阅读说明：本技术 一种铝合金镜面化学抛光液及其抛光方法 (Aluminum alloy mirror surface chemical polishing solution and polishing method thereof ) 是由 周家勤 于 2020-06-18 设计创作，主要内容包括：本发明公开了一种铝合金镜面化学抛光液,按重量百分比计由下列原料制成：聚二硫二丙烷磺酸钠3-5%、2-巯基苯并咪唑0.2-1%、硝酸铁3-5%、四甲基高氯酸铵0.5-2%、十二烷基磺酸钠0.5-1.5%、聚乙二醇0.1-0.3%、十三烷醇聚醚-4-羧酸钠0.1-0.3%、75wt%的硫酸15-25%、85wt%的磷酸余量。本发明的化学抛光液对铝合金表面抛光后可以达到镜面效果,可以有效解决现有技术中抛光液对铝合金表面抛光后转移性悬停时容易发生过腐蚀和光泽度变暗的问题,非常适宜自动线生产,大大提高化学抛光的生产效率和抛光成品率。(The invention discloses a chemical polishing solution for an aluminum alloy mirror surface, which is prepared from the following raw materials in percentage by weight: 3-5% of sodium polydithio-dipropyl sulfonate, 0.2-1% of 2-mercaptobenzimidazole, 3-5% of ferric nitrate, 0.5-2% of tetramethyl ammonium perchlorate, 0.5-1.5% of sodium dodecyl sulfate, 0.1-0.3% of polyethylene glycol, 0.1-0.3% of tridecyl alcohol polyether-4-sodium carboxylate, 15-25% of 75wt% of sulfuric acid and the balance of 85wt% of phosphoric acid. The chemical polishing solution can achieve a mirror effect after polishing the surface of the aluminum alloy, can effectively solve the problems that the polishing solution is easy to over-corrode and the glossiness becomes dark when the polishing solution is used for polishing the surface of the aluminum alloy and is suspended in a transferring manner in the prior art, is very suitable for automatic line production, and greatly improves the production efficiency and the polishing yield of chemical polishing.)

1. The chemical polishing solution for the aluminum alloy mirror surface is characterized by being prepared from the following raw materials in percentage by weight:

sodium polydithio-dipropanesulfonate 3-5%

2-mercaptobenzimidazole 0.2-1%

3 to 5 percent of ferric nitrate

Tetramethyl ammonium perchlorate 0.5-2%

Sodium dodecyl sulfate 0.5-1.5%

0.1 to 0.3 percent of polyethylene glycol

Tridecyl alcohol polyether-4-carboxylic acid sodium 0.1-0.3%

75wt% sulfuric acid 15-25%

85wt% phosphoric acid balance.

2. The aluminum alloy mirror surface chemical polishing solution according to claim 1, wherein the polyethylene glycol is PEG-400, PEG-600 or PEG-800.

3. The aluminum alloy mirror surface chemical polishing solution according to claim 1 or 2, characterized by being prepared from the following raw materials in percentage by weight:

sodium polydithio-dipropanesulfonate 3%

2-mercaptobenzimidazole 1%

4 percent of ferric nitrate

1 percent of tetramethyl ammonium perchlorate

Sodium dodecyl sulfate 1.5%

PEG-600 0.2%

Tridecyl alcohol polyether-4-carboxylic acid sodium 0.3%

75% by weight of sulfuric acid 20%

85wt% phosphoric acid balance.

4. The polishing method of the aluminum alloy mirror surface chemical polishing solution according to claim 1 or 2, characterized by comprising the following steps:

(1) heating the polishing solution to 70-90 ℃;

(2) immersing the aluminum alloy workpiece into the polishing solution for polishing for 0.5-3 min;

(3) taking out the aluminum alloy workpiece, suspending for no more than 1min, washing with water, and drying.

Technical Field

The invention belongs to the field of aluminum alloy surface treatment, and particularly relates to a chemical polishing solution for an aluminum alloy mirror surface and a polishing method thereof.

Background

Because the aluminum alloy has the advantages of light weight, easy processing, good corrosion resistance and the like, the aluminum alloy has quite wide application, plays an extremely important role in the hardware market, and is particularly widely applied to main materials of parts such as electronic and electric product shells and the like. The electronic and electric product shells and the like mostly require mirror surface brightness, and the processing amount of the products is large, so the method is particularly suitable for automatic production.

Mechanical polishing and chemical polishing are main methods for improving the brightness of aluminum products, wherein the chemical polishing process is simple and rapid, the processing area is large, the application is wide, the process is difficult to control, the polishing effect of mirror surface brightness is difficult to obtain generally, particularly, after polishing, excessive corrosion is easy to generate if the polishing is not washed quickly, defective products such as pits, stripes, fog films and the like appear, the time interval between the working procedures of an automatic production line is long, the compression space is limited, and the conventional chemical polishing process suitable for manual operation must be modified and optimized in order to improve the polishing quality and the qualification rate of products on the automatic line. Most chemical polishing products on the market are easy to be over-corroded when suspended in a transferring manner after the polishing process, and are not suitable for automatic line production.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the aluminum alloy chemical polishing solution suitable for automatic line production, and mainly solves the problems that the polishing solution is easy to over-corrode and darken in glossiness during transferring hovering after polishing the surface of the aluminum alloy in the prior art. In order to realize the purpose, the invention adopts the following technical scheme:

the chemical polishing solution for the aluminum alloy mirror surface is prepared from the following raw materials in percentage by weight:

sodium polydithio-dipropanesulfonate 3-5%

2-mercaptobenzimidazole 0.2-1%

3 to 5 percent of ferric nitrate

Tetramethyl ammonium perchlorate 0.5-2%

Sodium dodecyl sulfate 0.5-1.5%

0.1 to 0.3 percent of polyethylene glycol

Tridecyl alcohol polyether-4-carboxylic acid sodium 0.1-0.3%

75wt% sulfuric acid 15-25%

85wt% phosphoric acid balance.

Preferably, the polyethylene glycol is PEG-400, PEG-600 or PEG-800.

Preferably, the chemical polishing solution for the aluminum alloy mirror surface is prepared from the following raw materials in percentage by weight:

sodium polydithio-dipropanesulfonate 3%

2-mercaptobenzimidazole 1%

4 percent of ferric nitrate

1 percent of tetramethyl ammonium perchlorate

Sodium dodecyl sulfate 1.5%

PEG-600 0.2%

Tridecyl alcohol polyether-4-carboxylic acid sodium 0.3%

75% by weight of sulfuric acid 20%

85wt% phosphoric acid balance.

The invention adopts the mixed acid of phosphoric acid and sulfuric acid as a corrosion system. Phosphoric acid is a medium strong acid and mainly plays a role in leveling and brightening. Phosphoric acid can generate a layer of phosphate conversion film when corroding and dissolving the surface of the aluminum alloy, and the film hinders the diffusion of the metal surface polishing solution, so that the polishing process is relatively slow, the excessive corrosion of the polishing solution to the metal surface is prevented, the surface roughness of the aluminum alloy is reduced, the brightness is improved, and a smooth and bright surface is finally obtained. If the concentration of the phosphoric acid is too low, the phosphate conversion film cannot be effectively generated, cannot play a role in slowing down the polishing process, and is easy to over-corrode; if the concentration of phosphoric acid is too high, polishing efficiency is affected. Sulfuric acid, another corrosive acid of the present invention, is indispensable for its action in the polishing liquid. The sulfuric acid can fully dissolve the oxide film, thereby avoiding the gray oxide film on the surface of the aluminum alloy to reduce the glossiness. If the concentration of the sulfuric acid is too low, the dissolved oxide film is incomplete and the time is long; if the concentration of the sulfuric acid is too high, the corrosion is aggravated, over-corrosion is easy to occur, and the surface smoothness and the glossiness of the aluminum alloy are affected. Meanwhile, the sulfuric acid does not generate smoke, and the polishing environment can meet the environmental protection requirement.

The chemical polishing solution usually adopts nitric acid as a metal oxidant, but the nitric acid belongs to volatile acid, and toxic yellow smoke is easily generated in the reaction process, so that sodium nitrate and potassium nitrate are commonly used as the oxidants to effectively prevent the generation of irritant gas, but the oxidation effect of single nitrate is still lower than that of the nitric acid, the use amount of the nitric acid can increase the dosage of a corrosive agent to a certain extent, and in order to not reduce the oxidation performance and not generate the toxic yellow smoke, the invention adopts ferric nitrate and tetramethyl ammonium perchlorate which are in proper mass ratio as composite oxidants, and the ferric nitrate and the tetramethyl ammonium perchlorate are continuously oxidized into metal oxides on the surface in the aluminum alloy polishing process, and the metal oxides can avoid the over-corrosion problem in the polishing process. On one hand, the generation and dissolution of the metal oxide can reach dynamic balance by adding the composite oxidant, the polishing speed can be effectively inhibited, the surface of the aluminum alloy can be uniformly corroded, and then a good polishing effect is obtained, namely the flatness and the glossiness of the surface of the aluminum material can be improved. On the other hand, the addition of the composite oxidant can also inhibit the pitting corrosion problem of elements such as zinc, copper, magnesium and the like in the aluminum alloy during polishing, and the reason is that the passivation film layer generated under the action of the strong oxidant makes up the deficiency that the adhesive film layer generated under the action of phosphoric acid protects the concave part on the surface of the aluminum material, so that the next step of corrosion reaction is facilitated.

The surfactant system is formed by sodium dodecyl sulfate, polyethylene glycol and tridecyl polyether-4-sodium carboxylate according to a proper mass ratio. The reasonably compounded surfactant can reduce the surface tension between the surface of the aluminum alloy and the polishing solution, so that the polishing solution is more uniformly adsorbed on the surface of the aluminum alloy, the defects of pitting, scratches and the like are effectively reduced, and the polishing process is stably carried out. When the aluminum alloy is suspended in the air after being polished, the chemical polishing solution forms a barrier layer on the surface of the aluminum alloy, so that local over-corrosion caused by air intervention is avoided, the chemical polishing solution and the surface of the aluminum alloy are finally enabled to uniformly react, and meanwhile, the chemical polishing solution, the sodium polydithio-dipropionate and the 2-mercaptobenzimidazole brightener are cooperated, so that the quality of the polished surface can be further improved, and the polished surface is bright and flat.

The aluminum alloy chemical polishing solution is simple in preparation method, and can be prepared by sequentially adding sodium polydithio-dipropyl sulfonate, 2-mercaptobenzimidazole, ferric nitrate, tetramethylammonium perchlorate, sodium dodecyl sulfate, polyethylene glycol, trialkanol polyether-4-carboxylic acid sodium and 75wt% of sulfuric acid into 85wt% of phosphoric acid and uniformly stirring.

The polishing method of the aluminum alloy chemical polishing solution comprises the following steps:

(1) heating the polishing solution to 70-90 ℃;

(2) immersing the aluminum alloy workpiece into the polishing solution for polishing for 0.5-3 min;

(3) taking out the aluminum alloy workpiece, suspending for no more than 1min, washing with water, and drying.

The chemical polishing solution can achieve a mirror effect after polishing the surface of the aluminum alloy, can effectively solve the problems that the polishing solution is easy to over-corrode and the glossiness becomes dark when the polishing solution is used for polishing the surface of the aluminum alloy and is suspended in a transferring manner in the prior art, is very suitable for automatic line production, and greatly improves the production efficiency and the polishing yield of chemical polishing.

Detailed Description

The invention is further described below by way of examples.