Ceramic with special structure is an important branch of ceramic materials. It is characterized by high-temperature resistance, high strength, super hardness, wear resistance, corrosion resistance and other mechanical properties, which has important applications in metallurgy, aerospace, energy, machinery, optics and other fields.
Nitride ceramic is a new type of engineering ceramic developed in recent 20 years. It is different from ordinary silicate ceramics in that the combination of nitrogen and silicon is covalently bonded, so it has the characteristics of strong binding force and good insulation. Silicon nitride is high in strength and hardness and is one of the hardest materials in the world. It has excellent chemical corrosion resistance and is also a high-performance electrical insulation material.
The theoretical thermal conductivity of aluminum nitride is 320W/m•k, which is about 80% of that of copper. Aluminum nitride has low dielectric constant, high resistance, low density and thermal expansion coefficient close to silicon. Its comprehensive performance is better than that of Al2O3, BeO, SiC, etc., and it is used for high thermal insulation and electronic substrate materials.
Composite carbide ceramics
Boron carbide ceramics
The bending strength of high-density silicon carbide/boron carbide composite ceramics still can reach 500 ~ 600 MPa even under the high temperature of 1400 ° C. Silicon carbide/boron carbide composite special ceramic materials have the characteristics of small proportion, high hardness, high modulus and impact resistance, and are applied to the new generation of ceramic armor.
Zirconia toughened ceramics have made great progress in the study of structural ceramics. Apart from the stable zirconium oxide, the toughened matrix materials include alumina, thorium oxide, spinel stone, mullite and other oxide ceramics.
The composition of the modern electric light source has a high demand for high-temperature resistance, corrosion resistance and light transmittance of materials, and the total transmittance and mechanical properties of transparent alumina and aluminum nitride ceramic materials produced by microwave sintering are better than those produced by traditional methods. It is used in high-temperature optical window, probe and lamp tube.
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