Comparative study of the fabrication of ultrafine Ti(C,N)-based cermets by spark plasma sintering and conventional vacuum sintering

摘要

Spark plasma sintering (SPS) and conventional vacuum sintering (VS) were employed to fabricate ultrafine Ti(C,N)-based cermets. The shrinkage behavior, microstracture, and porosity and mechanical properties of the samples fabricated by SPS were compared with those of the samples sintered by VS using optical microscopy, scanning electron microscopy, universal testing machine, and rockwell tester. The results are as follows: (1) The shrinkage process occurred mainly in the range of 1000-1300 deg C during the VS process, and only a 0.2 percent linear shrinkage ratio appeared below 800 deg C; during the SPS process, a 60 percent dimensional change occurred below 800 deg C as a result of pressure action. (2) By utilizing the SPS technique, it is difficult for obtaining fully dense Ti(C,N)-based cermets. Due to the much existence of pores and un-combined carbon, the mechanical properties of the sintered samples by SPS are inferior to sintered ones by VS. (3) grain size of the samples sintered by SPS is still below 0.5 urn, but not by VS; because of low sintering temperature, there are no typical core/rim structures formed in the sintered samples by SPS1; the main microstructures of the sintered samples by SPS2 are a white core/grey shell structure, whereas by VS show a typical black core/grey shell structure.