CN112695326A

CN112695326A - Chromium-free and phosphorus-free polishing agent, aluminum workpiece and polishing treatment method thereof

Info

Publication number: CN112695326A
Application number: CN202011460877.0A
Authority: CN
Inventors: 王饶玲
Original assignee: Shenzhen Hengzhaozhi Technology Co Ltd
Current assignee: Shenzhen Hengzhaozhi Technology Co Ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-04-23

Abstract

The invention relates to a chromium-free and phosphorus-free polishing agent, an aluminum workpiece and a polishing treatment method thereof. The chromium-free and phosphorus-free polishing agent is used for surface pretreatment of aluminum workpieces and comprises the following components in parts by weight based on 100 parts by weight: 10-20 parts of nitric acid, 0.005-0.02 part of copper sulfate, 10-20 parts of ammonium bifluoride, 5-10 parts of oxalic acid, 3-5 parts of sorbitol, 0.5-3 parts of gum arabic and the balance of water. The polishing agent does not contain chromium components, meets the requirement of environmental protection, and after the treatment of the non-chromium and non-phosphorus polishing agent, the surface of an aluminum workpiece is clean and bright.

Description

Chromium-free and phosphorus-free polishing agent, aluminum workpiece and polishing treatment method thereof

Technical Field

The invention relates to the technical field of iron surface treatment, and particularly relates to a chromium-free and phosphorus-free polishing agent, an aluminum workpiece and a polishing treatment method thereof.

Background

In order to improve the surface properties or appearance of the product, the surface of the workpiece is usually treated. For example, surface treatment processes for stainless steel, zinc alloys, aluminum, and the like, and alloys thereof, are in great popularity. Furthermore, most workpieces are also subjected to a pretreatment, such as cleaning, desmutting, or degreasing, prior to surface treatment, and some metal workpieces are also subjected to a polishing treatment.

In general, in the mechanical processing and electronic and electrical industries, the cleaning and polishing treatment, i.e., polishing treatment, of aluminum and its alloys is common. Conventional non-chrome and non-phosphorus polishing agents generally employ mechanical polishing or three-acid polishing, wherein mechanical polishing has poor polishing effect on workpieces with complex geometries and is prone to cracking and scratching. The triacid in the triacid polishing, namely concentrated nitric acid, concentrated sulfuric acid and concentrated phosphoric acid, reacts violently under the high-temperature condition, gas is volatilized greatly, and a large amount of NO can be generated_XGas is unsafe, has great harm to the environment and large energy consumption.

Disclosure of Invention

In view of the above, a polishing agent with better physical appearance, higher mechanical properties, better corrosion resistance, easy cleaning, special effect, less odor and less energy consumption, a polishing method for aluminum workpieces, and an aluminum workpiece prepared by polishing are provided.

A chromium-free and phosphorus-free polishing agent comprises the following components in parts by weight based on 100 parts by weight: 10-20 parts of nitric acid, 0.005-0.02 part of copper sulfate, 10-20 parts of ammonium bifluoride, 5-10 parts of oxalic acid, 3-5 parts of sorbitol, 0.5-3 parts of gum arabic and the balance of water.

A polishing treatment method for an aluminum workpiece comprises the following steps: preparing the chromium-free and phosphorus-free polishing agent; immersing the aluminum workpiece into a chromium-free and phosphorus-free polishing agent solution, and washing the aluminum workpiece after treatment at preset time and temperature.

And an aluminum workpiece, the surface of which is polished by the aluminum workpiece polishing treatment method as described above.

The polishing agent does not contain chromium compounds and phosphorus, is more environment-friendly, is prepared into polishing solution of dilute acid solution series by using nitric acid and oxalic acid, is not treated by using concentrated acid, has mild reaction, and also shows good polishing effect. After the treatment of the chromium-free and phosphorus-free polishing agent, the surface of an aluminum workpiece has high light reflectivity and no defects of pitting, spots, white mist and the like, and the whole polishing treatment method has the advantages of simple process, small smell, convenient operation and low use cost.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The embodiment of the invention provides a chromium-free and phosphorus-free polishing agent, which is used for pretreating the surface of an aluminum workpiece and comprises the following components in parts by weight based on 100 parts by weight: 10-20 parts of nitric acid, 0.005-0.02 part of copper sulfate, 10-20 parts of ammonium bifluoride, 5-10 parts of oxalic acid, 3-5 parts of sorbitol, 0.5-3 parts of gum arabic and the balance of water.

Specifically, the weight part of the nitric acid is preferably 12 to 18 parts. The weight portion of the copper sulfate is preferably 0.01-0.02 part, the weight portion of the ammonium bifluoride is preferably 12-18 parts, and the weight portion of the oxalic acid is preferably 6-8 parts. The sorbitol is preferably 2-4 parts by weight, and the Arabic gum is preferably 1-2 parts by weight. In the acid raw material, the nitric acid is a nitric acid solution with the mass percentage of 68%, and the oxalic acid is a powder raw material. Although the nitric acid raw material is a concentrated acid solution, the nitric acid raw material becomes a dilute acid after being prepared into a polishing solution.

In the chemical etching process, the microscopic projections on the metal surface are in solution and the dissolution rate is much greater than that of the microscopic depressions, resulting in a gradually leveled and smooth, shiny surface. The proportion of each component is controlled to be balanced, so that a better polishing effect is achieved. Nitric acid, ammonium bifluoride and oxalic acid remove oxide scales and enable the surface of the aluminum to react quickly, nitric acid increases oxidizability to inhibit corrosion pits, and sorbitol enables the reaction to be uniform and consistent. Gum arabic can reduce the reaction rate of microscopic cavities. Copper sulfate can improve the reflectivity of the aluminum alloy.

The embodiment of the invention also provides an aluminum workpiece polishing treatment method, which comprises the following steps: preparing the chromium-free and phosphorus-free polishing agent; immersing the aluminum workpiece into a chromium-free and phosphorus-free polishing agent solution, performing treatment for a preset time, washing the aluminum workpiece with water, and drying.

Specifically, the predetermined time is 0.5 to 1 minute. Further, after polishing, passivation or oxidation is performed, and then washing and drying are performed. During polishing treatment, the temperature is controlled at 60-100 ℃. Furthermore, pretreatment such as degreasing, degreasing and descaling is performed before polishing.

The embodiment of the invention also provides the aluminum workpiece, which is polished by the polishing method of the aluminum workpiece, so that the aluminum workpiece forms a clean and bright surface. After the treatment of the non-chromium and non-phosphorus polishing agent, the surface of an aluminum workpiece is clean, the light reflectivity is high, and the whole polishing treatment method has the advantages of simple process, convenient operation and low use cost.

Specifically, the following examples illustrate that, since the composition of the aluminum alloy greatly affects the surface brightness after chemical polishing, generally, the higher the purity of the aluminum, the better the polishing brightness, and the following examples are made of Al — Mg alloy with aluminum in a mass fraction of 99.99%.

Example 1

The following components are mixed according to the following parts by weight (the total weight is 100 parts by weight): 10 parts of nitric acid, 0.005 part of copper sulfate, 10 parts of ammonium bifluoride, 5 parts of oxalic acid, 3 parts of sorbitol, 0.5 part of gum arabic and the balance of water.

The treatment method comprises the following steps: preparing a chromium-free and phosphorus-free polishing agent; deoiling and descaling an aluminum workpiece in advance, then washing with water, immersing the workpiece with a clean surface into a chromium-free and phosphorus-free polishing agent solution at 85 ℃, washing with water after 1 minute, and drying.

After the treatment by the chromium-free and phosphorus-free polishing agent solution, the surface of a workpiece is observed, and the whole surface is clean and bright and has consistent color and no spots, white fog, pitting corrosion and other abnormalities. The specular reflectivity is more than 40%.

Example 2

The following components are mixed according to the following parts by weight (the total weight is 100 parts by weight): 13 parts of nitric acid, 0.01 part of copper sulfate, 13 parts of ammonium bifluoride, 7 parts of oxalic acid, 4 parts of sorbitol, 1 part of gum arabic and the balance of water.

After the treatment by the chromium-free and phosphorus-free polishing agent solution, the surface of a workpiece is observed, and the whole surface is clean and bright and has consistent color and no spots, white fog, pitting corrosion and other abnormalities. The specular reflectivity is more than 50%.

Example 3

The following components are mixed according to the following parts by weight (the total weight is 100 parts by weight): 17 parts of nitric acid, 0.015 part of copper sulfate, 17 parts of ammonium bifluoride, 8 parts of oxalic acid, 4 parts of sorbitol, 2 parts of gum arabic and the balance of water.

After the treatment by the chromium-free and phosphorus-free polishing agent solution, the surface of a workpiece is observed, and the whole surface is clean and bright and has consistent color and no spots, white fog, pitting corrosion and other abnormalities. The specular reflectivity is more than 60%.

Example 4

The following components are mixed according to the following parts by weight (the total weight is 100 parts by weight): 20 parts of nitric acid, 0.02 part of copper sulfate, 20 parts of ammonium bifluoride, 10 parts of oxalic acid, 5 parts of sorbitol, 3 parts of gum arabic and the balance of water.

The treatment method comprises the following steps: preparing a chromium-free and phosphorus-free polishing agent; deoiling and descaling an aluminum workpiece in advance, then washing with water, immersing the workpiece with a clean surface into a chromium-free and phosphorus-free polishing agent solution at 85 ℃, washing with water after 40 seconds, and drying.

After the treatment by the chromium-free and phosphorus-free polishing agent solution, the surface of a workpiece is observed, and the whole surface is clean and bright and has consistent color and no spots, white fog, pitting corrosion and other abnormalities. The specular reflectivity is more than 80%.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and other changes and modifications can be made by those skilled in the art according to the spirit of the present invention, and these changes and modifications made according to the spirit of the present invention should be included in the scope of the present invention as claimed.

Claims

1. The chromium-free and phosphorus-free polishing agent is characterized by comprising the following components in parts by weight based on 100 parts by weight: 10-20 parts of nitric acid, 0.005-0.02 part of copper sulfate, 10-20 parts of ammonium bifluoride, 5-10 parts of oxalic acid, 3-5 parts of sorbitol, 0.5-3 parts of gum arabic and the balance of water.

2. The chromium-free and phosphorus-free polishing agent according to claim 1, wherein the nitric acid is present in an amount of 12 to 18 parts by weight.

3. The chromium-free and phosphorus-free polishing agent of claim 1 wherein the copper sulfate is present in an amount of 0.01 to 0.02 parts by weight.

4. The chromium-free and phosphorus-free polishing agent according to claim 1, wherein the ammonium bifluoride is present in an amount of 12 to 18 parts by weight.

5. The chromium-free and phosphorus-free polishing agent according to claim 1, wherein the oxalic acid is present in an amount of 6 to 8 parts by weight.

6. The chromium-free and phosphorus-free polishing agent according to claim 1, wherein the sorbitol is present in an amount of 2 to 4 parts by weight.

7. The chromium-free and phosphorus-free polishing agent according to claim 1 wherein the gum arabic is present in an amount of 1 to 2 parts by weight.

8. A polishing treatment method for an aluminum workpiece comprises the following steps: formulating a chromium and phosphorus free polishing agent according to any one of claims 1 to 7; immersing the aluminum workpiece into a chromium-free and phosphorus-free polishing agent solution, and washing the aluminum workpiece with water after the treatment at preset time and temperature, and entering the next procedure.

9. The method for polishing an aluminum workpiece according to claim 1, wherein the polishing is carried out after a predetermined time of 0.5 to 1 minute and at a predetermined temperature of 60 to 100 ℃, followed by passivation and then water washing and drying.

10. An aluminum workpiece, characterized in that the surface of the aluminum workpiece is polished by the aluminum workpiece polishing treatment method as set forth in claim 8.