Method for improving hardness and wear resistance of hard anodized film

Fiber parts in the industry, high-speed rotating parts such as rotors, yarn storage discs, and rollers, the micro-arc oxide film provides heat resistance, wear resistance and appropriate surface roughness, and has been used at home and abroad for many years. The full name of hard anodizing is hard anodizing. Hard anodizing of aluminum alloys is mainly used for engineering or military purposes, it is suitable for both deformed aluminum alloys and more likely for die cast alloy parts. The compactness of the porous layer is mainly determined by the voltage of the anodization. Under the constant current process, low solution te


mperature, high current density, and low sulfuric acid concentration will increase the thickness of the barrier layer of the anodized film, resulting in an increase in the anodization voltage and a decrease in the porosity of the anodized film. The microhardness also increases.

Before the applied voltage reaches the arcing voltage, the metal surface has been covered with an anodized film. Hard anodized films generally require a thickness of 25-150um, most of the hard anodized films have a thickness of 50-80um, and the film thickness is less than 25um. The hard anodized films are used for parts such as gear keys and spirals. , The thickness of the anodized film for wear resistance or insulation is about 50um. Under some special process conditions, it is required to produce a hard anodized film with a thickness of more than 125um, but it must be noted that the thicker the anodized film, the more obvious the outer layer is. The lower the microhardness can be, the rougher the surface of the film layer increases. This dielectric anodic oxide film causes the current to drop rapidly. In order to continue the growth of the oxide film, only increasing the voltage will break down the weak position of the original oxide film, resulting in local sparks to maintain the current required for the growth of the oxide film. The quality of the hard oxide film varies with the current density. Usually, as the current density increases, the porosity of the hard oxide film increases, and its hardness and wear resistance also increase.

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