Structural and Transport Properties of La0.85Te0.15MnO3 Manganite and its Composite with Al2O3

The manganite systems investigated during the present work are pure La0.85Te0.15MnO3 (LTMO) and its composite with 12% concentration of Al2O3 nano powder (LTMO + Al2O3). The materials were prepared by the modified auto combustion technique. The samples were characterized by X-ray diffraction. The powder X-ray diffraction pattern of pure LTMO at room temperature shows that sample is in single phase with no detectable secondary phases and the sample have a rhombohedral structure in hexagonal with the space group R3c. The XRD pattern of LTMO + 12% Al2O3 indicates the clear presence of Al2O3 nano phase in the composite. In the present study, the FTIR Spectroscopy of both samples was carried out. It is clear from the Vibrational assignment for the value of corresponding peak position of FTIR spectra that no extra unwanted impurity is present in samples. A quantitative analysis of the energy dispersive spectroscopy (EDS) data indicates that the observed concentration of elements are very close to the calculated values from its chemical formula. R-T measurements reveals that the addition of secondary phase in manganite strongly influenced on electronic and magnetoresistance behaviour. We summarise some of the salient features of the results.

Nanoceramic Composites for Nuclear Radiation Attenuation

The development of radiation attenuation materials with lean cross-sections is the need of the hour. However, the inherent threat of radiations accompanying these processes is of major concern. Thus, in an attempt to shield unnecessary radiations, several novel materials have been fabricated alongside the conventional materials available. Yet, there is a need for cost-effective, efficient shielding materials that have good mechanical strength and effective shielding properties. The present work investigates ceramic composite behaviors and radiation shielding capacity reinforced with lead oxide nano-powder. Developed nano-lead-based cement composites were subjected to mechanical tests to determine flexural and compressive strengths to check their suitability for structural applications. Further, the gamma attenuation test of the composites was conducted to determine their neutron absorption capacity. The addition of nano-leadoxide in the control beams was varied from 0.7 to 0.95 and 1 wt.% of the ceramic matrix. The percentage of nano-leadoxide that gives the best results in both enhanced properties and economic aspects was determined to be 0.6 wt.% of the cement.

Comparative Study of the Electrical, Thermal and Mechanical properties of Polypyrrole/CB/and Copper nano powder reinforced Polyester Hybrid Composites

The present research work based on Synthesis and characterization of Polypyrrole coated CB (carbon black), Copper, and VGCNF (vapor grown carbon nanofibers) hybrid composite. Two approaches were used comprising in situ polymerization of Polypyrrole/CB composite. The resulting composite was dispersed in with the measured quantity of Cu nano Powder and VGCNF in polyester at very high rate of dispersion to produced hybrid composite. The resulting composites were characterized by FTIR, electrical conductivity, mechanical properties, thermal analysis and UV visible spectroscopy.

First observation of radiolytic bubble formation in unstirred nano-powder sludges and a consistent model thereof

Experiments involving the irradiation of water contained within magnesium hydroxide and alumina nanoparticle sludges were conducted and culminated in observations of an increased yield of molecular hydrogen when compared to the yield from the irradiation of bulk water. We show that there is a relationship linking this increased yield to the direct nanoscale ionization mechanism in the nanoparticles, indicating that electron emission from the nanoparticles drives new radiative pathways in the water. Because the chemical changes in these sludges are introduced by irradiation only, we have a genuinely unstirred system. This feature allows us to determine the diffusivity of the dissolved gas. Using the measured gas production rate, we have developed a method for modelling when hydrogen bubble formation will occur within the nanoparticle sludges. This model facilitates the determination of a consistent radiolytic consumption rate coinciding with the observations of bubble formation. Thus, we demonstrate a nanoscale radiation effect directly influencing the formation of molecular hydrogen.

Biotribological performance of medical-grade UHMW polyethylene-based hybrid composite for joint replacement

Ultra high molecular weight polyethylene (UHMWPE) is widely used for articulating surfaces in total hip and knee replacements. In the present work, the tribological properties of UHMWPE-based nano composites were studied in order to meet the demands of current bearing applications. UHMWPE matrix reinforced with 0.5, 1, and 2 weight percentage of alumina nano powder were fabricated by hot pressing. The dispersion and microstructure of composite material was established by X-ray diffraction (XRD) and scanning electron microscope (SEM) micrograph. The tests were carried out on a reciprocating sliding pin-on-disc tribometer at human body temperature (37±1°C) under dry and human serum lubricating environments for a normal load of 46 N and 52 N, a constant sliding speed of 4 mm. Under these testing conditions, it has been observed that the wear behavior of the developed composites improved with increase in weight percentage of alumina nano powder. The results show that at 52 N load, the maximum value of wear rate was 7.9x10−7 mm3/Nm and the minimum value 1.6x10−7 mm3/Nm was obtained. SEM was used to examine the worn surface and it was observed that human serum adheres to the surface of the composite pins upon sliding, resulting in the formation of a film which results in better wear resistance of the composite pins under human serum lubrication than dry sliding. This study implies that the use of nano alumina power will reduce the wear of UHMWPE based composite under human serum lubrication.

An experimental study of De-Icing property using Reduced Graphene Oxide - Boron Nitride Nano Powder in CFRP

Icing is one of the critical factors that affects the flight of the aircraft in ways of drag. In this study, the rate of de-icing was experimented with the composite material using Boron Nitride Nano Powder (BNNP) and Reduced Graphene Oxide (rGO). Boron Nitride are highly thermal conductive and lesser toxic, and Graphene allows to be a good conductor of heat and electricity and thereby, these nanomaterials are used as a filler for de-icing application. The filler is mixed in Epoxy Resin using ultrasonicator. In order to get better specimen surface of composite, ultrasonic mixing method is used instead of hand-mixing. To fabricate Carbon Fiber Reinforced Polymer (CFRP) Hand Lay-up Method is carried out. The material characterization is done by X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). Mechanical properties are studied with Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and Water Droplet test. Moreover, the Carbon Fiber Reinforced Polymer surface shows extraordinary de-icing effect contrasted with the non-functionalized surface. This study has proved that the de-icing property is very much effective with Carbon Fiber Reinforced Polymer where Graphene and Boron Nitride as the filler.