Fabrication and Characterization of Alumina/Silver Nanocomposites

Abstract

Alumina/silver nanocomposites were fabricated using a soaking method through a sol-gel route to construct an intra-type nanostructure. The pulse electric-current sintering (PECS) technique was used to sinter the nanocomposites. Several specimens were annealed after sintering. The microstructure, mechanical properties, critical frontal process zone (FPZ) size, and thermo-mechanical properties of the nanocomposites were estimated. The relative densities of the specimens sintered at 1350 and 1450℃ were 95% and 99%, respectively. The maximum value of the three-point bending strength was found to be 780 ㎫ for the 2×2×10 ㎜ specimen sintered at 1350℃. The fracture toughness of the specimen sintered at 1350℃ was measured to be 3.60 ㎫·m 1/2 using the single-edge V-notched beam (SEVNB) technique. The fracture mode of the nanocomposites was transgranular, in contrast to the intergranular mode of monolithic alumina. The fracture morphology suggested that dislocations were generated around the silver nanoparticles dispersed within the alumina matrix. The specimens sintered at 1350℃ were annealed at 800℃ for 5 min, following which the maximum fracture strength became 810 ㎫ and the fracture toughness improved to 4. 21 ㎫m 1/2 . The critical FPZ size was the largest for the specimen annealed at 800℃ for 5 min. Thermal conductivity of the alumina/silver nanocomposites sintered at 1350℃ was 38 W/mK at room temperature, which was higher than the value obtained with the law of mixture.