Journal of Pure and Applied Ultrasonics

Vyoma Bhalla ¹, Devraj Singh ¹, Giridhar Mishra ¹, Meher Wan ²

Affiliations
1 Department of Applied Physics, Amity School of Engineering and Technology, Bijwasan, New Delhi-110061, IN
2 Advanced Technology Development Center, Indian Institute of Technology, Kharagpur-721302, IN

Abstract

The ultrasonic properties of europium chalcogenides EuX (X = O, S and Te) have been computed at room temperature along <100>, <110> and <111> orientations. The higher order elastic constants have also been computed using Coulomb and Born-Mayer potential upto second nearest neighbour and these are applied to compute ultrasonic properties. The mechanical and thermal properties like Youngs modulus, bulk modulus, Cauchy's relation, Zener anisotropy factor, fracture to toughness ratio, Debye temperature have also been calculated for finding the future performance of these materials. Since these materials follow the Born stability criteria, so these are mechanically stable. The fracture to toughness ratio is less than 1.75, hence these are brittle in nature. The results of present investigation have been analysed in correlation with mechanical and thermophysical properties of the similar materials.

Keywords

Monochalcogenides, Elastic Properties, Thermal Properties, Ultrasonic Properties.

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Vimal Pandey ¹, Giridhar Mishra ², Meher Wan ³, Devraj Singh ², A. K. Tiwari ⁴, R. R. Yadav ³, Bharat Mishra ⁵

Affiliations
1 Mahatma Gandhi Chitrakoot Gramodaya Vishwavidyalaya, Satna-485334, IN
2 Amity School of Engineering and Technology (Affiliated to GGSIP University), Bijwasan, New Delhi-110061, IN
3 University of Allahabad, Allahabad-211002, IN
4 B.S.N.V.P.G. College (University of Lucknow) Charbagh, Lucknow-226001, IN
5 Mahatma Gandhi Chitrakoot Gramoday Vishwavidyalaya, Satna-485334, IN

Abstract

Nanofluids have unique features different from conventional solid-liquid mixtures which have millimeter or micrometer sized particles dispersed in some base fluid. Due to their excellent characteristics, these new types of fluids have attracted wide interest in recent years. It is found that nanofluids have significantly higher thermal conductivity than the base fluids. In this work we focus on the ultrasonic and thermal properties of nanofluids. Nanofluids containing copper nanoparticles with base fluid polyvinyl alcohol (PVA) have been developed in our laboratory. These nanofluids are characterized by UV-Visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Temperature dependent ultrasonic velocity and ultrasonic attenuation measurements are performed for different concentration of the copper nanoparticles in the PVA. Hot Disk Thermal Constant Analyser is used for the measurement of the thermal conductivity of synthesized nanofluids. Experimental results show that the thermal conductivities of the nanofluids are higher than that of base fluid PVA. The obtained results were analyzed taking into account the ultrasonic and thermal behavior of matrix and particles. Possible mechanism for the enhancement of thermal conductivity of the nanofluids using theoretical model is also discussed.

Keywords

Nanofluids, Ultrasonic Properties, Enhanced Heat Transfer, Effective Thermal Conductivity, Brownian Motion.

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Meher Wan ¹

Affiliations
1 Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Khargpur-721302, IN

Abstract

The D.Phil. thesis focused on physics and chemistry of nanostructures e.g. nanofibers, nanotubes, spherical nanoparticles based nanofluids and nanocomposites leading to their applications as heat transfer based coolant liquids and dielectric materials with better heat conduction. Ultrasonic and thermal conductivity behaviour of synthesized materials has been studied in a wide range of temperatures and other variable physical conditions. When propagated in materials, ultrasonic waves are influenced by the microstructure, structural in homogeneities, nonlinear thermal/physical properties, reinforcement level of particles in nanocomposites, size and distribution of reinforcements, surface phenomenon etc. The attention has been paid on the ultrasonics based non-destructive characterization of the prepared materials.

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