Aluminum anode: In my time, I had the experience of looking at the crystal of a snowflake through a magnifying glass. The beautiful shape of the snowflake took my breath away and stuck in my mind. Now the surface of anodized film of aluminum is examined by electron microscope and is also impressed by its strict honeycomb microstructure.

The microstructure of anodic oxide films was only discovered around 1950-1960. With this kind of microporous structure, the anodic oxidation industry of aluminum develops rapidly, and has made great contribution to the development of human civilization.

The so-called honeycomb, or hexagonal structure, has a small diameter microhole in the center that grows perpendicular to the surface of the aluminum matrix.

After anodizing the aluminum matrix, a multi-pass anodizing film is generated, and there is a barrier between the anodizing film and the aluminum matrix. Anodic oxide film contains a certain hexagonal cell size and is named multi-pass anodic oxide film because of the formation of micropores in the middle. At the same time, the cell size and other parameters change with the treatment conditions of anodic oxidation, but the anodic oxidation film always maintains its fixed shape and structure characteristics. We have to marvel at the exquisite shape given by nature.