High strength and hardness sintered silicon nitride-based material

摘要

A sintered silicon nitride-based material contains, as main constituent, silicon nitride and/or SiAlON as primary crystalline phase, together with 0.5-3 wt.% Mg component (calculated as MgO) and 3-10 wt.% Yb component (calculated as Yb2O3), the material also contg. at least one secondary crystalline phase of Yb2Si3N4O3, Yb2Si3N2O5 or Yb4Si2N2O7 type. Also claimed is a process for prodn. of the above material by mixing and compacting the starting materials and then sintering at 1300-1550 (pref. 1350-1550) deg C pref. under conditions to give a material which contains 20-50 vol.% acicular crystals of silicon nitride and/or SiAlON and which includes at least one secondary crystalline phase as described above.