Silicon Nitride Ceramic PreparationSi3N4 ceramics can be prepared using a variety of methods, including hot pressing, atmospheric, pressure, and hot press sintering.
Reaction sintering method (RS)
It follows the standard forming procedure. The first step is to press the silicon powder into the desired form. Next, it’s placed in a nitriding furnace where it undergoes pre-nitriding or partial nitriding before being sintered. The pre-nitrided green bodies already have a certain strength. There are many mechanical processes that can be done to the green body, including turning, planing and milling. To obtain a product with minimal dimensional changes, the temperature must be above the melting points of silicon.
Hot Press Sintering
It uses Si3N4 Powder and small amounts of additives (such a MgO or Al2O3, MgF2, F2O3, etc.). It is pressed at above 1916 MPa, and heated to 1600 degrees for hot press molding or sintering. Si3N4 ceramics made by hot pressing are superior to those of Si3N4 that has been reaction sintered. They have high strength and density.
Atmospheric pressure-sintering method (PLS).
To increase the pressure of the sintering atmosphere nitrogen atmosphere, it uses the properties Si3N4 for decomposition temperature. Usually, N2 = 1atm is used, with a minimum of 1800degC. After atmospheric sintering has been completed at temperatures between 1700-1800 degC, air pressure sintering can be done at temperatures between 1800-2000degC.
Air pressure sintering technique (GPS).
At a pressure of 1-10 MPa and at temperatures of approximately 2000°C, silicon nitride can be air pressure sintered. The high nitrogen pressure prevents silicon nitride from decomposing at high temperatures. It is possible to produce a high toughness ceramic by using high temperature sintering with less sintering tools.
Silicon Nitride Ceramic ApplicationSilicon nitride Ceramics have exceptional mechanical properties, wear resistance corrosion resistance, and other excellent properties. This makes them widely used in many industrial areas such as metallurgy machinery energy, machinery, metallurgy, aerospace, chemical industry, and so forth.
Silicium nitride ceramics in mechanical engineering can be used to produce bearings. Cutting tools, high-temperature bolts. Drawing dies. Ball valves. Plungers. Sealing materials. Nozzles.
Hot-pressed silicon nitride ceramic tool have 5-15x higher durability than cemented carbide and 3-10x higher cutting speeds. Dispersion strengthening can be used to increase the performance and longevity of silicon-nitride tools by compounding TiC or ZrC.
Silicon nitride clay has excellent mechanical properties. It is both wear-resistant and self-lubricating. It is an excellent bearing material with a longer service life than other ceramic ones. It can withstand extreme temperatures and corrosion.
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