Experimental investigations on wear and friction behaviour of Si3N4p reinforced heat-treated aluminium matrix composites produced using electromagnetic stir casting process

Abstract

In recent years, Aluminium Matrix Composites (AMCs) are becoming attractive in fields of structural, tribological, electrical and electronics engineering because they offer advantages such as high strength to weight ratio, good tribological performance etc. In this work, AMCs were developed using electromagnetic stir casting (EMSC) process by reinforcing 4%, 8% and 12% by weight (wt.) Silicon Nitride (Si3N4) particle in AA 7075, and subsequently heat treatment was given to all specimen. Results revealed that, hardness of Heat-Treated (HT) AMCs were increased with Si3N4 addition in AA 7075. Tensile strength and flexural strength of HT AMCs were increased up to 8% wt. Si3N4 addition, but decreased at 12% wt. Si3N4 addition in AA 7075. Experimental studies of wear and friction behaviour were carried by varying operating parameters such as, sliding velocity, load and sliding distance on pin on disc machine. An increased in Si3N4 wt. percentage in matrix resulted into decreased in wear loss and Coefficient of fiction (COF). Wear loss of 12% wt. Si3N4p reinforced HT AMCs was decreased up to 37.17% as compared to HT AA 7075 matrix. Whereas, COF of 12% wt. Si3N4p reinforced HT AMCs was decreased up to 11.03% as compared to pure HT AA 7075. The wear loss was found to be decreased with increase in sliding velocity, while it increased with increase in sliding distance and load. The COF increased with increase in sliding distance, whereas decreased with increase sliding velocity and load. A rich tribochemical reaction layer was formed at interface, which helped to reduce wear loss and COF of AMCs. Energy dispersive spectroscope (EDX) and X-ray diffraction (XRD) techniques were used to recognize presence of elements in AMCs and also identify the oxides formed on worn out surfaces during sliding action. The Scanning Electron Microscope (SEM) was used for study of worn out surfaces. Regression models for wear loss and COF have been developed and validated; the models show good agreement between predicted and experimental data. The developed AMCs are useful in various product application such as, brake disc, cam, where wear and friction are significant phenomenon.