阅读说明：本技术 一种在钛或钛合金基材表面电镀金的方法 (Method for electroplating gold on surface of titanium or titanium alloy substrate ) 是由 庞美兴 曾文涛 于 2021-06-29 设计创作，主要内容包括：本发明涉及一种在钛或钛合金基材表面电镀金的方法,包括如下步骤：步骤一,除膜；步骤二,除油；步骤三,将钛或钛合金基材置于蚀刻溶液中进行蚀刻,中和除油过程中的溶液残留,增强钛或钛合金基材表面粗糙度；步骤四,将钛或钛合金基材表调溶液中进行表调,增强钛或钛合金基材表面结合力；步骤五,将钛或钛合金基材置于预镀镍溶液中进行电镀镍,预镀镍溶液包括50-70g/L的可溶性镍盐和0.5-2mL/L的羟乙酸镍；步骤六,在钛或钛合金基材表面电镀镍；步骤七,对钛或钛合金基材表面的镀镍层进行酸洗,活化镀镍层的表面；步骤八,将钛或钛合金基材进行电镀金,镀金溶液包括1.8-2.2g/L的氰化亚金钾、120-180g/L的开缸剂A、25-35g/L的开缸剂B、30-60mL/L的2-苯胺嘧啶-5-羧酸和2.5-5.5mL/L的乙醇胺。(The invention relates to a method for electroplating gold on the surface of a titanium or titanium alloy substrate, which comprises the following steps: step one, removing a film; step two, removing oil; step three, placing the titanium or titanium alloy base material in an etching solution for etching, neutralizing solution residues in the oil removal process, and enhancing the surface roughness of the titanium or titanium alloy base material; fourthly, performing surface adjustment on the titanium or titanium alloy substrate in the surface adjustment solution to enhance the surface bonding force of the titanium or titanium alloy substrate; placing the titanium or titanium alloy substrate in a nickel pre-plating solution for nickel electroplating, wherein the nickel pre-plating solution comprises 50-70g/L of soluble nickel salt and 0.5-2mL/L of nickel glycolate; step six, electroplating nickel on the surface of the titanium or titanium alloy substrate; step seven, carrying out acid cleaning on the nickel plating layer on the surface of the titanium or titanium alloy base material, and activating the surface of the nickel plating layer; step eight, performing gold electroplating on the titanium or titanium alloy substrate, wherein the gold plating solution comprises 1.8-2.2g/L of aurous potassium cyanide, 120-180g/L of a cylinder opener A, 25-35g/L of a cylinder opener B, 30-60mL/L of 2-anilinopyrimidine-5-carboxylic acid and 2.5-5.5mL/L of ethanolamine.)

1. A method for electroplating gold on the surface of a titanium or titanium alloy substrate is characterized by comprising the following steps:

removing a film, namely removing an oxide film on the surface of the titanium or titanium alloy substrate;

removing oil, namely removing oil stains on the surface of the titanium or titanium alloy base material;

thirdly, placing the titanium or titanium alloy base material into an etching solution for etching, neutralizing solution residues in the oil removal process, and enhancing the surface roughness of the titanium or titanium alloy base material;

fourthly, performing surface adjustment on the titanium or titanium alloy substrate in the surface adjustment solution to enhance the surface bonding force of the titanium or titanium alloy substrate;

putting the titanium or titanium alloy base material into a nickel pre-plating solution for nickel electroplating, wherein the nickel pre-plating solution comprises 50-70g/L of soluble nickel salt and 0.5-2mL/L of nickel glycolate;

step six, electroplating nickel on the surface of the titanium or titanium alloy substrate;

step seven, carrying out acid cleaning on the nickel plating layer on the surface of the titanium or titanium alloy base material, and activating the surface of the nickel plating layer;

step eight, performing gold electroplating on the titanium or titanium alloy substrate, wherein the gold plating solution comprises 1.8-2.2g/L of aurous potassium cyanide, 120-180g/L of a cylinder opener A, 25-35g/L of a cylinder opener B, 30-60mL/L of 2-anilinopyrimidine-5-carboxylic acid and 2.5-5.5mL/L of ethanolamine.

2. The method of claim 1, wherein: the etching solution comprises 300-400mL/L HF and 30-50mL/L HCl.

3. The method of claim 1, wherein: the surface conditioning solution comprises 30-50g/L NaBF₄30-50g/L of NaNO₃And 2-5g/L of Ti (SO)₄)₂。

4. The method of claim 1, wherein: the cylinder opening agent A is prepared by mixing sodium gold sulfite and ammonium sulfite according to the mass ratio of 1: 200-300.

5. The method of claim 1, wherein: the jar opener B is EDTA disodium.

Technical Field

The invention relates to a metal material surface treatment technology, in particular to a method for electroplating gold on the surface of a titanium or titanium alloy substrate.

Background

Titanium is a metal with high chemical property and activity, is very easy to passivate under the condition of oxygen, has excellent corrosion resistance, and has high specific strength, so the titanium and the titanium alloy are widely applied to a plurality of fields such as chemical industry, aerospace, military industry and the like. However, titanium and titanium alloys have poor conductivity and thus have limited applications, and therefore, the surfaces of titanium and titanium alloys are treated. For example, gold is electroplated on the surface of titanium or titanium alloy to improve the electrical and thermal conductivity of the material, reduce the infrared radiation capability of the material, and simultaneously enable brazing on the surface of the material. However, the technical problems of the existing technical scheme for electroplating gold on the surface of titanium or titanium alloy are as follows:

1. TiO is easily generated on the surface of titanium and titanium alloy₂Oxide film, after removing the oxide film on the surface of titanium or titanium alloy before gold plating, TiO is formed as long as titanium or titanium alloy is left in air or water for a few seconds₂Oxide film is generated again, and H, O, N and other elements in the air or cleaning liquid are easily transferred to TiO₂The factors not only obviously reduce the binding force between the subsequent gold plating layer and the titanium or titanium alloy, but also even cause the peeling and bubbling of the gold plating layer;

2. the potential of titanium and titanium alloy is very negative, so the surface is easily replaced by metal ions such as nickel, copper, gold and the like, and a replacement plating layer with very low bonding strength is formed, so that the bonding force between the gold plating layer and the titanium or titanium alloy is low;

3. the prior gold electroplating technology applied to the surfaces of titanium and titanium alloy is cyanide gold electroplating, but cyanide as a highly toxic chemical poses great threat to the environment and operators.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a method for electroplating gold on the surface of a titanium or titanium alloy substrate, the method has excellent bonding force between a gold-plated layer prepared on the surface of the titanium or titanium alloy substrate and the substrate, and the method can reduce the content of cyanide in a cyanide gold-plating solution, so that the cyanide gold-plating solution is low in toxicity and can be kept stable.

In order to achieve the purpose, the invention adopts the following technical scheme: a method for electroplating gold onto a surface of a titanium or titanium alloy substrate, the method comprising the steps of:

removing a film, namely removing an oxide film on the surface of a titanium or titanium alloy substrate;

removing oil, namely removing oil stains on the surface of the titanium or titanium alloy base material;

etching, neutralizing solution residues in the oil removing process, and enhancing the surface roughness of the titanium or titanium alloy substrate;

surface adjustment is carried out, and the surface binding force of the titanium or titanium alloy base material is enhanced;

step five, pre-plating nickel on the surface of the titanium or titanium alloy base material;

step six, electroplating nickel on the surface of the titanium or titanium alloy substrate;

step seven, carrying out acid cleaning on the nickel plating layer on the surface of the titanium or titanium alloy base material, and activating the surface of the nickel plating layer;

and step eight, performing gold electroplating on the titanium or titanium alloy base material.

Because the bonding force between the gold plating layer obtained by directly plating gold on the surface of the titanium or titanium alloy base material and the titanium or titanium alloy base material is poor, the nickel plating layer is firstly prepared on the surface of the titanium or titanium alloy base material and is used as a connecting layer to improve the bonding force between the gold plating layer and the titanium or titanium alloy base material.

In order to improve the bonding force between the gold-plated layer and the titanium or titanium alloy substrate, the core point comprises: 1. when nickel is pre-plated on the surface of the titanium or titanium alloy base material in the fifth step, a thin metal nickel layer with high bonding strength with the titanium or titanium alloy base material is formed, and only if the metal nickel layer has high bonding strength with the titanium or titanium alloy base material, electroplating thickening can be carried out on the basis of the metal nickel layer in the sixth step to obtain a nickel-plated layer with good bonding force; 2. and step eight, when the gold plating is carried out, the gold plating solution is required to have good dispersing capacity and covering capacity, so that a gold plating layer with good binding force and fine plating layer crystals is obtained by deposition on the nickel plating layer.

And in the fifth step, the titanium or titanium alloy base material is placed in a nickel pre-plating solution for nickel electroplating, the nickel pre-plating solution comprises 50-70g/L of soluble nickel salt and 0.5-2mL/L of nickel glycolate, the soluble nickel salt is a main source of nickel ions, and the nickel glycolate can reduce the internal stress of the formed metal nickel layer and improve the bonding strength of the metal nickel layer and the titanium or titanium alloy base material. The titanium or titanium alloy base material is used as a cathode, the stainless steel plate is used as an anode, the thickness of the metallic nickel layer obtained by the nickel preplating is not more than 2 mu m, the bonding strength of the metallic nickel layer and the titanium or titanium alloy base material can be influenced by the overlarge thickness, and the deposition rate of the nickel preplating is as follows: the deposition rate of 3ASD was about 0.5 μm/min.

The existing cyanide gold plating solution mainly comprises a gold cyanide complex salt and free cyanide, and the gold cyanide complex salt is a main source of gold ions, so that in order to reduce the content of cyanide in the cyanide gold plating solution, the core points comprise: 1. reducing the content of cyanide in the cyanide gold plating solution by reducing the content of free cyanide, but maintaining the stability of the gold plating solution and the original good dispersing capacity and covering capacity while reducing the content of the free cyanide; 2. other gold ion-containing salts are used to partially replace the gold cyanide complex salt to provide gold ions.

The gold plating solution of the present invention comprises: 1.8-2.2g/L of aurous potassium cyanide, 120-180g/L of a biscuit opening agent A, 25-35g/L of a biscuit opening agent B, 30-60mL/L of a brightening agent and 2.5-5.5mL/L of a wetting agent. Wherein, the potassium aurous cyanide is the main source of gold ions in the gold plating solution; the cylinder opening agent A can provide part of gold ions and stabilize the pH value of the solution; the jar opening agent B is used for preventing the brightener from decomposing; the brightener plays a role in generating hard and bright gold plating layers; the wetting agent helps to remove hydrogen gas in the cathode and thus prevents pinholes in the gold plating layer. When the gold plating solution is used for gold electroplating, the temperature of the gold plating solution is 25-55 ℃, a titanium or titanium alloy substrate at the temperature is used as a cathode, a metal titanium plate or metal platinum is used as an anode, and the current density is 0.1-0.3mA/cm during electroplating²The deposition rate of the gold plating solution is: the deposition rate of 0.5ASD was about 0.15 μm/min.

In the invention, the cylinder opening agent A is obtained by compounding sodium gold sulfite and ammonium sulfite according to the mass ratio of 1: 200-300. The jar opener B is EDTA disodium.

In the invention, the brightening agent is 2-aniline pyrimidine-5-carboxylic acid, and the wetting agent is ethanolamine. The inventor finds that the combination of brightener and wetting agent can be added into the gold plating solution to replace the action of free cyanide, thereby reducing the content of the free cyanide, the gold plating solution of the invention has good stability by adjusting the component proportion while reducing the toxicity, and the gold plating solution has no phenomena of turbidity, discoloration and the like within 30 days of use (including plating and supplementary components). Meanwhile, after 10mL of gold plating solution is continuously plated for 0.15Ah, a plating layer with excellent surface state can be obtained.

In the present invention, what is mainly responsible for reducing the cyanide content of the gold plating solution is the combined use of a brightener (2-anilinopyrimidine-5-carboxylic acid) and a wetting agent (ethanolamine), and the inventors found out that, in the combined test of the brightener and the wetting agent:

(1) if no brightener or wetting agent is added to the gold plating solution, the crystallization behavior of gold ions in the gold plating solution conforms to the theory of 'surface diffusion'. The electro-crystallization process of gold ions on the electroplated nickel layer on the surface of the titanium or titanium alloy substrate follows the growth mechanism of three-dimensional continuous nucleation, the growth of the gold-plated layer follows the Volmer-Weber mode, a plurality of three-dimensional islands are formed on crystal grains, the islands are gathered to form the gold-plated layer, and the obtained gold-plated layer is rough and not compact in surface.

(2) The brightener mainly plays a role in refining grains, the wetting agent mainly plays a role in leveling, and a bright and fine gold-plated layer can be obtained by adopting a mixed additive consisting of the brightener and the wetting agent, wherein the grain size of the gold-plated layer is within 160 nm. The synergistic coefficients of the brightener, the wetting agent and the combined additive formed by the two functions are respectively as follows: 5.8 percent, 0.48 percent and 20.43 percent, and the two additives have stronger synergistic action.

(3) If no brightener and wetting agent are added to the gold plating solution, the gold electrodeposition is subjected to a diffusion step; the brightener resists the electro-deposition of gold, and the gold electro-deposition rate is changed; the inhibition effect of the wetting agent on the electrodeposited zinc gold is not obvious, and the gold electrodeposition rate control step is not changed; when the brightener and the wetting agent are added into the gold plating solution at the same time, the inhibition effect is the maximum, and the electrodeposition is controlled by the electrochemical step.

(4) The brightening agent is added into the gold plating solution independently, so that the electro-crystallization mechanism of gold is changed, the brightening agent inhibits the growth of crystal nuclei, the overpotential of gold electrodeposition is increased, and the grains of the gold-plated layer are fine; the wetting agent is added into the gold plating solution independently, the electro-crystallization mechanism of gold is not changed, the additive B is adsorbed on the low potential point of the electroplated nickel layer on the surface of the titanium or titanium alloy substrate, and the active site is covered, so that the grain of the gold plating layer is large; when the brightener and the wetting agent are added into the gold plating solution at the same time, the inhibition effect on the growth of crystal nucleus is the maximum, and the obtained gold plating layer is bright and compact.

The beneficial effects of the invention at least comprise: 1. the binding force between the gold-plated layer and the titanium or titanium alloy substrate is improved; 2. the content of cyanide in the gold plating solution is reduced, and the toxicity of the gold plating solution is reduced.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

Taking an industrial titanium sheet (titanium alloy) with the reference number of TA2 and the volume of 35.0 multiplied by 50.0 multiplied by 1.0mm, the method for electroplating gold on the surface of the titanium or titanium alloy substrate for electroplating gold provided by the embodiment is adopted for the titanium sheet, and the specific steps are as follows:

firstly, removing a film, namely, using SiC sand paper (500#) to wet-grind the surface of a titanium sheet to be bright, placing the titanium sheet into a film removing agent solution (the mass content of active ingredients is not less than 75%) after water washing, and continuing for 15-25s, thereby removing an oxide film on the surface of a workpiece;

step two, deoiling, namely placing the titanium sheet in a deoiling solution for deoiling for 180-300s, thereby removing oil stains on the surface of the workpiece, wherein the deoiling solution comprises 30-50g/L of NaOH and 20-40g/L of NaCO₃20-40g/L of Na₃PO₄The temperature of the deoiling solution is 80-90 ℃; c

Step three, etching, namely placing the titanium plate in an etching solution at room temperature for etching for 15-25s so as to neutralize the residual oil removing solution on the surface of the titanium plate and enhance the surface roughness of the titanium plate, wherein the etching solution comprises 300-400mL/L HF and 30-50mL/L HCl;

fourthly, surface adjustment, namely, placing the titanium sheet in a surface adjustment solution for surface adjustment for 85 to 95 seconds so as to enhance the surface bonding force of the titanium sheet, wherein the surface adjustment solution comprises 30 to 50g/L of NaBF₄30-50g/L of NaNO₃And 2-5g/L of Ti (SO)₄)₂The temperature of the surface adjusting solution is 60-80 ℃,a layer of gray black film is generated on the surface of the titanium sheet after the surface adjustment is carried out on the titanium sheet;

step five, pre-plating nickel, namely putting the titanium sheet into a pre-plating nickel solution for nickel electroplating, wherein the pre-plating nickel solution comprises 50-70g/L of soluble nickel salt and 0.5-2mL/L of nickel glycolate, and the cathode current density is 0.5-1mA/cm²The electroplating time is 180-300 s;

step six, putting the titanium sheet into an electroplating nickel solution for electroplating nickel, wherein the electroplating nickel solution comprises 370-430g/L nickel sulfamate, 15-35g/L nickel chloride, 35-45g/L boric acid, 5-10mL/L softener (commercially available), and 0.5-2mL/L wetting agent (commercially available), and the electroplating nickel solution comprises the following steps: nickel sulfamate is the main source of nickel ions; the nickel chloride is used for increasing the conductivity of the plating solution, helping the anode to dissolve and reducing the anode polarization; boric acid is used to stabilize the pH; the softening agent is used for reducing the internal stress of the plating layer, increasing the ductility of the plating layer and improving the coverage capability of a low zone; the wetting agent is used to prevent pinholes in the coating. The time of nickel electroplating is 200-400s, and the cathode current density is 1-2mA/cm²The deposition rate of the electrolytic nickel plating solution is as follows: 5ASD deposition rate of about 1 μm/min;

step seven, carrying out acid cleaning on the nickel-plated layer on the surface of the titanium sheet, activating the surface of the nickel-plated layer, wherein an acid cleaning solution comprises 50-80mL/L sulfuric acid, and the acid cleaning time is 30-60 s;

step eight, carrying out gold electroplating on the titanium sheet, wherein the gold plating solution comprises: 1.8-2.2g/L potassium aurous cyanide, 120-180g/L cylinder opener A, 25-35g/L cylinder opener B, 30-60 mL/L2-anilinopyrimidine-5-carboxylic acid and 2.5-5.5mL/L ethanolamine, when the electrogilding is carried out, the temperature of the gilding solution is 25-55, the anode at the temperature adopts metal platinum, and the cathode current density is 0.1-0.3mA/cm²The plating time is 100-150 s.

And a water washing step is arranged between the adjacent steps, namely the surface of the titanium sheet is washed by distilled water.

The titanium sheet in this example was air-dried at 200 ℃ for not less than 4 hours after gold plating

Example 2

This example provides a method for electroplating gold on the surface of a titanium or titanium alloy substrate, which has the same specific steps as example 1, except that the method provided by this example is applied to a pure titanium plate, and the volume of the pure titanium plate is 35.0 × 50.0 × 1.0 mm.

The gold plating layers obtained in example 1 and example 2 were uniform and fine, had smooth surfaces, and were free from powder falling off during wiping. The gold plating layer is smooth, flat and compact. The gold plating layer was analyzed by scanning electron microscopy and no voids were observed. The titanium sheet after being plated is bent to one side by 90 degrees by a pliers, and then is bent to the other side by 90 degrees as rapidly as possible until the plated piece is broken, and the plating layer has good bonding force.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.