1. Advantages of silicon nitride ceramics
There are three crystal structures in silicon nitride, which are , and phases, among which the and phases are the most common forms of silicon nitride. Because the nitrogen atoms are very firmly bonded, silicon nitride has good properties such as high strength, high hardness and high temperature resistance, and the hardness can reach HRA91~93; it has good thermal hardness and can withstand high temperatures of 1300~1400C; and carbon The chemical reaction with metal elements is small, resulting in a low coefficient of friction; it is self-lubricating, so it is wear-resistant; it has strong corrosion resistance, except for hydrofluoric acid, it does not react with other inorganic acids, and it also has anti-corrosion properties at high temperatures. Oxidation ability; it also has good thermal shock resistance, and it will not crack when it is cooled sharply in the air and then heated sharply; silicon nitride ceramics have small high-temperature creep, and under the action of high temperature and fixed load, the slow plasticity produced The deformation is very small.
In addition, silicon nitride ceramics also have the advantages of high specific strength, high specific modulus, high thermal conductivity, and excellent electrical properties, so they have special application value in extreme environments such as high temperature, high speed, and strong corrosive media. One of the structural ceramic materials with development and application prospects is often the first choice in many applications that need to be tested. The following is an inventory of these application directions.
2. Application of silicon nitride ceramics
The application of silicon nitride first appeared in the 1950s. It was used as a bonding phase between silicon carbide and oxides for refractory materials, and then used to manufacture crucibles, thermocouple tubes, rocket nozzles, etc. In the 1960s, with the increasing demand for new materials with excellent high-temperature performance, the development speed of silicon nitride ceramics increased significantly. At present, the development of silicon nitride materials is mainly based on the ceramic and electronic industries, and is constantly expanding to other application fields.
(1) Silicon nitride ceramic bearings
Ceramic bearings have developed rapidly since they were developed in 1972. It has been widely used in precision machine tools, automobiles, aero engines, chemical instruments, superconducting devices and other fields.
(2) Aerospace field
In the field of aerospace, the requirements for material properties are very strict, challenging the limits of traditional materials. Si3N4 is a good choice for aerospace due to its high temperature strength, good fracture toughness, high hardness, high dielectric strength, excellent thermal shock resistance and tribological properties, which can ensure excellent mechanical reliability and wear resistance sex.
(3) Automobile engine high temperature components
Si3N4 ceramic components for automotive engines include: turbocharger turbine rotors, preheating combustion chambers, rocker arm inserts, injector connecting rods, valve guides, ceramic piston tops, glow plugs, etc., especially the most difficult ceramic rotor products have been Entering certain ceramic engines, small turbine rotors have entered commercial scale production.
(4) Silicon nitride ceramic heat dissipation substrate
The heat dissipation substrate in the electronics industry needs to discharge the heat of the components in the integrated circuit in a timely and effective manner. In addition, the substrate needs to have strong enough mechanical properties to cope with very harsh conditions such as temperature and pressure. Although the thermal conductivity of silicon nitride ceramics is lower than that of aluminum nitride and beryllium oxide, it is significantly higher than that of general structural ceramics, which can basically meet the heat dissipation requirements of the substrate; moreover, the strength and fracture toughness of silicon nitride ceramics are much higher than those of other ceramics. Substrate-based ceramics are heat-dissipating substrate materials with excellent comprehensive performance, and have been practically applied in the electronic control systems of high-speed rail and electric vehicles.
(5) Applications in other fields
Due to its excellent high temperature resistance and corrosion resistance, silicon nitride ceramics can be used in chemical corrosion-resistant and wear-resistant parts, semiconductor industry, including missile radome for national defense industry, ceramic materials for biomedical use, nuclear power main pump as sealing ring, Silicon nitride ceramic rings for polysilicon reduction furnaces, heat-insulating disk covers, and newly developed silicon nitride ceramic coil springs, which not only maintain high strength at 1000C, but also have strong corrosion resistance, are used in special valves .
In short, as a structural ceramic material with the best comprehensive performance, many application directions of silicon nitride have attracted the attention of the industry and laboratories.
Because of its relatively balanced performance in various aspects of its various aspects,silicon nitride ceramics, known as the best comprehensive performance in structural ceramic families. If you are interested in this product, you can buy confidently.