In the present study, the synergistic effect of hybrid boron nitride (BN) with graphene on the thermal conductivity of epoxy adhesives has been reported. Graphene was prepared by chemical reduction of graphite oxide (GO) in a mixture of concentrated H2SO4/H3PO4 acid. The particle size distribution of GO was found to be ~10 μm and a low contact angle of 54° with water indicated a hydrophilic surface. The structure of prepared graphene was characterized by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM). The thermal conductivity of adhesives was measured using guarded hot plate technique. Test results indicated an improvement in the thermal conductivity up to 1.65 W/mK, which was about ninefold increase over pristine epoxy. Mechanical properties of different epoxy formulations were also measured employing lap shear test. The surface characterization of different epoxy adhesive systems was characterized through XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. Fourier transform infrared also served to determine the nature of interactions between filler particles and epoxy resin. Non‐isothermal differential scanning calorimetric (DSC) technique was used to investigate the effects of graphene and BN particles on the cure kinetics and cross‐linking reaction of epoxy cured with amine curing agent. The Kissinger equation, the model‐free isoconversional Flynn–Wall–Ozawa method and the Ozawa model were used to analyze the kinetic parameter. Copyright © 2017 John Wiley & Sons, Ltd.

No abstract

No abstract

No abstract

High aspect ratio micro tools find numerous applications in the production of miniaturized components and structures for example, drilling of micro holes in ink jet nozzles, air bearings and biomedical devices, etc. The present study aims to machine micro rods using Reverse Micro Electrical Discharge Machining (R-µEDM) process.These micro rods can be used as micro tools for drilling micro holes. A detailed experimental investigation has been carried out with the help of Taguchi's orthogonal array for understanding the mechanism of the process. The process parameters such as voltage, feed rate and capacitance are considered to perceive their effect on response measures such as machining time, deviation in length, deviation in average diameter, standard deviation (SD) in diameter and surface roughness. The optimal process parametric condition of R-µEDM has been determined for desired performance i.e., obtaining the target length and average diameter of the micro rod and ensuring its straightness with minimum time duration. Confirmation experiment has been carried out at the optimum condition and accordingly the results have been presented. Surface morphology of the machined micro rod at the optimum condition has also been Downloaded by [University of Otago] at 21:36 27 July 2015 2 investigated. Micro rod of diameter 170 µm with a high aspect ratio of 18 has been successfully machined using this process.

Landslides are one of the many catastrophic events which result in massive destruction and loss of lives across the globe. Hence, an appropriate forecasting technique is essential in order to predict such potential weak slip planes which may eventually lead to landslides. Here, we present a study where Fracture Induced Electromagnetic Radiation (FEMR) technique has been used to identify such regions of potential "activity" in a study area around IISER Bhopal Hill, India, stretched along a length of approximately 1 km. The hill is majorly composed of basaltic rocks belonging to the Deccan traps which have been heavily weathered and have resulted in the formation of unconsolidated soil cover. In numerous locations, it has been observed that natural gullies have formed as a result of the breakage of masses from weak slip planes. In this study, we have taken linear measurements along four different profiles along and across the hill using a portable measuring device ANGEL-M. Anomalously high amplitudes of FEMR values are obtained in the regions which consist of weak slip planes which can be considered to be potential zones of future landslides. The results were further verified by calculating the factor of safety for a few locations along the profiles where anomalies in the FEMR data were compared. Consequently, predicting areas prone to natural calamities such as landslides has always been a priority in terms of current research. Hence, we have made an active endeavor to propose a new technique in order to identify landslide-prone areas by detecting the adjoining weak slip planes.

No abstract

Purpose -The aim of this paper is to predict the optimum settings of the process parameters for selective laser sintering process. Design/methodology/approach -A simulation model is prepared using author written subroutines in ANSYS w Parametric Design Language (APDLe) environment. The simulation model is then run at the experimentally designed points using central composite design approach. Based on the observations, a response surface is generated for the density of a sintered part as a function of various process parameters. Findings -The results indicate the optimum settings of the process variables to achieve a desired value of the density.Research limitations/implications -The developed simulation model can be used to predict the density of the final part with limited part geometries and may not be applicable for the complex shapes or with irregular features. Practical implications -The parameter settings as predicted by the simulation model may not be reproduced exactly by the experimental readings. Originality/value -The results of the simulation study concur with previous investigation by other researchers. Hence, the model can be suitably modified according to available data for different materials (amorphous and crystalline) taking the due considerations.