Heat conductivity, physico-mechanical properties and interrelations of them and structures of pressureless sintered composites produced of Si3N4-Al2O3-Y2O3(-ZrO2) nanodispersed system

The microstructures and properties of high-density materials produced by a pressureless sintering of nanodispersed powders of composition Si3N4-Al2O3-Y2O3(-ZrO2) have been studied. It has been found that these self-reinforced materials of low glass phase content exhibit the bending strength Rbm = 720–850 MPa, Vickers hardness = 15.3–15.7 GPa, fracture toughness = 6.0–6.1 MPa·m1/2, and heat conductivity = 15–25 W(m·K). The factors affecting physico-mechanical properties and heat conductivity of silicon-nitride materials have been discussed.