Chemical polishing technology for aluminum products
First, mechanical polishing the surface of aluminum products:
1. The mechanical polishing process is: rough grinding, fine grinding, polishing, polishing, sand blasting, brushing or rolling, etc. Different procedures are appropriately adopted according to the required surface roughness.
2. Chemical degreasing:
The chemical degreasing process is to remove the oil stain on the surface of the part by chemical reaction and physical and chemical action. Chemical degreasing is performed in a weakly alkaline solution.
The formula and process conditions of chemical degreasing fluid:
1. Formula: 30-50G / L sodium hydroxide, 0.5-1ML / L industrial detergent, 70-125G water.
2, process conditions: temperature: 50-60 ℃ time:
3, rinse with water after degreasing.
4. Chemical removal of oxide film: acid pickling treatment is used to neutralize the residual lye on the surface of the part, and remove its natural oxide film to expose the aluminum and aluminum alloy substrate of the part. The mixed solution was acid-washed to remove the dark silicon ash on its surface.
The formula of 洗 pickling solution:
Temperature: Room temperature time:
Acid solution for removing the oxide film on the surface of silicon-containing aluminum alloy parts and silicon ash:
33 volumes of concentrated nitric acid; 1 volume of concentrated hydrofluoric acid.
Temperature: Room temperature time:
After chemical pickling of aluminum and aluminum alloy products, they must be immediately washed with flowing warm water and cold water to remove residual acid, and then immersed in water for chemical polishing.
5. Chemical polishing:
Chemical polishing is a chemical processing method that uses the selective self-dissolving effect of aluminum and aluminum alloys in acidic or alkaline electrolyte solutions to level and polish the annual surface to reduce its surface roughness and PH. This polishing method has the advantages of simple equipment, no power supply, no restrictions on the size of the workpiece, high throwing speed, and low processing costs.
The purity of aluminum and aluminum alloy has a great influence on the quality of chemical polishing. The higher the purity, the better the polishing quality, and the worse it is.
Chemical polishing is performed using a brief viscous liquid film theory.
Polishing liquid formula and process conditions:
Formulation 1: (parts by weight
75Concentrated phosphoric acid 75%; concentrated sulfuric acid 8.8%; concentrated nitric acid 8.8%; urea 3.1%; amine sulfate 4.4%; copper sulfate 0.02%.
Temperature: 100-200 ℃ Time:
Formula 2: (parts by weight
85Concentrated phosphoric acid 85%; concentrated nitric acid 5%; glacial acetic acid 10%.
Temperature: 90-105 ℃ Time:
The preparation method of polishing liquid:
1. Put phosphoric acid, sulfuric acid, and nitric acid into a polishing tank in order according to a certain (%) weight, and carefully block them.
2. Then, according to the ingredients of the formula, dissolve a certain (%) weight of glacial acetic acid, urea, amine sulfate, and copper sulfate in water by adding them to the tank and mix well.
3. Then, under the stirring state, gradually adjust the above-mentioned polishing liquid to the temperature range required for each formula, and then perform chemical polishing.
Three, the impact of chemical polishing process conditions:
1. Temperature influence: The temperature should be controlled between 90-115 ℃, and the optimal temperature is 105 ℃.
2, the impact of polishing time: polishing time is inversely proportional to the polishing temperature, low temperature extends the polishing time, high temperature shrinks the polishing time.