High‐Performance Microwave‐Derived Multi‐Principal Element Alloy Coatings for Tribological Application

The authors report the development of Al_xCoCrFeNi (x = 0.1 to 3) high entropy alloy (HEA) coatings using a simple and straightforward microwave technique. The microstructure of the developed coatings is composed of a cellular structure and diffused interface with the substrate. The microstructure of the HEA coatings varies as a direct function of Al content. An increase in Al fraction shows structural transformation from FCC to BCC along with the evolution of σ and B₂ as the major secondary phases. The diffusion of Mo from the substrate enhances the mixing entropy and promotes σ‐phase formation. The HEA coatings show significantly high hardness compared to SS316L substrate steel (227 HV) with a maximum value of 726 HV observed for three‐molar composition. The fracture toughness exhibits an inverse correlation with the Al fraction with the highest value of around 49 MPa m^1/2 observed for Al_0.1CoCrFeNi coating. The equimolar coating composition shows lowest erosion rates among all the tested samples due to optimum combination of the mechanical properties. The erosion resistance of the equimolar coating is 2 to 5 times higher than steel substrate and around 1.5 times higher than the non‐equimolar counterparts depending upon the impingement angles.

     

Blends of biodiesels synthesized from non-edible and edible oils: Influence on the OS (oxidation stability)

Biodiesels jatropha and pongamia synthesized from their respective non-edible seed oils, and PBD (palm biodiesel) synthesized from edible oil were blended with different weight ratios to examine the influence on the OS (oxidation stability). Dependence of the OS on esters of fatty acid composition was also examined. Good correlation between the OS and PAME (palmitic acid methyl ester) was obtained. A correlation between the OS and X (total unsaturated fatty acid methyl ester) was also obtained. Using these correlations, OS of different biodiesel blends can be determined.     

Synergistic effect of metal deactivator and antioxidant on oxidation stability of metal contaminated Jatropha biodiesel

Biodiesel is relatively unstable on storage and European biodiesel standard EN-14214 calls for determining oxidation stability at 110 °C with a minimum induction time of 6 h by the Rancimat method (EN-14112). According to proposed National Mission on biodiesel in India, we have undertaken studies on stability of biodiesel from tree borne non-edible oil seeds Jatropha. Neat Jatropha biodiesel exhibited oxidation stability of 3.95 h. It is found possible to meet the desired EN specification for neat Jatropha biodiesel and metal contaminated Jatropha biodiesel by using antioxidants; it will have a cost implication, as antioxidants are costly chemicals. Research was conducted to increase the oxidation stability of metal contaminated Jatropha biodiesel by doping metal deactivator with antioxidant, with varying concentrations in order to meet the aforementioned standard required for oxidation stability. It was found that usage of antioxidant can be reduced by 30–50%, therefore the cost, even if very small amount of metal deactivator is doped in Jatropha biodiesel to meet EN-14112 specification.     

Real Time Multi Object Detection for Blind Using Single Shot Multibox Detector

Wireless Personal Communications - According to world health statistics 285 million out of 7.6 billion population suffers visual impairment; hence 4 out of 100 people are blind. Absence of vision...     

Effect of Welding Speed on Texture in Laser-Welded Dual-Phase Steel

Metallurgical and Materials Transactions A - The present study makes an attempt to understand the influence of welding speed on the formability of a welded microalloyed steel. An optimum heat input...     

Diode-Like Selective Enhancement of Carrier Transport through Metal–Semiconductor Interface Decorated by Monolayer Boron Nitride

2D semiconductors such as monolayer molybdenum disulfide (MoS₂) are promising material candidates for next-generation nanoelectronics. However, there are fundamental challenges related to their metal–semiconductor (MS) contacts, which limit the performance potential for practical device applications. In this work, 2D monolayer hexagonal boron nitride (h-BN) is exploited as an ultrathin decorating layer to form a metal–insulator–semiconductor (MIS) contact, and an innovative device architecture is designed as a platform to reveal a novel diode-like selective enhancement of the carrier transport through the MIS contact. The contact resistance is significantly reduced when the electrons are transported from the semiconductor to the metal, but is barely affected when the electrons are transported oppositely. A concept of carrier collection barrier is proposed to interpret this intriguing phenomenon as well as a negative Schottky barrier height obtained from temperature-dependent measurements, and the critical role of the collection barrier at the drain end is shown for the overall transistor performance.     

New digital phase-lock system for millimetre-wave Gunn oscillatorsused in radioastronomy

A new digital phase-lock system for the frequency stabilisation of millimetre-wave Gunn oscillators is described. The phase-locked loop circuit is built around a new GaAs phase/frequency comparator type 16G044 developed by Gigabit Logic Inc. The digital loop is much simpler, is more reliable, and outperforms its classical analogue counterpart, especially in frequency-agile applications     

Thin films of the solid electrolyte Ag19I15P2O7 I. Preparation and characterization of films

The solid electrolyte Ag₁₉I₁₅P₂O₇ tends to decompose when conventional methods are used to vacuum-deposit it, resulting in thin films which exhibit poor ionic conductivity. These films have been characterized for topography, stoichiometry and structure using scanning electron microscopy, reflection electron diffraction and X-ray techniques to show that they contain more iodine and less phosphorus than required by stoichiometry and that their structure is different from that of bulk Ag₁₉I₁₅P₂O₇. The use of various characterization techniques has helped in identifying the problems involved and has led to suitable adjustments in the deposition parameters which are needed to deposit thin films of high ionic conductivity successfully. For example, an ionic conductivity of 0.01 Ω^-1 cm^-1 was obtained by maintaining the substrates at 140–150°C. In addition, it is necessary to keep the source temperature at 1400–1600°C during flash evaporation while the potential across the electrodes should be about 700–900 V during r.f. sputtering. The activation energy for ionic conduction was found to be 4.9 kcal mol^-1. These films were found to be quite stable in the temperature range -40 to +80°C and at a relative humidity of up to 80%.