something about Monohydrallite
α alumina
In the lattice of type alumina, oxygen ions are closely packed in hexagonal form, and Al3+ is symmetrically distributed in the coordination center of the octahedron surrounded by oxygen ions. The lattice energy is very large, so the melting point and boiling point are very high. Alpha alumina, which is insoluble in water and acids and also known as aluminum oxygen in industry, is the basic raw material for making aluminum. It is also used for making firebrick, fireproof crucible, fireproof pipe and high temperature test instrument. It can also be used as abrasive, flame retardant, filler, etc. The highly pure alpha alumina is also used in the production of corundum, ruby and sapphire. Also used in the production of modern large-scale integrated circuit substrate.
γ alumina
Aluminum oxide is prepared by dehydration of aluminum hydroxide in the low temperature environment of 140-150℃, also known as active aluminum oxide and aluminum adhesive in the industry. In its structure, oxygen ions are approximately vertically centered and tightly packed, and Al3+ is irregularly distributed in octahedral and tetrahedral voids surrounded by oxygen ions. Alumina is insoluble in water and soluble in solutions of strong acids or bases. When heated to 1200℃, it is completely converted into alumina. Gamma alumina is a porous substance with an internal surface area of up to hundreds of square meters per gram and a high activity and adsorption capacity. Industrial products are often colorless or microstrip pink cylindrical particles, good pressure resistance. Adsorbents, catalysts and catalyst carriers are commonly used in petroleum refining and petrochemical industry. It is a deacidifier for transformer oil and turbine oil, and also used in chromatographic analysis. In the laboratory is a neutral strong desiccant, its drying capacity is no less than phosphorus pentoxide, after use under 175℃ heating 6-8h can be recycled and reused.
Β Alumina
There is also -Al2O3, which has ionic conduction (allowing Na to pass through) and is made from -bauxite as an electrolyte to a sodium-sulfur battery. This kind of battery has a broad application prospect because of its large storage capacity per unit weight and its ability to discharge large current. The battery has a negative extremely fused sodium, a positive polysulfide, and an electrolyte of -bauxite (a conductor of sodium ions).
The temperature range of the battery is 620 ~ 680K, and its storage capacity is 3 ~ 5 times that of the lead battery. Caustic soda is produced by using -Al2O3 ceramics as diaphragm of electrolytic salt water, which has the characteristics of high purity and little public hazard.
Abrasive alumina
Alumina is suitable for a variety of dry and wet treatment processes, can be any workpiece rough surface grinding fine, is one of the most economical abrasive. This sharp synthetic abrasive with water chestnut has a hardness second only to diamond, especially suitable for iron pollution when there are strict requirements for use. For the roughest cutting, can also be made into a pebble shape for precision size of the workpiece processing, to achieve very low roughness. Because of its high density, sharp and rhombic structure, it is one of the fastest cutting abrasives at present.
Alumina is used to produce brown corundum by electrofused high-quality bauxite, while high-quality aluminate is used to produce powder and white corundum. Their natural crystal structure gives them high hardness and fast cutting performance. At the same time, they are often used as raw materials for consolidation and coated abrasives.
Alumina can be recycled many times, the number of cycles is related to the material grade and the specific process, most of the standard abrasive blasting equipment can be used.
Industrial scope: aerospace industry, automotive industry, consumer goods processing, casting/die casting, OEM distributors, semiconductor industry and other fields.
Scope of application: pretreatment of surface electroplating, painting, glazing and ptFE coating; Aluminum and alloy products to remove burr, to remove pot dirt; Mold cleaning; Pretreatment of metal before blasting; Dry and wet grinding; Precise optical refraction; Grinding of minerals, metals, glass and crystals; Glass carving and paint additives.
