Alumina powder is an indispensable core and filler material in nanocomposites, and also serves as an important support compound for industrial catalysts. Porous carbon black is an integral ingredient in cosmetic products due to its thick consistency and ability to absorb impurities, while it serves as the basis for corundum, an abrasive used to polish gemstones.
Characteristics
Alumina powder is created by calcining aluminum hydroxide at high temperatures to remove water and produce aluminum oxide, then processed further to produce different forms with different properties and applications.
Dependent upon its grade, Alumina may range in texture from fine to coarse and have various levels of chemical purity and surface area. Grades with very low impurity levels are known as high-purity Alumina (HPA), while those with extremely large surface areas are known as Granular Alumina (GA), with lower purity ratings.
Fine alumina powders can be found in polishing compounds and catalyst support materials, as well as being utilized as filler material in plastics and rubber production processes. Furthermore, high-purity alumina is employed in producing sapphire substrates for electronic devices as well as being metal coated for use in high temperature brazing assemblies – in short it serves multiple uses and acts as an excellent electrical insulator.
Alumina can also be used as a protective coating on industrial products and machines, helping protect them from abrasion. Due to its superior hardness and strength, alumina makes ideal ceramic insulators and substrates, as well as thermal capacity and high melting point making it useful in producing refractory products used in applications like petrochemical processing, cement production, waste incineration and iron and steelmaking. Alumina may even be mixed with glass to increase strength.
Applications
Alumina powder is used in manufacturing a wide variety of industrial products, such as ceramics, metallurgy, electronics and catalyst production. Due to its thermal, chemical and mechanical properties, alumina is an ideal material for refractories, grinding wheels and wear-resistant applications as well as low friction levels that make it suitable for nanocomposites with biocompatibility requirements.
Due to its high melting point and thermal resistance, alumina is widely utilized in the production of electrical devices and semiconductors. Furthermore, heat sinks utilize it as a key component for dissipating heat generated in electronic components, and its low friction and insulating properties make it an excellent material choice for creating anti-abrasion coatings.
Calcined alumina is widely employed within the petrochemical industry to make ceramic proppants used during hydraulic fracturing operations to keep fractures open during hydraulic fracturing (fracking), thus aiding extraction of hydrocarbons from underground deposits.
Pure (99% alumina) alumina is widely used to manufacture parts for machinery and equipment that need to be resistant to abrasion, while still insulating effectively against noise and radiation. Common applications of this material are shafts, bearings, thrust washers and plungers on pumps that handle chemicals as well as laser components, electro optical devices, flow meters sensors and X-ray equipment.
Alumina can be transported by trucks or trailers specially equipped to carry heavy loads, railway, cargo ship or any other means designed to carry dry bulk commodities such as aluminum.
Manufacturing
Alumina is an indispensable material in many applications such as abrasives, sintered products, plasma spraying materials and fillers. Additionally, alumina can also be found as single crystals, supports for catalysts and fluorescent substances. Some uses of alumina require its high purity and narrow particle size distribution while other require specific shapes; for instance ceramic filters used at coal-fired power stations must contain 100 micron-diameter alumina powder filters for flue gas ducting require cylindrically-shaped powder with its diameter equal to 100 microns in diameter for optimal use.
Most alumina is produced through the Bayer process, which uses bauxite – an earth mineral – as its raw material. Mined from the earth and transported to alumina plants for dissolution with aqueous hydroxide solutions and filtering, some alumina is then sent onward to aluminum smelters where it’s electrolyzed into aluminum metal; remaining pieces are calcined for various ceramic products like insulators, refractories and abrasives as well as bone implants, bone/dental implants as well as laboratory ware and laboratory furnace refractory linings.
Alumina is a commodity, meaning its price fluctuates daily based on supply and demand. Manufacturers track this price closely in order to adjust production costs accordingly, usually shipping it bulk by truckload or railcar; depending on distance and speed required for transport it may also be delivered by ship.
Testing
Alumina is one of the most widely-used engineering ceramics. Its properties make it hard, chemically inert and stable at high temperatures; making alumina powder ideal for making wear-resistant materials and refractory products for various applications. Alumina also exhibits insulation and electrical properties; high purity grades may even be used as separators between anodes and cathodes to avoid short circuiting between these batteries.
Alumina is also an essential raw material in the production of silicon wafers for microchips and electronic devices, while it serves as an essential ingredient in producing light-emitting diodes (LEDs) due to its thermal resistance, high boiling/melting points and excellent conductivity properties.
The present invention describes a method for measuring impurities of an alumina powder sample. To do this, an alumina sample is exposed to an X-ray beam and its diffraction angle and intensity are then recorded for measurement. Subsequently, its lattice constant can be calculated and the correlation between it and impurity content of an alumina powder sample can be established.