Introducción
We believe that it’s no longer a hidden fact that aluminum oxide has gained so much popularity in the advanced ceramics industry. It is widely known for exceptional hardness and abrasiveness, which often makes it a cheaper alternative to industrial diamond. Interesting, right?
Today’s article provides a complete analysis of Aluminum Oxide, the qualities that make it outstanding and its numerous applications.
Characteristics of Aluminum Oxide
Aluminum Oxide is an odorless crystalline compound formed from the chemical combination of Aluminum and Oxygen. It’s a white solid compound with chemical formula Al2O3, commonly called Alumina, Corundum or Aloxide. It’s found mostly in the powdered form and a naturally occurring form; Aluminum (III) Oxide (Al2O3). It has a range of applications in the manufacturing, commercial, and chemical industries due to its outstanding qualities.
Aluminum Oxide is known for its excellent abrasiveness and exceptional hardness, and only Silicon Carbide and Diamond boosting of better quality than it. In actual fact, the Mohs scale of steel hardness placed the hardness for Aluminum Oxide at an impressive 9. Also, owing to the presence of Aluminum Oxide crystals, it’s a very suitable material for producing high-strength aluminum metals, oxide materiales cerámicos, strong abrasives, like sandpaper, and even as a substitute for valuable gems like Ruby, Sapphire, etc. This hardness also makes them useful in rough lapping operations.
Aluminum Oxide is mostly amphoteric in nature and possesses a high melting point of 2,072°C, thereby making it a good refractory material. It has a boiling point of 2,977°C and a density of 3.99g/cm³. It’s insoluble in any solvent, including water, possesses a high refractive index and thermal conductivity of about 30 Wm−1K−1. It also has a magnetic susceptibility of −37.0×10−6 cm³/mol.
Aluminum Oxide has an octahedral trigonal structure and a molecular weight of 101.960 g·mol−1. Naturally occurring forms of Al2O3, like corundum and bauxite, can be used in a rich variety of engineering firms as adsorbent materials or even desiccating agents.
Despite the hardness of Aluminum Oxide and the metallic oxide name given to it, it’s still very much a ceramic material, making it useful in the advanced ceramics industry. This is because this solid crystalline compound formed with the help of oxygen is known to be highly resistant to corrosion or rusting. Most importantly, it produces a thin layer which is firmly stuck, making it insoluble in whatever solvent it’s placed in.
Uses of Aluminum Oxide (Al2O3)
The uses of Aluminum Oxide are very numerous, as we mentioned earlier, some of them are:
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It is used as a catalyst in Chemical reactions
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It is used to eliminate gas streams from water while purifying the water.
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It is used in the production of glass.
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It is used as an excellent abrasive in sandpaper.
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Sodium vapour lamps make use of Alumina.
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Substrates for integrated circuits make use of aluminum oxide in the form of an electrical insulator.
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It is used as one of the ingredients in manufacturing cosmetic products like sunscreens, nail polish, lipstick, etc.
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It is used to coat kitchen utensils due to its scratch resistance and abrasiveness.
Production of Aluminum Oxide
Aluminum, its main constituent, exists as abundant laterites in the soil, red soil particularly, being that it’s the earth’s second most abundant metal. A good example of this laterite form used in Aluminum Oxide production is Bauxite, which consists of iron oxide impurities, quartz, silicates, 55% alumina, boehmite (γ−AlO(OH), diaspore (α−AlO(OH) and gibbsite (Al(OH)3).
It’s primarily produced from a simple chemical procedure known as the Bayer Process. This procedure thereafter culminates in calcination to finally yield the Aluminum Oxide powder. Now, let’s explain how this Bayer Process unfolds.
First, the ore containing Bauxite, under temperatures reaching 175°C, is broken down into a hot solution of Sodium Hydroxide. This leads to the formation of Sodium Aluminate. Then a phase of Alumina filtration follows. The Alumina filtered out is usually of High quality.
A precipitator tank is then employed in the cooling of this hot solution. Aluminum Hydroxide Crystals are gradually formed as the solution cools. Thereafter, the newly formed crystals under high temperatures of about 1,260°C are taken for calcination in a kiln. The final product here is the Aluminum Oxide powder.
Propiedades del óxido de aluminio
There are several qualities that make aluminum oxide a very essential material to so many sectors of the world economy today, including:
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It has a high melting point of 2,072°C.
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It has a high thermal conductivity of 30 Wm−1K−1.
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It has a molecular weight of 101.960 g·mol−1.
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It undergoes a strong neutralization reaction with sulphuric acid - Due to its amphoteric nature as a metallic oxide, it acts effectively as a base and an acid.
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Reaction with hydrochloric acid - Al2O3 reacts with acids like dilute Hydrochloric acid in the same way a sodium magnesium oxide would. This is due to the oxide ions in them. For example, in the case of the diluted Hydrochloric acid (6HCl), Aluminum oxide (Al2O3) would react with six moles of this compound to give Aluminum Chloride solution (2AlCl3).
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It has a density of 3.99g/cm³.
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It has a high boiling point of 2,977°C.
Mohs Hardness Scale
The Mohs hardness scale is an arbitrary non-linear scale that you can use to measure the ten readily available minerals like Alumina, Diamond, Silicon Carbide, etc., based on their respective hardness, resistance to scratch from harder materials, and their abrasiveness in a scale ranging from 1 to 10. It is said to be a non-linear scale since there’s no equality between relative hardness values.
Alumina Mohs hardness can be determined from observing if it gets scratched by another mineral of known hardness. Aluminum Oxide hardness makes it get an impressive 9 rating on the Mohs scale of mineral hardness. Only Gems like Diamond, advanced ceramic materials like Silicon Carbide and Boron Carbide are listed higher than Aluminum Oxide.
Diamond is at the top with a rating of 10 since it’s able to comfortably withstand scratch from other minerals. Steel Mohs scale is around 7.5 to 8 meaning, it could scratch softer minerals like Topaz and copper slag. This also means it could get scratched by harder minerals like Alumina and Diamond.
Alumina Modulus of Elasticity
This is the measurement of Alumina’s elasticity. It is the ratio of its elasticity in various quantities and degrees. It gives more details about the mechanical strength and resistance of Al2O3 to deformation. The pelletizing method and Tape Casting methods are usually the most common ways you can use to determine Alumina modulus of elasticity. The way you can differentiate these two methods is mainly by the uniformity of the thickness of the wafers used. The two methods involve using powder pressing, calcination, sintering, making pellets, and cutting them into wafers. Currently, 249 GPa is the known average value of Al2O3 modulus of elasticity, with respect to its density of 3.99g/cm³.
Dureza de la cerámica de alúmina
Modern ceramic materials benefit immensely from Aluminum Mohs hardness, as they possess impressive hard and scratch resistant surfaces. These Alumina Ceramics have a well organized and rigid crystal lattice structure that is tightly fitted.
High compressive strength, strong abrasiveness, resistance to corrosion, wear, and tear are some of the excellent mechanical properties you enjoy in Alumina Ceramics. This means these advanced ceramics can withstand heavy loads without changing their original structure. They can be used industrially under intense heat to make conveyor systems and pipes that require high levels of friction. It also has a chemically inert nature, which makes it a sound material for the production of lab equipment.
Rockwell Hardness of Aluminum and Vickers Hardness Test are two of the most common procedures you can use to measure the hardness of Alumina ceramics. You can do this test by using an indenter on the surface of the material and then measuring the deformation you see. You can also derive the mechanical properties of the alumina ceramics from the results obtained from these tests.
However, owing to the brittle nature of Alumina ceramics especially when put under bending forces or tension, their toughness and durability can be boosted by certain polymers and metals in an electrochemical process known as Anodizing; Thereby increasing their efficiency.
Alumina Grades
Aluminum Oxide exists in various forms and grades due to the various industrial processes available. Some of these grades are:
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Fused white alumina
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Fused brown alumina
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Alúmina calcinada
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Reactive grade alumina
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Bubble alumina
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Activated alumina
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Submicron alumina.
Specific properties and applications are associated with these various alumina grades.
Applications of Aluminum Oxide
Aluminum Oxide can be utilized in various sectors globally. We will look closely at the major applications, which include:
Advanced Ceramics Industry
Aluminium oxide hardness and strength is very useful in the advanced ceramics industry. It is used in making furnace insulation and kiln linings. Aside from also being used as a cheap alternative to Industrial Diamond, It’s widely utilized as a good abrasive. Aluminum Oxide Crystals make up the bulk of many sandpapers. Grinding operations also benefit greatly from Al2O3 due to its low heat retention and low specific heat.
Metalurgia
Aluminum metal gets its abrasiveness and hardness from Aluminum Oxide. The high melting point and refractive index makes it a good refractory material for the production of aluminum metal. Recent studies stated that in 2015, 80-90% of Aluminum oxide globally produced was utilized in the production of aluminum metals yearly.
Plastics and Cosmetics
The Plastics and cosmetics Industry aren’t left out, as they tend to effectively use Aluminum oxide as their filers. This is made possible due to the inert nature and whiteness of the compound.
Vaso
Aluminum Oxides are a major component of Glass. Its scratch resistant abilities ensure that metal coatings, glass and optical equipment are well protected.
Paint
Industries that deal in paint manufacturing use flakes from Aluminum Oxide to achieve reflective decorative effects.
Composite fiber
Commercial fiber materials owe their high performance to Aluminum Oxide hardness. Al2O3 has made the production of Alumina Nanofibers a growing trend recently.
Militar
Alumina Ceramic Plates are components that make military body armor to be bulletproof and sound. Alumina Ceramic amors, a product of Aluminum Oxide hardness are mainly used by the military and with time, it has greatly developed the quality and efficiency of the military.
Semiconductors and Electronics
Circuit boards, semiconductors, capacity dielectrics and power electronics generally use the insulating properties of Aluminum Oxide. Its electrical insulating properties make it essential to these circuit boards, semiconductors and capacitor dielectrics.
Medicamento
Modern Medicine owes some of its technological advancements to Aluminum Oxide. Aluminum Oxide hardness has been found to be biocompatible with medical devices, artificial joints and bones, as well as dental implants.
Global Market Size of Aluminum Oxide
The Aluminum Oxide market is increasing at a phenomenal pace. In 2022, the market size was estimated to be $20 billion. Currently it’s at a Compound Annual Growth Rate (CAGR) of 7%, and as a result is forecasted to reach $70 billion dollars by 2030. Here at GGSCeramics, we provide you with high performance Aluminum Oxide products with very high purity and impressive density for any of your applications.
Preguntas frecuentes
Is aluminium oxide basic or acidic?
Aluminium oxide is a metallic oxide that is amphoteric. That means it could act as a base and also as an acid. The nature of the substance it’s reacting with determines if it would act as a base or an acid.
What are the methods used to determine the Alumina Modulus of Elasticity?
There are 2 methods used, which are the pelletizing method and the tape casting method.
What liquids normally react to aluminium?
Liquids like diluted Hydrochloric acids, liquid bromine, and Aluminium Chloride are some of the liquids that at room temperature could possibly react with Aluminium Oxide.
Conclusión
With rapid advancements in modern technology and industrialization, Aluminum Oxide is becoming a game-changer and key player in various material sectors. Its usefulness in several industries ranging from production of a wide variety of advanced ceramics materials, utilizations in power electronics, medicine and many others, makes it a safe and interesting sector to invest in.