Silicon nitride ceramics—the “leader” in four major fields
Silicon nitride (Si3N4) is a covalently bonded compound composed of silicon and nitrogen. It was discovered in 1857 and was mass-produced as a ceramic material by 1955. Silicon nitride ceramics have many advantages that metal materials and polymer materials do not have, such as high temperature resistance (bending strength can reach more than 350MPa at 1200°C), acid and alkali corrosion resistance, self-lubrication, etc., and are widely used in aerospace, national defense and military industries. , widely used in the mechanical field.
Mechanical field
Silicon nitride ceramics are mainly used in the machinery industry as valves, pipes, classifying wheels and ceramic cutting tools. The most widely used silicon nitride ceramic bearing balls are silicon nitride ceramic bearing balls.
Silicon nitride bearing balls can rotate up to 600,000 revolutions per minute during use. They are mainly used in precision machine tool spindles, high-speed bearings for electric spindles, aerospace engines, automobile engine bearings and other equipment bearings.
Silicon nitride ceramic bearing balls have outstanding advantages compared with steel balls: low density, high temperature resistance, self-lubricating, and corrosion resistance. As a high-speed rotating body, the ceramic ball generates centrifugal stress, and the low density of silicon nitride reduces the centrifugal stress on the outer ring of the high-speed rotating body. Dense Si3N4 ceramics also exhibit high fracture toughness, high modulus properties and self-lubricating properties, and can excellently resist a variety of wear and endure harsh environments that may cause other ceramic materials to crack, deform or collapse, including extreme temperatures, large temperature differences, Ultra high vacuum. Silicon nitride bearings are expected to find wide application in various industries.
Wave-transparent materials field
Porous silicon nitride ceramics have relatively high flexural strength and lower density, which is one of the key factors for their application in aerospace. It is also creep-resistant (compared to metals), which improves the structure’s stability at high temperatures. This material has a variety of additional properties, including hardness, electromagnetic properties and thermal resistance, and is used as a wave-transparent material to make radomes and antenna windows. With the development of the national defense industry, missiles are developing towards high Mach number, wide frequency band, multi-mode and precision guidance. Silicon nitride ceramics and their composite materials have excellent properties such as heat protection, wave transmission, and load-bearing, making them one of the new generation of high-performance wave-transparent materials studied.
Semiconductor field
In addition to excellent mechanical properties, silicon nitride ceramics also exhibit a range of excellent thermal conductivity properties, making them suitable for use in the demanding semiconductor field. Thermal conductivity is the inherent ability of a material to transfer or conduct heat. Due to the unique chemical composition and microstructure of silicon nitride, it has excellent comprehensive properties compared with alumina ceramics and aluminum nitride ceramics.
Bioceramics field
As a new generation of bioceramic materials, silicon nitride ceramics not only have the excellent qualities of ceramic materials, but also have good radiographic properties, anti-infection properties, biocompatibility properties and osseointegration properties.
The above-mentioned excellent properties of silicon nitride ceramics make it an ideal biomaterial, and it is used in biosensors, spine, orthopedics, dentistry and other implants.