Chemical synthesis and densification of a novel Ag/Cr ₂ O ₃ -AgCrO ₂ nanocomposite powder

Abstract Ag/Cr ₂ O ₃ -AgCrO ₂ nanocomposite powders were chemically synthesized using a chemical precipitation method. The synthesis method stages included precipitation and calcination. The initial precipitates contained Cr(OH) ₃ ·3H ₂ O and Ag ₂ CO ₃ compounds. Calcination of the initial precipitates led to thermal decomposition of the precipitates and evaporation of volatile compounds such as H ₂ O and CO ₂ . The calcined precipitates contained silver, chromium oxide, and silver-chromia. The crystallite size of Ag ₂ CO ₃ and Ag were determined as 18.9 and 45 nm, respectively. The scanning electron microscopy investigations showed that the particle size of the initial precipitates was lower than 100 nm. The calcined powders were sintered at 550°C in air atmosphere. The sintered samples were cold-repressed under 300 and 550 MPa. It was found that by increasing the repressing compaction magnitudes, the density and hardness of the sintered samples were increased. The scanning electron microscopy evaluation of the densified samples showed nearly dense microstructure.