• Ajibola, Olawale Olarewaju

Abstract

Reports of many functional deficiencies are these days rampant in many aluminium products flooding the Nigeria markets. These emanate from the local aluminium manufacturing, cottage foundry industries and much more from goods imported in the country. The study investigates the metallurgical properties of as-received and cast aluminium alloy samples used in the floating piston/calliper of the automobile hydraulic master brake cylinder. Commercially available aluminium alloy is procured from which callipers were cast and characterised. The study compares the physical properties by Hardness test, microstructural properties using high resolution metallurgical microscope, X-Ray Diffraction, chemical composition using Atomic Absorption Spectrophotometry. The as-received samples are characterised by poor metallurgical qualities such as variation in weight and density, low HBN, low tensile strength, high porosity and sand inclusions from the previous poor casting practices, hence abnormalities result under usage. The aluminium alloy was technically cast at pouring temperature higher than 750 oC using sand mould of high permeability. The casting gave higher HBN values of eutectic-AlSi structured aluminium alloy. The tensile strength calculated as approximate relationship between the hardness and the tensile strength, gave lower 329.09 Mpa and 154.78 Mpa strength for as-received samples as compared with the cast alloy having 353.58 Mpa and 226.49 Mpa tensile strength values respectively.

Topics

• density
• impedance spectroscopy
• inclusion
• x-ray diffraction
• aluminium
• strength
• aluminium alloy
• hardness
• chemical composition
• permeability
• casting
• tensile strength
• porosity
• spectrophotometry