M.Sc. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary: In this study, a series of binary aluminum-zinc, ternary aluminum-zinc-copper, quaternary aluminum-zinc-copper-silicon and aluminum-zinc-copper-nickel alloys were prepared by permanent mould casting. Their microstructure and mechanical properties were investigated in the as-cast and heat treated conditions and the effects of zinc, copper, silicon and nickel additions on these properties were determined. The friction and wear properties of the alloys were investigated under different test conditions including sliding distance, pressure, sliding speed and oil rate using a conforming block-on-disc test machine. The results obtained from these alloys were compared with those obtained from SAE 65 bearing bronze. It was observed that the microstructure of binary Al-40Zn alloy consisted of aluminum-rich α dendrites surrounded by eutectoid α + η phase. In addition to these phases θ, silicon or Al3Ni particles were observed in the ternary or quaternary alloys containing copper, silicon or nickel. It was found that the hardness of Al-40Zn-(1-5)Cu alloys increased continuously with increasing copper content, but their tensile strength showed a decrease when the copper content exceeded %3. It was also observed that the additions of silicon and nickel decreased the tensile strength and elongation of Al-40Zn-3Cu alloy. It was shown that the friction coefficient of the alloys decreased with increasing pressure, but their temperature and volume loss showed reverse trend. It was observed that sliding speed has no considerable effect on friction coefficient of alloys, but their temperature and volume loss increased with it. Adhesion was found to be the most effective wear mechanism for the Al-40Zn based alloys, but both abrasion and adhesion operated for the wear of the SAE 65 bronze. As a result of this study, it was concluded that the Al-40Zn based alloys were much superior to the SAE 65 bronze as far as their wear resistance is concerned.
Key Words: Al-Zn, Al-Zn-Cu, Al-Zn-Cu-Si and Al-Zn-Cu-Ni Alloys, Microstructural and Mechanical Properties, Friction, Wear and Lubrication Properties, Structure-Property Relationships | |||||||||||||||||||||