Evaluation of mechanical wear and corrosion properties of Al2219 Si3N4 composite produced by squeeze casting

Abstract

This thesis covers the investigation related to evaluation of mechanical, wear and corrosion properties of Al2219- Si3N4 composites produced by squeeze casting. It covers the investigation with the help of optical microscopy, energy-dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The focus of this study is to analyse the impact of Si3N4 reinforcement on microstructure, mechanical attributes, wear properties and corrosion behaviour of the Al2219- Si3N4 composites. The microstructure analysis verified the presence of the Si3N4 reinforcement particulates in the synthesized composites. It also confirmed the even and uniform spread of the reinforcement particulates within Al2219 alloy matrix. The positive impact of the Si3N4 reinforcement is observed on the mechanical properties. There is a rise in ultimate tensile strength as well as yield tensile strength with an increase in the weight percentage of reinforcement. Similar effects are observed on hardness as well as impact energy of the composites. However, these improvements in mechanical properties are accompanied by a drop in percentage elongation denoting a decrease in ductility. It is found that the higher resistance to wear is offered by the composites with higher proportion of the reinforcement with constant load as well as constant sliding speed conditions. The rate of wear was greatly dependent on the changes in normal load applied. With addition in load, the rate of wear had increased for given specimen for given sliding speed conditions. Wear rate was greatly influenced by the changes in sliding speed of a disc. With the change in sliding speed, the rate of wear changed in proportion for given specimen and for given loading conditions. When comparing the mechanical characteristics with the wear loss of the synthesized composites, there was a similar trend. Wear loss was greatest for monolithic Al2219 alloy and lowest for composite Al2219 with 12 weight percent silicon nitride reinforcement. A corrosion...