High-temperature insulation wool (HTIW)
High-temperature insulation wool is an accumulation of fibres of different lengths and diameters, produced synthetically from mineral raw materials. The group of the HTIWs include amorphous alkaline earth silicate wool (AES) and alumino silicate wool (ASW) as well as polycrystalline wool (PCW) (VDI 3469; DIN-EN 1094) with a classification temperatures >1000 °C. Besides the differences in the chemical composition, manmade fibres have parallel edges in contrast to natural fibres.
Alkaline earth silicate wool (AES wool)
Also known as “high-temperature glass wool" (HTGW), AES Wool consist of amorphous fibres, which are produced by melting a combination of CaO-, MgO-, SiO2 and ZrO2 (see also VDI 3469, Parts 1 and 5). Products made from AES are generally used at application temperatures less than 900 °C and in continuously operating equipment and domestic appliances.
Alumino silicate wool (ASW)
Alumino silicate wool also known as “refractory ceramic fibre” (RCF), are amorphous fibres produced by melting a combination of Al2O3 and SiO2, usually in a weight ratio 50:50 (see also VDI 3469 Parts 1 and 5, as well as TRGS 521). Products made of alumino silicate wool are generally used at application temperatures of greater than 900°C and in intermittently operating equipment and critical application conditions (see Technical Rules TRGS 619).
Polycrystalline wool (PCW)
Polycrystalline wool consists of fibres containing greater than 70 wt.% Al2O3; they are produced by a "sol-gel method" from aqueous spinning solutions. The water-soluble green fibres obtained as a precursor are crystallized by means of heat treatment (see also VDI 3469 Parts 1 and 5). Polycrystalline wool is generally used at application temperatures greater than 1300 °C and in critical chemical and physical application conditions, also at lower temperatures.