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Classification Of Nitrides

wallpapers Resource 2020-12-03
Nitride. Nitride is a type of nitrogen compound, in which nitrogen has a -3 valence, including metal nitrides, non-metal nitrides and ammonia (NH3, nitrogen negative trivalent). It is customary to regard ammonia as a special substance. Included in the nitride.
 
Metal nitrides have high thermal stability and can be used as high-temperature insulating materials. The thermal stability of non-metallic nitrides is also relatively high, each with special properties. Hexagonal boron nitride is an excellent lubricant; while cubic boron nitride has high hardness and can be used to make turning tools and drill bits.
 
Main classification
 
Metal nitride refers to a compound formed by a metal element and nitrogen. Important ones are lithium nitride (Li3N), magnesium nitride (Mg3N2), aluminum nitride (AlN), titanium nitride (TiN), tantalum nitride (TaN) and so on. Most of them are insoluble in water and have high thermal stability, and can be used as high-temperature conductive materials, such as titanium nitride, tantalum nitride, vanadium nitride (VN), etc. A few are completely hydrolyzed in water to form metal element hydroxides and release ammonia, such as magnesium nitride and aluminum nitride. Some metal nitrides can be directly combined with metal after heating. Some are made by heating metals, metal oxides or metal chlorides in a stream of ammonia.
 
Important non-metallic nitrides include boron nitride (BN), phosphorus pentanitride (P3N5), silicon nitride (Si3N4) and so on.

 
Classification of binary compounds
 
The binary compound formed by nitrogen and the element with less electronegativity does not include the binary compound of nitrogen and hydrogen or halogen and azide. Divided into four categories according to properties: ①Nitrides of alkali metals and alkaline earth metals, also known as ionic nitrides, which have low thermal stability and are easy to hydrolyze to produce ammonia and metal hydroxides; ②Nitrides of transition elements, called ionic nitrides It is a metallic nitride, which generally has high hardness, high melting point, high chemical stability, and has the appearance and conductivity of a metal; ③Nitrides of copper group and zinc group elements are between the metal type and the covalent type The transition form is called intermediate nitride; ④Nitrides from boron group to chalcogenide elements have a covalent structure, called covalent nitrides, which are generally very stable.
 
Alkali metals react with nitrogen to form azides, which are decomposed to form nitrides after careful heating. Other nitrides are generally prepared by direct reaction of elemental elements with nitrogen. Nitrides of boron, silicon, titanium, vanadium and tantalum are often used as abrasives and crucibles because they are hard, refractory and resistant to chemical attack.

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