ã€China Aluminum Industry Network】 1. Introduction After nearly 20 years of development, China's aluminum industry has formed a complete industrial system and has become one of the pillar industries of the national economy. It is widely used in various industries including aerospace, transportation, and building materials. industry. At present, the aluminum industry has undergone technological transformation and has entered a period of development of medium-to-high-grade aluminum. With the diversification of market demands, it has also promoted the development of aluminum surface treatment technology, from a single silver and white bronze material to powder coating and spraying. Fluorocarbon coating, organic and inorganic dyeing, electrophoretic coating, mechanical and chemical polishing, etc., the appearance of aluminum profiles include gold, golden, champagne, imitation stainless steel and various colors, as well as display mirror, sandstone, matt Such special effects as pearl and pearl are various varieties and colors. In these processing methods, the pre-treatment processes such as degreasing, pickling, neutralization, and washing are indispensable. The development of anti-corrosion technologies for these pre-treatment tanks has become an important issue in the aluminum processing industry. Taking into account the cost and practicality, these pre-treatment tanks are mostly made of reinforced concrete, usually horizontal or vertical tanks, and the storage of sulfuric acid, hydrofluoric acid, caustic soda and other media in the tank will be related to the free hydrogen in the cement cured product. Calcium oxide, tricalcium aluminate, etc. react to form soluble salts, resulting in corrosion of concrete structures and affecting the service life of equipment. How to choose corrosion-resistant materials and ensure effective protection of these tanks, and at the same time ensure long equipment operation cycle and reasonable construction cost, etc., are the actual problems faced by new and expanded aluminum profile processing plants. 2. Common aluminum surface treatment process 2.1 Common aluminum surface treatment process A. Degreasing (water washing 1) B. Alkali washing (water washing 2) C. Pickling, neutralization (water washing 3) D. Anodizing (washing 4 ) E. Electrolytic coloring --- F. Sealing 2.2 The main role of each process A. Degreasing: Removal of aluminum surface oil (stain) stains, etc., the use of alkaline degreaser, weak alkaline degreaser (Japanese technology more Used) sulfuric acid, nitric acid and so on. B. Alkali wash: remove oxide film and shallow surface defects, usually use caustic soda, concentration: 4-10%; temperature control: 50-60°C, aluminum ion concentration control: 50-60g/l; when aluminum ion concentration When it is too low (<30g/l), precipitation and agglomeration are likely to occur; It can be solved by adding auxiliaries, increasing the concentration of aluminum ions or circulating outside the tank, and recovering the precipitate; More effective method: to extend the time, increase the temperature of caustic washing; but washing 2 must be equipped with washing device, timely cleaning. C. Pickling, Neutralization: The purpose is to remove light and remove the gray matter (mainly: Fe, Cu, Mn, Si, etc.) produced on the surface of the caustic wash, usually 50% by volume of nitric acid or a certain concentration (150-200g). /l) Sulfuric acid.