hydrated aluminum oxide, also known as alumina trihydrate (ATH), is a naturally occurring substance that has the formula Al2O3+3H2O. It is an effective fire retardant and smoke suppressant that decomposes to aluminum oxide and water under conditions of high heat and humidity.
It is used in a number of applications including in polymer composites, cable compounds, solid surface counter tops, and as a fire retardant filler for ceramics. It is also used to make a variety of adsorbents and chemical filtration products.
The chemistry of hydrated aluminum oxide is complex and includes numerous phases. One of the most common and commercially important is gibbsite, which is found in bauxite ore. The rarer polymorphs are bayerite, doyleite, and nordstrandite.
The amorphous phase of gibbsite and its two rarer polymorphs are hydrothermally soluble in NaOH solutions at moderate temperatures. Hence, these materials can be extracted from the bauxite ore and refined to extract aluminum. It is then combined with other alloying elements to create various forms of aluminum metal, including a-alumina and boehmite. It is also used in refractory, ceramic and polishing applications.