Anodizing is essentially the electrolysis of water.

Development of the aluminum industry

Aluminum is one of the six major metal elements in nature, and China has abundant aluminum resources, exceeding the content of iron.2/3, but in terms of resource development and utilization, it is far behind iron resources. The main reason is the lack of resource utilization and product development; currently, China has listed aluminum resource development as a key project, mainly reflected in the industrial manufacturing sector. In recent years, the speed of product development and application of aluminum profiles has accelerated, the capacity and technology for aluminum resource development have been continuously improved, the variety of products has rapidly increased, and the utilization rate of aluminum resources has been continuously enhanced, accelerating the process of aluminum resource development in China.Aluminum profilesThe processing flow of aluminum profile products:
 

Chemical properties and physical performance of aluminum:

The surface of aluminum is silver-white, relatively light in weight, but has high electrical conductivity, thermal conductivity, and ductility. Compared to other metals, it has very high corrosion resistance; pure aluminum is a very soft material that must be strengthened by adding other alloying elements; aluminum is a very active chemical element that can dissolve in both acids and bases, making it a typical amphoteric substance. When exposed to air for a long time, it naturally forms a protective film on its surface, providing some protection.

Processing flow of aluminum profile products:

Aluminum is synthesized with other alloying elements and cast into aluminum ingots (aluminum ingots are raw materials used to cast aluminum rods).

Aluminum ingots are then cast into aluminum rods (aluminum rods are raw materials used to produce extruded industrial aluminum profiles).

To make industrial aluminum profiles from aluminum rods, the following process is required:

①: Furnace heating.

②: Mold design (the mold is designed according to product requirements for extrusion shaping).

③: Using an extrusion machine (6063-T5Common profile extrusion machines generally operate at1300-1600tons. If higher specifications are needed for profiles, a more powerful extrusion machine should be used based on actual conditions.) to extrude and obtain industrial aluminum profile products with different cross-sections through the mold.

④: Aluminum profile correction.

⑤: Straightening.

⑥: Aging (aging is a key step that affects the strength and hardness of industrial aluminum profile products).

⑦: Anodizing treatment.

⑧: Sandblasting anodizing (sandblasting anodizing refines the surface stretch marks of profiles and serves as secondary treatment to refineindustrial aluminum profile's surface micropores and enhance oxidation resistance).
 

The anodizing treatment process for industrial aluminum profiles:

① Surface treatment of aluminum profiles:

Surface treatment of aluminum profiles, also known as surface pre-treatment, involves using physical and chemical substances to remove dirt from the surface of aluminum profiles, exposing the raw material underneath for subsequent anodizing treatment.
 

② Degreasing process for aluminum profiles:

The purpose of the degreasing process for aluminum profiles is to removeAluminum profiles's industrial lubricants and anti-corrosion oils as well as impurities attached to the profile's surface, ensuring uniform alkaline etching and cleanliness of the alkaline etching tank; improving the quality of surface treatment for aluminum profiles.
 

③ Acid etching process for aluminum profiles:

The acid etching process for aluminum profiles is performed after degreasing to remove oxides formed by other metal elements on the surface after oxidation and natural oxide films formed on the profiles; after acid etching treatment, immediate rinsing with water is required. The water washing temperature should be controlled at early50(°C) to avoid streaks on the profile's surface before proceeding with flowing water rinsing. Due to copper content in the aluminum profile, after acid etching, if the surface appears dark, it needs to be soaked in nitric acid solution for3-5-minute immersion to achieve a bright silver color on the surface.
 

④ Alkaline etching process for aluminum profiles:

's alkaline etching process aims to remove residual substances and degraded layers from the surface during oxidation similar to acid etching; it also eliminates scratches left on the surface during extrusion. The alkaline etching treatment plays a crucial role in enhancing overall quality.
 

⑤ Neutralization process for aluminum profiles:

's neutralization process aims to remove insoluble copper, manganese, iron, silicon alloy elements or impurities left on the surface after acid and alkaline treatments. It neutralizes any residual alkaline solution left after alkaline etching. Generally, a method using a solution of nitric acid at a concentration of 30%-50% is employed.的硝酸溶液，, For high-silicon aluminum alloys cast into alloys, a mixed acid solution with nitric acid and hydrofluoric acid in a volume ratio of 1:3 is used. Silicon reacts with hydrofluoric acid to form fluorosilicic acid which leaves the surface of aluminum.
 

⑥ Anodizing treatment for aluminum profiles:

's anodizing treatment method involves using a solution as a medium with sharp discharge to form an oxide film on the surface of aluminum profiles, making themAluminum profiles's corrosion resistance extremely strong. The protective layer obtained from anodized aluminum profiles has high hardness and corrosion resistance with standard thickness ranging from 10-12.μ can better improve the oxidation resistance of aluminum profiles and enhance the aesthetics of the profiles.

Sulfuric acid anodizing commonly uses 10-20% H2SO4 as the electrolyte, with a working temperature of 15-20℃, a current density of 1-2.5 A/dm2, and an electrolysis time depending on the required film thickness, generally between 20-60 minutes. Direct current is the most common power source, and the applied voltage varies based on the conductivity of the electrolyte, temperature, and aluminum content, typically around 15-20V. The process parameters have a significant impact on the performance of the film.

Surface sealing treatment of aluminum profiles:

Aluminum profilesAfter anodizing treatment, micro-pores will form on the surface, which are prone to oxidation corrosion during use. Therefore, sealing treatment should be performed after anodizing. The sealing treatment method for aluminum profiles after anodizing generally adopts a cold air sealing process (the cold sealing process originated in Europe). Sulfuric acid anodizing commonly uses 10-20% H2SO4 as the electrolyte, with a working temperature of 15-20℃, a current density of 1-2.5 A/dm2, and an electrolysis time depending on the required film thickness, generally between 20-60 minutes. Direct current is the most common power source, and the applied voltage varies based on the conductivity of the electrolyte, temperature, and aluminum content, typically around 15-20V. The process parameters have a significant impact on the performance of the film.