Electrical discharge machinable ytterbia samaria co-stabilized zirconia tungsten carbide composites

Abstract

Composite ceramics of stabilizer oxide coated ytterbia-samaria costabilized zirconia (1.5Yb1.5Sm-TZP) and 24-32 vol% of tungsten carbide as an electrically conductive dispersion were manufactured by hot pressing at 1300-1400 °C for 2 h at 60 MPa pressure. The materials were characterized with respect to microstructure, phase composition, mechanical properties and electrical discharge machinability by die sinking. Materials with a nanocomposite microstructure and a strength of up to 1700 MPa were obtained. An attractive toughness of 6-6.5 MPa√m is achieved as 40-50% of the zirconia transformed upon fracture. The materials show fair material removal rates of 1 mm³/min in die sinking. Smooth surfaces indicate a material removal mechanism dominated by melting.