Surface treatment of the hottest cast aluminum and

Surface treatment of cast aluminum and aluminum alloy: aluminum chemical polishing technology

I. mechanical polishing of the surface of aluminum products as of August 2015:

1. The mechanical polishing process is: rough grinding, fine grinding, polishing, polishing, sandblasting, brushing or rolling, etc., and different processes are appropriately adopted according to the roughness of the surface

II. Chemical oil removal:

the chemical oil removal process is to remove the oil stain on the surface of the workpiece by means of chemical reaction and physical-chemical action. Chemical oil removal is carried out in weak alkaline solution

formula and process conditions of chemical degreasing solution:

1. Formula: sodium hydroxide g/l, industrial detergent 0 Ml/l, water G

2. Process conditions: temperature: ℃ time: min

3. Wash with clean water after oil removal

4. Chemical removal of oxide film: carry out pickling treatment to neutralize the residual alkaline solution on the surface of the workpiece, and remove its natural oxide film to expose the aluminum and aluminum alloy matrix of the workpiece. For the production of silicon containing aluminum alloy, it must be pickled with mixed solution to remove the dark silicon floating ash on the surface

pickling solution formula:

concentrated nitric acid solution 200~270ml/l

temperature but due to test configuration degree: room temperature time: Min

pickling solution formula for removing oxide film and silicon floating ash on the surface of silicon containing aluminum alloy parts:

concentrated nitric acid 3 volume; Concentrated hydrofluoric acid 1 volume

temperature: room temperature time: Min

after chemical pickling, aluminum and aluminum alloy parts must be cleaned immediately 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 aluminum and aluminum alloy to make selective self dissolution in acidic or alkaline electrolyte solution to level and polish the surface of the year, so as to reduce its surface roughness and pH. This polishing method has the advantages of simple equipment, no power supply, no restriction on the external size of the workpiece, high polishing speed and low processing cost

the purity of aluminum and aluminum alloy has a great impact on the quality of chemical polishing. The higher its purity, the better the polishing quality, and vice versa

chemical polishing is carried out using a brief viscous liquid film theory

polishing solution formula and process conditions:

Formula 1: (parts by weight)

concentrated 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: ℃ time: Min

formula 2: (parts by weight)

concentrated phosphoric acid 85%; Concentrated nitric acid 5%; Glacial acetic acid 10%

temperature: ℃ time: Min

preparation method of polishing solution:

1. First, gradually pour phosphoric acid, sulfuric acid and nitric acid into the polishing tank according to a certain (%) weight, and carefully block it. Focus on the development of products such as polylactic acid (PLA), polybutyric acid butyl ester (PBS), poly-p-benzoic acid 2-alcohol ester (PET, PTT), Polyhydroxyalkanoic acid (PHA), polyamide (PA)

2. According to the composition of the formula, dissolve a certain (%) weight of glacial acetic acid, urea, amine sulfate, and copper sulfate with water respectively, and add them into the tank to mix well

3. Then, under the stirring state, gradually adjust the above polishing solution to the temperature range required by each formula, and then carry out chemical polishing

III. Influence of chemical polishing process conditions:

1 OEM and temperature influence provided for many enterprises: the temperature should be controlled between ℃, of which the best temperature is 105 ℃

2. Influence of polishing time: the polishing time is inversely proportional to the polishing temperature. Low temperature prolongs the polishing time, and high temperature shrinks the polishing time. (end)