Effect of Applied Pressure on Densifieation and Mechanical Properties of Sialon-ZrN Composites Fabricated Through a Reaction Bonding /Gas Pressure Sintering Process

摘要

Sialon-ZrN composites have been produced by reaction bonding and gas pressure sintering, and the effects of applied pressure on the sintering and properties has been investigated. The results showed that composites were mainly composed of P-Sialon and ZrN, with intermediate phases (including Y2SiAlO5N, Al2SiO5 and Y2Si2O7) for 0.4 MPa and Y5Si4Al2O_(17)N for 1.0 MPa. The mass loss decreased with pressure increase due to suppression of thermal decomposition of the Sialon. Composites sintered under 1.0 MPa had better densifieation than those sintered under 0.4 MPa, and presented greater mechanical properties. Under 1.0 MPa, compared to the monolithic Sialon, the addition of ZrN resulted in an increased hardness up to 30% ZrN, with the highest hardness of 16.16 GPa being observed with 20% ZrN. The hardness decreased with higher ZrN content due to the weak bonding between the ZrN particles and the Sialon matrix. However this resulted in a continuous increase in fracture toughness, reaching a maximum of 5.41MPam1/2 with 50% ZrN.