Influence of the colloidal processing route on the mechanical properties of Ti(C,N)-based cermets

Abstract

Cermets constituted by 85 vol.% Ti(C,N) and a Fe-Ni alloy as metal matrix present a great potential due to its combination of properties, such as high wear and oxidation resistance, together with high values of hardness. In this work, colloidal techniques are proposed as alternative processing method that permits to obtain highly dispersed phases in an aqueous media, avoiding milling, and leading to homogeneous microstructures. These techniques also permit a variety of forming methods. Stable aqueous suspensions of Fe-Ni powders and Ti(C,N) particles have been prepared and different forming methods were used to obtain bulk samples: Slip casting (SC); Slip Casting+ Cold Isostatic Pressing (SC-CIP); Spray-Dry+ Uniaxial Pressing (SOP). The SO provides spherical granules with high compressibility able to be shaped by uniaxial pressing. All the samples prepared were sintered in vacuum to near full density. The mechanical strength was determined by biaxial bending performed on discs using the ball-on-threeballs (838) method, with the subsequent fractographic analysis to investigate the effect of the processing route. The fracture resistance was measured on Single Edge V-Notched Beam (SEVNB) specimens fabricated through SOP tested under 4-point-bending.