Overview
ISO 10074:2021 - Anodizing of aluminium and its alloys - Specification for hard anodic oxidation coatings on aluminium and its alloys - defines technical requirements and test methods for hard anodizing (hard anodic oxidation) on aluminium and its alloys. The standard covers material classification, appearance, coating thickness, surface density, wear/abrasion resistance, Vickers microhardness, and corrosion resistance, and it specifies the information the customer must supply to the anodizer. It excludes processes such as plasma electrolytic oxidation, micro‑arc oxidation, spark anodizing and related plasma or spark-based treatments.
Key topics and requirements
- Scope & exclusions: Applies to electrolytic hard anodic coatings on cast and wrought aluminium; not applicable to plasma or spark-based coatings.
- Material classification: Five alloy groupings (e.g., Class 1 - most wrought alloys; Class 2 - high‑Cu or high‑Mg/7xxx alloys; Class 3 - casting alloys) that affect required properties.
- Appearance: Uniform visual finish; no spalling, blistering or powdery (“burnt”) areas; crazing/microcracks are normally acceptable.
- Thickness: Typical range 25 μm to 150 μm (low ~≤25 μm, normal 50–80 μm, high 150 μm); measurement by eddy‑current (ISO 2360) or microscopical method (ISO 1463).
- Surface density: Measured per ISO 2106; minimum mass per unit area specified for alloy classes (e.g., Class 1 ≥1100 mg/dm2; Class 2(a)/(b) and Class 3(a) ≥950 mg/dm2). Note: ISO 2106 uses a chromium(VI) reagent - hazardous.
- Wear/abrasion testing: Primary methods are abrasive wheel (ISO 8251) and abrasive jet; Taber allowed if specified. Acceptance criteria (pretest and test strokes, relative mean specific abrasion resistance) are provided (see Table 2).
- Other tests/annexes: Vickers microhardness, breakdown voltage (ISO 2376), salt‑spray corrosion (ISO 9227), sampling, process qualification, packaging and processing guidance.
Practical applications
ISO 10074:2021 is used where hard anodic coatings are required for:
- Wear and abrasion resistance (gears, sliding components)
- Electrical and thermal insulation
- Dimensional build‑up/repair of worn parts
- Corrosion protection (when sealed)
It informs specification writing, quality control, acceptance testing, and supplier contracts.
Who should use it
- Anodizers and surface‑treatment shops for process control and customer coordination
- Design and manufacturing engineers specifying coatings for components in automotive, aerospace, industrial machinery and defense
- Quality assurance and procurement teams for lot acceptance tests and supplier approval
Related standards
ISO 8251, ISO 2106, ISO 2360, ISO 1463, ISO 2376, ISO 9227 and ISO 4516 are referenced for specific test and measurement methods; consult these standards when implementing ISO 10074:2021.