Glossary

Alumina
Chemical formula Al2O3; compound of aluminum and oxygen. Refined from the chemical breakdown of bauxite; alumina is the starting material for the extraction of aluminum by means of the electrolytic reduction process. One kilogram of aluminum is produced from two kilograms of alumina.

Aluminum
Third most common element in the earth's crust. Chemical symbol Al. Silvery and shiny, atomic weight 26.98 g/mol, density 2.78 g/cm. Melting point 660°C (993 K), boiling point 2,467°C (2,740 K). Corrosion resistant against oxygen and atmospheric humidity. Produced by means of the electrolytic reduction process. First displayed in public at the World Exhibition in Paris in 1855. Since then, widespread use in the form of pure metal or as alloys.

Aluminum alloy
(From Latin "Alligare", bind) Mixture of aluminum base metal with one or more alloying elements that are either metallic or non-metallic (such as silicon). Depending on the type and amount of elements, as well as the treatment, a difference is drawn between "casting alloys"and "wrought alloys". The aim of alloying is to enhance the properties of the base metal, e.g. the strength and corrosion resistance. Aluminum is predominantly used in the form of alloys, except for commercially pure and high-purity aluminum.

Aluminum liner materials
Liners are cylindrical-shaped insets, which are needed in the cylinders of engine blocks in order to provide a suitable surface for the pistons and piston rings to slide on. More and more, newly developed aluminum materials are replacing the previously used liners, made from gray cast iron.

Aluminum oxide
See alumina

Anode
Positive electrode. Input material for the electrolytic reduction process. Anodes consist of petroleum coke and coal tar pitch. "Green" anodes are formed from these raw materials, then baked at temperatures of up to 1,250°C and subsequently used as electrically conductive anodes.

Anode carbon
Carbon that is shaped and baked (calcined) at a high temperature into anodes used in prebake cells.

Anode effect
Sudden increase in cell voltage, due to either insufficient alumina being dissolved in the electrolyte or the temperature in the electrolyte being too low.

Anode paste
Mixture of petroleum coke and pitch which is added to the Søderberg anode and constitutes the positive pole in the cell. Anode paste is also used to produce prebaked anodes.

Bauxite
Ore with aluminum hydroxide as its main constituent; initial material for the extraction of aluminum. Around four kilograms of bauxite are needed to produce one kilogram of aluminum. Bauxite takes its name from "Les Baux" in southern France where the red ore was first discovered in 1822. Today, over 90 per cent of bauxite comes from the tropical regions of Australia, West Africa and Brazil.

Billet
Extrusion ingot cut to length.

Cathode
Negative electrode. The term is used to describe the cathodic part of a cell, i.e. the steel shell with lining. The actual cathode is the metal surface.

Cell
Electrolytic reduction cell.

CF gases
Polyfluorinated carbons are greenhouse gases that occur during an anode effect when a cell has insufficient alumina. The cell starts producing the polyfluorinated carbons CF4 and small quantities of C2F6 instead of CO2.

Contract Manufacturing
Outsourcing; contracting a third party to manufacture a portion of a complete production line

Core Package System
Precision sand casting process that is specially suited to the volume production of castings, such as engine blocks and cylinder heads.

Corrosion resistant
Protected against aggressive attack from oxygen, water and numerous chemicals by a natural oxide layer, aluminum is corrosion resistant: the protective effect can be specifically enhanced by alloys or surface treatment.

Cryolite
Chemical compound of aluminum fluoride and sodium fluoride, the main materials in the electrolyte.