Manufacturing of Alumina-Zirconia-CNT Ceramic Composites: A comparison of Conventional and Alumina-Graphite Powder Bath Sintering methods

The Zirconia (ZrO2) and Carbon Nano Tubes (CNTs) embedded Alumina (Al2O3) composite fabricated using conventional sintering (CS) possess higher strength, better micro-hardness and more toughness as compared to pure alumina. However, several researchers have reported nonuniform mechanical properties in CS. This non-uniformity can be eliminated using the novel Alumina-Graphite Powder Bath (AGPB) sintering technique. In AGPB, the alumina composites are surrounded by an equal proportion mixture of alumina-graphite powders, providing indirect uniform heating. This converts the heat transfer mode from convectionradiation to conduction and produces uniform mechanical properties across the sintered surface. In this paper, both AGPB and CS techniques were used to fabricate Alumina-ZirconiaCNT (AZC) composites. The uniformity of Physico-mechanical properties was compared for AGPB-AZC and CS-AZC composites. The AGPB-AZC composites exhibited better hardness and minimum pore dispersion as compared to CS-AZC composites. The AGPB-AZC FESEM analysis revealed the formation of single-crystal structures across the sintered surface, which eventually improved the hardness. The mean hardness of the AGPB-AZC (1829.95 HV) composite was enhanced by 43% compared to CS-AZC (1273.5 HV).