Tips You Need to Know About Anodizing Aluminum Parts
Anodizing is a way of protecting metal surfaces with the electrolytic process. This process introduces an oxide layer which boosts durability, component appearance, paint adhesion and prevents against corrosion. Anodizing is useful in various materials, but this piece will focus on aluminum.
How to do anodize aluminum parts
In preparation of anodizing aluminum parts or aluminum, you first have to clean and wipe it off thoroughly. Proceed to place the aluminum part or aluminum in an electrolytic solution such as sulphuric acid or chromic acid. Electrolytes are solutions with electrical conductivity and contain a lot of negative and positive ions ready for exchange.
Apply the positive electric charge to the aluminum, to make it an anode, and put the negative charge on the suspended plates inside the electrolyte. This circuit will make the positive ions move to the cathode (negative plates), and the negative ions will move to the anode, the aluminum or part of aluminum.
From this point, your electrochemical solution makes pores open on the aluminum surface. This process allows the escape of the positive ions. There are three variations of anodizing aluminum, and they include anodized Type I, Type II, Type III and Alodine.
What is the barrier layers?
Pores may form on the aluminum surface thanks to the electrochemical reaction. These pores create a pattern and start eroding down to the substrate. The surface aluminum merges with the negative oxygen ions to make an aluminum oxide, which is known as the barrier layer. The barrier layer prevents any further chemical reactions in those areas.
As you continue supplying current, the reactive and weak spots of the pores will continue going deeper inside the substrate. This process creates a series of hollow structures that look like columns.
What’s the hard anodizing
Hard anodizing, also known as Type III, provides significant resistance against corrosion and wear-resistance in harsh environments or in the moving mechanical aluminum parts which experience too much friction. If you want to hard anodize, continue applying current until the pore depth is past 10 microns, to 25 microns and beyond. This costly process requires a lot of time; however, it produces top-notch results.
What’s the Alodine anodizing?
Alodine is a chemical film. Chemical films are coatings for chemical conversion mainly used in corrosion protection of aluminum. In the Alodine coatings, the outer part of the metal surface undergoes chemical transformation to create a protective layer. It often has two common colors gold and nature.
The aluminum anodizing has corrosion protection function.
Aluminum does not rust. However, it may depreciate due to oxidation. Oxidation refers to a reaction to oxygen. An exposure of aluminum to the atmosphere will create an aluminum oxide layer which offers some protection against more corrosion. Aluminum not only has to be resistant to pure water and air but also salt water, acid rain as well as other contaminants. Hence, most of the aluminum parts we suggest clients do the finishing, which has two main reasons included appearance and itself corrosion will be better.
The metallic sheen on the surface of anodized aluminum
You will notice that after coloring, the anodized aluminum will have a metallic appearance. This metallic sheen depends on two factors. First, the electrochemical uniform etching left behind a rough part. When the pores are more in-depth, the surface will be rougher, but the shades will be more durable.
Secondly, when light strikes the surface, it interacts partly with the colorant and some parts will interact with the uncolored metal. Therefore, as light reflects your eye, it will be a merger of two unique wavelengths interacting as they bounce back from the different surfaces. The oxide layer thickness also plays a role here. Thick layers have better absorption of dyes while the thinner layers generate the metallic sheen.
Can you anodize the entire part?
To anodize a part, you have to immerse it in various chemical baths. To hold a part in a position that prevents it from falling to the bottom, you will have to place on a hanger. When hanger touches the part, that area becomes blocked, and the chemicals for anodizing will not work correctly.
How to do color to the surface of aluminum parts
The process of coloration functions through injecting a color pigment to the empty pores of the aluminum parts. Once the pigment gets to the surface, you should seal it to preserve the color. This process generates the visual effect which does peel off or fade away. So the anodizing aluminum parts can be done many different colors such as red, blue, gold, silver and the others.