Mechanical and microstructural characterization of graphene reinforced Alumina Ceramic matrix composite

Abstract

• Graphene was used as the reinforcement material at different weight proportions like 0.25, 0.5, 0.75, and 1.0 to develop graphene-reinforced alumina ceramic matrix composites. • At a graphene concentration of 0.5 weight per cent, the flexural strength of the alumina ceramic material increased by 49.26% (612 MPa), and its fracture toughness improved by 40.42% (6.6 MPa m 1/2 ). • Adding 0.25wt% graphene has reduced the coefficient of friction (COF) by 64.12% and 51.01% at normal and elevated temperatures, respectively. • As the proportion of graphene increases, the Vickers hardness of the composite materials tends to decrease. • Beyond 0.75 wt% of Graphene addition, minor agglomeration of graphene begins to occur, leading to a decline in mechanical characteristics due to the formation of clusters that disrupt the uniformity of the composite matrix. Monolithic alumina (Al 2 O 3 ) demonstrates potential for several high-performance structural applications, including engine turbine components and high-temperature aerospace materials. However, its mechanical constraints, including brittleness and diminished fracture resistance, have hindered its wider utilization. This study addresses these difficulties by fabricating and characterizing graphene-reinforced alumina ceramic matrix composites to improve their mechanical and wear properties. A uniform distribution of sub-micron and nano-phase particles inside the alumina matrix was attained via ball milling, thereafter subjected to hydraulic pressing and sintering in a tube furnace at 1600°C for 4 hours under an inert Argon environment. Graphene was integrated as a reinforcing agent at different weight percentages (0, 0.25, 0.5, 0.75, and 1.0 wt%). The results indicated that increased graphene content led to a reduction in Vickers hardness, but flexural strength and fracture resistance initially enhanced, reaching a maximum for 0.5 wt%, before decreasing at elevated concentrations. At 0.5 wt% graphene, the flexural strength increased by 49.26% to 612 MPa, and fracture resistance improved by 40.42% to 6.6 MPa·m 1/2 . The results demonstrate that a graphene content of 0.5 wt% is best for enhancing the mechanical performance of alumina composites. Graphene markedly enhanced the tribological performance of alumina composites, in addition to mechanical property improvements. The addition of 0.25 wt% graphene decreased the wear rate under both ambient and elevated temperature conditions. Furthermore, the coefficient of friction (COF) diminished by 64.12% at ambient temperatures and 51.01% at increased temperatures. These enhancements underscore graphene's dual function in augmenting both strength and wear resistance, rendering it an exceptionally useful reinforcement material. Altering the graphene concentration from 0 to 1 wt% revealed that optimal attributes were attained at particular weight percentages. The research verifies that graphene-reinforced alumina composites not only overcome the mechanical constraints of monolithic alumina but also offer improved performance for sophisticated structural applications. These findings emphasize the necessity of customizing reinforcement amounts to attain a balance among mechanical strength, fracture resistance, and tribological characteristics.

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