CHARACTERIZATION OF WARM ROLLED SPRAY FORMED ALUMINIUM-SILICON GRAPHITE COMPOSITE

Abstract

Aluminium alloys and their composites serve as essential engineering materials, in recent times, to manufacture a plethora of components for automotive, sports, aerospace, and marine applications. This is primarily due to their excellent physical, mechanical, and tribological properties. Different types of materials (such as ceramic, intermetallic, self-lubricating, and their combination) can be incorporated, in the alloys/composites of Al, as reinforcements to achieve excellent tensile, hardness, and tribological properties at ambient as well as high temperature, which make these materials attractive for numerous applications. These reinforcement materials are generally incorporated or generated in the alloy/composites by different processes. However, low dense reinforcement such as graphite or liquid immiscible alloy-based composite is difficult to form through conventional manufacturing processes e.g. traditional casting processes possess inferior mechanical properties, due to weak bonding between the reinforcement and matrix, as well as dendritic structure. Such issues limit the manufacturing of these composite through conventional methods and demand the use of unconventional processes to fabricate materials with required properties. To overcome these problems, the present work investigated the effect of a unique spray forming process to fabricate the Al-Si alloy based auto/self-lubricating AMMCs followed by warm rolling for the tribological applications. To achieve the objective of the present work, an attempt has been made to synthesis the uncoated graphite (400 mesh) reinforced Al-6Si alloy based composite through the spray forming route. Modification in microstructures and density were achieved through the warm rolling. The concept of spray forming, followed by warm rolling is relatively new. First, the spray forming process parameters for the development of Al-Si alloy based composites have been optimized to achieve defect-free preform. For this purpose, four composites of Al-6wt.% Si with different amounts of graphite particles, namely 1 wt.%, 2 wt.%, 3 wt.%, and 4 wt.% were fabricated. These composites are designated as C1, C2, C3, and C4, respectively. EDS elemental mapping and XRD analysis confirmed the successful formation of the composites and the distribution of graphite particles in the aluminium matrix.