Dry sliding wear behavior and its relation to microstructure of artificially aged Al-Si-Mg/TiB2 in situ composites

Abstract

Mechanical stir casting is utilized to produce an artificially aged Al-Si-Mg alloy, whereas halide slat (K₂TiF₆ and KBF₄) synthesis is utilized to produce Al-Si-Mg/TiB₂ aluminum matrix composites. The dry sliding pin on disc wear test was conducted using a DUCOM/TR-20LE-PHM-200 machine to simulate an automobile application (Piston-Ring assembly).  Where pistons are made of aluminum alloy (for the Pin) and rings are made of grey cast iron (for the disc material). At room temperature, a wear test was conducted by altering the ageing time (3, 6, 9, 12), sliding speed (2, 2.5 m/s), and applied load (14.71, 19.62, 24.52 N) with the disc speed (500 rpm) held constant (10 min).  The results indicate that the aluminum matrix composite (AMC) wear rate is reduced by 37 percent at higher sliding speeds (2.5 m/s) and by 4 percent at lower sliding speeds (2.0 m/s) compared to the base alloy. Field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis revealed that the formation of the mechanically mixed layer (MML) or oxidative layers on the worn surfaces reduces the wear rate under conditions of longer ageing time, higher sliding speed, and lower applied load. The research demonstrates that composite wear is a function of sliding velocity, aging period, and applied force. As sliding speed rose from 2 m/s to 2.5 m/s, the wear rate of composites dropped reasonably, yet composites are softer than basic alloys. It is conceivable due to the presence of a considerable amount of MML and the formation of oxidative layers between pins and their equivalents.