What is alumina powder?
Alumina powder, also known as aluminium oxide or activated alumina, is a chemical compound that is mainly used to produce aluminium – one of the most important metals in the advancement of a low-carbon economy and throughout the global industry as a whole.
Alumina powder is created from bauxite, the principal ore of aluminium. The bauxite ore consists of a mixture of gibbsite, boehmite, iron oxides, iron hydroxides, quartz, and clay minerals. Alumina is extracted via the Bayer process, where the chemical component Al2O3 (alumina powder) is distilled from the bauxite mineral mixture.
The unique characteristics that make alumina ideal for aluminium production also make it valuable for a host of other applications, particularly ones that require hardness and resistance to abrasion or other forms of chemical wear. Alumina powder is also ideal for products that require corrosion and wear resistance, and for products that require high thermal conductivity, such as electrically and thermally insulating applications.
Properties of alumina
Alumina has relatively high melting and boiling point, as well as a very high hardness level. Its mechanical and compressive strengths are both higher than many comparative materials, and its electrical resistivity and thermal conductivity make alumina an ideal choice for many electrical products.
Below is a table of alumina’s main properties:
|Melting Point||2,072 °C (3,762 °F; 2,345 K)|
|Boiling point||2,977 °C (5,391 °F; 3,250 K)|
|Hardness||15 – 19 GPa (9 on the Mohs scale)|
|Electrical Resistivity||1012 – 1013 Ωm|
|Mechanical strength||300 – 630 MPa|
|Compressive strength||2,000 – 4,000 MPa|
|Thermal conductivity||20 – 30 W/mK|
|Molecular mass||101.96 g/mol|
What are some of the best uses of alumina powder?
Alumina is a vital material in industrial applications, as well as other areas of science, engineering, and technology. It is used in everything from construction materials and abrasives to biomedical devices and chemical catalysts. Alumina powder is almost as ubiquitous as aluminium itself, which is one of the most used materials in the modern world.
Below are 10 of the most important and useful applications of alumina in various areas of industry.
Alumina is amply utilised in a variety of industrial abrasive materials that are used to shape industrial components. This is due in large part to its superior hardness and strength, allowing the alumina to work through these machines and applications. Interestingly, the roles can also be reversed, with alumina being used as a coating to protect against abrasion from other industrial machinery and products.
Refractory products often use alumina powder because of its high melting point and thermal capacity. In situations where the strength of the refractory must be retained at high temperatures, alumina becomes particularly useful.
Some examples of refractories include iron and steelmaking, cement production, petrochemical processing, and waste incineration.
Alumina is a great addition to the creation and production of glass products, especially when increased strength and durability are needed. Bulletproof and shatterproof glass are often made using alumina powder. And although there is no such thing as a truly unbreakable glass, alumina has been studied for its potential in creating this very thing.
Alumina powder is used heavily in ceramics, particularly in the advanced or technical ceramics known as “engineered” ceramics. These materials are crafted for especially harsh applications that require increased wear resistance, thermal stability, and many of the other characteristics that make alumina such a valuable component of so many products.
Due to alumina’s hardness and desirable chemical properties, it is a preferred material for numerous biomedical applications. Alumina is used in bearings for hip replacements, in prosthetic limbs, bionic implants, prosthetic eye substitutes, tissue reinforcements, and a host of dental implants.
It is also used in the medical industry outside the body — in lab equipment and tools like crucibles, furnaces, and other labware.
Military and protective equipment
Alumina is adept at creating military and civilian protective equipment due to its strength and lightweight qualities. Body armour, vehicle armour, and aircraft armour are all created using alumina, with the latter being the largest market for the material in this field. It is also used in making bulletproof windows and ballistics for stationary objects.
With a high melting and boiling point, as well as excellent thermal resistive properties, alumina powder is ideal for electrical insulators.
It is also an essential component in microchips and is a great material to use for insulating heatsinks.
Alumina powder is an important material used in the formation of rubies and sapphires — corundum, which is its crystalline form, is the base element for these and other gems.
Alumina is also used as a polishing powder for some of the most difficult gems, including those with hardness levels of 8.
With alumina being a chemically inert substance, it can be used as a filler in plastics, bricks, and other heavy clayware such as kilns. Also, due to its abrasive nature, it can be used as sandpaper for construction activities.
Broad industrial applications
Alumina can be used in a wide variety of industrial applications, from piping components such as elbows, tees, and straight pipes, to hydro cyclones, reducers, nozzles, and valves. It is also a very useful material for machining tools, cutting tools, thermocouple sheaths, and wear-resistant pump impellers.
Alumina is a fairly common compound that can be sourced from many areas of the world. It is relatively inexpensive, with the average price staying around 10-90€ over the past decade. Many specifications can be sourced directly from Matmatch, as well as material traders in Europe and around the world, depending on what is needed. Visit the alumina search page on Matmatch to explore the different materials and their suppliers.
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*This article is the work of the guest author shown above. The guest author is solely responsible for the accuracy and the legality of their content. The content of the article and the views expressed therein are solely those of this author and do not reflect the views of Matmatch or of any present or past employers, academic institutions, professional societies, or organizations the author is currently or was previously affiliated with.
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