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Si3N4 powder preparation and applications

What is Si3N4 powder?

Si3N4 powder is most chemically and thermodynamically stable.  It is also the most important compound commodity.

Si3N4 powder is a kind of high-strength hard ceramic with certain thermal conductivity, low thermal expansion coefficient, and high elastic modulus in a wide temperature range. Different from ordinary ceramics, it has high fracture toughness. These properties combine to give it excellent thermal shock resistance, the ability to withstand high structural loads at high temperatures, and excellent wear resistance. They are commonly used in applications requiring high durability and high temperatures, such as gas turbines, automotive engine parts, bearings, and metal cutting parts.NASA's space shuttle uses Si3N4 powder to make main engine bearings. Si3N4 powder film is a common insulating layer for silicon-based semiconductors, and a cantilever made of Si3N4 powder is the sensing component of the atomic force microscope.


Si3N4 powder preparation history

The synthesis of Si3N4 powder was first reported by Henri Edin St. Clair de Vere and Friedrich Weiler in 1857. In their reported synthesis, another crucible filled with silicon is buried in a carbon-filled one and heated to reduce the infiltration of oxygen. They reported a product of nitrogen compounds they called silicon, but they were unable to figure out its chemical composition. In 1879 Paul Schuetzenberger reported it as a compound of Si3N4 by mixing silicon with a lining (a paste made from charcoal, coal, or coke mixed with clay as a crucible lining) and heating it in a blast furnace. In 1910 Ludwig Weiss and Theodor Engelhardt heated silicon under pure nitrogen to obtain Si3N4.In 1925, Friederich and Sittig synthesized Si3N4 powder by heating silicon dioxide and carbon to 1250-1300°C in a nitrogen atmosphere by carbothermic reduction method

In the following decades, Si3N4 powder received little attention and research until commercial applications appeared. From 1948 to 1952, Acheson started the Emery Company near Niagara Falls, New York, and registered several patents for the manufacture and use of Si3N4 powder. In 1958, Si3N4 powder produced by Union Carbide was used to make thermocouple tubes, rocket nozzles, and crucible for melting metal. British work on Si3N4 powder began in 1953 to make high-temperature parts for gas turbines. Thus, bonded Si3N4 powder and hot-pressed Si3N4 powder were developed. In 1971 the Defense Advanced Research Projects Agency (DARPA) of the U.S. Department of Defense awarded Ford and Westinghouse a $17 million contract to develop two ceramic gas turbines.

Si3N4 powder processing method

As a granular material, Si3N4 powder is difficult to process — it cannot be heated above its melting point of 1850°C, because above this temperature it breaks down into silicon and nitrogen. Therefore, the traditional hot pressing sintering technology is problematic. The bonding of Si3N4 powder powders can be done by adding other substances such as sintering AIDS or adhesives to induce a degree of liquid phase sintering at lower temperatures and then bonding into bulk materials. But because of the need to add adhesives or sintering AIDS, this method can introduce impurities into the resulting block material. The use of spark plasma sintering is another method that can be used to produce more pure bulk materials. The compacted powder is subjected to electric pulses over a very short period. In this method, compact and dense Si3N4 powder blocks can be obtained at temperatures of 1500 — 1700°C.

Si3N4 powder Supplier

TRUNNANO (aka. Luoyang Tongrun Nano Technology Co. Ltd.) is a trusted global chemical material supplier & manufacturer with over 12 years of experience in providing super high-quality chemicals and Nanomaterials. Currently, our company has successfully developed a series of materials. The Si3N4 powder produced by our company has high purity, fine particle size, and impurity content. Send us an email or click on the needed products to send an inquiry.

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