Silicon nitride ceramics, an inorganic material ceramic that does not shrink when sintered. Silicon nitride is very strong, especially hot pressed silicon nitride, is one of the hardest substances in the world. It has properties such as high strength, low density and high temperature resistance.
Market applications of silicon nitride ceramics
Automotive industry: the main application of sintered silicon nitride in the automotive industry as an engine part material. In spark ignition engines, silicon nitride is used for rocker arm pads for lower wear, turbochargers for lower inertia and less engine lag, and exhaust gas control valves for increased acceleration.
Bearings: Silicon nitride ceramics have good impact resistance compared to other ceramics. For this reason, ball bearings made from silicon nitride ceramics are used in performance bearings. A representative example is the use of silicon nitride bearings in the main engine of the NASA space shuttle. Since silicon nitride ball bearings are harder than metal, this reduces contact with the bearing tracks. Silicon nitride ball bearings can be found in high-end automotive bearings, industrial bearings, wind turbines, motorsports, bicycles, skates and skateboards.
Silicon nitride bearings
High-temperature materials: Silicon nitride has long been used in high-temperature applications. In particular, it has been identified as one of the few monolithic ceramic materials capable of surviving the severe thermal shocks and thermal gradients generated in hydrogen/oxygen rocket motors.
Silicon nitride thruster. Left: mounted on a test stand. Right: testing with H2O2 propellant
Medical: Silicon nitride has many orthopedic applications. The material is also an alternative to PEEK (polyether ether ketone) and titanium for spinal fusion devices. The hydrophilic, microstructured surface of silicon nitride contributes to the material's strength, durability and reliability compared with PEEK and titanium.
Spinal Fusion
Metal Cutting Tools: Bulk, monolithic silicon nitride is used as a material for cutting tools because of its hardness, thermal stability and wear resistance. It is especially recommended for high-speed machining of cast iron. Thermal hardness, fracture toughness and thermal shock resistance mean that sintered silicon nitride can cut cast iron, hardened steel and nickel-based alloys.
Ceramic tools
Electronics: Often used as insulators and chemical barriers in the manufacture of integrated circuits to electrically isolate dissimilar structures or as etch masks in body micromachining. As a passivation layer for microchips, it is superior to silica because it is a significantly better diffusion barrier to water molecules and sodium ions, two major sources of corrosion and instability in microelectronics.