There are two production methods for silicon nitride ceramic products, namely reaction sintering and hot pressing. The reaction sintering method is to mold silicon powder or a mixture of silicon powder and silicon nitride powder according to the general production method of ceramic products. Then, in the nitriding furnace, pre-nitriding is carried out at a temperature of 1150~1200°C. After obtaining a certain strength, it can be machined and then further nitrided at 1350~1450°C for 18~36 hours until it is completely converted into silicon nitride.
Products made in this way have an accurate size and a stable volume. The hot pressing method is to heat press and sinter silicon nitride powder with a small amount of additives (such as MgO, Al2O3, MgF2, AlF3 or Fe2O3, etc.) at a pressure of more than 19.6Mpa and a temperature of 1600~1700°C. Usually, hot-pressed products have a higher density and better performance than those obtained by reaction sintering.