Surface passivating inert metal and plating solution and passivating method thereof

Abstract

The invention discloses a surface passivating inert metal, a plating solution thereof and a passivating method, and belongs to the technical field of inert metal surface treatment. The plating solution comprises sulfydryl silane, amino silane, acid, deionized water and absolute ethyl alcohol. And the inert metal subjected to surface pretreatment is put into a plating solution to be subjected to electrolytic treatment and dipping treatment correspondingly, and then the inert metal with the silane composite passive film on the surface is obtained through stepped curing treatment. The plating solution is simple in component, stable in system and low in price; the preparation method of the plating solution is simple and easy to operate; the passivating treatment method is short in technological process and high in preparation efficiency; the prepared silane composite passivation film is uniform and compact in structure, colorless and transparent, can keep good gloss of the inert metal surface, and has excellent properties such as oxidation resistance, corrosion resistance and insulation.

Description

Technical Field

[0001] The invention belongs to the technical field of inert metal surface treatment, and in particular relates to an inert metal for surface passivation treatment, a plating solution thereof and a passivation treatment method. Background Art

[0002] Inert metals have good electrical conductivity, thermal conductivity, catalytic activity and metallic luster. They are widely used in the fields of electronics, petrochemicals, medicine and health, and have high economic added value. If the surface of an inert metal is oxidized or corroded, it will affect its appearance and performance, causing great economic losses. For example, silver is prone to sulfide or oxidation in sulfur-containing, high-temperature or humid environments, and its surface color turns black or gray, which will reduce the electromagnetic shielding performance of the silver foil and the capacity and withstand voltage performance of the silver foil capacitor; copper in Cl-containing environments will be easily sulfided or oxidized. - In an oxidizing acid or alkaline environment, it is prone to corrosion, and its surface color turns black or green, which will reduce the thermal conductivity of the copper heat exchanger and affect the water quality in the copper pipe. Therefore, it is usually necessary to passivate the surface of the inert metal to improve its surface anti-oxidation and corrosion resistance and extend its service life.

[0003] The traditional surface passivation treatment of inert metals generally uses chromate of inorganic passivation system, and the prepared chromate passivation film has good oxidation resistance and corrosion resistance. However, hexavalent chromium ions are carcinogenic and will cause serious harm to the human body and the environment. With the improvement of human environmental awareness, the use of chromate has been restricted. Therefore, chromium-free passivation systems have gradually developed, including organic passivation systems and chromium-free inorganic passivation systems. At present, the passivation film prepared by the chromium-free inorganic passivation system has poor bonding with the substrate, the film layer is not dense, and the glossiness of the surface of the inert metal is significantly reduced. Compared with the inorganic passivation system, the organic passivation system has the characteristics of economy, greenness and high efficiency.

[0004] Among organic passivation systems, silane passivation systems are widely used for corrosion protection of metals. Silane passivation systems are non-toxic, and the silane film is colorless and transparent, with little effect on the surface gloss of the metal. Silane easily forms chemical bonds with active metals, has good binding force with 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 properties. However, due to the low surface activity of inert metals, the current single silane passivation system and the existing single impregnation method are used to passivate the surface of inert metals. The passivation film formed on the surface of the inert metal has poor binding force, and the anti-oxidation, corrosion resistance and insulation properties of the passivation film layer are insufficient.

[0005] Therefore, it is urgent to develop a green and environmentally friendly inert metal surface treatment plating solution and a new passivation treatment method thereof, to prepare a surface passivation film with high bonding strength with the inert metal substrate, strong anti-oxidation and corrosion resistance, and good insulation effect, so as to obtain high-performance surface passivation treated inert metals. Summary of the invention

[0006] The purpose of the present invention is to develop a surface passivation treatment inert metal and its plating solution and passivation treatment method, which effectively solves the above-mentioned problems of the passivation film formed on the surface of the inert metal using the traditional single silane passivation system and the single impregnation method. Mercaptosilane and aminosilane are combined to form a composite silane passivation system, and the electrolysis method is introduced to cooperate with the impregnation method, and then combined with the step curing treatment, so as to obtain a composite passivation film with high density, thick size and good bonding strength with the inert metal surface on the surface of the inert metal. Electrolytic treatment can activate the surface of inert metal, and make mercaptosilane gather on the surface of inert metal, and aminosilane stay away from the surface of inert metal, so as to promote the formation of coordination bonds between mercapto group and inert metal surface first, and generate a passivation film with strong binding force with inert metal matrix; impregnation treatment makes amino group and mercapto group electrostatically attracted, and makes hydrogen bond or Si-O-Si cross-linking structure fully formed between Si-OH, and increases the density and thickness of silane composite passivation film; step curing treatment can realize slow volatilization of solvent in low temperature curing stage, effectively avoid the problems of insufficient low temperature curing, low degree of intermolecular cross-linking and non-dense film layer, and keep the film layer intact and defect-free; high temperature curing stage can form effective cross-linking between Si-OH, and solve the problem of violent volatilization of solvent in traditional high temperature curing, which leads to easy cracking of film layer, and obtain uniform and complete silane composite passivation film.

[0007] According to a first aspect of the technical solution of the present invention, a plating solution for treating the surface of an inert metal is provided, wherein the components of the plating solution for treating the surface of an inert metal include mercaptosilane, aminosilane, acid, deionized water and anhydrous ethanol.

[0008] Further, 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.

[0009] Furthermore, the concentration of the mercaptosilane is 10 to 100 mL / L, the concentration of the aminosilane is 10 to 50 mL / L, the concentration of the acid is 1 to 20 mL / L, the composition ratio of the mercaptosilane, the aminosilane and the acid is 1 to 10:1 to 5:1 to 2; the volume percentage of the deionized water is 5% to 90%, and the volume percentage of the anhydrous ethanol is 10% to 95%.

[0010] Furthermore, the components of the plating solution for inert metal surface treatment also include a crosslinking agent, which is at least one of ethyl orthosilicate, methyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane, and trimethoxysilane, and the concentration of the crosslinking agent is 1 to 50 mL / L.

[0011] Furthermore, the components of the plating solution for treating the surface of an inert metal also include a pigment or a dye.

[0012] Furthermore, the method for preparing the plating solution for inert metal surface treatment comprises the following steps:

[0013] Step 1: adding the mercaptosilane and the aminosilane to a solution consisting 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 with the acid;

[0015] Step 3: hydrolyzing the mixed solution obtained in step 2 at a constant temperature to obtain the plating solution for the surface treatment of the inert metal.

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

[0017] Furthermore, the temperature of the isothermal hydrolysis is 20-70° C. and the time is 5-72 hours.

[0018] According to a second aspect of the technical solution of the present invention, a method for surface passivation treatment of an inert metal is provided, wherein the inert metal surface treatment plating solution according to any of the above aspects is used for passivation treatment, comprising the following steps:

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

[0020] Step 2: electrolytically treating the surface pretreated inert metal using the inert metal surface treatment plating solution;

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

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

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

[0024] Furthermore, the step curing treatment includes a first stage curing treatment and a second stage curing treatment, the first stage curing treatment is performed at a temperature of 20 to 100° C. and a time of 0.1 to 24 hours, and the second stage curing treatment is performed at a temperature of 50 to 160° C. and a time of 0 to 3 hours.

[0025] Furthermore, 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 a third aspect of the technical solution of the present invention, there is provided a surface passivation treated inert metal, wherein the surface passivation treated inert metal is subjected to surface passivation treatment using the method according to any one of the above aspects.

[0027] The beneficial effects of the present invention are:

[0028] (1) The plating solution for treating the surface of an inert metal of the present invention comprises mercaptosilane, aminosilane, acid, anhydrous ethanol and deionized water, and is a composite silane passivation solution. Compared with the traditional inorganic passivation solution and the organic passivation solution, it has the advantages of being green and non-toxic, having fewer types of additives, simple composition, good plating solution stability, and low price. Furthermore, the surface passivation treatment method based on the plating solution for treating the surface of an inert metal adopts a combination of electrolysis treatment, immersion treatment and step-by-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, and the performance of the passivation film prepared by combining the traditional immersion treatment with the curing treatment is significantly improved. The film layer structure is uniform and dense, the bonding strength with the surface of the inert metal substrate is high, and the requirements of insulation, oxidation resistance and corrosion resistance of the inert metal surface can be achieved at the same time, and the surface gloss of the inert metal will not be affected.

[0029] (2) The method for preparing the plating solution for treating the surface of an inert metal of the present invention has a simple process, is easy to operate, is green and environmentally friendly, has a low preparation cost, and is convenient for mass production.

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

[0031] Figure 1 This is the inert metal surface passivation treatment process of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and examples. It is necessary to point out here that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Skilled technicians in this field can make non-essential improvements and adjustments based on the contents of the above invention.

[0033] The invention provides a plating solution for treating the surface of an inert metal, the components of which include 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 also includes a crosslinking agent, and the crosslinking agent is at least one of tetraethyl orthosilicate, methyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane, and trimethoxysilane, and the concentration of the crosslinking agent is 1 to 50 mL / L.

[0038] In a preferred embodiment, the components of the plating solution for inert metal surface treatment further include pigments or pigments.

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

[0040] Step 1: adding the mercaptosilane and the aminosilane to a solution consisting of the deionized water and the anhydrous ethanol, and stirring to obtain a mixed solution;

[0041] Step 2: adjusting the pH value of the mixed solution with the acid;

[0042] Step 3: hydrolyzing the mixed solution obtained in step 2 at a constant temperature to obtain the plating solution for the surface treatment of the inert metal.

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

[0044] In a preferred embodiment, the temperature of the isothermal hydrolysis is 20-70° C. and the time is 5-72 hours.

[0045] The present invention further provides a method for passivating the surface of an inert metal, using the above-mentioned plating solution for passivation treatment. Figure 1 The process flow of inert metal surface passivation is shown, including the following steps:

[0046] Step 1: performing surface pretreatment on the inert metal to remove pollutants on the surface of the inert metal to obtain a surface pretreated inert metal;

[0047] Step 2: electrolytically treating the surface pretreated inert metal using the inert metal surface treatment plating solution;

[0048] Step 3: then performing an immersion treatment on the surface pretreated inert metal after the electrolytic treatment to obtain a surface treated inert metal;

[0049] Step 4: performing a step curing treatment on the surface treated inert metal to prepare a silane composite passivation film on the surface of the inert metal to obtain a surface passivated inert metal.

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

[0051] In a preferred embodiment, the step curing treatment includes a first stage curing treatment and a second stage curing treatment, wherein the temperature of the first stage curing treatment is 20-100°C and the time is 0.1-24h, and the temperature of the second stage curing treatment is 50-160°C 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 above materials.

[0053] The present invention further provides a surface passivation treated inert metal, wherein the surface passivation treated inert metal is passivated using any of the surface passivation treatment methods described above.

[0054] Embodiment 1:

[0055] First, pour 100-200mL of deionized water and 100-200mL of anhydrous ethanol into a beaker, add 20-70mL / L of 3-mercaptopropyltrimethoxysilane, 10-40mL / L of aminopropyltrimethoxysilane, and 30-50mL / L of ethyl orthosilicate in sequence, adjust the pH value of the solution to 3-6 with 10-20mL / L of organic acid, and hydrolyze at 40-60℃ in a water bath for 5-12h to obtain a surface treatment plating solution. Pre-treat the surface of the copper sheet, perform ultrasonic cleaning in anhydrous ethanol to remove pollutants on the surface of the copper sheet; then place the copper sheet in the surface treatment plating solution and heat at a current density of 0.005-1A / dm 2 Under the conditions of , an electrolytic treatment is first performed for 1 to 5 minutes, and then an immersion treatment is performed for 5 to 10 minutes; finally, a step curing treatment is performed, the temperature of the first stage curing treatment is 30 to 40°C, the time is 30 to 120 minutes, and the temperature of the second stage curing treatment is 50 to 100°C, and the time is 30 to 60 minutes; finally, a silane composite passivation film is prepared on the surface of the copper sheet to obtain a surface passivated copper sheet, and the surface passivation film layer has good transparency and high bonding strength with the inert metal substrate.

[0056] Embodiment 2:

[0057] First, pour 150-200mL of deionized water and 50-100mL of anhydrous ethanol into a beaker, add 30-80mL / L of 3-mercaptopropyltriethoxysilane and 20-50mL / L of aminopropyltriethoxysilane in turn, adjust the pH value of the solution to 5-8 with 1-5mL / L of organic acid, and hydrolyze at 30-70℃ in a water bath for 10-24h to obtain a surface treatment plating solution. Pre-treat the silver foil, perform ultrasonic cleaning in anhydrous ethanol to remove pollutants on the surface of the silver foil; then place the silver foil in the surface treatment plating solution and rinse at a current density of 0.001-0.01A / dm 2Under the conditions of , an electrolytic treatment is first performed for 3 to 8 minutes, and then an immersion treatment is performed for 5 to 15 minutes; finally, a curing treatment is performed, and the curing treatment temperature is 40 to 50°C and the time is 30 to 600 minutes; finally, a silane composite passivation film is prepared on the surface of the silver foil to obtain a surface passivated silver foil, and the surface passivation film layer has good transparency and high bonding strength with the inert metal substrate.

[0058] Embodiment 3:

[0059] First, pour 50-100 mL of deionized water and 150-200 mL of anhydrous ethanol into a beaker, and add 40-100 mL / L of 3-mercaptopropylmethyldimethoxysilane, 10-30 mL / L of 4-amino-3,3-dimethylbutyltrimethoxysilane, and 20-50 mL / L of polyvinyl alcohol in sequence, adjust the pH value of the solution to 4-7 with 5-10 mL / L of organic acid, and hydrolyze at a constant temperature of 20-50° C. in a water bath for 24-72 hours to obtain a plating solution for surface treatment. The copper foil is subjected to surface pretreatment, and ultrasonic cleaning is performed in anhydrous ethanol to remove pollutants on the surface of the copper foil; then the copper foil is placed in a surface treatment plating solution and immersed for 5 to 20 minutes; finally, a step curing treatment is performed, wherein the temperature of the first stage curing treatment is 30 to 50°C and the time is 30 to 180 minutes, and the temperature of the second stage curing treatment is 70 to 120°C and the time is 40 to 180 minutes; finally, a silane composite passivation film is prepared on the surface of the copper foil to obtain a copper foil with surface passivation treatment, and the surface passivation film layer has good transparency and high bonding strength with the inert metal substrate.

[0060] In summary, the present invention discloses a surface passivation treated inert metal, a plating solution and a passivation treatment method. The plating solution has simple composition, 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 prepared silane composite passivation film 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 anti-oxidation, anti-corrosion and insulation properties.

[0061] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0062] The present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A plating solution for inert metal surface treatment, characterized in that: The components of the plating solution for treating the surface of an inert metal include mercaptosilane, aminosilane, acid, deionized water and anhydrous ethanol.

2. The plating solution for inert metal surface treatment 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 to 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 to 50 mL / L; 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; wherein the concentration of the acid is 1 to 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%.

3. The plating solution for inert metal surface treatment according to claim 1, characterized in that: The components of the plating solution for inert metal surface treatment also include a crosslinking agent, which is at least one of ethyl orthosilicate, methyl orthosilicate, polyvinyl alcohol, trimethylolpropane, trimethylolethane, and trimethoxysilane, and the concentration of the crosslinking agent is 1 to 50 mL / L.

4. The plating solution for inert metal surface treatment according to claim 1, characterized in that: The components of the plating solution for treating the surface of an inert metal further include a coloring matter or a pigment.

5. The plating solution for inert metal surface treatment according to claim 1, characterized in that: The method for preparing the plating solution for inert metal surface treatment comprises the following steps: Step 1: adding the mercaptosilane and the aminosilane to a solution consisting 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 with the acid; Step 3: hydrolyzing the mixed solution obtained in step 2 at a constant temperature to obtain the plating solution for the surface treatment of the inert metal.

6. The plating solution for inert metal surface treatment according to claim 5, characterized in that: The pH value of the mixed solution is 3-8; the temperature of the constant temperature hydrolysis is 20-70° C. and the time is 5-72 hours.

7. A method for surface passivation of an inert metal, characterized in that: The method of using the plating solution for treating the surface of an inert metal according to any one of claims 1 to 6 for passivation treatment comprises the following steps: Step 1: performing surface pretreatment on the inert metal to remove pollutants on the surface of the inert metal to obtain a surface pretreated inert metal; Step 2: electrolytically treating the surface pretreated inert metal using the inert metal surface treatment plating solution; Step 3: then performing an immersion treatment on the surface pretreated inert metal after the electrolytic treatment to obtain a surface treated inert metal; Step 4: performing step curing treatment on the surface treated inert metal, preparing a silane composite passivation film on the surface of the surface treated inert metal, and obtaining the surface passivated inert metal.

8. The surface passivation treatment method of an inert metal according to claim 7, characterized in that: The current density of the electrolytic treatment is 0 to 5 A / dm 2 , time is 10 to 600s, the immersion treatment time is 30 to 3600s; the step curing treatment includes a first stage curing treatment and a second stage curing treatment, the first stage curing treatment temperature is 20 to 100°C, the time is 0.1 to 24h, the second stage curing treatment temperature is 50 to 160°C, the time is 0 to 3h.

9. The surface passivation treatment method of an inert metal according to claim 7, characterized in that: 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.

10. A surface passivation treated inert metal, characterized in that: The surface passivation treated inert metal is subjected to surface passivation treatment by the method according to any one of claims 7 to 9.

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