Overview
ISO 8080:2021 - "Aerospace - Anodic treatment of titanium and titanium alloys - Sulfuric acid process" specifies requirements for producing and testing an unsealed anodic coating on titanium and its alloys using the sulfuric acid process. The standard is intended for aerospace applications where the anodic coating is used with solid film lubricants to protect titanium fasteners against galling, provide limited protection of less noble metals from galvanic corrosion when in contact with titanium, or for other approved uses.
Key topics and technical requirements
- Anodizing electrolyte: Technical grade sulfuric acid in water, nominal 200–400 g/L H2SO4, maintained within ±10% of chosen composition; chloride (as NaCl) ≤ 0.2 g/L; dissolved titanium (as Ti) ≤ 20 g/L.
- Process temperature: Solution used at (20 ± 5) °C with suitable temperature control.
- Equipment: Corrosion-resistant or lined tanks, auxiliary cathode plates (when required), and a variable direct current (v.d.c.) power source with voltage/current monitoring. All suspension fixtures must be titanium or titanium alloy.
- Surface preparation: Thorough alkaline cleaning (no chlorinated solvents or methyl alcohol), acid pickling (reference nitric/hydrofluoric mix and concentration ranges given), rinsing, and etching to ensure a clean, bright surface. Alternative mechanical activation is permitted if agreed by OEM and processor.
- Anodizing procedure: Parts are immersed as the anode; recommended voltage cycle 15–20 V for ~15 min (or until desired colour). Recommended initial current density ~0.2 A/dm² reducing to ~0.05 A/dm² over most of the cycle. Agitation and repositioning are advised for intricate parts to avoid gas entrapment.
- Post-treatment: Thorough cold and hot water rinses, drying, and handling to avoid contamination prior to subsequent surface treatments.
- Quality and inspection: Processor typically responsible for inspection. Coating should be smooth, adherent, uniform, and exhibit a uniform blue‑violet colour. Nonconforming parts may be repickled and reprocessed only after QA consultation. Sample approval and full quality documentation are required on request.
- Packaging/delivery: Parts must be packaged to protect against handling damage, weather, and transport hazards.
Applications and users
ISO 8080:2021 is primarily used by:
- Aerospace OEMs and suppliers (fasteners, structural titanium components)
- Metal finishing and anodizing processors serving aviation industry
- Procurement and quality engineers specifying surface treatments
- Maintenance and refurbishment facilities where controlled titanium anodizing is required
Typical uses include protecting titanium fasteners against galling when coated with solid film lubricants and providing limited galvanic protection for contact with less noble metals.
Related notes
ISO 8080:2021 lists no normative references. Buyers and processors should coordinate process parameters and approval criteria with the purchaser or OEM to ensure compliance with contractual and safety requirements.