make intensive and long-term silver plating process researches, the silver electroplating technology realizes industrial production at present and obtains good social effect and economic effect, the silver plating also has the defects of slow plating speed, insufficient white and bright appearance of a plating layer, insufficient firmness of combination, poor appearance of the plating layer and the like. Therefore, there is a need to develop a silver plating brightener which can make the plating surface smooth, bright and highly combined to meet the requirements of actual production.

Disclosure of Invention

The invention aims to provide a silver plating brightener and a preparation method thereof, the main components of the brightener comprise deionized water, a metal compound, a surfactant, a complexing agent, ammonia water and an alkaline compound, the brightener has the advantages of high silver plating speed, full bright surface, fine crystallization of a plating layer, high hardness, excellent conductivity, high binding degree and the like, and the brightener is simple in preparation process, easy to control and suitable for industrial production and application.

The technical scheme of the invention is as follows:

the silver plating brightener comprises the following components in parts by weight;

50-80 parts of deionized water, 1-10 parts of metal compound, 0.1-3 parts of surfactant, 0.5-5 parts of complexing agent, 5-10 parts of ammonia water and 7 parts of alkaline compound.

As a limitation of the present invention, the metal compound is KCNSe or Sb ₂ O ₅ 、Sb ₂ O ₃ Or any two or any three of antimony potassium tartrate.

As a second limitation of the present invention, the surfactant is one or more of betaine, fatty alcohol-polyoxyethylene ether, fatty amide phosphate, fatty amide propyl phosphate betaine, diethylenetriamine, polyethyleneimine, or N-alkyl alanine salt.

As a third limitation of the present invention, the complexing agent is a mixture of 1:1 and EDTA.

As a fourth limitation of the present invention, the alkaline compound is prepared by compounding sodium hydroxide and potassium hydroxide according to a weight ratio of 6.

The invention also provides a preparation method of the silver plating brightener, which comprises the following steps in sequence:

s1, adding a metal compound into deionized water, and stirring for 20min to obtain A;

s2, heating the A to 40 ℃, adding a surfactant and a complexing agent into the A, and uniformly stirring to obtain B;

and S3, cooling the B to room temperature, sequentially adding ammonia water and an alkaline compound, and stirring until the solution is clear to obtain the silver plating brightener.

The silver plating brightener is used for adding the silver plating brightener into silver plating solution to plate a silver layer on a piece to be plated, and the technological parameters of the electroplating process are as follows: the pH value of the silver plating bath solution is 12-14, the temperature range is 15-35 ℃, and the operating current density is 0.3-2.0A/dm ² And the silver content in the bath solution is 30-60g/L.

The formula of the brightener has important influence on the silver plating effect of the brightener, which mainly influences nucleation and growth of silver grains. The metal compound acts as a stress relief agent and a brightener during grain growth. In the electroplating process, as silver is deposited on the surface of a cathode, electrochemical reaction is continuously generated in an electroplating system, chemical components of a plating solution near the electrode are continuously changed, along with the electroplating, the resistance of the plating solution is increased, the polarization of the electrode is generated, and the current efficiency is reduced. When the bright liquid does not contain the metal compound, the charge transfer capacity of the system is relatively poor, so that the quantity of silver ions deposited on the surface of the cathode is reduced in the same time, silver crystal nuclei are fewer, the crystal growth speed is higher, the crystal grains are coarse, the surface of a plating layer is in a coarse granular structure, and the brightness is very low. After the metal compound, the surfactant and other substances in the formula are compatible, the surface of a plated coating presents a regular net structure, the metal compound is strongly adsorbed on certain active points of a cathode under the synergistic action of the surfactant, the complexing agent, the alkaline compound and other substances, so that crystals grow in an oriented mode during silver electric crystallization, the crystal grains are fine, the net structure is finally formed, and the surface is smooth and bright and high in firmness.

The surface active agent with proper proportion can be diffused and adsorbed on the convex and convex parts with larger surface tension, active parts and special crystal faces of the object, so that silver atoms adsorbed on the surface of the object are migrated to the concave parts on the surface of the object and enter crystal lattices, thereby playing the role of brightening and leveling. The surfactant with polar groups adopted by the invention has good solubility and diffusion capability in aqueous solution, can be adsorbed on the convex parts with larger surface tension of the electrode, and has larger polarity because the surface of the cathode, particularly the convex parts on the surface, is influenced by unsaturated chemical bonds. The surfactant with polar groups is preferably adsorbed at the places, and simultaneously under the synergistic action of metal compounds in the brightener, the deposition, nucleation, oriented growth and growth of silver ions are influenced together, so that the silver ions are firstly deposited in concave positions on the surface of the cathode in the electroplating process, and are uniformly deposited on all parts of the surface of the cathode after the surface is leveled, and finally, a high-quality silver coating is formed.

The technical effects obtained by adopting the technical scheme are as follows:

1. the brightener has the advantages of high silver plating speed, full bright surface, fine crystal grains, fine crystallization of a plating layer, high hardness of 160-200HV, excellent conductivity, high binding degree and the like;

2. the preparation process of the brightener is simple and easy to control, and is suitable for industrial production and application.

3. The brightener can widen the application range of the pH, the temperature and the current density of the electroplating solution, and has wider applicability;

4. the brightener has good dispersibility for metal particles precipitated in electroplating, is beneficial to improving the smoothness and brightness of the surface of a plated part, and improves the quality of the whole silver coating;

5. the brightener can reduce surface (interface) surface tension, is favorable for wetting a plated part, and is favorable for smoothly carrying out a later electroplating process to ensure that the silver deposition speed is high and the plating layer is thick.

The invention is suitable for preparing the silver plating brightener.

The following description will be provided to further explain the embodiments of the present invention in detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a microstructure of a silver-plated layer surface of example 1 of the present invention under a metallographic microscope at 400 times magnification;

FIG. 2 is a photoelectron spectrum of the surface of a silver plating layer in example 1 of the present invention.

Detailed Description

In the following examples, commercially available reagents were used as the reagents unless otherwise specified, and conventional experimental methods and detection methods were used as the following experimental methods and detection methods unless otherwise specified.

EXAMPLE 1 silver plating brightener

To 74g of deionized water, a metal compound (1 g of KCNSe, 5g of Sb) was added at room temperature ₂ O ₅ ) Stir for 20min, wait for it to dissolve completely. Heating the solution to 40 ℃, and sequentially adding 1g of betaine, 0.25g of glycerol, 0.25g of EDTA and 0.1g of fatty alcohol-polyoxyethylene ether CH ₃ (CH ₂ ) ₇ O(CH ₂ CH ₂ O) ₇ H. 0.9g of fatty acid amide propyl phosphate betaine, and stirred until it was completely dissolved. And then cooling the solution to room temperature, sequentially adding 10g of ammonia water, 6g of NaOH and 1g of KOH, stirring and waiting for the solution to be completely clarified to obtain the silver plating brightener.

The brightener prepared in this example was added to the silver plating solution to perform electroplating, and the silver plating surface of the plated article was tested, as shown in fig. 1 and 2, the plating layer formed after the brightener of the present invention was added had crystal grains with uniformly distributed sizes on the surface, the crystal grains were between several microns, and the crystal grains were fine.

As can be seen from FIG. 2, the Ag content on the surface of the plating layer was 99.6%, and the Mg content was 0.4%.

The coating prepared by the embodiment has better smoothness, brightness and flatness, high surface hardness of 200HV measured by a Vickers hardness tester, high deposition speed and thick coating, and the coating thickness can reach 9.3 microns within 2 minutes under the current of 2.0A.

EXAMPLE 2 silver plating brightener

To 50g of deionized water at room temperature was added a metal compound (0.3g of KCNSe,0.7g of Sb) ₂ O ₃₎ And stirring for 20min to wait for complete dissolution. The solution was warmed to 40 ℃ and 1g betaine, 0.5g glycerol, 0.5g EDTA, 0.5g fatty amide phosphate, 0.5g fatty amide propyl phosphate betaine, 1g N-alkyl alanine salt were added in sequence and stirred until they were completely dissolved. And then cooling the solution to room temperature, sequentially adding 5g of ammonia water, 6g of NaOH and 1g of KOH, stirring and waiting for the solution to be completely clarified to obtain the silver plating brightener.

The brightening agent prepared in the embodiment is added into the silver plating solution for electroplating, and the surface of the silver plating layer of the plated part is tested, so that the smoothness, the brightness and the flatness of the plating layer prepared in the embodiment reach better states, the surface hardness of the plating layer is high, the surface hardness measured by a Vickers hardness tester is 178HV, the deposition speed is high, the plating layer is thick, and the thickness of the plating layer can reach 9.1 micrometers within 2 minutes under the current of 2.0 amperes.

Example 3A silver plating brightener

To 80g of deionized water, a metal compound (2 g of Sb) was added at room temperature ₂ O ₅ ，3g Sb ₂ O ₃ ) Stir for 20min, wait for it to dissolve completely. Heating the solution to 40 ℃, and adding 0.05g of polyethyleneimine and 0.05g of polyethyleneimine in sequenceg diethylenetriamine, 1g glycerol and 1g EDTA. Stirring until it is completely dissolved. And then cooling the solution to room temperature, sequentially adding 8g of ammonia water, 6g of NaOH and 1g of KOH, and stirring until the solution is completely clear to obtain the silver plating brightener.

The brightening agent prepared in the embodiment is added into the silver plating solution for electroplating, and the surface of the silver plating layer of the plated part is tested, so that the smoothness, the brightness and the flatness of the plating layer prepared in the embodiment reach better states, the surface hardness of the plating layer is high, the surface hardness measured by a Vickers hardness tester is 160HV, the deposition speed is high, the plating layer is thick, and the thickness of the plating layer can reach 9.0 micrometers within 2 minutes under the current of 2.0 amperes.

EXAMPLE 4A silver plating brightener

To 74g of deionized water, at room temperature, was added a metal compound [2g of antimony potassium tartrate (C) ₈ H ₄ K ₂ O ₁₂ Sb ₂ ),3gSb ₂ O ₅ ，5gSb ₂ O ₃ ]And stirring for 20min to wait for complete dissolution. Heating the solution to 40 ℃, and sequentially adding 1g of betaine and 0.1g of fatty alcohol-polyoxyethylene ether CH ₃ (CH ₂ ) ₇ O(CH ₂ CH ₂ O) ₇ H. 0.9g of fatty acid amide propyl phosphate betaine, 1g of N-alkyl alanine salt, 2.5g of glycerin, and 2.5g of EDTA, and stirred until they are completely dissolved. And then cooling the solution to room temperature, sequentially adding 5g of ammonia water, 6g of NaOH and 1g of KOH, and stirring until the solution is completely clear to obtain the silver plating brightener.

The brightener prepared in the embodiment is added into the silver plating solution for electroplating, and the surface of the silver plating layer of a plated piece is tested, so that the smoothness, the brightness and the flatness of the plating layer prepared in the embodiment reach better states, the surface hardness of the plating layer is high, the surface hardness measured by a Vickers hardness tester is 192HV, the deposition speed is high, the plating layer is thick, and the plating layer thickness can reach 9.2 micrometers within 2 minutes under the current of 2.0 amperes.

Example 5 comparative example

In this example, a series of experimental studies were conducted on the effect of the addition of different metal compounds on the brightener, which was prepared in the same manner as in example 1 except that: the brightener formula is different from the brightener, and the dosage of other components is the same as that in example 1, specifically as follows:

group A: the brightener is not added with metal compounds;

group B: the brightener is added with a sulfur-containing compound (sodium thiosulfate) to replace a metal compound;

group C: the brightener is added with metal compound (1 g KCNSe, 5g K) ₂ Se)；

Group D: 1g of single metal compound KCNSe is added into the brightening agent;

group E: the brightener is added with a single metal compound of 5g of Sb ₂ O ₅ ；

And F group: 1g of selenious acid which is a single metal compound is added into the brightening agent;

group G: the brightener is added with metal compounds (1 g selenious acid, 5g Sb) ₂ O ₅ )

Group H: the brightener was added with a single metal compound 2g of antimony potassium tartrate (C) ₈ H ₄ K ₂ O ₁₂ Sb ₂ )；

Group I: no complexing agent is added into the brightening solution;

the brightening solution of the group is prepared and then added into the silver plating solution to plate the surface of a plated part, and the result condition of the silver plating layer is shown in the table.

TABLE 1 results comparison Table

Group of	Smoothness and brightness	Flatness of	Hardness (HV)	Surface silver content%
					Group A	In general	In general	130	98.0
Group B	Difference between	In general terms	125	97.0
					Group C	Is preferably used	Is very good	155	99.0
Group D	Is better	Is better	152	99.0
					Group E	Is very good	Is preferably used	148	99.3
Group F	Is preferably used	Is very good	155	99.1
					Group G	Is very good	Is preferably used	157	99.2
Group H	Is very good	Is preferably used	150	99.0
					Group I	In general	In general	130	97.0

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (6)

1. A silver plating brightener is characterized by comprising the following components in parts by weight;

50-80 parts of deionized water, 1-10 parts of metal compound, 0.1-3 parts of surfactant, 0.5-5 parts of complexing agent, 5-10 parts of ammonia water and 7 parts of alkaline compound.

2. The method of claim 1The silver plating brightener is characterized in that the metal compound is KCNSe or Sb ₂ O ₅ 、Sb ₂ O ₃ Or any two or any three of antimony potassium tartrate.

3. The silver plating brightener as claimed in claim 1, wherein the surfactant is one or more of betaine, fatty alcohol polyoxyethylene ether, fatty amide phosphate, fatty amide propyl phosphate betaine, diethylenetriamine, polyethyleneimine or N-alkyl alanine salt.

4. The silver plating brightener according to claim 1, wherein the complexing agent is prepared from a mixture of the following components in a weight ratio of 1:1 and EDTA.

5. The silver plating brightener according to claim 1, wherein the alkaline compound is a mixture of sodium hydroxide and potassium hydroxide in a weight ratio of 6.

6. The process for producing a silver-plating brightener as claimed in any one of claims 1 to 5, characterized by being produced by the following steps in the order named:

s1, adding a metal compound into deionized water, and stirring for 20min to obtain A;

s2, heating the A to 40 ℃, adding a surfactant and a complexing agent into the A, and uniformly stirring to obtain B;

and S3, cooling the B to room temperature, sequentially adding ammonia water and an alkaline compound, and stirring until the solution is clear to obtain the silver plating brightener.

Images