The iPod mini has an anodised aluminium surface, and comes in many colours

Anodizing or Anodising is a process used to protect aluminium from abrasion and corrosion and to allow it to be dyed in a wide range of colors. The process derives its name from the fact that the part to be treated forms the anode portion of a electrical circuit in this electrolytic process. iPod mini (2nd generation) File links The following pages link to this file: IPod mini Categories: Images with unknown source ... iPod mini (2nd generation) File links The following pages link to this file: IPod mini Categories: Images with unknown source ... iPod minis. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2. ... In dermatology, an abrasion is superficial damage to the skin, generally not deeper than the epidermis. ... Corrosion is deterioration of useful properties in a material due to reactions with its environment. ... A dye can generally be described as a coloured substance that has an affinity to the substrate to which it is being applied. ... An anode (from the Greek άνοδος = going up) is the positive electrode in an electrolytic system or circuit. ... An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ...

A layer of aluminium oxide is created on the surface of the aluminium from the action of the current being passing through the part which is bathed in an acid solution. This aides in the formation of the oxide layer. This oxide layer increases both the hardness and the corrosion resistance of the aluminium. The oxide forms as microscopic hexagonal "pipe" crystals of corundum, with each having a central hexagonal pore (which is also the reason that an anodized part can take on color in the dying process). Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with chemical formula Al2O3. ... An oxide is a chemical compound of oxygen with other chemical elements, e. ... In materials science, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. ... A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ... A regular hexagon A hexagon (also known as sexagon) is a polygon with six edges and six vertices. ... Quartz crystal A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. ... A pore, in general, is some form of opening, usually very small. ...

The aluminium oxide coating is grown from and into the surface of the aluminium. Because of this (unlike coatings), it is not prone to peeling or cracking. It also possesses excellent thermal and electrical insulation qualities.

Where appearance is important, the oxide surface can be dyed before the sealing stage, as the dye enters the pores in the oxide surface. The number of dye colors is almost endless, however the lighter colors tend to look better than darker ones.

Alternatively, metal (usually tin) can be electrolitically deposited in the pores of the anodic coating to provide colors that are more resistant to fading (light fast). Metal dye colors range from pale champagne to black. Bronze shades are preferred for architectural use. General Name, Symbol, Number tin, Sn, 50 Chemical series poor metals Group, Period, Block 14 (IVA), 5, p Density, Hardness 7310 kg/m3, 1. ... [[image: brass, a subset of the bronze alloys in which zinc is the principal additive cupronickel, an alloy used on ships lost-wax casting External links Flash animation of lost-wax casting Bronze Casting process explained - good pictures Categories: Alloys | Art materials ... Architecture (in Greek αρχή = first and τέχνη = craftsmanship) is the art and science of designing buildings and structures. ...

After dying, the surface is usually sealed by using hot water or steam to convert the oxide into its hydrated form, reducing the porosity of the surface as the oxide swells. In physical chemistry and in engineering, steam refers to vaporized water. ... Hydrates are compounds formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts. ...

External links

• Coating and Fabrications Magazine (http://www.coatfab.com/anodising.htm)
• Hard Anodising Ltd (http://www.hard-anodising.co.uk/tap.asp)