ABSTRACT
Due to their flexible nature, which involves mixing the components of various substances through layers or matrixes and thus a percentage of each substance's physical properties, composite materials have gained traction in the world today and are becoming more common use in industrial and specialized applications in general. The majority of metal complexes have restrictions that make them inappropriate for usage in today's technological era. As a result, composites – which are materials made by combining numerous components or constituent materials with varying advantageous features, either chemical or mechanical, or both, to create a material with varying characteristics are becoming more popular. Because of the large number of combinations that can be done to generate adequate material, are the materials of choice from the base components. As we've seen, composites can have a wide range of properties due to their different structures, which are made up of different reinforcements and metal matrices. The aim of this work is to determine the effect of cooling rate (cooling in air) on some mechanical properties of squeeze cast aluminium composites.
The aluminium scrap which were used in window production was gotten from Akin and PawPaw Aluminium Company, Benin City. The reinforcement used was sawdust which was carbonize at the foundry workshop in the Department of Production Engineering, University of Benin, Benin City. A sample of the pure aluminium scrap was produced and sent for elemental characterization at Engineering Materials Development Institute (EDMI), Akure. The samples produced have circular cross-section, and are produced to a near net shape. The tensile test was performed by applying a tensile force to the samples using the universal testing machine and measuring various properties of the samples under stress. The Brinell Hardness test used in this study was carried out by applying a constant load of 750 kg on a hardened steel ball-type indenter, 10 mm in diameter, to the flat surface of the sample. The load was held for about 30 seconds after which the diameter of the recovered indentation is measured in millimetres. This time is required to ensure that plastic flow of the work metal has stopped. The Brinell hardness value is then evaluated by taking the mean diameter of the indentation and calculating the Brinell hardness number (HB) by dividing the applied load by the surface area of the indentation. Then Mechanical test was carried out on the squeeze cast metal matrix composite which shows us that tensile strength is maximum at 10% and hardness increases as percentage of reinforcement increases as seen in the result of 15% reinforcement on the hardness table compared to 5% reinforcement.
From the investigation, it is concluded that squeeze casting is a very effective method to processing aluminium alloy, exhibiting appreciable grain refinement and significant improvement in hardness and ultimate tensile strength.
