Effect of Drying Methods of Alumina Powder and Graphene Oxide Mixture on the Mechanical and Electrical Properties of Sintered Composites Fabricated by Spark Plasma Sintering

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This paper presents a study on graphene-reinforced alumina ceramic composites and the resulting mechanical and electrical properties. Three drying methods were chosen for the fabrication of the initial mixtures: spray, freeze, and vacuum. Spark plasma sintering was chosen as a method of consolidating mixtures. A combination of spray drying and spark plasma sintering makes it possible to produce a high-density (99%) ceramic nanocomposite with improved mechanical properties. The hardness and crack resistance values were increased by 6 and 28%, respectively, compared to other materials studied in this work. This improvement is due to an extremely good dispersion of graphene in the composite, which leads to the decrease in the grain size of the ceramic matrix and consequently reduces the probability of crack occurrence. In addition to these exceptional mechanical properties, the sintered composites also showed high electrical conductivity, which allows the compacts to be machined using electrical discharge machining and thus facilitates the fabrication of ceramic components with sophisticated shapes while reducing machining costs.