Malek Ali

Wear Resistance of Al-12Si Alloys by Reinforcing TiC and TiN Particles

AbstractThis study presents the mechanical properties of the Al-12Si matrix composite reinforced by various amounts of titanium carbide (TiC) and titanium nitride (TiN) particles. The wear behavior was investigated using a pin-on-disk wear testing machine with varying parameters such as normal load, reinforcement percentage, and track velocity. The results show that the wear of the Al-12Si matrix reinforced by 5, 10, and 15% TiC particles at 150 rpm with 15-N loads was 73×10−3,61×10−3,and 50.5×10−3 mm3, respectively, which is less than the wear for the same composites at 225 rpm with a 15-N load. This is because of the length of rubbing is more in the case of a higher speed. The results also show that the wear of the samples was decreased with an increasing percentage of reinforcement of TiN at both sliding speeds (150 and 225 rpm). The hardness of the Al-12Si/TiC composites with 5% TiC particles was found to be 50, and the hardness of same composites with 15% TiC reinforcements was 67, which is less than...

Development of wireless Bluetooth heart rate remote monitoring system

This paper presents design and development of a new heart rate remote monitoring device using Microcontroller and wireless Bluetooth that transmits and displays precise readings of the heart rate on laptop. However, the signal is basically the number of beats per minute of the heart and should be monitored from time to time to detect any abnormalities of the heart rate. This system consists of two phases; the integrated pulse rate measurement circuit to detect the pulses on the fingertip that include pulse detection, signal extraction, pulse amplification. Furthermore the microcontroller circuit which processes the detected signal via wireless Bluetooth device which is responsible of the heart rate transmitting readings. (4 pages)

Effect of Mo-Si Molar Ratio on the Synthesis of MoSi2 Through Mechanical Alloying

In this work, mechanical alloying (MA) technique, which involves repeated cold welding, fracturing and re-cold welding of powder particles, was used to produce molybdenum disilicide (MoSi2) starting from elemental powder mixtures of Mo and Si. The effects of composition of starting materials on the formation mechanism and phase formation were investigated. Two different molar ratios of Mo:3Si and Mo:4Si were prepared in addition to the stoichiometric powder mixture Mo:2Si. Intermittent sampling was done from 4 to 20 h. Samples were characterized by using X-ray diffraction (XRD)/scanning electron microscopy analyses and crystallite size calculated was based on the conventional Scherrer method. With stoichiometric powder mixture, MoSi2 was synthesized based on the mechanism of mechanically induced self-propagating reaction (MSR). Increasing Si content clearly delayed the MSR and the reactants were gradually converted to both α-MoSi2 and β-MoSi2 phases over a relatively long time. Agglomeration was noticed in samples, even though with different extents. The samples were then heat treated at 900°C. The phase transformation and crystallite size evolutions of the heat-treated powders were characterized by XRD. Final product of Mo:2Si mixture included Mo5Si3 compound, while for other compositions with extra Si the final product was α-MoSi2 and the excess Si.