Silicon nitride ceramics not only have excellent mechanical properties but also have good thermal conductivity. The theoretical thermal conductivity of a silicon nitride single crystal can reach 320 W/(m·K). Therefore, silicon nitride ceramics as a high-power heat dissipation substrate is currently a hot research topic. It has been widely used in pure electric/hybrid electric vehicles.

Silicon nitride is a covalently bonded compound with a Si-N covalent bond content of up to 70%. Since silicon nitride powder decomposes at around 1700°C and its sintering self-diffusion coefficient is small, it is difficult to sinter. How to simply and effectively prepare high-density silicon nitride ceramics is very critical.

What method of sintering silicon nitride?

The commonly used methods for preparing silicon nitride ceramics are hot pressing sintering, hot isostatic pressing sintering, reaction sintering, gas pressure sintering, and spark plasma sintering. Among them, spark plasma sintering (SPS) has the advantages of a fast heating rate and cooling rate. High-density silicon nitride ceramics can be prepared in a short time (usually 5 to 10 minutes).