Chemical oxidation. oxide film is thin, thickness is about 0.5-4μM, porous, soft, good adsorption, can be used as the base layer of organic coating, but its wear resistance and corrosion resistance is not as good as anodic oxide film;
Author: Anna
There are two main types of hard oxidation processing:
① Chemical oxidation. oxide film is thin, thickness is about 0.5-4μM, porous, soft, good adsorption, can be used as the base layer of organic coating, but its wear resistance and corrosion resistance is not as good as anodic oxide film;
② electrochemical oxidation, oxide film thickness is about 5-20μm (hard anodic oxide film thickness can reach 60-200μm), high hardness, good heat resistance, good insulation, higher corrosion resistance than chemical oxide film, and good adsorption ability. Aluminum and aluminum alloy chemical oxidation treatment equipment is simple, easy to operate, high production efficiency, no electricity consumption, wide range of application, and not limited by the size and shape of the parts.
According to the nature of the solution, the chemical oxidation process of aluminum and aluminum alloy can be divided into two categories: alkali oxidation and acid oxidation.
According to the nature of the film, it can be divided into oxide film, phosphate film, chromate film and chromate phosphate film. Aluminum is a relatively active metal with a standard potential of -1.66v, and an oxide film with a thickness of 0.01-0.1μM can be formed naturally in air. The oxide film is amorphous, thin and porous, and has poor corrosion resistance.
However, if aluminum and its alloys are placed in a suitable electrolyte, an oxide film is formed on the surface of the aluminum product as the anode under the action of the applied current, which is called anodic oxidation.
By selecting different types and concentrations of electrolytes and controlling the process conditions during the oxidation process, anodic oxide films with different properties and thicknesses ranging from tens to hundreds of microns can be obtained. The film's corrosion resistance, wear resistance and decorative properties are significantly improved. There are many different anodizing methods, such as anodizing of aluminum, anodizing sulfuric acid anodizing: Aluminum and its alloys are anodized in dilute sulfuric acid electrolyte by DC and AC anodizing to obtain colorless and transparent oxide film with thickness of 5 to 20μm and good adsorption.
Sulfuric acid anodizing is a simple process, stable solution, easy to operate, wide range of allowable impurity content, small electricity consumption, low cost, and suitable for processing almost aluminum and various aluminum alloys, so it has been widely used in China.