Zhongshan Shanfeng CNC Welding Aluminum Products Co., Ltd.
Zhongshan Shanfeng CNC Welding Aluminum Products Co., Ltd
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Anodized aluminum parts anodizing process surface treatment technology aluminum alloys Hard anodizing Aluminum anodized parts aerospace parts electrolytic process automotive components
Definition of Hard Anodizing
Hard anodizing is a thick film anodizing process, which is a specialized surface treatment technology for aluminum and aluminum alloys. This process allows the anodic oxide film to reach a maximum thickness of about 250 microns. A microhardness of 1500 kg/mm² can be achieved on pure aluminum, while on aluminum alloys, the microhardness can reach between 400 to 600 kg/mm². The oxide film layer has poor thermal conductivity, with a melting point of 2050°C and a relatively high resistivity. After sealing treatment (immersion in insulating material or wax), the breakdown voltage can reach 2000V. It has excellent corrosion resistance in the atmosphere, high wear resistance, serves as an ideal thermal insulation layer, possesses good electrical insulation properties, and exhibits a series of advantages, including a strong bond with the substrate metal.
Advantages of Hard Anodizing
The surface hardness of aluminum alloys can reach around HV500 after hard anodizing.
Oxide film thickness ranges from 25 to 250 microns.
Strong adhesion: The oxide film formed through hard anodizing penetrates 50% into the aluminum alloy and adheres 50% to the surface.
Good insulation: The breakdown voltage can reach 2000V.
Excellent wear resistance: For aluminum alloys with copper content exceeding 2%, the maximum wear index is 3.5 mg/1000 revolutions. For all other alloys, the wear index should not exceed 1.5 mg/1000 revolutions.
Non-toxic: The oxide film and the electrochemical process used to produce the anodic oxide film are harmless to humans.
Currently, the following two types of hard anodizing are widely used:
(1) Sulfuric acid hard anodizing DC method;
(2) Oxalic acid hard anodizing AC/DC gravity separation method.
Among them, the sulfuric acid method is currently the most widely used hard anodizing method.
Applicable fields of hard anodizing
Mainly used for aluminum and aluminum alloy parts that require high wear resistance, heat resistance, and good insulation performance. Products that have undergone hard anodizing have extremely high corrosion resistance and wear resistance, good insulation, and a series of advantages such as strong bonding with the base metal. Therefore, they are widely used in the fields of national defense industry, mechanical parts manufacturing industry, medical accessories, electronic accessories, etc.