In the Middle Ages, aluminum was more expensive than gold. Currently, aluminum products are cheap and available to everyone thanks to new mining and processing techniques. Statistics show that there has been more than a six-fold increase in the consumption of this metal in the world since the 1970s.
Aluminum is valued for its low density and good mechanical properties. This metal conducts electricity and heat well. Aluminum castings are easily formed. They are well processed mechanically in many ways. The products obtained from it are light and durable.
Aluminum oxidizes quickly and creates a natural protective layer on the surface that protects the metal from further corrosion. However, this is not permanent security. The layer is less than 1µm thick and is easily damaged. The removed coating exhibits renewable features, which in turn has a negative effect on the element.
A much better and more durable coating can be obtained in the electrochemical anodizing process. The action of appropriate chemical agents on the metal in a given cycle allows anodic layers with controlled thickness, strength and desired appearance to be obtained.
In the anodizing process, aluminum components gain aesthetics, electrical resistance, mechanical resistance to abrasion and corrosion. This type of protection is particularly essential for machine and equipment components that wear mechanically, are exposed to adverse weather conditions, are placed in water or soil, and are expected to be durable and look great for many years.
Most of the aluminum objects around us are anodized. Everywhere we can see housing of home appliances, furniture elements, window profiles or car parts subjected to earlier anodizing.
They look nice, are colorful or shiny and in addition very durable.
The anodizing process takes place in chemical electrolyte solutions baths, which react with the metal under the influence of flowing current. Such chemical treatment consists of many stages, such as cleaning, degreasing, etching, and numerous rinses. All these processes are designed to properly prepare the surface of the workpiece before the main stage, which is anodizing.
In this process, an appropriate amount of current is passed through the electrolyte. A durable protective layer is then formed on the workpiece surface with a thickness of 5 to even 300µm. This is much more compared to what is produced by natural oxidation.
To obtain specific aesthetic values, the resulting protective layer is easy to color and polish. Modern methods also allow for selective anodizing of selected areas, e.g. only selected regions of the car engine.
In Poland, there are many plants specializing in anodizing. Their production lines allow you to process even a few meters long items. Nowadays, operations are computer-controlled CNC and robotics, and quality control over the quality of the process.
The quality of anodized surfaces is tested in laboratories, which include check thickness, structure, roughness, abrasion and corrosion resistance, hardness and sealing quality of produced coatings. Everything that is important for an aluminum product.
Undoubtedly, it can be stated that anodizing will permanently accompany aluminum products, and new electrochemical methods will allow obtaining products with extraordinary possibilities.