A polymer colloidal solution having dispersed nanoparticles of Cu metal has been developed using a novel chemical method. Colloidal solutions of representative concentrations of 0.2 to 2.0 wt% Cu-nanoparticles con-ten...A polymer colloidal solution having dispersed nanoparticles of Cu metal has been developed using a novel chemical method. Colloidal solutions of representative concentrations of 0.2 to 2.0 wt% Cu-nanoparticles con-tents in the primary solutions were prepared to study the modified ultrasonic attenuation and ultrasonic velocity in polyvinyl alcohol (PVP) polymer molecules on incorporating the Cu-nanoparticles. The synthesized copper metal nanoparticles dispersed in the polymer solutions were characterized by UV-Visible absorption spectros-copy, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The nanofluid sample showed a symmetrical peak at 592 nm due to the surface plasmon resonance of the copper nanoparticles. XRD results confirmed that copper nanoparticles were crystalline in the colloidal solution. The TEM micrograph revealed spherical copper nanoparticles having diameter in the range 10 - 40 nm. A characteristic behaviour of the ultra-sonic velocity and the attenuation are observed at the particular temperature/particle concentration. It reveals that the colloidal suspension occurs in divided groups in the small micelles. The results are discussed in correlation with the thermophysical properties predicting the enhanced thermal conductivity of the samples.展开更多
The ultrasonic properties like elastic constant, ultrasonic velocity in the hexagonal structured nanocrystalline RuCo alloys have been studied along unique axis at room temperature. The second and third order elastic ...The ultrasonic properties like elastic constant, ultrasonic velocity in the hexagonal structured nanocrystalline RuCo alloys have been studied along unique axis at room temperature. The second and third order elastic constants (SOEC & TOEC) have been calculated for these alloys using Lennard-Jones potential. The orientation dependent ultrasonic velocity has been also evaluated to study the anisotropic behaviour of these alloys. The velocities VL and VS1 have minima and maxima, respectively at 45° with unique axis of the crystal, while VS2 increases with the angle from unique axis. The inconsistent behaviour of angle-dependent velocities is associated to the action of second order elastic constants. Debye average ultrasonic velocities of these alloys are increasing with the angle and has maximum at 55° with unique axis at room temperature. Hence, when a ultrasonic wave travels at 55° with unique axis of these alloys, then the average ultrasonic velocity is found to be maximum. Elastic constants and density are mainly the affecting factor for anomalous behaviour of ultrasonic velocity in these alloys. The mechanical and ultrasonic properties of Co0.75Ru0.25 alloy will be better than the other compounds due to their high SOEC, ultrasonic velocity and low ultrasonic attenuation. Co0.75Ru0.25 alloy is more suitable for industrial and other uses, as it has the highest elastic constants and lowest ultrasonic attenuation in comparison to other of these alloys. The results of this investigation are discussed in correlation with other known thermophysical properties.展开更多
文摘A polymer colloidal solution having dispersed nanoparticles of Cu metal has been developed using a novel chemical method. Colloidal solutions of representative concentrations of 0.2 to 2.0 wt% Cu-nanoparticles con-tents in the primary solutions were prepared to study the modified ultrasonic attenuation and ultrasonic velocity in polyvinyl alcohol (PVP) polymer molecules on incorporating the Cu-nanoparticles. The synthesized copper metal nanoparticles dispersed in the polymer solutions were characterized by UV-Visible absorption spectros-copy, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The nanofluid sample showed a symmetrical peak at 592 nm due to the surface plasmon resonance of the copper nanoparticles. XRD results confirmed that copper nanoparticles were crystalline in the colloidal solution. The TEM micrograph revealed spherical copper nanoparticles having diameter in the range 10 - 40 nm. A characteristic behaviour of the ultra-sonic velocity and the attenuation are observed at the particular temperature/particle concentration. It reveals that the colloidal suspension occurs in divided groups in the small micelles. The results are discussed in correlation with the thermophysical properties predicting the enhanced thermal conductivity of the samples.
文摘The ultrasonic properties like elastic constant, ultrasonic velocity in the hexagonal structured nanocrystalline RuCo alloys have been studied along unique axis at room temperature. The second and third order elastic constants (SOEC & TOEC) have been calculated for these alloys using Lennard-Jones potential. The orientation dependent ultrasonic velocity has been also evaluated to study the anisotropic behaviour of these alloys. The velocities VL and VS1 have minima and maxima, respectively at 45° with unique axis of the crystal, while VS2 increases with the angle from unique axis. The inconsistent behaviour of angle-dependent velocities is associated to the action of second order elastic constants. Debye average ultrasonic velocities of these alloys are increasing with the angle and has maximum at 55° with unique axis at room temperature. Hence, when a ultrasonic wave travels at 55° with unique axis of these alloys, then the average ultrasonic velocity is found to be maximum. Elastic constants and density are mainly the affecting factor for anomalous behaviour of ultrasonic velocity in these alloys. The mechanical and ultrasonic properties of Co0.75Ru0.25 alloy will be better than the other compounds due to their high SOEC, ultrasonic velocity and low ultrasonic attenuation. Co0.75Ru0.25 alloy is more suitable for industrial and other uses, as it has the highest elastic constants and lowest ultrasonic attenuation in comparison to other of these alloys. The results of this investigation are discussed in correlation with other known thermophysical properties.
