page_title: Silicon nitride
section_title: High-temperature material
hierarchical_section_title: Silicon nitride / Applications / High-temperature material
caption_attribution_description: English: Silicon nitride thruster. Left: Mounted in test stand. Right: Being tested with H2/O2 propellants
context_page_description: Silicon nitride is a chemical compound of the elements silicon and nitrogen. Si
  ₃N
  ₄ is the most thermodynamically stable of the silicon nitrides. Hence, Si
  ₃N
  ₄ is the most commercially important of the silicon nitrides when referring to the term "silicon nitride". It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H
  ₂SO
  ₄. It is very hard. It has a high thermal stability.
context_section_description: Silicon nitride has long been used in high-temperature applications. In particular, it was identified as one of the few monolithic ceramic materials capable of surviving the severe thermal shock and thermal gradients generated in hydrogen/oxygen rocket engines. To demonstrate this capability in a complex configuration, NASA scientists used advanced rapid prototyping technology to fabricate a one-inch-diameter, single-piece combustion chamber/nozzle (thruster) component. The thruster was hot-fire tested with hydrogen/oxygen propellant and survived five cycles including a 5-minute cycle to a 1320 °C material temperature.
  In 2010 silicon nitride was used as the main material in the thrusters of the JAXA space probe Akatsuki.
  Silicon nitride was used for the "microshutters" developed for the Near Infrared Spectrograph aboard the James Webb Space Telescope. According to NASA: The "operating temperature is cryogenic so the device has to be able to operate at extremely cold temperatures. Another challenge was developing shutters that would be able to: open and close repeatedly without fatigue; open individually; and open wide enough to meet the science requirements of the instrument. Silicon nitride was chosen for use in the microshutters, because of its high strength and resistance to fatigue." This microshutter system allows the instrument to observe and analyze up to 100 celestial objects simultaneously.
caption: Silicon nitride thruster. Left: Mounted in test stand. Right: Being tested with H2/O2 propellants
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