Influence of Process Parameters on Cu–Fly Ash Composite by Powder Metallurgy Technique

In this study influence of compaction pressure, sintering temperature, and sintering time on mechanical and wear behavior of the fly ash reinforced copper-based composites are analyzed. The composites were prepared by powder metallurgy (P/M) technique with copper as matrix, 5 and 10 wt% of fly ash as reinforcement. The green compacts were prepared at three different pressures such as 350, 400, and 450 MPa. The prepared green composites were sintered at 700, 800, and 900 °C for the time period of 30, 60, and 90 min, respectively. From the results it is observed that when the process parameter increases the density, hardness, compression strength, and wear resistance increases.     

New approach for prediction of influence of vehicle dynamics parameters on instability of unmanned track vehicle using robotic approach

Journal of Mechanical Science and Technology - Achieving stability of unmanned, heavy tracked vehicles is challenging, especially under conditions of teleoperation because the remote operator...     

Hierarchical NiMoS and NiFeS Nanosheets with Ultrahigh Energy Density for Flexible All Solid‐State Supercapacitors

Highly flexible supercapacitors (SCs) have great potential in modern electronics such as wearable and portable devices. However, ultralow specific capacity and low operating potential window limit their practical applications. Herein, a new strategy for the fabrication of free‐standing Ni?Mo?S and Ni?Fe?S nanosheets (NSs) for high‐performance flexible asymmetric SC (ASC) through hydrothermal and subsequent sulfurization technique is reported. The effect of Ni²⁺ is optimized to attain hierarchical Ni?Mo?S and Ni?Fe?S NS architectures with high electrical conductivity, large surface area, and exclusive porous networks. Electrochemical properties of Ni?Mo?S and Ni?Fe?S NS electrodes exhibit that both have ultrahigh specific capacities (≈312 and 246 mAh g^?1 at 1 mA cm^?2), exceptional rate capabilities (78.85% and 78.46% capacity retention even at 50 mA cm^?2, respectively), and superior cycling stabilities. Most importantly, a flexible Ni?Mo?S NS//Ni?Fe?S NS ASC delivers a high volumetric capacity of ≈1.9 mAh cm^?3, excellent energy density of ≈82.13 Wh kg^?1 at 0.561 kW kg^?1, exceptional power density (≈13.103 kW kg^?1 at 61.51 Wh kg^?1) and an outstanding cycling stability, retaining ≈95.86% of initial capacity after 10 000 cycles. This study emphasizes the potential importance of compositional tunability of the NS architecture as a novel strategy for enhancing the charge storage properties of active electrodes.     

Investigation on the effect of NiO content on spray deposited ZnO for selective ammonia detection

Journal of Materials Science: Materials in Electronics - Zinc Oxide/Nickel Oxide (ZnO/NiO) heterostructures were deposited using the spray pyrolysis technique by varying NiO content. The X-ray...     

Performance Comparison of Microstrip Patch Antenna Using h-BN Nanoceramic Substrate and FR4 Substrate

The recent communication receiver requires compact size, low cost, less weight and high-performance antenna for broadband applications. This paper compares the performance of the microstrip patch antenna designed using h-BN nano ceramic substrate with antenna designed using FR4 substrate. In this proposed new substrate is developed using powder metallurgy principle. Simulated and experimental results shows that proposed substrate for patch antenna in S-band applications achieve good resonance at two different frequencies 2.2 and 2.6 GHz with reflection coefficient of ?35 and ?40 dB respectively. Same antenna structure using FR4 structure is achieving good resonance at multiple frequency and broadband characteristics in C-band and X-band of the radio spectrum.

     

Nano Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Induced Fluxoid Jumps and Low Field Enhanced Critical Current Density in MgB<Subscript>2</Subscript> Superconductor

Nano particle of Fe₃O₄ (nFe₃O₄) up to 6 at% were doped in the superconducting MgB₂ samples. Despite the strong ferromagnetic nature of Fe₃O₄, both the ac susceptibility and the resistivity measurements show that up to 4 at% of Fe₃O₄, T _c =38 K is not changed, whereas for 6% T _c decreases by 6 K. This indicates that a low concentration of Fe does not substitute either the Mg or B sites and probably occupies the intergrain spaces. For 0.5% doped Fe₃O₄, an increase in J _c with respect to the pure MgB₂ samples is observed in the lower field and temperature regions (H<2 T and 20 K) indicating an enhanced flux pinning and the magnetic activation, i.e., the interaction between the magnetic dipole of Fe ion and the vortices is weak in comparison to the effective pinning potential. Whereas, at H>2 T, J _c of the doped samples is always less than that of MgB₂, and the activation is dominant in comparison with the effective pinning potential provided by the doping. Flux jumps are observed in lower T and H regions for the samples doped up to 1% nFe₃O₄ only. Magnetization plots of higher Fe content samples exhibited clear paramagnetic background. Mossbauer measurements for the higher (4, 6 at%) nFe₃O₄ doped MgB₂ samples show that at RT, the hyperfine field for both samples is ∼100 kOe and ∼120 kOe at 90 K. This means that the nFe₃O₄ particles decompose and form possibly an intermetallic Fe-B phase in the matrix.     

Steady MHD Casson Ohmic heating and viscous dissipative fluid flow past an infinite vertical porous plate in the presence of Soret,Hall, and ion‐slip current

In the present study, the influence of Hall and ion‐slip current on steady magnetohydrodynamics mixed convective, Ohmic heating, and viscous dissipative Casson fluid flow over an infinite vertical porous plate in the presence of Soret effect and chemical reaction are investigated. The modeling equations are transformed into dimensionless equations and then solved analytically through the multiple regular perturbation law. Computations are performed graphically to analyze the behavior of fluid velocity, temperature, concentration, skin friction, Nusselt number, and Sherwood number on the vertical plate with the difference of emerging physical parameters. This study reflects that the incremental values of Casson fluid parameter and Schmidt number lead to reduction in velocity. However, fluid velocity rises due to enhancement of ion‐slip parameter but an opposite effect is observed in case of Hall parameter. In addition, the Sherwood number declines with enhancing dissimilar estimators of the chemical reaction, Schmidt number, as well as Soret number.     

Compact analytical model for single gate AlInSb/InSb high electron mobility transistors

We have developed a 2D analytical model for the single gate Al In Sb/In Sb HEMT device by solving the Poisson equation using the parabolic approximation method.The developed model analyses the device performance by calculating the parameters such as surface potential,electric field distribution and drain current.The high mobility of the Al In Sb/In Sb quantum makes this HEMT ideal for high frequency,high power applications.The working of the single gate Al In Sb/In Sb HEMT device is studied by considering the variation of gate source voltage,drain source voltage,and channel length under the gate region and temperature.The carrier transport efficiency is improved by uniform electric field along the channel and the peak values near the source and drain regions.The results from the analytical model are compared with that of numerical simulations(TCAD) and a good agreement between them is achieved.     

Syntheses and Magnetic-Properties of Zn-Diluted Sr-Based Perovskite Cobalt Oxides, Sr1?x Zn x CoO3; 0.05≤x≤0.3

In order to check the solubility of Zn in the (Sr_1?x Zn _x )CoO₃ perovskite structure and their research findings, several polycrystalline samples have been prepared under wide extreme synthesis conditions at 6?GPa/1300?C1650?°C. While 0.05??x??0.3 compositions revealed single phased cubic structure materials, x>0.3 showed multi-phased materials for (Sr_1?x Zn _x )CoO₃ system. Like other substituted perovskite cobalt oxide systems (Ca, Y, Ho and Ce), the transport properties of the present materials show rather sizable changes with respect to ??x??, although there are insignificant variations in lattice parameter and in Curie temperature, T _c . All the present samples show soft ferromagnetism with T _c in the range of 272?C285?K for 0.05??x??0.3. The effective paramagnetic moment, P _eff determined from the paramagnetic region decreases upon the substitution of Zn for Sr-site. These P _eff (3.3?C2.8???_B/Co) values for 0.05??x??0.3 compositions seem to suggest that the Co⁴⁺ lie in intermediate spin (IS) state for the present (Sr_1?x Zn _x )CoO₃ series, although they are slightly smaller than those expected for IS-Co⁴⁺; P _eff=3.87???_B/Co. The electrical resistivity is found to increase with increase of ??x?? for the investigated samples. The temperature and field dependence of both positive and negative magnetoresistance (MR) are noted for the Zn substituted samples. About 5% of ?CMR is observed for x=0.05 sample around the transition temperature (280?K) under the field strength difference, ??H=90?kOe. The present research findings are compared with our previous results on different perovskite cobalt oxides.     

Cluster synthesis and direct ordering of rare-earth transition-metal nanomagnets

Rare-earth transition-metal (R-TM) alloys show superior permanent magnetic properties in the bulk, but the synthesis and application of R-TM nanoparticles remains a challenge due to the requirement of high-temperature annealing above about 800 °C for alloy formation and subsequent crystalline ordering. Here we report a single-step method to produce highly ordered R-TM nanoparticles such as YCo(5) and Y(2)Co(17), without high-temperature thermal annealing by employing a cluster-deposition system and investigate their structural and magnetic properties. The direct ordering is highly desirable to create and assemble R-TM nanoparticle building blocks for future permanent-magnet and other significant applications.