Why Does Titanium Alloy Anodization Work And How Does It Work?

​The naturally formed oxide film on the surface of  pure titanium alloy  is thin and non-compact. It is difficult to meet performance requirements under complex working conditions. Anodization technology constructs a firmly bonded, performance-controllable oxide film on the titanium alloy surface through electrochemical reactions. This significantly enhances corrosion resistance, wear resistance, decorativeness, and functional properties. It has become one of the key technologies for titanium alloy surface modification.

Degreasing: Remove surface organic contaminants. Avoid residual oil and chemical solutions.
Pickling: Eliminate oxide scale and surface defects. Prevent excessive corrosion of the substrate.
Water Washing: Prevent contamination from residual chemical solutions
Rinse with tap water first, then deionized water; rinse at least 3 times after pickling. For precision workpieces, additional activation can be added to prevent regenerated oxide scale.

1. Clamping and Circuit Connection
Pretreated titanium alloy workpieces must be securely clamped to avoid local film absence due to poor contact during anodization. Clamping should prevent fixture shielding to ensure full contact between the workpiece surface and the electrolyte. For circuit connection, the workpiece serves as the anode. For uniform coloring, replace the cathode with a titanium plate and maintain a cathode-anode area ratio of 1:1 to improve film uniformity.

2. Electrolyte Selection
Sulfuric acid-based: Fast film formation, colorless and transparent film, moderate corrosion resistance, low cost. Suitable for general decorative parts, structural components, and insulating parts.
Oxalic acid-based: Dense film, excellent corrosion resistance. Color can be adjusted from golden yellow to blue, green, or purple by regulating voltage. Suitable for aerospace components and precision electronic parts.
Phosphoric acid-chromic acid-based: Extremely high corrosion resistance, suitable for harsh corrosive environments such as marine and chemical industries. Due to the toxicity of chromic acid, strict environmental controls are required, leading to limited application.
Environmentally friendly type: Fluoride-free, chromium-free, low toxicity, easy waste liquid treatment. Multicolor coloring achievable by voltage adjustment, with good film adhesion. Suitable for high-end fields such as medical devices and food-contact components.

3. Process Parameter Control
Voltage: Voltage also determines interference coloring-higher voltage results in thicker films and more distinct colors.
Current density: Too low current leads to slow film formation, while excessive current causes local overheating, resulting in film cracking and ablation.
Temperature: Sodium bicarbonate-based environmentally friendly electrolytes require strict temperature control at 25~45℃ to prevent electrolyte decomposition.
Time: Conventional 10-60min ,Environmentally friendly electrolytes enable fast film formation in only 5-30s.

Post-washing:Preventing film corrosion and discoloration and ensuring subsequent sealing effectiveness.
Sealing treatment: Fill film pores to improve compactness and protective performance. ① Boiling water sealing ② Salt solution sealing
Drying: Dry the workpiece after sealing to avoid yellowing or mold growth caused by residual moisture. For decorative workpieces, lightly polish with a clean cotton cloth after drying to enhance brightness.

Compared with surface treatment technologies like electroplating and spraying, the anodized oxide film exhibits stronger adhesion to the substrate, superior corrosion resistance, and high process controllability. Functional customization can be achieved through parameter adjustment. Most electrolytes are recyclable, offering significant environmental advantages.