A study is made of the damage resistance and strength degradation of nitrided pressureless sintered (NPS) silicon nitride ceramics. The silicon nitride is prepared by cost-effective NPS process combining by nitridation and consecutive pressureless sintering. Contact testing with spherical indenters is used to characterize the damage response. Examination of the indentation sites indicates a quasi-plastic damage modes are observed. Bend tests on specimens containing quasi-plastic contact damages reveal those materials to be not susceptible to strength degradation.

As an alternative to degassing pipe and rotor blade using in molten aluminum industry, we investigate the mechanical properties of silicon nitride ceramic components prepared by nitrided pressureless sintered (NPS) process, which process is the continuous process of nitridation reaction process combined with pressureless sintering. Mechanical properties of silicon nitride prepared by NPS process with sintering additives of 5wt% Y2O3, 5wt% Al2O3 and 20wt% Si show high strength, >500 MPa, high hardness, 12.6 GPa, and superior damage tolerances with high fracture toughness, 9.8 MPam1/2.

No abstract

No abstract