Surface process

Hardcoat anodising

Name: Hentschel Harteloxal
Address: Paul-Strähle-Straße 14, Schorndorf, Baden-Württemberg, 73614, DE
Telephone: +49 7181 97785-0

Electrolytic oxidation of aluminium for particularly hard, wear-resistant layers up to 100 µm.

Aluminium
20–100 µm
Wear protection

Hardcoat anodising is the electrolytic oxidation of aluminium alloys; the process is also known as hard anodising or hard coating. The resulting layers are used wherever high wear resistance and good tribological properties are required. Hardcoat layers are between 20 and 100 µm thick and considerably harder and denser than conventional anodised layers.

Half of the layer thickness is converted from the base material, 50 % grows outwards. The hardness depends strongly on the alloy used, as not all alloying elements form oxides, and is approx. 380–450 HV. As a ceramic layer, hardcoat anodising also offers good electrical insulation, high thermal resistance, very good dimensional accuracy and excellent adhesion. Hardcoat layers are food-safe.

Properties

Very good corrosion and wear resistance
High hardness 400–500 HV, depending on the base material
Good reproducibility, layer thickness ± 5 µm
Food-safe
Good dimensional accuracy and throwing power
Good electrical insulation
Good sliding properties – can be further improved with PTFE

Applications

Mechanical and apparatus engineering
Medical devices
Aerospace technology
Packaging technology
Hydraulics and pneumatics
Drive technology
Vacuum technology
Paper industry

Post-treatment

Sealing to improve corrosion resistance (some hardness is lost)
PTFE impregnation to improve sliding properties (not permanent in highly abrasive applications)
Black dyeing: the alloy-related brown to grey natural colour, which darkens with increasing thickness, can be dyed over. Anodising dyes are not opaque – black anodising is darker in direct comparison.

Technical data