Phases of Aluminium Oxide and Hydroxide
Industrial-use aluminium oxides can have various crystalline forms including corundum (α-Al2O3), β-aluminium oxide, γ-aluminium oxide and others.
High α-aluminium oxide content materials are used for the industrial production of refractory and electrical insulation products, as well as electro- and radioceramics. This phase of aluminium oxide is also used for the manufacturing of special types of ceramics, polishing and abrasive materials and electrical porcelain.
β-aluminium oxide, being, compositionally, a mixture of the oxides of aluminium and sodium, is used as a solid metal-conducting electrolyte. γ-aluminium oxide is applied as a catalyst carrier or a raw material for the industrial production of mixed catalysts and desiccants, which are needed for various processes in the chemical and petrochemical industries.
Low α-aluminuim oxide-content powders are suitable for the production of high-alumina cements, or can be used as catalysts, inert fillers and adsorbents in the chemical industry and for various physical researches.
Extra pure types of aluminium oxide are applied for the production of high-quality ceramics, used in electronics, and monocrystals for LED and laser equipment.
Depending on aluminium hydroxide modification and processing capacities, several types of bauxites are singled out, including gibbsite (hydrargilite) bauxites, containing aluminium hydroxide in the form of Al(OH)3, gibbsite-boehmite, boehmite (AlООН), boehmite-diaspore and diaspore (recrystallized AlООН modification), as well as unstable compounds, such as bayerite and nordstrandite.
Gibbsite (hydrargillite) is aluminium oxide trihydrate in the form of Al2O3∙3H2O, Al(OH)3, occurring in bauxites and acting as an intermediate product in the process of alumina production by the alkaline method. Gibbsite can be found in bauxites in one of three modifications: amorphous, crystalline and cryptocrystalline. Under normal conditions, this phase of aluminium hydroxide is the most stable form.
Diaspore and boehmite, expressed as Al2O3∙Н2О, AlO(OH), are polymorphic modifications of aluminium oxide monohydrate, which occur in nature in bauxites, crystallize in the orthorhombic system and may have crystalline or cryptocrystalline forms.
MICROINTECH has perfect R&D and production facilities to develop and produce the necessary varieties and special grades of aluminium oxide or hydroxide, which comply in terms of chemical, phase and grain-size composition with all the requirements of our customers The enterprise produces milled active aluminium oxide and milled thermoactivated aluminium hydroxide.