Effect of composite sintering additives containing non-oxide on mechanical, thermal and dielectric properties of silicon nitride ceramics substrate

Silicon nitride (Si3N4) ceramics with magnesium silicon nitride (MgSiN2) and Y2O3 as sintering additives were prepared by the gas-pressure sintering method. By changing the contents of MgSiN2 and Y2O3 in the range of 7–9 mol% and the proportion of MgSiN2 in the sintering additives, the effect of the MgSiN2 and Y2O3 additives on the combination properties (mainly include thermal conductivity, mechanical and dielectric properties) and microstructure of the Si3N4 ceramics was comprehensively analyzed to explore the accurate composition of sintering additives for manufacturing Si3N4 ceramics substrate. The results showed that the amount and combinations of MgSiN2 and Y2O3 significantly affected the grain boundary composition, lattice oxygen, and grain size of the Si3N4 ceramics. This was important for determining the thermal conductivity, mechanical and dielectric properties of the Si3N4 ceramics. Compared with the previous most research focused only on how to acquire high thermal conductivity through long-term heat preservation at high temperature, this work fully demonstrated the effect of the composite sintering additives containing non-oxide on the combination properties (thermal conductivity, mechanical and dielectric properties) of Si3N4 ceramic substrate.