WO2016106523A1 - Trivalent chromium/aluminum passivation treatment process and application thereof - Google Patents

Abstract

A trivalent chromium/aluminum passivation treatment process comprising the following steps: using an acidic degreaser to remove grease and oxide scale from the surface of an aluminum material, rinsing with water, desmutting, rinsing with water, then using a trivalent chromium/aluminum passivation agent to treat said surface, then rinsing with water, drying, and forming a passivation film on said surface. An aluminum material or aluminum alloy product obtained from the treatment process is also disclosed.

Description

 Trivalent chromium-aluminum passivation treatment process and its application Technical field

 The invention relates to the technical field of metal surface treatment, in particular to a trivalent chromium-aluminum passivation treatment process and an application thereof.

Background technique

Metal surfaces are usually treated to improve surface properties or appearance. For example, the surface treatment of aluminum and its alloys goes deep into all walks of life. Passivation of the surface of aluminum and its alloys is a relatively common treatment process.

The existing passivation treatment process is: degreasing→water washing→water washing→passivation→water washing→water washing→drying. This treatment process has the following disadvantages: the oil consumption is large, the bath liquid is easy to age, the surface of the aluminum material is easy to produce black ash, the surface is not adjusted, the passivation is affected, and the adhesion of the passivation film is poor.

technical problem

 In view of this, a trivalent chromium-aluminum passivation process and a application thereof with fine film formation, safety, environmental protection and corrosion resistance are provided.

Technical solution

A trivalent chromium-aluminum passivation treatment process for aluminum pre-treatment or aluminum finished product treatment, which comprises the steps of: de-oiling the surface of the aluminum material with alumina acid, removing water, washing, light, washing, The surface of the aluminum material is treated with a trivalent chromium-aluminum passivating agent to form a passivation layer, washed with water, dried, and a passivation film is formed on the surface of the aluminum.

 And, the treatment is carried out by a trivalent chromium-aluminum passivation treatment process as described above to obtain an aluminum or aluminum product.

Beneficial effect

The above-mentioned trivalent chromium-aluminum passivation treatment process adopts trivalent chromium to passivate the aluminum surface, and is suitable for forming a passivation film on the surface of the aluminum or aluminum alloy part before painting, so that the coating layer during coating is firmly bonded and durable. , not easy to fall off; or the final treatment of the aluminum finished product to form a passivation protective film. The formed passivation film is highly resistant to corrosion, especially acid and alkali corrosion. Moreover, the process uses trivalent chromium instead of Cr ⁶⁺ ions, which is safer and more environmentally friendly. The treated waste liquid is easy to handle, and the black ash on the surface of the aluminum material can be eliminated after the light treatment, and the passivation film formed later has stronger adhesion. After the process, the aluminum material or the aluminum product has a bright appearance.

DRAWINGS

 BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a photograph of a product after treatment of a trivalent chromium-aluminum passivation treatment process according to a second embodiment of the present invention.

 Figure 2 is a photograph of the product after the light treatment in Comparative Example 5.

Figure 3 is a photo of the product without light treatment.

Embodiments of the invention

 The invention will be described in detail below with reference to specific embodiments and drawings.

 Embodiments of the present invention provide a trivalent chromium-aluminum passivation treatment process for pre-coating aluminum processing or aluminum finished product processing, which includes the following steps:

 S01: removing the surface of the aluminum material by dehydration with alumina acid and removing the scale, and washing with water;

 S02: light treatment, light-treating the surface of the aluminum material with a light-emitting agent, removing surface ash or black ash, and then washing with water;

 S03: The surface of the aluminum material is treated with a trivalent chromium-aluminum passivating agent to form a passivation layer, washed with water, dried, and a passivation film is formed on the surface of the aluminum.

 In step S01, the aluminate is dehydrated to include the following components in a mass ratio: 0.5-1.5% hydrofluoric acid, 0-1% Sulfuric acid, 0-0.5% phosphoric acid, 0.05-0.15% surfactant and balance water. The aluminolysis is preferably selected from the following components in a mass ratio: 0.8-1.2% hydrofluoric acid, 0.6-0.8% sulfuric acid, 0.3-0.5% phosphoric acid, 0.1-0.12% surfactant and balance water. Wherein, the content of the hydrofluoric acid raw material (ie, the concentration of the solute in the hydrofluoric acid raw material, the same below) is 55wt%, the content of sulfuric acid raw material is 98 wt%, the content of phosphoric acid raw material is 85wt%, the content of surfactant raw material is above 98%, and the surfactant is preferably nonylphenol ethoxylate NP-9. , TX-9, TX-10 or NP-10. The degreasing and descaling process is carried out by soaking or spraying aluminum, and the soaking treatment time is preferably 3-15 minutes, more preferably 3-10. The spray treatment time is preferably from 1 to 7 minutes, more preferably from 2 to 5 minutes.

The aluminum acid stripping of the present embodiment can be applied to the soaking of various aluminum or aluminum alloy profiles or aluminum finished products, aluminum products, etc., and the aluminum acid stripping is an acidic degreasing agent which is compounded by various surfactants and has Extremely strong decontamination, dispersion, emulsification and solubilization. During the treatment, the decontamination is thorough and rapid, and the aluminum or aluminum parts will not be over-etched. (blackening) phenomenon, production is safe and reliable.

In addition, preferably, the embodiment adds a water washing process before degreasing, which can wash away most of the aluminum chips and some dirt generated during the processing of the aluminum material, thereby reducing the consumption and pollution of the degreasing tank and the degreasing tank. Then, the surface impurities of the degreasing and descaling are washed away with water. Preferably, the free acidity with aluminoic acid is 16-30 pt, 1 pt = 0.01 mol/L of H ⁺ .

 Step S02 is a light-emitting process, and the light-removing process in the embodiment can effectively remove the black ash generated during degreasing, and the cleanliness is up to 99.9% In addition, the surface of the aluminum alloy can be adjusted to be flat, which effectively ensures the passivation rate and the firmness of the passivation. After the light is washed, it can be washed with hot water. It can ensure that the aluminum material is cleaned more cleanly and dried more quickly. It avoids some high-demand aluminum materials that are not reoxidized in time due to drying. Through the light-emitting treatment, the dust on the surface of the material can be quickly removed, the workpiece can be restored to the original color, and the adhesion of the passivation film can be improved.

 Preferably, the light-emitting agent comprises the following components in a mass ratio: 5-8% nitric acid, 0-2% sulfuric acid, 1-2% Hydrochloric acid and the balance of water. The content of nitric acid raw material is 68%, the content of sulfuric acid raw material is 98%, and the content of hydrochloric acid raw material is 33%. The light treatment time is 30-60 seconds, and the total acidity of the light-emitting agent is controlled at 50-200pt range.

 When the light is emitted, the immersion treatment time with the light-emitting agent is preferably 0.5 to 2 minutes, more preferably 1-2 minutes, and the spray treatment time is preferably 0.5-1 minute. The trivalent chromium aluminum passivating agent preferably comprises the following components in a mass ratio: chromium nitrate or chromium sulfate or chromium chloride 0.15-0.5%; potassium fluorotitanate 0.03-0.07%, ammonium hydrogen fluoride 0.01-0.03%; citric acid 0.1-0.3%, water balance. More preferably, it comprises the following components in a mass ratio: chromium nitrate or chromium sulfate or chromium chloride 0.3-0.4%; potassium fluorotitanate 0.04-0.05%, ammonium hydrogen fluoride 0.02-0.03%; citric acid 0.2-0.3%, water balance.

 In this embodiment, the trivalent chromium aluminum passivating agent comprises the following components in a mass ratio: chromium nitrate or chromium sulfate or chromium chloride 0.15-0.5% , potassium fluorotitanate 0.03-0.07%, ammonium hydrogen fluoride 0.01-0.03%, citric acid 0.1-0.3%, water balance. Preferably, the mass percentage of each component is: chromium nitrate or chromium sulfate or chromium chloride 0.2-0.3%, potassium fluorotitanate 0.04-0.06%, ammonium hydrogen fluoride 0.02-0.03%, citric acid 0.2-0.3% , the amount of water. The passivation treatment is by soaking or spraying, and the soaking treatment time is preferably 1-5 minutes, more preferably 2-4, and the spraying treatment time is preferably 1-2 minutes.

The trivalent chromium aluminum passivating agent of the present embodiment is a trivalent chromium reagent, which is suitable for impregnation foaming and spray passivation of various aluminum alloy parts or aluminum finished products, and can form a yellow to blue layer on the surface of the material. A corrosion-resistant passivation layer that does not contain Cr ⁶⁺ ions to provide a coating finish or to form a passivation film on the finished surface. The passivating agent is a safe and environmentally friendly reagent, and the waste liquid treated by the passivating agent is easy to handle and has low processing cost. The total acidity of the trivalent chromium-aluminum passivator is controlled at 2-4 pt.

 Preferably, the drying is natural drying or drying, and the drying temperature is lower than 80 °C. Industrial water can be used for washing, PH The value is about 6-7, and it is washed for 1-2 minutes at normal temperature.

The present invention also provides the use of the above process, that is, processing by using a trivalent chromium-aluminum passivation treatment process as described above to obtain an aluminum material or an aluminum product. When the aluminum material treated by the treatment process is applied, the coating has good adhesion and is easy to be coated, and the formed coating has strong corrosion resistance, especially acid and alkali corrosion resistance.

 Hereinafter, the process flow of the trivalent chromium-aluminum passivation process of the embodiment of the present invention will be described by way of specific examples.

 Examples 1 to 3 and Comparative Examples 4 to 6

 1) Prepare the aluminate according to the mass ratio of Table 1. Wash the aluminum to be treated first, remove the aluminum chips, and then soak in the aluminate, soak at room temperature. 10 minutes, wash with industrial tap water 1-2 times.

 2) According to the mass ratio of Table 1, prepare the light agent, soak the aluminum material treated in the previous step in the light-emitting agent, soak it at room temperature. Minutes, wash with industrial tap water 1-2 times to completely remove black ash.

 3) Prepare a trivalent chromium-aluminum passivation agent according to the mass ratio of Table 1, and immerse the light-treated aluminum material in a passivating agent and soak it at room temperature. In minutes, wash with industrial tap water 1-2 times and dry at 70 °C for 20 minutes.

 4) Neutral salt spray test and 100-test test after painting

Neutral salt spray test conditions: sodium chloride solution concentration 50 g / L, daily calibration concentration once PH value 6.5 6.5-7.2, nozzle pressure is 1.00 ± 0.01 kgf / cm ² , spray volume is 1.0 ~ 2.0 ml / 80cm ² / h, collect for more than 16 hours, and find the average value, the temperature of the salt water tank is 35 ± 1 °C, and the temperature of the laboratory is 35 ± 1 °C. After the coating of the aluminum material after the above various examples and comparative examples was formed, the coating was subjected to the GBT9286-1998 standard test and the grade was determined. The test results are shown in Table 1.

 As shown in Figure 1, the surface of the aluminum that has been exposed to light is very bright, bright, and free of impurities, and Figure 2 Although there is a light-emitting treatment, the light-emitting agent of the present invention is not used, and the black ash effect is poor, and the aluminum surface has residual ash and the color is gray. image 3 It is a photo of aluminum that has not been exposed to light, and it can be seen that there is black ash on the surface of the untreated aluminum.

 Table 1 Quality ratio and test results of various reagents in each example

Reagent	Serial number	Example 1	Example 2	Example 3	Comparative example 4	Comparative example 5	Comparative example 6
Aluminate	Hydrofluoric acid (%)	0.6	1.0	1.2	0	1.0 hydrochloric acid	1.0 hydrochloric acid
	Sulfuric acid (%)	0.6	0.5	0.3	1.2	0	0.5
	Phosphoric acid (%)	0.2	0.1	0.1	0.2	0.6	0
	Surfactant (%)	0.1 NP-9	0.1NP-10	0.2 TX-9	0.2 TX-9	0.2 TX-9	0.1TX-10
	Water (%)	98.5	98.3	98.2	98.6	98.2	98.4
Light agent	Nitric acid (%)	5	6	7	5	8	7
	Sulfuric acid (%)	2	1	1	5	2	3
	Hydrochloric acid (%)	2	2	1	0	0	0
	Water (%)	91	91	91	90	90	90
Deactivator	Chromium nitrate (%)	0.2	0.3	0.4	0.1	0.8	0.6
	Potassium fluorotitanate (%)	0.06	0.05	0.04	0	0	0
	Ammonium hydrogen fluoride (%)	0.02	0.02	0.02	0.01	0.03	0.04
	Citric acid (%)	0.1	0.2	0.3	0.2 boric acid	0.2 boric acid	0.2 boric acid
	Water (%)	99.62	99.43	99.24	99.69	98.97	99.16
Adhesion	GBT9286-1998 standard	0	0	0	3	1	2
Neutral salt spray test	Condition as stated above	270 hours no change	256 hours no change	245 hours no change	Corrosion occurs in 10 hours	Corrosion occurs in 18 hours	Corrosion occurs in 12 hours

It should be noted that the present invention is not limited to the above embodiments, and other changes may be made by those skilled in the art according to the inventive spirit of the present invention, and the changes according to the inventive spirit of the present invention should be included in the present invention. Within the scope of the claimed invention.

Claims (10)

1. A trivalent chromium-aluminum passivation treatment process for aluminum pre-treatment or aluminum finished product treatment, which comprises the steps of: de-oiling the surface of the aluminum material with alumina acid, removing water, washing, light, washing, The surface of the aluminum material is treated with a trivalent chromium-aluminum passivating agent to form a passivation layer, washed with water, dried, and a passivation film is formed on the surface of the aluminum.
2. The trivalent chromium-aluminum passivation treatment process according to claim 1, wherein the aluminate de- ing comprises the following components in a mass ratio: 0.5-1.5% Hydrofluoric acid, 0-1% sulfuric acid, 0-0.5% phosphoric acid, 0.05-0.15% surfactant and balance water.
3. Claims 1 The trivalent chromium-aluminum passivation treatment process is characterized in that the surface of the aluminum material is degreased or descaled by aluminum acid or the surface of the aluminum material is treated with a trivalent chromium aluminum passivator to soak or spray aluminum. Material processing.
4. The trivalent chromium-aluminum passivation treatment process according to claim 3, wherein the immersion treatment time is 3-15 minutes, and the spray treatment time is 1-7. Minutes.
5. The trivalent chromium-aluminum passivation treatment process according to claim 1, wherein the free acidity of the aluminate is 16-30 pt.
6. The trivalent chromium-aluminum passivation treatment process according to claim 1, wherein the light-emitting agent comprises the following components in a mass ratio: 5-8% nitric acid, 0-2% sulfuric acid, 1-2% hydrochloric acid and the balance water.
7. The trivalent chromium-aluminum passivation treatment process according to claim 6, wherein the light-emitting treatment time is 30-60 seconds, and the free acidity of the light-emitting agent is controlled at 50-200pt range.
8. Claims 1 The trivalent chromium aluminum passivation treatment process is characterized in that the trivalent chromium aluminum passivation agent comprises the following components according to mass ratio:

   Chromium nitrate or chromium sulfate or chromium chloride 0.15-0.5%

   Potassium fluorotitanate 0.03-0.07%

   Ammonium hydrogen fluoride 0.01-0.03%

   Citric acid 0.1-0.3%

   Water balance.
9. Claims 1 The trivalent chromium aluminum passivation treatment process is characterized in that the trivalent chromium aluminum passivation agent comprises the following components according to mass ratio:

   Chromium nitrate or chromium sulfate or chromium chloride 0.2-0.3%

   Potassium fluorotitanate 0.04-0.06%

   Ammonium hydrogen fluoride 0.02-0.03%

   Citric acid 0.2-0.3%

   Water balance.
10. The treatment is carried out by a trivalent chromium-aluminum passivation treatment process according to any one of claims 1 to 9 to obtain an aluminum or aluminum product.