Synthesis and Characterization of Ag-8 %wt Cr2O3 Composites Prepared by Different Densification Processes

Abstract

A novel Ag-8 %wt Cr2O3 composite prepared via powder metallurgy route. Silver and chromium oxides were used as starting powders. The powder mixtures were mechanically milled by a SPEX high energy mill for 5 h. Based on the thermogravimetric analysis (TGA) and X-Ray Diffraction (XRD) results, the milled powders were calcined in an argon atmosphere at 550 °C. During calcination, the silver oxide decomposed into silver. The results showed that the Heckel equation was the preferred one for description the cold compressibility of the powders. The calcined powders were consolidated by Press-Sinter-Repress (PSR), Press-Sinter-Repress-Anneal (PSRA) and Spark Plasma Sintering (SPS) processes. The Field Emission Scanning Electron Microscope (FESEM) investigations showed a nearly dense microstructure of the sintered samples. However, the hardness of the pressed-sintered-repressed samples was 81 Vickers which was the highest among the processed specimen. Furthermore, the flexural strength of the PSR and SPS processed samples were 231 and 255 MPa, respectively which were too higher than that of the annealed specimens. The results confirmed the effect of microstructural parameters such as Cr2O3 particle size and processing route on the mechanical properties of the sintered composites.