Role of Binder Phase in Si₃N₄Cutting Tools

Abstract

The behavior of hot-pressed Si{sub 3}N{sub 4} tools during the machining of cast iron was tested. Hot-pressed materials having different types and amounts of intergranular phase and different microstructures and levels of microhardness were considered. The performance of Si{sub 3}N{sub 4}-based materials depends on the characteristics of the intergranular phase, which condition the chemical resistance of the tool under attack of the chemical elements of the cast iron, and on the microhardness. By using alumina as a sintering aid and zirconia as the toughening phase, hot-pressed materials with different amounts of {beta}{prime}-sialon were obtained, which, through the optimization of the microstructure and phase composition, exhibit very promising behavior as cutting tools.