Alumina (Al2O3)
Alumina is the most mature of the engineering ceramics, offering excellent electrical insulation properties together with high hardness and good wear resistance but relatively low strength and fracture toughness.
Aluminas are generally white but are sometimes pink (88% alumina)or brown (96% Alumina). The colour is derived from either the sintering additives or impurities in the raw materials. ELE Advanced Ceramics produces a range of alumina from 96% - 99.9% purity.
Alumina has a high melting point, high hardness and high mechanical strength, although mechanical strength is reduced at temperatures above 1000°C. Due to the relatively large coefficient of thermal expansion, thermal shock resistance is reduced.
Alumina is an electrically insulating material, with a high electrical resistivity, increasing with purity.
Good chemical stability of alumina, leads to a high corrosion resistance. It is insoluble in water and only slightly soluble in strong acid and alkaline solutions.
