by Gel » Wed Apr 08, 2015 12:33 pm
by DaveBerlin » Wed Apr 08, 2015 3:10 pm
Anodising is an electrochemical technique most usually applied to aluminium and its alloys. These are treated to form a structured surface oxide layer. This layer has anti-corrosion and decorative properties.
The anodising techniques applied on aluminium are divided into:
Sulphuric acid-anodising / Hard anodizing / Chromium acid anodising.
Anodising of aluminium is frequently applied. Since the anodised layer is thin and transparent, surface damage and scrapes are easily visible. Before anodising aluminium components must be treated carefully in order to prevent damage.
Aluminium anodising: properties : The layer thickness of an anodising layer made in a (standard) sulphuric acid anodising bath can be selected to be between 1 and approx. 30 micrometer.
Hard anodising gives layers of approx. 5 up to 100-150 micrometer thick (dependent of the type of hard anodising bath).
The layer grows partially (approx. 60%) out of the substrate so that an anodising layer of 20 micrometer will give rise to an extra thickness of the component of 8 micrometer.
Anodised aluminium can be given many different colours. If coloured with inorganic dyes, they show very reproducible and stable colours (organic dyes are less stable).
Sulphuric acid anodising treatment strongly reduces the fatigue strength of aluminium so that this process is less suitable for components subjected to fatigue. Chromium acid anodising is better suited for fatigue resistance applications. Anodising layers are also suited as substrate for adhesive or for organic top layers. They are not very resistant to hydrogen fluoride containing cleaning products. Also strong alkaline solutions and acids attack anodising layers. The corrosion resistance of sulphuric acid anodising layers is caused by sealing of the pores with aluminium hydrate.
by Gel » Wed Apr 08, 2015 3:17 pm
by duncho » Wed Apr 08, 2015 9:11 pm
by Gel » Wed Apr 08, 2015 9:47 pm
by duncho » Wed Apr 08, 2015 9:53 pm
by SplanK » Thu Apr 09, 2015 7:44 am
by jonceebee » Thu Apr 09, 2015 9:13 am
by DaveBerlin » Fri Apr 10, 2015 2:53 pm
by Gel » Fri Apr 10, 2015 4:49 pm