Aluminium oxide,A new generation of indispensable hard materials |
Aluminium oxide is white solid. It's a compound composed of aluminum, oxygen and the molecular formula Al2O3. Bauxite is another name for it in the fields of mining, ceramics, materials science and materials.
Spherical Alumina is a chemical material that has many excellent properties. These include high hardness and strength, as well as corrosion resistance and resistance to heat. Spherical Alumina, which has these properties, is widely used for ceramic materials, chemical mechanical polished abrasives (CMP), catalysts, and catalyst carriers. Alumina can be broadly divided into aqueous or anhydrous.
Alumina trihydrate includes industrial aluminum hydroxide, mayalite (1-Al2O3H2O), boraxite (2-Al2O3H2O), alumina monohydrate including diaspore and pseudo-boehmite. Alumina trihydrate, including industrial aluminum hydroxide (α-Al2O3·H2O), mayalite (β1-Al2O3·H2O) and boraxite (β2-Al2O3·H2O): alumina monohydrate, including boehmite (α) -Al2O3·H2O), diaspore (β-Al2O3·H2O): pseudo-boehmite (Al2O3·1.3-2.2H2O).
Alumina is available in at least eight different types of crystals, including (amorphous), (amorphous), (cubic-system), (cubic-system), (monoclinic-crystal) (), (tetragonal), (hexagonal), (hexagonal). These are all isomers. -Al2O3 has a stable thermal phase after a high temperature heat treatment. The other is a unstable transition state alumina.
The chemical and physical characteristics of different crystal forms of Alumina are very different. For example, the density, pore structures, specific surfaces, thermal stability etc. The properties of alumina are different when it is prepared using different methods.
, Al2O3 : is an amorphous form of alumina that is formed by the rapid dehydration, and then quenching, of precursors. It is known in the United States as "quick-powder" and abroad it is referred to as FCA (Flash Calcined Alumina). It is a strong water absorber and has a high hydration activity. This makes it suited for use as binders and water absorbing agents. It has a wide range of applications.
Al2O3 (Al2O3-): The product obtained by dehydrating the precursor at low temperature has a very large surface area. However, it has poor thermal stabilities and is susceptible to crystal transformations at high temperatures.
Al2O3 is a catalyst with a strong adsorption capability. It's also called activated Alumina. In general, the surface area is very large, bulk density is low, a special pore structure can be obtained, thermal stability, mechanical strength, and performance are easily altered.
Al2O3 : the product of the dehydration of the precursor at temperatures over 600 °C. Although its surface area is small and its pore volume is smaller, it has better thermal stability, making it suitable for use as the catalytic carrier in high-temperature reactions.
-Al2O3 : Also called corundum, this is the final thermostable crystal form that results from dehydrating transitional alumina. This is the most commonly used alumina type, and it is free of any water. It is compact and has a very small surface area. The melting point can reach 2050° C. It is also high in hardness and strength. It is widely used in high temperature resistant materials, ceramic composites and abrasive material.
Crystalline transformation alumina
When calcined, aqueous, alumina is heated to different temperatures. As the water is removed from the structure, the oxygen and aluminum atoms are constantly changing. This causes the alumina to change from amorphous, to crystallized, forming various unstable transitions. Once the temperature exceeds 1,200 ° C a phase transition is triggered, where the oxygen atoms become a hexagonal, tightly packed structure. This forms a thermally-stable phase Al2O3.
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