Silicon nitride protection tube
With light weight and stiffness, Si3N4 ceramic can be used to make ball bearings, it has higher accuracy than metal bearings, generates less heat, and can operate in higher temperature and corrosive media. The steam nozzle made of Si3N4 ceramic has characteristics such as wear-resisting and heat-resistance. It is not obvious to damage the boiler after 650°C for several months, while other heat-resistant and corrosion-resistant alloy steel nozzle can only use for 1-2 months under the same conditions. The Si3N4 glow plug developed jointly by the Shanghai Institute of Ceramics, Chinese Academy of Sciences and the Shanghai Institute of Internal Combustion Engines, has solved the problem of cold starting of diesel engines and is suitable for direct injection or non-direct injection diesel engines. This glow plug is the most advanced and ideal diesel engine ignition device today. The Japan Atomic Energy Research Institute and Mitsubishi Heavy Industries Corporation have successfully developed a new rough pump with a rotor composed of 11 Si3N4 ceramic turntables. Because the pump uses a Si3N4 ceramic rotor with a small coefficient of thermal expansion and precision air bearings, it can operate normally without lubrication and cooling media. If such a pump is combined with an ultra-vacuum pump such as a turbo-molecular pump, a vacuum system suitable for use in nuclear fusion reactors or semiconductor processing equipment can be formed.
The above are just a few examples of applications of Si3N4 ceramics as structural materials. It is believed that with the improvement of Si3N4 powder production, molding, sintering, and processing technology, its performance and reliability will continue to increase, and silicon nitride ceramics will be more widely used. Due to the improvement of Si3N4 raw material purity, the rapid development of Si3N4 powder molding technology and sintering technology, and the continuous expansion of application fields, Si3N4 is being used as an engineering structural ceramic, which occupies an increasingly important position in the industry. Si3N4 ceramic has excellent comprehensive performance and abundant resources. It is an ideal high-temperature structural material and has a wide range of applications and markets. Countries around 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 incomparable with general metal materials. It can withstand the harsh working environment where metal or polymer materials are difficult to handle, and has a wide range of application prospects. It has become the key basic material supporting the pillar industries of the 21st century after the 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, and are an important member of the high-temperature structural ceramics family. Si3N4 ceramics have superior mechanical properties, thermal properties, and chemical stability compared to other high-temperature structural ceramics such as oxide ceramics, carbide ceramics, etc. Therefore, Si3N4 ceramics are considered to be the most promising materials for high-temperature structural ceramics.
It can be predicted that with the continuous progress of ceramic basic research and new technology development, especially the improvement of complex parts and large parts manufacturing technology, Si3N4 ceramic materials will be more widely used as excellent engineering materials.
