GB/T 47040-2026Aerospace - Sulfuric acid anodizing of titanium and titanium alloys - Treatment process (English PDF)

4.1 Process Requirements

4.1.1 The anodizing solution should consist of an aqueous solution of industrial sulfuric acid, with a nominal concentration of.200 g/L to 400 g/L of H2SO4. The solution composition...

The concentration should be maintained within ±10% of the selected nominal components. The chloride content, calculated as NaCl, should not exceed 0.2 g/L. If procurement is approved...

If the parties agree and the obtained membrane meets all other requirements of this document, the chemical composition of the solution may be altered.

4.1.2 The content of dissolved metals in the solution, calculated as titanium ions, should not exceed 20 g/L.

4.1.3 The solution should be used at a temperature of 20°C±5°C. The temperature control equipment should be able to maintain the solution temperature at the control setpoint.

Within ±5°C range.

4.1.4 The solution should be stored in a corrosion-resistant steel tank or a steel tank lined with acid-resistant material. Except in cases where the storage tank is lined with lead, the storage tank lining should be...

An auxiliary cathode plate made of a material that will not contaminate the solution.

4.1.5 A DC (VDC) power supply and related control equipment and instruments for reading voltage and current are required.

4.1.6 All fastening devices for parts shall be made of titanium or titanium alloy, such as wire, hooks, clamps and hangers.

4.1.7 Pickling solutions containing the following concentrations of a mixture of nitric acid and hydrofluoric acid can be used as a reference.

---280g/L~560g/L of HNO3 (69%);

---15g/L~25g/L HF (70%).

When the anodic oxide film meets all the requirements of this document, and the original equipment manufacturer (OEM) and processor agree, it is possible to modify the nitrification process.

The concentration of acids and hydrofluoric acid, or the availability of alternative chemical products.

4.2 Preparations before anodizing

4.2.1 Parts shall be thoroughly alkaline cleaned to ensure that all surfaces are free of contaminants such as grease, oil and factory markings.

4.2.2 Degreasing should not be performed using chlorinated solvents or methanol.