Silicon Nitride Ceramics
silicon nitride ceramic is an inorganic material ceramic that does not shrink during sintering. Silicon nitride is very strong, especially hot-pressed silicon nitride, which is one of the hardest substances in the world. With high strength, low density, high temperature and other properties.
Si3N4ceramic is a covalent bond compound, the basic structural unit is [SiN4] Tetrahedron, the silicon atom is located in the center of the tetrahedron, and there are four nitrogen atoms around it, which are located at the four vertices of the tetrahedron, and then in the form of every three tetrahedron sharing an atom, forming a continuous and strong network structure in three-dimensional space.
basic nature
silicon nitride are attributed to this structure. PureSi3N4is 3119, there are alpha and beta two crystal structures, are hexagonal crystal form, its decomposition temperature in the air is 1800 DEG C, in the 011MPa nitrogen is 1850 DEG C.Si3N4thermal expansion coefficient is low, high thermal conductivity, so its excellent thermal shock resistance. The hot-pressed sintered silicon nitride will not break even when it is heated to l000 ℃ and put into cold water. At not too high temperatures,Si3N4has high strength and impact resistance, but above 1200 ℃ will be damaged with the increase of use time, so that its strength is reduced, and fatigue damage is more likely to occur above 1450 ℃, soSi3N4generally does not exceed 1300°C. DueSi3N4is low, which is much lighter than steel and engineering super-heat-resistant alloy steel, so it is used in places where the material is required to have high strength, low density, high temperature resistance and other properties.Si3N4ceramics to replace alloy steel is more appropriate.
Material Performance
Si3N4ceramic materials as an excellent high-temperature engineering materials, the most can play an advantage is its application in the field of high temperature.Si3N4is: (1) give full play to and useSi3N4itself; (2) inSi3N4powder sintering, the development of some new flux, research and control of the existing flux of the best composition;Si3N4and SiC and other materials composite, in order to produce more high-performance composite materials.Si3N4ceramics in automobile engines has created a new situation for the development of new high-temperature structural materials. The automobile industry itself is a multi-discipline industry that integrates the great achievements of various technologies. China is an ancient civilization with a long history. It has made brilliant achievements in the history of ceramic development. With the process of reform and opening up, one day, China It is bound to be among the world's major automobile industry countries, creating new glories for the development of ceramics.
it is extremely high temperature resistant, its strength can be maintained to a high temperature of 1200 ℃ without decreasing, it will not melt into a molten body after being heated, and it will not decompose until 1900 ℃. It has amazing chemical corrosion resistance, can withstand almost all inorganic acids and 30% caustic soda solution, and can withstand the corrosion of many organic acids. At the same time, it is also a high-performance electrical insulating material.
Related Applications
utilizationSi3N4the characteristics of light weight and high rigidity, can be used to manufacture ball bearings, it has higher precision than metal bearings, generate less heat, and can operate in higher temperatures and corrosive media. UseSi3N4ceramics have the characteristics of wear resistance and heat resistance, and have no obvious damage after being used in 650 ℃ boilers for several months, while other heat-resistant and corrosion-resistant alloy steel nozzles can only be used for 1 - 2 months under the same conditions. Developed by the Shanghai Institute of Ceramics, Chinese Academy of Sciences and the Shanghai Internal Combustion Engine Research Institute of the Ministry of ElectromechanicalSi3N4glow plug solves the problem of difficult cold start of diesel engines and is suitable for direct injection or non-direct injection diesel engines. This glow plug is the most advanced and ideal ignition device for diesel engines today. The Japan Atomic Energy Research Institute and Mitsubishi Heavy Industries have successfully developed a new crude pump with 11Si3N4ceramic turntable. Since the pump uses a very small coefficient of thermal expansionSi3N4ceramic rotors and precision air bearings, so that it can operate normally without lubrication and cooling media. If this pump is combined with a super vacuum pump such as a turbo-molecular pump, it can form a vacuum system suitable for nuclear fusion reactors or semiconductor processing equipment.
above justSi3N4ceramics as structural materials are believed to follow.Si3N4the improvement of powder production, molding, sintering and processing technology, its performance and reliability will continue to improve, and silicon nitride ceramics will be more widely used. DueSi3N4the improvement of raw material purity,Si3N4powder molding technology and sintering technology, as well as the continuous expansion of application fields,Si3N4is becoming more and more important in industry as engineering structural ceramics.Si3N4ceramics is an ideal high-temperature structural material with excellent comprehensive properties and abundant resources. It has a broad application field and market, and countries all over the world are competing for research and development. Ceramic materials have the characteristics of wear resistance, corrosion resistance, high temperature resistance, oxidation resistance, thermal shock resistance and low specific gravity, which are difficult to compare with general metal materials. It can withstand the harsh working environment that metal or polymer materials are difficult to do, and has a wide range of applications. It has become the key basic material supporting the pillar industry in the 21st century after metal materials and polymer materials, and has become one of the most active research fields. Nowadays, all countries in the world attach great importance to its research and development.Si3N4ceramics have more excellent mechanical properties, thermal properties and chemical stability. Therefore, it is considered to be the most potential material in high-temperature structural ceramics.
Product Parameters
The company is mainly hot-pressed sintered silicon nitride. The volume density (g/cm & sup3;) of the product is between 3.2 and 3.3, the hardness (HRA) is between 90 and 92, the bending strength (MPa) is between 800 and 1200, and the maximum working temperature (℃) is 800 ℃.
