CN107574430A - A kind of silicate bright blue passivation liquid and preparation method thereof - Google Patents

Abstract

The invention discloses a silicate blue-white passivation solution and a preparation method thereof, belonging to the technical field of metal material surface treatment. The composition of the passivation solution of the present invention is: sodium silicate 26~34g/L, malic acid 2~4g/L, sodium fluoride 8~12g/L, hydrogen peroxide 9~14mL/L, aminotrimethylene phosphonic acid 8 ~13mL/L, the rest is water, and the pH value is 3.0~3.5; the preparation method of the passivation solution is to add sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, and hydrogen peroxide to deionized water in sequence Mix in water evenly, add water to the required volume, and adjust the pH value to 3.0~3.5 with sulfuric acid to obtain the silicate blue-white passivation solution. The passivation film of the zinc coating treated by the passivation solution is blue-white, bright in color, uniform in film formation, and excellent in corrosion resistance, and the passivation solution does not contain trivalent chromium, hexavalent chromium and other harmful substances, which is environmentally friendly and pollution-free , the passivation process is simple, the passivation efficiency is high, and the film layer has good corrosion resistance.

Description

A kind of silicate blue-white passivation solution and preparation method thereof

technical field

The invention relates to a silicate blue-white passivation solution and a preparation method thereof, belonging to the technical field of metal material surface treatment.

Background technique

Electro-galvanizing passivation process is one of the most commonly used steel anti-corrosion technologies. It is a very effective way to improve the corrosion resistance of steel. It is widely used in many fields such as automobiles, electric power, shipbuilding, aviation, machinery, construction, hardware, and home appliances. . In order to improve the corrosion resistance and bright appearance of steel products, electroplating and passivation treatment are generally carried out on them. Blue-white passivation has a simple and elegant appearance and excellent performance. It is favored by the market and has always been one of the most important post-treatment processes for galvanized parts. After treatment, the galvanized parts appear light blue and bright in appearance, which can not only maintain The natural color of the metal improves the corrosion resistance of the product, so the blue and white passivation process is widely used in various metal protection industries.

In the common chromium-free passivation process, the corrosion resistance of organic passivation is good, but the adhesion and heat resistance are poor, and the corrosion resistance of single inorganic passivation is slightly worse than that of organic passivation. Inorganic and organic composite passivation is the synergistic corrosion inhibition and performance complementation between inorganic molecules or ions and organic molecules, which further improves the corrosion resistance of the passivation film. It should be pointed out that there are still many chromium-free passivation technologies used alone. Defects, or poor corrosion resistance, or poor appearance, or poor electrical grounding performance, or high price, it is difficult to meet the application requirements.

Divided by the main film-forming salt, the currently reported chromium-free blue-white passivation systems include silicate systems, tungstate systems, molybdate systems, rare earth metal salt systems, titanium salt systems, and organic passivation systems. The existing silicate system is low in cost and non-toxic, but the passivation solution is unstable and the corrosion resistance needs to be improved; the tungstate system is high in cost and poor in corrosion resistance; the molybdate system has a good effect of delaying corrosion. Low toxicity, but the requirement for film thickness is too high, and the cost is high; the rare earth metal salt system has low toxicity, good stability, and good corrosion inhibition effect, but the cost is high; the titanium salt system has high corrosion resistance, but the cost is high. High; the organic system has high corrosion resistance, but there are many types of film-forming agents, the passivation process is complicated, and the passivation cost is high.

Contents of the invention

In order to overcome the deficiencies of the existing silicate passivation solution technology, the present invention provides a blue-white silicate passivation solution. The components of the passivation solution are: sodium silicate 26 ~ 34g/L, malic acid 2 ~4g/L, sodium fluoride 8~12g/L, hydrogen peroxide 9~14mL/L, aminotrimethylene phosphonic acid 8~13mL/L, the rest is water, and the pH value is 3.0~3.5.

The preparation method of the silicate blue-white passivation solution of the present invention is: adding sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, and hydrogen peroxide into deionized water in sequence and mixing evenly, adding water to the desired volume Need volume, use sulfuric acid to adjust the pH value to 3.0~3.5 to get the silicate blue-white passivation solution.

The silicate blue-white passivation solution can be used in the post-galvanizing treatment process of steel parts. The passivation film of the zinc coating after using this passivation solution is blue-white, bright in color, uniform in film formation, and excellent in corrosion resistance. , high passivation efficiency, and good corrosion resistance of the film.

The sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid and hydrogen peroxide described in the present invention are commercially available analytically pure chemical reagents.

The method for passivating electrogalvanized and hot-dip galvanized materials using the blue-white silicate passivation solution of the present invention is as follows: clean the electrogalvanized materials (obtained by conventional methods) with water, and perform light-emitting treatment according to conventional methods , take out the material and wash it with water, then immerse the material in the blue-white silicate passivation solution, soak for 5-30 seconds at room temperature, take it out, wash it with water, and then dry it.

The light-emitting treatment (conventional method) is: put the galvanized material into the light-emitting liquid composed of HNO ₃ and H ₂ O, soak it at room temperature for 3 to 5 seconds, and then take it out, wherein the light-emitting liquid is specifically formulated The ratio is: HNO ₃ with a mass concentration of 65% 5~15mL/L, and the rest is H ₂ O.

The cleaning method for the galvanized, polished and passivated material is: rinse with tap water, or rinse in a tank or pool filled with clean water until the surface of the plated piece is cleaned.

The drying method of the passivated galvanized material is: drying naturally, or drying with a hair dryer, or drying at a constant temperature of 60° C. in a thermostat.

The water used in each process involved in the present invention is tap water or distilled water.

The beneficial effects of the present invention are:

(1) The silicate blue-white passivation solution of the present invention can be used in the post-galvanizing treatment process of iron and steel parts. The passivation film of the zinc coating after using the passivation solution is blue-white, bright in color and uniform in film formation. Excellent corrosion resistance, high passivation efficiency, and good corrosion resistance of the film;

(2) The passivation solution of the present invention does not contain toxic substances such as chromium, which overcomes the shortcomings of chromate passivation technology such as high toxicity and non-environmental protection, and can realize clean production of galvanized products;

(3) The passivation treatment process of the passivation solution of the present invention is simple, the passivation time is short, the passivation efficiency is high, the film layer has strong adhesion, and the film layer thickness is uniform;

(4) The passivation film obtained by the passivation solution of the present invention has excellent corrosion resistance. After the test with 5% CuSO ₄ , the time for the passivation film to completely turn black exceeds 60 seconds, and the time for white rust to appear through the neutral salt spray test exceeds 72 seconds. Hour.

detailed description

The present invention will be described in further detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the content described.

Example 1: The components of the silicate blue-white passivation solution in this example are sodium silicate 30 g/L, malic acid 3 g/L, sodium fluoride 9 g/L, hydrogen peroxide 9 mL/L, amino triethylene oxide Methylidene phosphonic acid 8mL/L, the rest is water, pH value is 3.0;

The preparation method of the silicate blue-white passivation solution in this embodiment is: according to the above components, sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, and hydrogen peroxide are sequentially added to deionized water and mixed evenly. Add water to make it to the required volume, adjust the pH value to 3.0 with sulfuric acid to obtain the silicate blue-white passivation solution;

The passivation solution prepared in this embodiment is used for passivation electrogalvanized steel sheet:

(1) The electrogalvanized steel sheet is obtained by the following method: the low-carbon steel sheet of 40mm*50mm*0.5mm is subjected to pretreatments such as derusting, degreasing, activation, etc. before electroplating, and then put into a conventional electroplating solution for Electroplating, galvanizing bath composition and operating conditions are: ZnCl ₂ 70 g/L, KCl 175 g/L, boric acid 30 g/L, brightener 0.5ml/L, softener 17 ml/L, plating The pH value of the solution was 5.4, the current density was 1.5 A/dm ² , the temperature was room temperature, and the electroplating time was 20 minutes to obtain an electro-galvanized steel sheet for use;

(2) Prepare light-emitting liquid: prepare chemically pure HNO ₃ and water to make 10 mL/L light-emitting liquid, and set aside;

(3) Clean the electrogalvanized steel sheet obtained in step (1) with tap water, then immerse it in the light-emitting solution obtained in step (2), stay at room temperature for 5 seconds, take it out, clean it with tap water, and then immerse it in the passivation solution. After soaking at room temperature for 15 seconds, take it out, wash it with tap water and dry it with a hair dryer;

The steel plate treated by the passivation solution is blue-white, bright in color, uniform in film formation, high in passivation efficiency, and good corrosion resistance of the film layer. After the 5% CuSO4 test, the passivation film completely turns black for more than 60 seconds. The salt spray test showed white rust for more than 96 hours.

Example 2: The components of the silicate blue-white passivation solution in this example are sodium silicate 34 g/L, malic acid 4 g/L, sodium fluoride 12 g/L, hydrogen peroxide 10 mL/L, amino triethylene oxide Methylidene phosphonic acid 13 mL/L, the rest is water, pH value is 3.5;

The preparation method of the silicate blue-white passivation solution in this embodiment is: according to the above components, sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, and hydrogen peroxide are sequentially added to deionized water and mixed evenly. Add water to the required volume, adjust the pH value to 3.5 with sulfuric acid to obtain the silicate blue-white passivation solution;

The passivation solution prepared in this embodiment is used for passivation electrogalvanized steel sheet:

(1) The electrogalvanized steel sheet is obtained by the following method: the low-carbon steel sheet of 40mm*50mm*0.5mm is subjected to pretreatments such as derusting, degreasing, activation, etc. before electroplating, and then put into a conventional electroplating solution for Electroplating, galvanizing bath composition and operating conditions are: ZnCl ₂ 70 g/L, KCl 175 g/L, boric acid 30 g/L, brightener 0.5ml/L, softener 17 ml/L, plating The pH value of the solution was 5.6, the current density was 1.5 A/dm ² , the temperature was room temperature, and the electroplating time was 20 minutes to obtain an electro-galvanized steel sheet for use;

(2) Prepare light-emitting liquid: prepare chemically pure HNO ₃ and water to make 5mL/L light-emitting liquid, and set aside;

(3) Clean the electrogalvanized steel sheet obtained in step (1) with tap water and then immerse it in the light-emitting solution obtained in step (2), stay at room temperature for 3 seconds, take it out, clean it with tap water, and then immerse it in the passivation solution. After soaking at room temperature for 30 seconds, take it out, wash it with tap water and dry it with a hair dryer;

The steel plate treated by the passivation solution is blue-white, bright in color, uniform in film formation, high in passivation efficiency, and good corrosion resistance of the film layer. Tested by 5% CuSO4, the passivation film completely turns black for more than 70 seconds. The salt spray test showed white rust for more than 72 hours.

Example 3: The components of the silicate blue-white passivation solution in this example are sodium silicate 26 g/L, malic acid 2 g/L, sodium fluoride 8 g/L, hydrogen peroxide 14 mL/L, amino trimethylene Base phosphonic acid 10mL/L, the rest is water, pH value is 3.2;

The preparation method of the silicate blue-white passivation solution in this embodiment is: according to the above components, sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, and hydrogen peroxide are sequentially added to deionized water and mixed evenly. Add water to the required volume, adjust the pH value to 3.2 with sulfuric acid to obtain the silicate blue-white passivation solution;

The passivation solution prepared in this embodiment is used for passivation electrogalvanized steel sheet:

(1) The electrogalvanized steel sheet is obtained by the following method: the low-carbon steel sheet of 40mm*50mm*0.5mm is subjected to pretreatments such as derusting, degreasing, activation, etc. before electroplating, and then put into a conventional electroplating solution for Electroplating, galvanizing bath composition and operating conditions are: ZnCl ₂ 70 g/L, KCl 175 g/L, boric acid 30 g/L, brightener 0.5ml/L, softener 17 ml/L, plating The pH value of the liquid is 5.8, the current density is 1.5 A/dm ² , the temperature is room temperature, and the electroplating time is 20 minutes, so as to obtain an electro-galvanized steel sheet for use;

(2) Prepare light-emitting liquid: prepare chemically pure HNO ₃ and water to make 15mL/L light-emitting liquid, and set aside;

(3) Clean the electrogalvanized steel sheet obtained in step (1) with tap water, then immerse it in the light-emitting solution obtained in step (2), stay at room temperature for 4 seconds, take it out, clean it with tap water, and then immerse it in the passivation solution. After soaking at room temperature for 5 seconds, take it out, wash it with tap water and dry it with a hair dryer;

The steel plate treated by the passivation solution is blue-white, bright in color, uniform in film formation, high in passivation efficiency, and good corrosion resistance of the film layer. After the 5% CuSO4 test, the passivation film completely turns black for more than 60 seconds. The salt spray test showed white rust for more than 72 hours.

The specific implementation of the present invention has been described in detail above, but the present invention is not limited to the above-mentioned implementation, within the knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety.

Claims (2)

1. A silicate blue-white passivation solution, characterized in that: the components of the passivation solution are sodium silicate 26~34g/L, malic acid 2~4g/L, sodium fluoride 8~12g/L , hydrogen peroxide 9~14mL/L, aminotrimethylene phosphonic acid 8~13mL/L, the rest is water, and the pH value is 3.0~3.5. 2. the preparation method of silicate blue-white passivation solution described in claim 1 is characterized in that, concrete steps are as follows: sodium silicate, malic acid, sodium fluoride, aminotrimethylene phosphonic acid, hydrogen peroxide are added successively Mix it evenly in deionized water, add water to the required volume, and adjust the pH value to 3.0~3.5 with sulfuric acid to obtain the silicate blue-white passivation solution.