Introduction of Common Non-oxide Ceramics

Introduction of Common Non-oxide Ceramics

Non-oxide ceramic raw materials rarely exist in nature. the raw materials need to be synthesized manually, and then ceramic products are made according to the ceramic technology. today, this paper introduces the properties and characteristics of silicon nitride ceramics, boron nitride ceramics, and silicon carbide ceramics.

Technical ceramics are widely used in industry, and non-oxide ceramics account for a large proportion of ceramics. Non-oxide ceramics mainly refer to nitride ceramics, carbide ceramics, boride ceramics, and silicide ceramics. They are generally combined by strong covalent bonds.

Non-oxide ceramic raw materials rarely exist in nature. the raw materials need to be synthesized manually, and then ceramic products are made according to the ceramic technology. today, this paper introduces the properties and characteristics of silicon nitride ceramics, boron nitride ceramics, and silicon carbide ceramics.

Silicon Nitride (Si3N4) Ceramics

Silicon nitride (Si3 Nl) is a covalent bond compound, it has two crystal types, namely a-Si3 N4 and B-Si3. B-Si3 N4 is a needle-shaped crystal, a-Si3 Ni is a granular crystal, both of which belong to the hexagonal crystal system.

Due to the high temperature and wear resistance of Si3N4 ceramics, good thermal shock resistance, corrosion resistance, low friction coefficient, and low thermal expansion coefficient, it has been widely used in many industrial fields.

Mingrui Ceramic | Technical Ceramics Customizing & Machining

Boron Nitride (BN) Ceramics

The structure and some properties of boron nitride (BN) are similar to graphite, and there are two crystal types: hexagonal and cubic. Hexagonal can be converted into cubic BN under the conditions of 1300~1800℃ and 6.5MPa, and its hardness is second only to diamond.

The hexagonal BN material with the main crystalline phase has machinability and white lubricity, and can be used as high-temperature bearings. It has good thermal resistance and is an ideal high-temperature insulating and heat-dissipating material, metallurgical container, and high-temperature abrasive material.

Silicon Carbide (SiC) Ceramics

Silicon carbide (SiC) ceramics have two crystal types, one is a-SiC. It belongs to the hexagonal crystal system. It is a high-temperature stable type; the other is B-SiC, which belongs to the face-centered cubic crystal system and is a low-temperature stable type. a-SiC can be transformed into B-SiC crystal form in the temperature range of 2100~2400℃.

Silicon carbide ceramics have high-temperature strength, low high-temperature creeps, high hardness, wear resistance, corrosion resistance, oxidation resistance, high thermal conductivity, high electrical conductivity, and good thermal stability, so it is a good high-temperature structural ceramic material above 1400 ℃.

At first, it was mainly used as refractory materials and abrasives, such as steel-making nozzle bricks, furnace lining, kiln furniture, grinding wheels, etc., and then gradually used in some technical fields as high-temperature structural materials or heating elements, such as rocket exhaust nozzles, gas turbine blades, electrodes of magnetic fluid generators, electric furnace heating elements, etc.

 

Hits:  UpdateTime:2021-08-23 10:36:01  【Printing】  【Close

Leave a Message

Leave a Message