MICROSTRUCTURE AND SINTERING MECHANISM OF SiC CERAMICS REINFORCED WITH NANOSIZED ZrO2

Abstract

Silicon carbide-based (SiC) ceramics has attracted quite broad attention due to their excellent mechanical, chemical and thermal properties. However, their widespread industrial application is hindered by difficulties in sintering and poor fracture toughness of sintered bodies. In this work, we present an alternative way to produce SiC-based ceramics with improved microstructure and mechanical properties. We incorporated ZrO2 nanofibres into the ceramic matrix to achieve a combined reinforcing effect of partially stabilized zirconia, namely fibre and phase transformation strengthening. For comparison, we also prepared silicon carbide ceramics containing yttria stabilized zirconia (YSZ) particles. SiC-based green bodies containing 5, 10 and 15 wt % ZrO2 nanofibres and particles, respectively, were subjected to spark plasma sintering (SPS) at relatively low (1700 °C) temperatures with high heating and cooling rates. The effects of nanofibres on mechanical properties were studied by determining the Vickers hardness and Young's modulus of sintered ceramics from instrumented indentation tests. The microstructural patterns were investigated, as well. *Corresponding Authors: Eszter Bódis E-Mail: bodis.eszter@ttk.mta.hu [a]

Fabrication of graded alumina by spark plasma sintering

“…Hulbert et al [18] combined various materials by in situ reactions to develop tailored structured B 4 C-Al, TiB 2 -B 4 C, and HfB 2 -SiC ceramic composites. In our previous study [19], we also assumed a temperature gradient during the SPS process, since the SiC-ZrO 2 composites crystallized in different phase compositions at the opposite sides of the sintered bodies. Although numerous studies have reported on the development of a temperature gradient in the sample during the SPS process, we still have rather limited knowledge on the extent of the temperature difference inside the sample during sintering.…”

High-temperature evolution of diamond-SiC composites

“…NDs are also attractive as reinforcing materials since diamond particles incorporated into metals [11,12], ce-Silicon carbide (SiC), similarly to diamond, has excellent physical and chemical properties, such as high hardness, high thermal conductivity, high wear and corrosion resistance, as well as low thermal expansion [17]. However, it is rather rigid and has catastrophic fracture behaviour, which can be improved by the addition of multilayer graphene [18] or ZrO 2 nanofibre [19]. Since diamond has the highest fracture resistance its addition to SiC can also be a promising way to improve the fracture behaviour of SiC and thus to synthesize SiC-diamond composites for preparing super-hard cutting tools.…”