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By Dr.Zhang from Nanjing Normal University | 17 June 2019 | 0 Comments

New Breakthroughs Has Been Made in the Research and Development of Aluminum Oxide!

New Breakthroughs Has Been Made in the Research and Development of Aluminum Oxide!
 
What is aluminum oxide?
Alumina oxide is an amphoteric oxide of aluminum, and its chemical formula is Al2O3. It is also commonly known as alumina. Aluminum oxide is an electrical insulator, but has a high thermal conductivity for ceramic materials. The world's annual production of alumina is about 45 million tons, of which more than 90% is used to make aluminum. The main applications of special alumina are refractory, ceramic, polishing and abrasive applications. Large tonnage is also used in the manufacture of zeolite, coating titanium pigment, and as a flame retardant/smoke suppressant.
 
What are the properties of aluminum oxide?
Aluminum oxide is insoluble in water. In its most common crystalline form, called corundum or alpha-aluminum oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools.
Thanks to aluminum oxide, metallic aluminum is resistant to weathering. Metal aluminum reacts well with atmospheric oxygen, forming a thin layer of aluminum oxide passivation (4 nanometers thick) on any exposed aluminum surface. This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be improved by a process called anodic oxidation. Many alloys, such as aluminum bronze, take advantage of this property by adding a certain percentage of aluminum to the alloy to improve corrosion resistance. Aluminum oxide produced by anodic oxidation is usually amorphous, but the discharge assisted oxidation process, such as plasma electrolysis oxidation, leads to a large proportion of crystal aluminum oxide in the coating, increasing its hardness.
 
What are the uses of aluminum oxide?

 
  1. Insulating material
Alumina is used as an insulating material in the ceramic industry. The porous ceramics are well tolerant to most acids except phosphoric acid and hydrofluoric acid. These ceramics are preferred for their inertness and the fact that they can be used and reused in many process applications.
  1. Manufacturing

Due to its low reactivity with acid and high boiling point, Alumina is used in the manufacture of refractory materials. Refractories must be resistant to high temperature, pressure and acidity. Aluminum oxide is used in thermal testing instrumentations. In the electronics industry, it is used to make passive components for interconnection as well as in the making of resistors and capacitors.
  1. Abrasive
Aluminum oxide is used for its hardness and strength. It is widely used as an abrasive, including as a cheap alternative to industrial diamond. Many types of sandpaper use alumina crystals. In addition, its low heat retention and low specific heat make it widely used in grinding operations, especially cutting tools. As a powdery abrasive mineral, together with silica, it is the main constituent of the cue tip "chalk" used in billiard. Aluminum oxide powder is used in some CD/DVD polishing and scratch repair kits. Its polishing quality also lags behind its use in toothpaste. It is also used in microdermabrasion, both in the machine process through dermatologists and estheticians, and as a manual dermal abrasive used according to manufacturer's instructions.
  1. Body armor
Some body armors use alumina ceramic plates, often combined with aramid or ultra-high molecular weight polyethylene (UHMWPE), to combat most rifle threats. Alumina ceramic armor is easily available to most civilians in jurisdictions where it is legal but not military.
 

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