The requirement for the production of dense silicon nitride ceramics is the presence of a liquid phase under sintering conditions, since the strongly covalent Si-N bonds limit the mass transfer by solid-state diffusion even at high temperatures [LAN91]. Therefore, the addition of additives is essential. In addition, Si₃N₄ decomposes at temperatures above 1900 °C.

The most common method for producing dense workpieces from Si₃N₄ is the sintering of shaped silicon nitride powders in a nitrogen atmosphere with the addition of additives such as aluminum or yttrium oxide or a mixture thereof. These additives form a glass (Y-Si-Al-O-N) or crystalline phase (Yttrium Aluminum Garnet (YAG)) enveloping the Si₃N₄ grains. In order to lower the necessary additive content and to improve the mechanical properties can be sintered under elevated pressure [HEI10].

For reaction bonded Si₃N₄ (RBSN), the correspondingly shaped silicon powder is nitrided in nitrogen atmosphere below its melting temperature. In this case, almost no shrinkage occurs, whereby a costly reworking usually omitted. In addition, the raw materials used are relatively cheap. Due to the poor diffusion of nitrogen in the Si₃N₄ formed so only small workpieces can be made. In addition, RBSN materials have a high porosity which, compared to dense Si₃N₄ ceramics, leads to inferior mechanical properties. A subsequent sintering process allows higher densities, but also leads to shrinkage of the component [KOL18].