M. Devika; N. Koteeswara Reddy; V. Jayaram; K. P. J. Reddy
Abstract
In this article the sustainability of ZnO nanostructures under dynamic shock waves has been investigated. ZnO nanorods were synthesized on stainless steel (SS) substrates and exposed to shock waves in an inert atmosphere. The impact of shock waves on physical properties of ZnO nanostructures was analyzed. ...
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In this article the sustainability of ZnO nanostructures under dynamic shock waves has been investigated. ZnO nanorods were synthesized on stainless steel (SS) substrates and exposed to shock waves in an inert atmosphere. The impact of shock waves on physical properties of ZnO nanostructures was analyzed. ZnO nanostructures grown on SS substrates exhibit excellent sustainability over different shock waves generated temperatures and pressures. The crystal structure and surface morphology of shock waves treated ZnO nanorods remain the same as untreated ones and however, the chemical stoichiometry and light emission properties are significantly changed. From these investigations it is emphasized that ZnO nanostructures could be adopted for various applications in space engineering technology where the surrounding temperature and pressure is below 8000 K and 2 MPa.
V. Jayaram; K. P. J. Reddy
Abstract
This paper presents a novel method of interaction of zirconia with strong shock wave in presence of dissociated/non-dissociated gas species for short duration using shock tube. Cubic zirconia (c-ZrO2) was synthesized by solution combustion method and exposed to strong shock heated N2 and O2 test gases ...
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This paper presents a novel method of interaction of zirconia with strong shock wave in presence of dissociated/non-dissociated gas species for short duration using shock tube. Cubic zirconia (c-ZrO2) was synthesized by solution combustion method and exposed to strong shock heated N2 and O2 test gases in a free piston driven shock tube (FPST). FPST is used to heat the test gases to very high temperature of about 7540-9530 K (estimated) and reflected shock pressure of about 65-70 bar for short duration (2-3 ms). X-ray diffraction (XRD) study shows the phase transformation of c-ZrO2 to m-ZrO2. Scanning electron microscopy (SEM) images shows the formation of sharp nano/micro zirconia needles due to melting and nucleation during super heating and cooling at the rate of about 10 6 K/s. These types of sharp nano/micro needles are observed for the first time in this shock tube experiment. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy show no change in electronic structure and chemical composition of ZrO2 which indicates that the reaction is fully catalytic. This unique experimental methodology can be used to study the chemistry of materials under extreme thermodynamic conditions which is of seminal importance in space, nuclear and other high temperature applications.
