Inert metal surface passivation treatment and plating solution and passivation treatment method

Abstract

The application discloses an inert metal surface passivation treatment method and a plating solution thereof, and belongs to the technical field of inert metal surface treatment. The plating solution comprises mercapto silane, amino silane, acid, deionized water and anhydrous ethanol; the inert metal after surface pretreatment is put into the plating solution to be subjected to electrolytic treatment and immersion treatment respectively, and then stepwise solidification treatment is carried out to obtain the inert metal with a silane composite passivation film on the surface. The plating solution has simple components, stable system and low price; the preparation method of the plating solution is simple and easy to operate; the passivation treatment method has a short technological process and high preparation efficiency; and the prepared silane composite passivation film is uniform and dense, colorless and transparent, can keep the inert metal surface with good gloss, and has excellent oxidation resistance, corrosion resistance and insulation and other performances.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inert metal surface treatment, and particularly relates to a surface passivation treatment inert metal, a plating solution thereof and a passivation treatment method. BACKGROUND

[0002] Inert metals have good electrical conductivity, thermal conductivity, catalytic activity and metallic luster, and are widely used in the fields of electronics and electrical appliances, petroleum and chemical industry, and medicine and health care, etc., and have high economic added value. If the surface of the inert metal is oxidized or corroded, the appearance and use performance thereof will be affected, and great economic losses will be caused. For example, silver is easy to be sulfidized or oxidized in the environment containing sulfur, high temperature or humidity, etc., the surface color thereof becomes black or gray, and the electromagnetic shielding performance of the silver foil and the capacity and voltage resistance performance of the silver foil capacitor will be reduced; copper is easy to be corroded in the environment containing Cl - , oxidizing acid or alkaline environment, the surface color thereof becomes black or green, and the thermal conductivity of the copper heat exchanger will be reduced and the water quality in the copper pipeline will be affected. Therefore, the inert metal usually needs to be subjected to surface passivation treatment to improve the surface anti-oxidation and corrosion resistance, etc., and prolong the service life.

[0003] The traditional surface passivation treatment of the inert metal generally adopts the inorganic passivation system of chromate, and the prepared chromate passivation film has good anti-oxidation and corrosion resistance. However, hexavalent chromium ions have carcinogenic effect, and will cause serious harm to the human body and the environment. With the improvement of human environmental protection consciousness, the use of chromate has been limited. Therefore, the chromium-free passivation system has gradually developed, including the organic passivation system and the chromium-free inorganic passivation system. At present, the passivation film prepared by the chromium-free inorganic passivation system has poor adhesion to the substrate, the film layer is not dense, and the surface luster of the inert metal will be obviously reduced. Compared with the inorganic passivation system, the organic passivation system has the characteristics of economy, greenness and high efficiency, etc.

[0004] In the organic passivation system, the silane passivation system is widely used for the corrosion protection of metals. The silane passivation system is non-toxic, the silane film is colorless and transparent, and has little influence on the surface luster of the metal. The silane is easy to form chemical bonds with the active metal, has good adhesion to the substrate, and can form a dense cross-linked network structure between molecules. Therefore, the passivation film layer prepared by the silane passivation system has good anti-oxidation, corrosion resistance and insulation, etc. However, due to the low surface activity of the inert metal, the inert metal surface is subjected to passivation treatment by the current single silane passivation system and the existing single immersion method, the adhesion of the passivation film formed on the inert metal surface is poor, and the anti-oxidation, corrosion resistance and insulation, etc. of the passivation film layer are insufficient.

[0005] Therefore, it is urgent to develop a green and environment-friendly plating solution for inert metal surface treatment and a new passivation treatment method, to prepare a surface passivation film with high adhesion to the inert metal substrate, strong oxidation resistance and corrosion resistance, and good insulation effect, and to obtain a high-performance surface passivation treated inert metal. SUMMARY

[0006] The purpose of the present application is to develop a surface passivation treated inert metal, a plating solution and a passivation treatment method, to effectively solve the above-mentioned problems existing in the passivation film formed on the surface of the inert metal by using the traditional single silane passivation system and the single immersion method. The mercapto silane and amino silane are combined to form a composite silane passivation system, and the electrolytic method is introduced to work together with the immersion method, and then the step curing treatment is combined, so as to obtain a composite passivation film with high density, large size and good adhesion to the surface of the inert metal on the surface of the inert metal. The electrolytic treatment can activate the surface of the inert metal, at the same time, the mercapto silane is gathered on the surface of the inert metal, and the amino silane is far away from the surface of the inert metal, which promotes the mercapto silane to form a coordination bond with the surface of the inert metal in priority, and generates a passivation film with strong adhesion to the inert metal substrate; the immersion treatment makes the amino and mercapto silane electrostatically attracted, at the same time, the hydrogen bond or Si-O-Si cross-linking structure is fully formed between Si-OH, which increases the density and thickness of the silane composite passivation film; the step curing treatment can realize slow evaporation of the solvent in the low-temperature curing stage, effectively avoiding the problems of insufficient traditional low-temperature curing, low intermolecular cross-linking degree and non-dense film layer, maintaining the integrity of the film layer without defects, and the high-temperature curing stage can form effective cross-linking between Si-OH, solving the problem of easy cracking of the film layer caused by the violent evaporation of the solvent during the traditional high-temperature curing, and obtaining a uniform and complete silane composite passivation film.

[0007] According to the first aspect of the technical scheme of the present application, a plating solution for inert metal surface treatment is provided, and the components of the plating solution for inert metal surface treatment include mercapto silane, amino silane, acid, deionized water and anhydrous ethanol.

[0008] Further, the mercapto silane is at least one of 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl methyl dimethoxysilane and 3-mercaptopropyl methyl diethoxysilane; the amino silane is at least one of aminopropyl trimethoxysilane, aminopropyl triethoxysilane, 4-amino-3,3-dimethylbutyl trimethoxysilane, (2-aminoisopropyl) triethoxysilane and 3-aminopropyl methyl diethoxysilane; the acid is at least one of an organic acid or an inorganic acid, the organic acid is at least one of formic acid, acetic acid, trifluoroacetic acid, propionic acid, benzoic acid, citric acid, phytic acid, malic acid, tartaric acid, tannic acid or lactic acid, and the inorganic acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, boric acid, phosphoric acid, carbonic acid, chlorosulfonic acid or hydrofluoric acid.

[0009] Further, the concentration of the mercapto silane is 10-100 mL / L, the concentration of the amino silane is 10-50 mL / L, the concentration of the acid is 1-20 mL / L, the composition ratio of the mercapto silane, the amino silane and the acid is 1-10:1-5:1-2; the volume percentage of the deionized water is 5%-90%, and the volume percentage of the anhydrous ethanol is 10%-95%.

[0010] Further, the plating solution for inert metal surface treatment further comprises a cross-linking agent, the cross-linking agent is at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane and trimethoxysilane, and the concentration of the cross-linking agent is 1-50 mL / L.

[0011] Further, the plating solution for inert metal surface treatment further comprises a pigment or a dye.

[0012] Further, the preparation method of the plating solution for inert metal surface treatment comprises the following steps:

[0013] Step 1: adding the mercapto silane and the amino silane into a solution composed of the deionized water and the anhydrous ethanol, and stirring to obtain a mixed solution;

[0014] Step 2: adjusting the pH value of the mixed solution by using the acid;

[0015] Step 3: performing constant temperature hydrolysis on the mixed solution obtained in Step 2 to obtain the plating solution for inert metal surface treatment.

[0016] Further, the pH value of the mixed solution is 3-8.

[0017] Further, the temperature of the constant temperature hydrolysis is 20-70°C, and the time is 5-72 h.

[0018] According to the second aspect of the technical scheme of the present application, a surface passivation treatment method of inert metal is provided, which uses the plating solution for inert metal surface treatment according to any one of the above aspects to perform passivation treatment, and comprises the following steps:

[0019] Step 1: performing surface pretreatment on the inert metal to remove contaminants on the surface of the inert metal to obtain a surface pretreated inert metal;

[0020] Step 2: performing electrolytic treatment on the surface pretreated inert metal by using the plating solution for inert metal surface treatment;

[0021] Step 3: then performing immersion treatment on the surface pretreated inert metal after electrolytic treatment to obtain a surface treated inert metal;

[0022] Step 4: performing a step curing treatment on the surface-treated inert metal, and preparing a silane composite passivation film on the surface of the inert metal to obtain a surface passivation-treated inert metal.

[0023] Further, the current density of the electrolytic treatment is 0-5 A / dm 2 , and the time is 10-600 s, and the time of the immersion treatment is 30-3600 s.

[0024] Further, the step curing treatment comprises a first stage curing treatment and a second stage curing treatment, the temperature of the first stage curing treatment is 20-100℃, and the time is 0.1-24 h, and the temperature of the second stage curing treatment is 50-160℃, and the time is 0-3 h.

[0025] Further, the inert metal is at least one of gold, silver, platinum, palladium, rhodium, iridium, osmium, ruthenium, copper, or an alloy of any of the above materials.

[0026] According to the third aspect of the technical scheme of the present application, a surface passivation-treated inert metal is provided, which is surface passivation-treated by the method according to any one of the above aspects.

[0027] The present application has the following advantages:

[0028] (1) The plating solution for inert metal surface treatment of the present application comprises mercaptosilane, aminosilane, acid, anhydrous ethanol and deionized water, and is a composite silane passivation solution. Compared with traditional inorganic passivation solution and organic passivation solution, the plating solution has the advantages of green and non-toxic, fewer types of additives, simple composition, good stability of plating solution, low price, etc. Further, the surface passivation treatment method based on the plating solution for inert metal surface treatment combines electrolytic treatment, immersion treatment and step curing treatment to prepare a silane composite passivation film on the surface of the inert metal. The process flow is short, the passivation treatment efficiency is high, the production cost is low, the performance of the passivation film prepared by the method is significantly improved compared with the traditional method of combining immersion treatment and curing treatment, the film layer structure is uniform and dense, the bonding strength with the inert metal substrate surface is high, the requirements of insulation, oxidation prevention and corrosion resistance of the inert metal surface can be simultaneously met, and the surface gloss of the inert metal is not affected.

[0029] (2) The preparation method of the plating solution for inert metal surface treatment of the present application has the advantages of simple process, easy operation, green environmental protection, low preparation cost and easy batch production.

[0030] (3) The surface passivation film layer of the surface passivation-treated inert metal of the present application has good transparency, high bonding strength with the inert metal substrate, and excellent oxidation prevention, corrosion resistance and insulation performance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The present application provides a passivation process for inert metal surface. DETAILED DESCRIPTION

[0032] The present application will be described in detail below with reference to the accompanying drawings and examples. It is necessary to point out here that the examples are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. The skilled in the art can make non-essential improvements and adjustments according to the content of the above-mentioned application.

[0033] The present application provides a plating solution for inert metal surface treatment, which comprises mercaptosilane, aminosilane, acid, deionized water and anhydrous ethanol.

[0034] In a preferred embodiment, the mercaptosilane is at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropylmethyldiethoxysilane; the aminosilane is at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, (2-aminoisopropyl)triethoxysilane and 3-aminopropylmethyldiethoxysilane; the acid is at least one of an organic acid or an inorganic acid, the organic acid is at least one of formic acid, acetic acid, trifluoroacetic acid, propionic acid, benzoic acid, citric acid, phytic acid, malic acid, tartaric acid, tannic acid or lactic acid, and the inorganic acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, boric acid, phosphoric acid, carbonic acid, chlorosulfonic acid or hydrofluoric acid.

[0035] In a preferred embodiment, the concentration of the mercaptosilane is 10-100 mL / L; the concentration of the aminosilane is 10-50 mL / L; and the concentration of the acid is 1-20 mL / L.

[0036] In a preferred embodiment, the composition ratio of the mercaptosilane, the aminosilane and the acid is 1-10:1-5:1-2; the volume percentage of the deionized water is 5%-90%, and the volume percentage of the anhydrous ethanol is 10%-95%.

[0037] In a preferred embodiment, the composition of the plating solution for inert metal surface treatment further comprises a crosslinking agent, which is at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane and trimethoxysilane, and the concentration of the crosslinking agent is 1-50 mL / L.

[0038] In a preferred embodiment, the composition of the plating solution for inert metal surface treatment further comprises a pigment or a dye.

[0039] In a preferred embodiment, the preparation method of the plating solution for the inert metal surface treatment comprises the following steps:

[0040] Step 1: the mercapto silane and the amino silane are added into a solution consisting of the deionized water and the anhydrous ethanol, and after stirring, a mixed solution is obtained;

[0041] Step 2: the pH value of the mixed solution is adjusted by the acid;

[0042] Step 3: the mixed solution obtained in Step 2 is subjected to constant temperature hydrolysis, and the plating solution for the inert metal surface treatment is obtained.

[0043] In a preferred embodiment, the pH value of the mixed solution is 3-8.

[0044] In a preferred embodiment, the temperature of the constant temperature hydrolysis is 20-70℃, and the time is 5-72h.

[0045] The present application further provides a surface passivation treatment method of inert metal, which uses the plating solution as described above for passivation treatment. Figure 1 A surface passivation treatment process of inert metal is shown, which comprises the following steps:

[0046] Step 1: the inert metal is subjected to surface pretreatment to remove the contaminants on the surface of the inert metal, and a surface pretreated inert metal is obtained;

[0047] Step 2: the surface pretreated inert metal is subjected to electrolytic treatment by using the plating solution for the inert metal surface treatment;

[0048] Step 3: then, the surface pretreated inert metal after electrolytic treatment is subjected to immersion treatment, and a surface treated inert metal is obtained;

[0049] Step 4: the surface treated inert metal is subjected to stepwise solidification treatment, and a silane composite passivation film is prepared on the surface of the inert metal, and a surface passivated inert metal is obtained.

[0050] In a preferred embodiment, the current density of the electrolytic treatment is 0-5A / dm 2 , the time is 10-600s, and the time of the immersion treatment is 30-3600s.

[0051] In a preferred embodiment, the stepwise solidification treatment comprises first stage solidification treatment and second stage solidification treatment, the temperature of the first stage solidification treatment is 20-100℃, the time is 0.1-24h, the temperature of the second stage solidification treatment is 50-160℃, and the time is 0-3h.

[0052] In a preferred embodiment, the inert metal is at least one of gold, silver, platinum, palladium, rhodium, iridium, osmium, ruthenium, copper, or an alloy of any of the foregoing.

[0053] The present application also provides an inert metal surface passivation treatment, which is passivated by the surface passivation treatment method of any one of the above.

[0054] Example 1:

[0055] First, 100-200 mL of deionized water and 100-200 mL of anhydrous ethanol are poured into a beaker, 3-mercaptopropyltrimethoxysilane with a concentration of 20-70 mL / L, aminopropyltrimethoxysilane with a concentration of 10-40 mL / L, and tetraethyl orthosilicate with a concentration of 30-50 mL / L are sequentially added, an organic acid with a concentration of 10-20 mL / L is used to adjust the pH value of the solution to 3-6, and hydrolysis is performed in a water bath pot at a constant temperature of 40-60°C for 5-12 h to obtain a surface treatment plating solution. The copper sheet is subjected to surface pretreatment and ultrasonic cleaning in anhydrous ethanol to remove contaminants on the surface of the copper sheet. Then, the copper sheet is placed in the surface treatment plating solution and subjected to electrolytic treatment at a current density of 0.005-1 A / dm 2 for 1-5 min and then immersed for 5-10 min. Finally, stepwise solidification treatment is performed, the first stage of solidification treatment is performed at a temperature of 30-40°C for 30-120 min, and the second stage of solidification treatment is performed at a temperature of 50-100°C for 30-60 min. A silane composite passivation film is finally prepared on the surface of the copper sheet to obtain a surface passivation treated copper sheet, and the surface passivation film layer has good transparency and high bonding strength with the inert metal substrate.

[0056] Example 2:

[0057] First, 150-200 mL of deionized water and 50-100 mL of anhydrous ethanol are poured into a beaker, 3-mercaptopropyltrimethoxysilane with a concentration of 30-80 mL / L, aminopropyltrimethoxysilane with a concentration of 20-50 mL / L, and an organic acid with a concentration of 1-5 mL / L are sequentially added, the pH value of the solution is adjusted to 5-8, and hydrolysis is performed in a water bath pot at a constant temperature of 30-70°C for 10-24 h to obtain a surface treatment plating solution. The silver foil is subjected to surface pretreatment and ultrasonic cleaning in anhydrous ethanol to remove contaminants on the surface of the silver foil. Then, the silver foil is placed in the surface treatment plating solution and subjected to electrolytic treatment at a current density of 0.001-0.01 A / dm 2The silver foil is surface passivated by first electrolyzing for 3-8 min, then immersing for 5-15 min, and finally solidifying at 40-50 DEG C for 30-600 min.

[0058] Example 3:

[0059] First, 50-100 mL of deionized water and 150-200 mL of anhydrous ethanol are poured into a beaker, and 3-mercaptopropylmethyldimethoxysilane with a concentration of 40-100 mL / L, 4-amino-3, 3-dimethylbutyltrimethoxysilane with a concentration of 10-30 mL / L, and polyvinyl alcohol with a concentration of 20-50 mL / L are sequentially added, and the pH value of the solution is adjusted to 4-7 by using an organic acid with a concentration of 5-10 mL / L, and then the solution is hydrolyzed in a water bath at 20-50 DEG C for 24-72 h to obtain a surface treatment plating solution. The copper foil is surface pretreated and ultrasonically cleaned in anhydrous ethanol to remove contaminants on the surface of the copper foil, and then immersed in the surface treatment plating solution for 5-20 min, and finally subjected to stepwise solidification treatment, in which the first stage of solidification treatment is performed at 30-50 DEG C for 30-180 min, and the second stage of solidification treatment is performed at 70-120 DEG C for 40-180 min. A silane composite passivation film is finally prepared on the surface of the copper foil to obtain a surface passivated copper foil, and the passivation film layer has good transparency and high bonding strength with the inert metal substrate.

[0060] In summary, the present application discloses a surface passivation treatment method for inert metals, a plating solution therefor, and a passivation treatment method, the plating solution has simple components, a stable system, and a low price, the preparation method of the plating solution is simple and easy to operate, the passivation treatment method has a short process flow and high preparation efficiency, the silane composite passivation film prepared has a uniform and dense structure, is colorless and transparent, can maintain a good gloss on the surface of the inert metal, and has excellent properties such as oxidation resistance, corrosion resistance, and insulation.

[0061] The above-mentioned example numbers of the present application are only for description, and do not represent the advantages and disadvantages of the examples.

[0062] The present application is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative and not limiting, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and these all belong to the protection of the present application.

Claims

1. A method for passivating the surface of an inert metal, characterized in that, The composition of the plating solution for inert metal surface treatment used in the surface passivation treatment method comprises mercaptosilane, aminosilane, acid, deionized water and anhydrous ethanol; The surface passivation treatment method comprises the following steps: Step 1: surface pretreatment of inert metal to remove contaminants on the surface of the inert metal to obtain surface pretreated inert metal; Step 2: electrolytic treatment of the surface pretreated inert metal with the plating solution for inert metal surface treatment to form a passivation film with strong bonding force with the inert metal substrate; Step 3: immersion treatment of the surface pretreated inert metal after electrolytic treatment to allow electrostatic attraction between amino and mercapto groups and to form hydrogen bonds or Si-O-Si crosslinking structure between Si-OH to increase the density and thickness of the passivation film, thereby obtaining surface treated inert metal; Step 4: stepwise curing treatment of the surface treated inert metal, which comprises a low-temperature curing stage and a high-temperature curing stage, the low-temperature curing stage allowing slow evaporation of solvent to keep the film intact without defects, and the high-temperature curing stage allowing effective crosslinking between Si-OH, thereby preparing a silane composite passivation film on the surface of the surface treated inert metal to obtain surface passivated inert metal.

2. The method of passivating the surface of a noble metal according to claim 1, characterized in that, The current density of the electrolytic treatment is 0-5 A / dm 2 The temperature of the low-temperature curing treatment is 20-100 °C, and the time is 0.1-24 h. The temperature of the high-temperature curing treatment is 50-160 °C, and the time is 0-3 h.

3. The method of passivating the surface of a noble metal according to claim 1, wherein The inert metal is at least one of gold, silver, platinum, palladium, rhodium, iridium, osmium, ruthenium, copper or an alloy of any of the above materials.

4. The surface passivation treatment method of inert metal according to claim 1, characterized in that: The mercaptosilane is at least one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropylmethyldiethoxysilane, wherein the concentration of the mercaptosilane is 10-100 mL / L; The aminosilane is at least one of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, (2-aminoisopropyl)triethoxysilane and 3-aminopropylmethyldiethoxysilane, wherein the concentration of the aminosilane is 10-50 mL / L; The acid is at least one of organic acid or inorganic acid, the organic acid is at least one of formic acid, acetic acid, trifluoroacetic acid, propionic acid, benzoic acid, citric acid, phytic acid, malic acid, tartaric acid, tannic acid or lactic acid, and the inorganic acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, boric acid, phosphoric acid, carbonic acid, chlorosulfonic acid or hydrofluoric acid, wherein the concentration of the acid is 1-20 mL / L; The composition ratio of the mercaptosilane, the aminosilane and the acid is 1-10:1-5:1-2, the volume percentage of the deionized water is 5%-90%, and the volume percentage of the anhydrous ethanol is 10%-95%.

5. The method of passivating the surface of a noble metal according to claim 1, wherein The composition of the plating solution for inert metal surface treatment further comprises a crosslinking agent, which is at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane and trimethoxysilane, and the concentration of the crosslinking agent is 1-50 mL / L.

6. The method of passivating the surface of a noble metal according to claim 1, wherein The plating solution for the inert metal surface treatment further comprises a pigment or a dye.

7. The method of passivating the surface of a noble metal according to claim 1, wherein The preparation method of the plating solution for the inert metal surface treatment comprises the following steps: Step 1: adding the mercapto silane and the amino silane into a solution composed of the deionized water and the anhydrous ethanol, and stirring to obtain a mixed solution; Step 2: adjusting the pH value of the mixed solution by using the acid; Step 3: performing constant temperature hydrolysis on the mixed solution obtained in Step 2 to obtain the plating solution for the inert metal surface treatment.

8. The method of passivating the surface of a noble metal according to claim 7, characterized in that, The pH value of the mixed solution is 3-8; the temperature of the constant temperature hydrolysis is 20-70 ℃, and the time is 5-72 h.

9. A surface passivated inert metal, characterized in that, The inert metal is surface passivated by using the method according to any one of claims 1-8.

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