What is Titanium Anodizing Process?
The anodizing process of titanium uses titanium as the anode and stainless steel or other metals as the cathode. With the help of a certain electrolyte, the oxidation reaction occurs on the surface of the titanium alloy through an electrochemical reaction to form an oxide film.
This oxide film has a very obvious reflection and refraction effect on light, and oxide films of different thicknesses will show different colors and are protective. Therefore, it is an ideal decorative layer and wear-resistant layer and is widely used in construction. , aviation, medicine and other fields.
Why Titanium Parts Be Anodized?
Enhanced corrosion resistance: Titanium itself has good corrosion resistance, but anodizing can form a dense oxide layer on its surface, further improving its corrosion resistance and making it more suitable for use in harsh environments.
Improve surface hardness: Anodizing treatment can form a higher-hardness oxide layer on the titanium surface, improving its surface hardness and wear resistance, thereby increasing its service life and reducing surface wear.
Improve the surface texture: The oxide layer of anodized titanium has a certain surface texture, which can make the appearance of the titanium material more beautiful and have certain decorative properties.
Electrochemical applications: Anodizing can change the electrochemical properties of titanium surface, giving it better performance in electrochemical applications such as batteries and electrolytic capacitors.
Enhanced biocompatibility: When titanium is anodized, a dense oxide layer forms on its surface, helping to improve its biocompatibility and making it more suitable for applications such as medical implants.
Anodizing Process of Titanium and Titanium Alloys
Remove oil (strong alkaline degreasing agent) → water washing → initial 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)→wash→sealed→dry.
1. Remove Oil
Degreasing is to remove the oil remaining on the titanium surface during rolling. Because the oil-adhering part has poor water permeability, uneven coloring is prone to occur when pickling the titanium surface.
2. Initial Pickling
The initial pickling is to form a pear-skin pattern on the surface of titanium and its alloys. Using hydrofluoric acid with a concentration of 5% by weight to pickle titanium can promote the formation of pear skin patterns.
3. Second 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 ions into a certain titanium-containing complex after the hydrofluoric acid dissolves the surface dirt once.
4. Anodizing
Using phosphoric acid with a concentration of 1% by weight in the electrolyte, the aluminum plate is used as the cathode, and the pre-treated titanium plate is used as the anode for constant voltage treatment. As the voltage increases, the oxide film on the titanium surface thickens, showing various color changes.
5. Sealing
In order to improve the corrosion resistance, anti-pollution 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 organic matter 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.
Application of Anodized Titanium
Corrosion-resistant coating: Anodized titanium can enhance the corrosion resistance of titanium materials, giving them a longer service life in harsh environments, such as ship parts and chemical equipment in seawater.
Electrochemical applications: Due to its good electrochemical properties, anodized titanium is widely used in batteries, electrolytic capacitors, electrolytic cells and other fields.
Decoration and beautification: Anodized titanium has good surface texture and color stability, so it is used as decorative materials, such as building facades, furniture, jewelry, etc.
Medical devices: Due to its biocompatibility and corrosion resistance, anodized titanium is commonly used in the manufacture of medical devices and implants, such as artificial joints, dental implants, etc.
Optical applications: Anodized titanium has a wide range of applications in optical devices, such as mirrors, optical filters and coating materials.
Conclusion
Titanium anodizing is to use electrolysis to produce an oxide film on the surface of titanium. Through current and voltage adjustment, the titanium metal is subjected to full color surface treatment and gradient color surface treatment. In addition to decoration, the anodizing process also forms a dense film layer on the surface of titanium metal, which enhances mechanical properties, wear and weather resistance, insulation, and improves the bonding force with the coating.
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