Abstract
Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological properties, particularly in the higher load regime.
Highlights
Composites based on aluminium and its alloys, compared to unreinforced material, offer a number of attractive properties, such as greater strength, improved stiffness, reduced density, and improved temperature properties
Composites based on boron fibre–reinforced aluminium alloys have been known since the 1960s, when they were first used in aerial construction [3]
In the 90s, hybrid composites emerged that, besides increased strength or creep resistance due to additional components, were characterised by increased tribological properties resulting from the addition of graphite solid lubricant [5,6]
Summary
Composites based on aluminium and its alloys, compared to unreinforced material, offer a number of attractive properties, such as greater strength, improved stiffness, reduced density (weight), and improved temperature properties (creep resistance). A number of materials, mainly ceramic, such as SiC, Al2 O3 , B4 C, Si3 N4 , AlN, TiC, TiB2 , and TiO2 , have been proposed to alter the properties of the aluminium matrix, often with very different morphology, ranging from equilibrium particles to whiskers or fibre forms [4]. In the 90s, hybrid composites emerged that, besides increased strength or creep resistance due to additional components, were characterised by increased tribological properties resulting from the addition of graphite solid lubricant [5,6]. The success achieved in these materials involved the use of completely new manufacturing methods to which we can include powder metallurgy [7,8]
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