Silicon Nitride (Si3N4) Ceramics
1.Automotive Industry: The main application of sintered silicon nitride is in the automotive industry as an engine parts material. In spark ignition engines, silicon nitride is used for rocker pads for lower wear, turbochargers for lower inertia and less engine lag, and exhaust control valves for increased acceleration.
Bearings: Silicon nitride ceramics have good impact resistance compared to other ceramics. Therefore, ball bearings made of silicon nitride ceramics are used in performance bearings. A representative example is the use of silicon nitride bearings in the main engines of NASA's space shuttles. Since silicon nitride ball bearings are harder than metal, this reduces contact with the bearing track. Silicon nitride ball bearings can be found in high-end automotive bearings, industrial bearings, wind turbines, motorsports, bicycles, skates, and skateboards.
2.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 that can survive the severe thermal shock and thermal gradients generated in hydrogen/oxygen rocket engines.
3.Medical: Silicon nitride has many orthopedic applications. The material is also an alternative to PEEK (polyetheretherketone) and titanium for spinal fusion devices. Compared to PEEK and titanium, the hydrophilic, microstructured surface of silicon nitride contributes to the material's strength, durability, and reliability.
4.Metal Cutting Tools: Bulk, monolithic silicon nitride is used as a material for cutting tools due to its hardness, thermal stability and wear resistance.It is particularly recommended for high-speed machining of cast iron.Hot hardness, fracture toughness and thermal shock resistance mean that sintered silicon nitride can cut cast iron, hard steels and nickel-based alloys.
5.Electronics: Often used as an insulator and chemical barrier in the manufacture of integrated circuits to electrically isolate different structures or as an etch mask in bulk micromachining. As a passivation layer for microchips, it is superior to silicon dioxide because it is a significantly better diffusion barrier to water molecules and sodium ions, two major sources of corrosion and instability in microelectronics.
