how to anodize titanium?

How to anodize titanium

Frist Learn,What is anodize titanium?

Taken from WikipediaAnodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. In a nutshell for Titanium products, anodizing turns titanium cool colors!

Anodic films are most commonly applied to protect aluminium alloys, although processes also exist for titanium, zinc, magnesium, niobium, zirconium, hafnium, and tantalum.

Application of anodize titanium:

Aerospace companies use the anodizing process to protect metals from aging, wear and corrosion.

The titanium anodizing process is widely used in the medical device industry because anodized titanium parts are non-toxic and suitable for biomedical applications such as orthopaedic implants.

Also used in jewelry manufacturing.

orthopaedic implants

So how to anodize titanium?

The anodizing coloring process of titanium and its alloys is as follows:

Degreasing (strong alkaline degreaser) → water washing → primary pickling (hydrofluoric acid aqueous solution) → water washing → secondary pickling (hydrofluoric acid + hydrogen peroxide aqueous solution) → water washing → anodizing (constant voltage in phosphoric acid aqueous solution) Electrolysis) → washing → sealing → drying.

1. Remove oil

Degreasing is to remove the oil remaining on the titanium surface during rolling. Due to the poor water permeability of the oil attached part, uneven coloring is prone to occur when the titanium surface is pickled.

2. Initial pickling

The initial pickling is to form a pear skin pattern on the surface of titanium and its alloys. The titanic acid wash with 5% weight concentration of hydrofluoric acid can promote the formation of pear skin pattern.

3. Secondary pickling

The second pickling is to remove the powdery dirt formed on the surface by the first pickling. In addition, in order to avoid uneven pickling, it is necessary to use hydrofluoric acid and hydrogen peroxide aqueous solution to stabilize the titanium ion into a titanium-containing complex after hydrofluoric acid once dissolves the surface dirt.

4. Anodizing

Using the phosphoric acid with 1% weight concentration of the electrolyte, the aluminum plate was used as the cathode, and the pretreated titanium plate was used as the anode for constant voltage treatment. As the voltage increases, the oxide film on the titanium surface thickens, showing various color changes.

anodizing color

Table: Relationship between anodizing voltage, color and film thickness

5. Close

In order to improve the corrosion resistance, pollution resistance and wear resistance of the anodized film, titanium and its alloys need to be sealed with hot water, steam, and solutions containing inorganic salts and organics after anodizing and coloring.

6. Dry

After sealing, wipe off the moisture on the workpiece with a clean cotton cloth and let it dry naturally.

To sum up, “how to anodize titanium” can be seen that the anodizing process of titanium and its alloys is relatively simple, and the color formed on the surface is rich, and the cost is relatively low, so it is easy to be popularized in the industry, and it is a kind of good development prospect. Oxidative coloring technology.

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