R. A. Shakoor

Fabrication and Mechanical Properties of Extruded Al-SiC Nanocomposites

This work aims to investigate the effect of SiC addition on structural, microstructural and mechanical properties of developed Al-Sic nanocomposites. Al metal matrix composites reinforced by nanosized SiC particles were fabricated using high energy ball milling and microwave sintering process followed by hot extrusion. The XRD analysis indicated that the dominant components were Al and SiC. SEM/EDX micrographs showed homogenous distribution of SiC nanoparticles in Al matrix. Mechanical characterizations revealed that the addition of nanosize SiC particulates to a simultaneous increase in microhardnes, yield strength, ultimate compressive/tensile strength and reduction in ductility of the matrix. This improvement in mechanical properties can be attributed to the homogeneous distribution of reinforcement (SiC particles) and dispersion strengthening mechanism.

Development of Metal Matrix Composites Using Microwave Sintering Technique

In this book chapter, aluminum (Al)-based metal matrix composites (AMMCs) with various reinforcing ceramic particles, such as SiC, Si 3 N 4 , and Al 2 O 3 , were produced by microwave sintering and subsequent hot extrusion processes. The role of various nano/ micro-sized reinforcements in altering the structural, mechanical, and thermal properties of the microwave-extruded composites was systematically studied. The X-ray diffraction (XRD) patterns indicated that the main components were Al, SiC, Si 3 N 4 , and Al 2 O 3 for the studied Al-SiC, Al-Si 3 N 4 , and Al-Al 2 O 3 composites, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) elemental mapping confirm the homogeneous distribution of reinforcing particles in the Al matrix. Mechanistic studies revealed that the Al-Si 3 N 4 metal matrix composite exhibited superior hardness, ultimate compression/tensile strength, and Young’s modulus, while having a lower coefficient of thermal expansion compared to other studied Al composites. Findings presented are expected to pave the way to design, develop, and synthesize other aluminum-based metal matrix composites for automotive and industrial applications.

Surface engineering of the PLA films for fabricating dexterous humidity sensors

This study presents the surface engineering of the thin films of a biodegradable polymer, poly lactic acid (PLA), for its application in moisture/humidity sensors. The PLA films were deposited on the comb-like pre-patterned indium tin oxide coated glass substrates. The surface morphology of the thin film was modified by using various etchants having different solubilities in PLA. The surface morphology of the thin films was studied by using atomic force microscope and surface profilometer. The modified surfaces feature of the PLA films made them attractive to use as humidity sensors. The humidity sensing characteristics of the surface modified films were investigated by measuring the resistance and capacitance over a wide range of relative humidity levels (20–90% RH). An increase in capacitance and a decrease in resistance was observed by raising the humidity level inside the testing chamber. The proposed PLA based humidity sensor showed small hysteresis, high sensitivity and fast response & recovery time.

Poly(3-Hexylthiophene) (P3HT), Poly(Gamma-Benzyl-l-Glutamate) (PBLG) and Poly(Methyl Methacrylate) (PMMA) as Energy Harvesting Materials

The average temperature of the earth is rising at an alarming rate. The rising symptoms of global warming led us to a situation where we have to find out an alternative way for energy harvesting without disconcerting the homeostasis of nature. Therefore, finding renewable and clean energy sources has become one of the foremost challenges of modern societies. Polymer composites have found considerable attention in energy harvesting, especially for but not limited to organic solar cells, transducers and energy storage applications. For example, poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) have proven among the best combination for organic solar cell application and have persisted prominent for a decade. Being a semicrystalline polymer, P3HT is well known as a donor material with a wide absorption range of the solar spectrum and comparable high conductivity. Similarly, poly(gamma-benzyl-l-glutamate) (PBLG) was found out to be an excellent choice in flexible transducer applications because of its stability and high piezoelectric coefficients. Finally, poly(methyl methacrylate) (PMMA) was proved to be an ideal polymeric material for energy storage applications because of its highly effective insulating properties. In this chapter, we review the recent progress in the field of energy harvesting and storage materials such as P3HT, PBLG and PMMA and their role in maximizing the efficiency of energy devices.