Black Machining Anodized Aluminum 6061 7075 Anodizing Cast Aluminum

Aluminum products can be anodized to make a black surface treatment process Ordinary anodizing Anodized Processing

Black anodizing is an electrochemical process that converts the metal surface into a high-performance, durable aluminum with an oxide layer. Because this aluminum coating is applied to the surface, it will not peel or chip. The coating itself is very hard, corrosion-resistant, and very durable for many heavy-duty applications. Custom black anodizing is a strictly controlled oxidation process at low temperatures. The aluminum is soaked in an acid electrolyte and electrodes are connected to transmit current to give the metal the desired color, and then sealed to protect the coating. The aluminum finish is more wear-resistant and corrosion-resistant than traditional aluminum.

In mechanical design, we use aluminum the most. In order to prevent rust, scratches, decoration, etc., its surface is often black anodized or electroless nickel-plated. For example, the common surface treatments of aluminum alloys 6061 and 7075 are:

Oxidation black, sub-black, hard black, hard white, white, color surface treatment, chemical nickel plating.

What is anodizing?

As you and I know, aluminum reacts easily with oxygen to form a very thin oxide film in the air. This naturally formed protective film can prevent rust, thus giving aluminum a certain degree of corrosion resistance. However, this film is very thin and will corrode due to chemical reactions caused by the environment, so protective surface treatment is required, and anodizing is one of the protections.

What is the anodizing process?

Anodizing is a surface treatment process in which non-ferrous metals such as aluminum, magnesium, and titanium are electrolyzed as anodes in an acidic electrolyte to form a dense oxide film on the surface of the material to resist corrosion, improve wear resistance, and play a decorative role.

Anodizing microstructure:

1. Formation of barrier oxide over the entire area

2. Local electric field distribution caused by surface fluctuations

3. Dissolution to produce small pores by enhancing the electric field and/or temperature

4. Stable small pore growth

The anodized film is usually transparent and microscopically porous. The diameter of these pores is 100Å-300Å (1Å=0.1nm). In fact, there are an astonishing 50-70 billion pores per cubic centimeter.

For example, if every hole in the oxide film is filled with red dye, red anodizing will be produced and a colored surface will be formed, which will remain until the oxide film itself is worn away. Similarly, other color dyes can form corresponding colored anodizing. So, black anodizing is actually filling the anodized surface with black pigment.

Applications of anodizing

1) Personal electronic products, such as smartphones and tablets.

2) Decorative colored accessories, such as carabiners, metal pens, flashlights, etc.

3) Bicycle parts.

There are many other industrial applications, such as increasing the corrosion resistance of aluminum aircraft parts, preventing chemical corrosion of parts exposed to chemicals, enhancing the scratch resistance of parts, preventing wear of threaded components, etc.