CN112226791A - Trivalent chromium plating solution, preparation method thereof and trivalent chromium plating method - Google Patents
Trivalent chromium plating solution, preparation method thereof and trivalent chromium plating method Download PDFInfo
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- CN112226791A CN112226791A CN202011159134.XA CN202011159134A CN112226791A CN 112226791 A CN112226791 A CN 112226791A CN 202011159134 A CN202011159134 A CN 202011159134A CN 112226791 A CN112226791 A CN 112226791A
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- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/04—Electroplating: Baths therefor from solutions of chromium
- C25D3/06—Electroplating: Baths therefor from solutions of chromium from solutions of trivalent chromium
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/04—Electroplating: Baths therefor from solutions of chromium
- C25D3/10—Electroplating: Baths therefor from solutions of chromium characterised by the organic bath constituents used
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Abstract
The application discloses a trivalent chromium plating solution, a preparation method thereof and a trivalent chromium plating method, belonging to the technical field of electroplating processes, and the trivalent chromium plating solution comprises the following components in parts by weight: 90-120 parts of chromium trichloride, 250 parts of conductive salt 200-650 parts of buffer agent, 40-60 parts of complexing agent, 0.05-0.1 part of wetting agent, 0.2-0.4 part of iron powder and 650 parts of deionized water 450-80. The trivalent chromium plating layer prepared by using the trivalent chromium plating solution solves the problems of yellowing and whitening of a common trivalent chromium plating layer, and also has the effect of slight dark color of imitation stainless steel color.
Description
Technical Field
The application relates to the technical field of electroplating processes, in particular to a trivalent chromium plating solution, a preparation method thereof and a trivalent chromium plating method.
Background
At present, chromium plating is one of the most widely applied plating in the electroplating industry, and chromium plating has the advantages of good hardness, wear resistance, corrosion resistance, decoration and the like, can be used as not only a decorative plating layer, but also a functional plating layer, and occupies an important position in the electroplating industry. For a long time, chromium plating uses hexavalent chromium, but hexavalent chromium has high toxicity and can cause cancer, the traditional hexavalent chromium plating process is gradually replaced and eliminated with the increasing attention of various countries in the world to environmental problems, trivalent chromium electroplating is taken as the most important electroplating which can directly and effectively replace hexavalent chromium, the problem of high toxicity of hexavalent chromium is solved, and the trivalent chromium electroplating has the advantages of high hardness, wear resistance, corrosion resistance and the like, and the trivalent chromium electroplating has incomparable superiority compared with the hexavalent chromium electroplating in terms of process performance or environmental protection.
The chloride system is a common system in the trivalent chromium electroplating process at present, and has the advantages of good conductivity, low bath pressure, high bath dispersing capacity, covering capacity and current efficiency, wide bright current density range, low anodic oxygen evolution overpotential, difficult oxidation of trivalent chromium and the like.
However, the problem of yellowing or whitening is common in the current commercial trivalent chromium coatings.
Disclosure of Invention
Aiming at the defects in the prior art, the first purpose of the application is to provide the trivalent chromium plating solution, the trivalent chromium plating layer prepared by using the trivalent chromium plating solution solves the problems of yellowing and whitening of the common trivalent chromium plating layer, and the precipitation of chlorine can be reduced when the trivalent chromium plating solution is used for electroplating.
The second purpose of the application is to provide a preparation method of the trivalent chromium plating solution, which is used for preparing the trivalent chromium plating solution.
The third purpose of the application is to provide a trivalent chromium plating method, and the method for preparing the trivalent chromium plating layer has the advantages of simple process and easily controlled process conditions.
In order to achieve the first object, the present application provides the following technical solutions:
a trivalent chromium plating solution comprises the following components in parts by weight:
90-120 parts of chromium trichloride, 250 parts of conductive salt 200-650 parts of buffer agent, 40-60 parts of complexing agent, 0.05-0.1 part of wetting agent, 0.2-0.4 part of iron powder and 650 parts of deionized water 450-80.
By adopting the technical scheme:
chromium trichloride is used as main salt, and the chloride system plating solution has better conductivity, low voltage, high dispersion capacity, covering capacity and current efficiency; preferably, the buffering agent adopts boric acid, and the boric acid has better effect on stabilizing the pH value of the plating solution in the plating solution of a chloride system; preferably, the wetting agent is sodium alkylsulfonate, and the addition of the sodium alkylsulfonate can reduce the pinholes of the plating layer, thereby improving the quality of the plating layer.
Adding iron powder into the chromium plating solution of trivalent chromium, wherein the chromium plating solution of trivalent chromium in a chloride system can generate toxic chlorine, the iron powder reacts with hydrogen ions in the chromium plating solution of trivalent chromium to generate ferrous ions, the ferrous ions can react with the chlorine to generate chloride ions and ferric ions, and the precipitation of the chlorine is inhibited by adding the iron powder; secondly, iron ions in the plating solution move to the cathode, so that the current efficiency of the cathode is improved, and the covering capacity of the plating solution is improved; and thirdly, iron ions are reduced by electrons obtained at the cathode and then are plated on the surface of the product together with chromium, the interlayer contains a small amount of iron, and the interlayer acts with the formula in the proportion to form a slight dark color imitating the color of stainless steel, so that the problems of yellowing and whitening of a common trivalent chromium plating layer are solved.
Preferably, the trivalent chromium plating solution also comprises 0.1-0.2 part of ferroferric oxide.
By adopting the technical scheme, the current efficiency of the cathode is low in the chromium plating process, a large amount of hydrogen is easily generated, if the hydrogen dissolved in the metal is not released in time in the metal solidification process, the hydrogen can diffuse to the vicinity of the defect in the metal, atomic hydrogen is combined into molecular hydrogen at the defect and continuously gathers, so that huge internal pressure is generated, the metal is cracked, and the added ferroferric oxide can react with the hydrogen to generate ferric ions and water, so that the separation of the hydrogen is effectively inhibited.
Preferably, the trivalent chromium plating solution also comprises 0.05 to 0.1 part of diphenylcarbodihydrazide.
By adopting the technical scheme, part of trivalent chromium ions lose electrons at the anode to generate hexavalent chromium ions, the diphenylcarbonyldihydrazide can react with the hexavalent chromium ions to generate the trivalent chromium ions, and the content of the hexavalent chromium ions in the plating solution can be reduced by adding the diphenylcarbonyldihydrazide, so that the toxicity of the product is reduced.
Preferably, the trivalent chromium plating solution also comprises 0.5-0.7 part of hydrofluoric acid.
By adopting the technical scheme, hydrofluoric acid can react with boric acid in the plating solution to generate fluoboric acid, the fluoboric acid can react with ferrous ions to generate ferrous fluoborate, and the ferrous fluoborate has a catalytic effect in the chromium plating process.
Preferably, the conductive salt is one of ammonium chloride, potassium chloride or sodium chloride.
By adopting the technical scheme, the conductive salt can improve the conductive capability of the trivalent chromium plating solution, thereby effectively reducing the consumption of electric energy.
Preferably, the complexing agent is one of formic acid, acetic acid or malic acid.
By adopting the technical scheme, the complexing agent can be effectively complexed with the main salt of the trivalent chromium plating solution in the process to form stable metal complex ions, so that the concentration polarization and the electrochemical polarization of the trivalent chromium plating solution are increased, the metal deposition speed is reduced, and the trivalent chromium plating layer is more delicate.
In order to achieve the second object, the present application provides the following technical solutions:
a preparation method of trivalent chromium plating solution comprises the following steps:
step 1: adding conductive salt and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 50-60 ℃, and stirring until the conductive salt and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 5-8 hours by using an electrolytic net, wherein the current of the electrolytic net is 15-30A during electrolysis;
and 4, step 4: adding a complexing agent and a wetting agent in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight parts, stirring for dissolving, and adding deionized water in corresponding weight parts.
By adopting the technical scheme, firstly, conductive salt and boric acid are added into an electroplating bath filled with deionized water at 50-60 ℃, the PH of the plating solution is stabilized and the conductive capacity of the plating solution is improved, then chromium trichloride is added and the plating solution is weakly electrolyzed for 5-8 hours by using an electrolytic network of 15-30A, the conductive capacity of the plating solution is further improved, then, a complexing agent and a wetting agent are added into the electroplating bath, the complexing agent can reduce the generation of precipitates in the plating solution, the wetting agent can reduce the surface tension of the plating solution and reduce pinholes of the plating layer, finally, iron powder is added, the iron powder is dissolved in the plating solution to obtain iron ions, and the iron ions are plated on the surface of a product together with chromium after being subjected to electron.
In order to achieve the third object, the present application provides the following technical solutions:
a trivalent chromium plating method comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath using the trivalent chromium plating solution of claims 1-7 for electroplating, wherein the relevant parameters of the trivalent chromium plating solution during electroplating are as follows: pH: 2.5-2.8, current density of 10-30A/dm2, temperature of 30-40 ℃, and electroplating time of 3-6 minutes;
4) and (3) drying: and cleaning the electroplated plated piece, drying the water on the surface of the chromium layer by blowing, and then baking the plated piece at the temperature of 70-80 ℃ for 20-30 minutes to obtain the product.
By adopting the technical scheme, the part to be electroplated is pretreated and plated with the base layer and then is put into the electroplating bath for electroplating, which is beneficial to electroplating; relevant parameters during electroplating are well controlled, so that the prepared trivalent chromium plating layer has high hardness and moderate thickness; and obtaining the chromium coating with the effect of slight dark color and luster like the stainless steel color after the drying treatment of the plated part.
Preferably, the workpiece is used for trial plating before the plated item is plated.
By adopting the technical scheme, the workpiece is firstly used for trial plating before electroplating, whether the color of the workpiece after trial plating meets the requirement is observed, and if the color of the workpiece does not meet the requirement, the trivalent chromium plating solution is reconfigured.
Preferably, the metal impurity content of the trivalent chromium plating solution before electroplating is as follows: zinc <5ppm, copper <5ppm, nickel <15ppm, lead <5 ppm.
By adopting the technical scheme, the content of the metal impurities is controlled, and the excessive metal impurities can influence the color of the product, for example, the excessive zinc can whiten the surface of the product.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the preparation process of the trivalent chromium plating solution is simple, the process conditions are easy to control, the problems of yellowing and whitening of a common trivalent chromium plating layer are solved, the obtained product has the effect of slight dark color of the imitation stainless steel color, and the trivalent chromium plating layer also has the advantages of high hardness, moderate thickness and the like;
2. diphenylcarbonyldihydrazine is added into the trivalent chromium plating solution, the diphenylcarbonyldihydrazine can react with hexavalent chromium ions to generate trivalent chromium ions, and the addition of the diphenylcarbonyldihydrazine can effectively inhibit the content of the hexavalent chromium ions and reduce the toxicity of the product;
3. hydrofluoric acid is added into the trivalent chromium plating solution, the hydrofluoric acid can react with boric acid to generate fluoboric acid, the fluoboric acid can react with ferrous ions to generate cuprous fluoborate, and the cuprous fluoborate has the function of a catalyst in the chromium plating process.
Detailed Description
The present application will be described in further detail with reference to examples.
The following examples and comparative examples have the following raw material sources as shown in the table:
TABLE 1
Preparation example 1
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 90g of chromium trichloride, 200g of potassium chloride, 6.0g of boric acid, 40g of malic acid, 0.05g of sodium alkylsulfonate, 0.2g of iron powder and 664g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 50 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 5 hours by using an electrolytic net, wherein the current is 15A when the electrolytic net is electrolyzed;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight parts, stirring for dissolving, and adding deionized water in corresponding weight parts.
Preparation example 2
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 100g of chromium trichloride, 225g of potassium chloride, 40g of boric acid, 50g of malic acid, 0.07g of sodium alkylsulfonate, 0.3g of iron powder and 685g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 55 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 6 hours by using an electrolytic net with the current of 20A;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight portions, stirring to dissolve, and adding deionized water in corresponding weight portions.
Preparation example 3
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 120g of chromium trichloride, 250g of potassium chloride, 80g of boric acid, 60g of malic acid, 0.1g of sodium alkylsulfonate, 0.4g of iron powder and 490g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 60 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 8 hours by using an electrolytic net with the current of 30A;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight portions, stirring to dissolve, and adding deionized water in corresponding weight portions.
Preparation example 4
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 95g of chromium trichloride, 210g of potassium chloride, 30g of boric acid, 45g of malic acid, 0.06g of sodium alkylsulfonate, 0.25g of iron powder and 620g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 53 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 6 hours by using an electrolytic net with the current of 20A;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight portions, stirring to dissolve, and adding deionized water in corresponding weight portions.
Preparation example 5
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 115g of chromium trichloride, 240g of potassium chloride, 30g of boric acid, 45g of malic acid, 0.06g of sodium alkylsulfonate, 0.35g of iron powder and 570g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 57 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 7 hours by using an electrolytic net with the current of 22A;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight portions, stirring to dissolve, and adding deionized water in corresponding weight portions.
Preparation example 6
The trivalent chromium plating solution of the preparation example comprises the following components by weight: 113g of chromium trichloride, 230g of potassium chloride, 35g of boric acid, 45g of malic acid, 0.06g of sodium alkyl sulfonate, 0.35g of iron powder and 577g of deionized water.
The preparation method of the trivalent chromium plating solution of the preparation example comprises the following steps:
step 1: adding potassium chloride and boric acid in corresponding weight parts into an electroplating bath filled with deionized water at 56 ℃, and stirring until the potassium chloride and the boric acid are completely dissolved;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 7 hours by using an electrolytic net with the current of 23A;
and 4, step 4: adding malic acid and sodium alkylsulfonate in corresponding parts by weight into the electroplating bath, and stirring for dissolving;
and 5: adding iron powder in corresponding weight portions, stirring to dissolve, and adding deionized water in corresponding weight portions.
Preparation example 7
A preparation method of trivalent chromium plating solution is different from the preparation method of the trivalent chromium plating solution in the preparation example 6 in that: after the iron powder is added in the step 5 and stirred to be dissolved, 0.15g of ferroferric oxide is also added and stirred to be dissolved
Preparation example 8
A preparation method of trivalent chromium plating solution is different from the preparation method of the trivalent chromium plating solution in the preparation example 6 in that: after the iron powder is added and stirred to dissolve in the step 5, 0.07g of diphenylcarbodihydrazide is also added and stirred to dissolve.
Preparation example 9
A preparation method of trivalent chromium plating solution is different from the preparation method of the trivalent chromium plating solution in the preparation example 6 in that: after the iron powder is added in the step 5 and stirred to be dissolved, 0.5g of hydrofluoric acid is also added and stirred to be dissolved.
Preparation example 10
A preparation method of trivalent chromium plating solution is different from the preparation method of the trivalent chromium plating solution in the preparation example 6 in that: and 5, after adding the iron powder, stirring and dissolving, sequentially adding 0.15g of ferroferric oxide, 0.07g of diphenylcarbodihydrazide and 0.5g of hydrofluoric acid, and stirring until dissolving.
Preparation example 11
The present preparation differs from preparation 6 in that: the potassium chloride was replaced with an equal weight portion of ammonium chloride.
Preparation example 12
The present preparation differs from preparation 6 in that: the potassium chloride is replaced by sodium chloride with equal weight parts.
Preparation example 13
The present preparation differs from preparation 6 in that: replacing the malic acid with formic acid with equal weight portion.
Preparation example 14
The present preparation differs from preparation 6 in that: replacing malic acid with acetic acid in equal weight parts.
Example 1
In this embodiment, the trivalent chromium plating solution used in the method for plating chromium with trivalent chromium is the trivalent chromium plating solution prepared in preparation example 1.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution during electroplating are as follows: pH: 2.5, the current density is 10A/dm2, the temperature is 30 ℃, and the electroplating time is 3 minutes;
4) and (3) drying: and cleaning the electroplated plated part, drying the water on the surface of the chromium layer by blowing, putting the plated part at the temperature of 70 ℃ for baking for 20 minutes, taking out and cooling.
Example 2
In this embodiment, the trivalent chromium plating solution used in the method for plating chromium with trivalent chromium is the trivalent chromium plating solution prepared in preparation example 2.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution are as follows: pH: 2.6, the current density is 20A/dm2, the temperature is 35 ℃, and the electroplating time is 4 minutes;
4) and (3) drying: and cleaning the electroplated plated part, drying the water on the surface of the chromium layer by blowing, then baking the plated part at the temperature of 75 ℃ for 25 minutes, taking out and cooling.
Example 3
The trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 3.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution are as follows: pH: 2.8, the current density is 30A/dm2, the temperature is 40 ℃, and the electroplating time is 6 minutes;
4) and (3) drying: and cleaning the electroplated plated part, drying the water on the surface of the chromium layer by blowing, then putting the plated part at the temperature of 80 ℃ for baking for 30 minutes, taking out and cooling.
Example 4
The trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 4.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution are as follows: pH: 2.6, the current density is 15A/dm2, the temperature is 32 ℃, and the electroplating time is 4 minutes;
4) and (3) drying: and cleaning the electroplated plated part, drying the water on the surface of the chromium layer by blowing, then putting the plated part into a furnace for baking at 73 ℃ for 22 minutes, taking out and cooling.
Example 5
In this embodiment, the trivalent chromium plating solution used in the method for plating chromium with trivalent chromium is the trivalent chromium plating solution prepared in preparation example 5.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution are as follows: pH: 2.7, the current density is 25A/dm2, the temperature is 37 ℃, and the electroplating time is 5 minutes;
4) and (3) drying: and cleaning the electroplated plated piece, drying the water on the surface of the chromium layer by blowing, then baking the plated piece at the temperature of 78 ℃ for 27 minutes, taking out and cooling.
Example 6
The trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 6.
The trivalent chromium plating method of the embodiment comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath of the trivalent chromium plating solution using the formula for plating, wherein the related parameters of the trivalent chromium plating solution are as follows: pH: 2.7, the current density is 25A/dm2, the temperature is 37 ℃, and the electroplating time is 5 minutes;
4) and (3) drying: and cleaning the electroplated plated piece, drying the water on the surface of the chromium layer by blowing, then baking the plated piece at the temperature of 78 ℃ for 27 minutes, taking out and cooling.
Example 7
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this example is the trivalent chromium plating solution prepared in preparation example 7.
Example 8
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 8.
Example 9
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 9.
Example 10
This example differs from example 6 in that: in this embodiment, the trivalent chromium plating solution used in the trivalent chromium plating method is the trivalent chromium plating solution prepared in preparation example 10.
Example 11
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 11.
Example 12
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this embodiment is the trivalent chromium plating solution prepared in preparation example 12.
Example 13
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this example is the trivalent chromium plating solution prepared in preparation example 13.
Example 14
This example differs from example 6 in that: the trivalent chromium plating solution used in the trivalent chromium plating method of this example is the trivalent chromium plating solution prepared in preparation example 14.
Example 15
A trivalent chromium plating method comprises the following steps,
1) trial plating: the workpiece for trial plating is put into the plating bath of the trivalent chromium plating solution in the preparation example 6 for plating, and relevant parameters during plating are as follows: pH: 2.7, the current density is 25A/dm2, the temperature is 37 ℃, and the electroplating time is 5 minutes;
2) drying the workpiece: and cleaning the electroplated workpiece, drying the water on the surface of the chromium layer by blowing, then baking the workpiece at the temperature of 78 ℃ for 27 minutes, taking out and cooling.
3) And (4) observing results: and (3) observing whether the color of the electroplated workpiece meets the requirement, if not, re-preparing the trivalent chromium plating solution in the preparation example 6, then returning to the step 1, and if so, performing the next step.
4) Pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
5) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
6) electroplating: placing the part to be electroplated after plating the base layer into the electroplating bath of the trivalent chromium plating solution in preparation example 6 for electroplating, wherein relevant parameters during electroplating are as follows: pH: 2.5-2.8, current density of 10-30A/dm2, temperature of 30-40 ℃, and time of 3-6 minutes;
7) and (3) drying: and cleaning the electroplated plated piece by using deionized water, drying the water on the surface of the chromium layer by blowing, and baking the plated piece at the temperature of 70-80 ℃ for 20-30 minutes to obtain the product.
Comparative example 1
This comparative example is different from example 6 in that iron powder is not contained in the composition of the trivalent chromium plating bath.
Comparative example 2
The present comparative example differs from example 6 in that the equal mass of iron powder is replaced with manganese powder.
Comparative example 3
The present comparative example differs from example 6 in that the equal mass of iron powder is replaced by copper powder.
Comparative example 4
This comparative example differs from example 6 in that the sodium alkylsulfonate and the like was replaced by sodium alkylsulfonate.
Performance test
The trivalent chromium plating layers obtained in examples 1 to 15 and comparative examples 1 to 4 were used as samples for the tests.
Test one, chromium layer hardness test: the test equipment uses HX-1000 microhardness tester produced by Shanghai second optical instrument factory, and the test part of the sample can be the surface or the section of the coating. When the surface of the coating is tested, the center of the main surface is preferably used, and the interference of the surface defects of the coating on the test is avoided. In the same test part of the test sample, the distance between the indentations should be more than 2.5 times of the diagonal length of the indentations. For the same sample, it should be measured three times or more under the same conditions, and the arithmetic mean value is taken as the measurement result of the hardness of the plating layer.
Test II, chromium layer thickness test: the test equipment uses an OU 3500F type coating thickness gauge of the times company to test at the center of the main surface of the coating, so as to avoid testing at the surface defect of the coating. For the same sample, the measurement should be performed three or more times under the same conditions, and the arithmetic mean value is taken as the measurement result of the thickness of the plating layer.
And thirdly, testing the porosity of the chromium layer: the porosity was determined according to GB/T17721-1999 porosity test iron reagent test for Metal coverings.
Test four, detecting the color of the chromium layer: and the plated part is placed in a place with sufficient light by adopting a visual inspection mode, and the plated part is observed in all directions.
TABLE 2 results of the trivalent chromium plating test of examples 1 to 15 and comparative examples 1 to 4
As can be seen from Table 2, the chromium (III) plating layers prepared from the chromium (III) plating solutions of examples 1 to 15 of the present application all exhibited a slightly dark stainless steel color.
In comparative examples 1 to 6, the chromium trivalent chromium plating layer of example 6 is preferred in terms of hardness and thickness when the composition in the chromium trivalent chromium plating bath is changed.
Comparing examples 6 and 7, the porosity of example 7 is significantly less than example 6, indicating that the addition of magnetite reduces the porosity of the trivalent chromium coating.
Compared with the examples 6-10, the hardness and the thickness of the trivalent chromium plating layer can be improved and the porosity of the trivalent chromium plating layer can be reduced by simultaneously adding a small amount of ferroferric oxide, diphenylcarbodihydrazide and hydrofluoric acid.
In comparative examples 6, 11 and 12, the use of potassium chloride as a conductive salt is preferred in terms of hardness and thickness of the trivalent chromium plating layer when the amount of the components is constant.
In comparative examples 6, 13 and 14, the complexing agent used malic acid was preferred in terms of hardness and thickness of the trivalent chromium plating layer at constant amounts of the components.
Example 6, in comparison with comparative examples 1-4, shows that the main reason why the trivalent chromium plating layer produces a slight dark color imitating the color of stainless steel is due to a small amount of iron covering the surface of the trivalent chromium plating layer, and secondly, sodium alkylsulfonate also affects the brightness of the dark color.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (10)
1. A trivalent chromium plating solution is characterized in that: the composition comprises the following components in parts by weight:
90-120 parts of chromium trichloride;
200 portions and 250 portions of conductive salt;
6.0-80 parts of a buffering agent;
40-60 parts of a complexing agent;
0.05-0.1 part of wetting agent;
0.2-0.4 part of iron powder;
450 portions and 650 portions of deionized water.
2. The trivalent chromium plating solution according to claim 1, characterized in that: the trivalent chromium plating solution also comprises 0.1-0.2 part of ferroferric oxide.
3. The trivalent chromium plating solution according to claim 1, characterized in that: the trivalent chromium plating solution also comprises 0.05-0.1 part of diphenyl carbodihydrazide.
4. The trivalent chromium plating solution according to claim 1, characterized in that: the trivalent chromium plating solution also comprises 0.5-0.7 part of hydrofluoric acid.
5. The trivalent chromium plating solution according to claim 1, characterized in that: the conductive salt is one of ammonium chloride, potassium chloride or sodium chloride.
6. The trivalent chromium plating solution according to claim 1, characterized in that: the complexing agent is one of formic acid, acetic acid or malic acid.
7. A method for preparing a trivalent chromium plating solution according to claims 1 to 6, characterized by: the method comprises the following groove matching steps:
step 1: adding conductive salt and a buffering agent in corresponding parts by weight into an electroplating bath filled with deionized water, and stirring until the conductive salt and the buffering agent are completely dissolved, wherein the temperature of the deionized water is 50-60 ℃;
step 2: adding chromium trichloride in a corresponding weight part into the electroplating bath, and stirring until the chromium trichloride is completely dissolved;
and step 3: electrolyzing for 5-8 hours by using an electrolytic net, wherein the current of the electrolytic net is 15-30A during electrolysis;
and 4, step 4: adding a complexing agent and a wetting agent in corresponding parts by weight into the electroplating bath, and stirring until the complexing agent and the wetting agent are dissolved;
and 5: adding iron powder in corresponding weight parts, stirring for dissolving, and adding deionized water in corresponding weight parts.
8. A trivalent chromium plating method is characterized in that: the method comprises the following steps:
1) pretreatment: hanging a piece to be electroplated, and carrying out wax removal, oil removal, acid-base neutralization and cleaning on the surface of the piece to be electroplated;
2) plating a base layer: plating copper or bright nickel on the surface of the part to be electroplated, and cleaning;
3) electroplating: placing the part to be electroplated after the base layer is plated into an electroplating bath using the trivalent chromium plating solution of claims 1-7 for electroplating, wherein the pH of the trivalent chromium plating solution is 2.5-2.8, the temperature is 30-40 ℃, the current density is 10-30A/dm2, and the electroplating time is 3-6 minutes;
4) and (3) drying: and cleaning the electroplated plated piece by using deionized water, drying the water on the surface of the chromium layer by blowing, and baking the plated piece at the temperature of 70-80 ℃ for 20-30 minutes to obtain the product.
9. The trivalent chromium plating method according to claim 8, characterized in that: and (3) trial plating the part to be plated through the workpiece before electroplating, and observing the color of the part to be plated after trial plating.
10. The trivalent chromium plating method according to claim 8, characterized in that: the metal impurity content of the trivalent chromium plating solution before electroplating is as follows: zinc <5ppm, copper <5ppm, nickel <15ppm, lead <5 ppm.
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