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As the data rate and density of digital high-speed systems are getting higher, far-end crosstalk (FEXT) noise becomes one of the major issues that limit signal integrity performance. It was commonly believed that FEXT would be eliminated for striplines routed in a homogeneous dielectric, but in reality, FEXT can always be measured in striplines on the fabricated printed circuit boards. A slightly different dielectric permittivity ( ${{\bm{\varepsilon }}_{\bm{r}}}$ ) of prepreg and core may be one of the major contributors to the FEXT. This article is focusing on providing a practical FEXT modeling methodology for striplines by introducing an approach to extract ${{\bm{\varepsilon }}_{\bm{r}}}$ of prepreg and core. Using the known cross-sectional geometry and measured S-parameters of the coupled stripline, the capacitance components in prepreg and core are separated using a two-dimensional solver, and the ${{\bm{\varepsilon }}_{\bm{r}}}$ of prepreg and core is determined. A more comprehensive FEXT modeling approach is proposed by applying extracted inhomogeneous dielectric material information. more...

The main objective of this study was to design a journal bearing, such that it can withstand the forces that arise in context to increasing the length of the shaft in an automotive turbocharger. The work will also provide information on how the design changes affect the overall performance of the bearing. The design changes include the thickness of the oil film, the number of grooves, the dimension of the grooves, the number of inlets and outlets, the dimension of the babbitt and mainly the length of the journal bearing. The simulation models were created using CATIA V5 and the analysis is done using ANSYS 19.2. The flow is considered to be laminar and is calculated using Reynold’s Equation. The new concept gave insight on how the design considerations affect the pressure distribution and the pressure developed. From the results, it was interpreted that the new design can withstand the four times the pressure while distributing the pressure over twice the original design. more...

Composite materials are developed with the sole intention of augmenting the properties of metal/alloy through the addition of reinforcing materials. The composite of Al-6082 alloy with 5%, 10%, 15% and 20% percent by weight nano-SiC particulate reinforcement was successfully fabricated using the standard stir casting method. Using the rule of mixture, the physical properties such as the density, Poisson’s ratio, and the Young’s modulus were computed for the fabricated composites. The rule of mixture showed that the density and Young’s modulus was highest for composite with 20% nano-SiC reinforcement at 2.802 gms/cm3 and 136.2 MPa respectively. Whereas the Poisson’s ratio was maximum for composite with 5% nano-SiC reinforcement at 0.3225. For the strength evaluation, aappropriate specimens were prepared according to ASTM standards from the fabricated composites to test the hardness, tensile strength, compression strength, and impact strength. The hardness was tested using the Brinell’s hardness tester, which showed an increasing trend in the BHN, from 5% to 20%, at 84.34 to 93.39 N/mm2 respectively. The tensile tests showed an increasing tensile strength with a maximum measured at 327.94 MPa, for composite with 15% SiC. The tensile strength however reduced with further increase in nano-SiC reinforcement content at 20%. The compression tests showed a gradual increase in the compressive strength starting at 28.96 MPa for 5% nano-SiC reinforcement content, to 48.97 MPa for 20% nano-SiC reinforcement content. The impact tests conducted using the Charpy Test showed a gradual decrease in the impact strength starting at 6.2 Joules for 5% nano-SiC reinforcement content, to 4.8 Joules for 20% nano-SiC reinforcement content. This is due to the reducing toughness in the composites with a gradual increase in the nano-SiC reinforcement. The strength evaluation showed that for applications requiring maximum hardness and compression loads, the MMC of Al-6082 with 20% nano-SiC reinforcement would be best suited. It was also concluded that the applications with maximum tensile loading requirements, the MMC of Al-6082 with 15% nano-SiC reinforcement would be suitable. Furthermore, the impact strength evaluations has shown that the composite is highly unsuitable for applications with impact loading conditions. more...

The metal casting process is one of the industry's most significant production processes and is also one of the eco-friendly techniques for making usable parts. Metal smelts are the main melting process that takes several stages. However, concerning increased energy consumption, longer casting periods, and major failures, the conventional casting process does have significant problems. New methods are being developed to address these deficiencies of classic casting procedures. The technique of microwave casting is one of the innovative methods that satisfy current needs in the business. The process involves complexity of understanding the heating rate, material interaction phenomenon etc. A 3-D model of the in situ casting process was generated through COMSOL multiphysics software tool. A complete simulation based studies were carried out to predict the thermal history of the metal melting. The simulation results obtained by considering various power levels (1500 W to 3500 W) to predict melting time, average heating rate, desired energy to melt the materials. It was observed that the role of electric field distribution inside the microwave applicator and distribution of the temperature in the charge play a important role at hot spot condition and also to increase in temperature in the charge. It is noted that energy decreases are 15.37% at 3500 W, 9.8% at 2000 W, 16.67% at 2500 W, and 13.6% at 3000 W. Finally, the simulation data showed that the heating of the bulk metal is rapid and consistent at specific location of the mold assembly. more...

This paper reports on a study of the high-temperature tribological performance of self-lubricating nickel-based composite clad. A porous and crack free clad containing matrix, reinforcement, and lubricant phase is developed on titanium 31 alloy using microwave irradiation. The microstructure of both NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad revealed very good metallurgical bonding with the substrate. The average microhardness of NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad is 710.58 HV and 650.25 HV respectively, is comparatively higher than the titanium 31 substrate (320 HV). The addition of Ag and BaF2 solid lubricants in the clad endowing clad to operate at a broad temperature range. Compared with the NiCrSiB/WC clad, solid lubricant encapsulate clad has shown very low friction coefficient and wear rates. The sliding wear characteristics of the clad were investigated by varying load and temperatures. The results revealed that oxide phases (NiO and Cr3O) and lubricant phases (Ag and BaWO4) formed at low and high temperatures are adequate to reduce delamination and material loss. more...

The present article reports a simple and cost-effective process to prepare the crystalline MgAl2O4 spinel using non-stoichometric amount of magnesium nitrate, aluminium nitrate by solution combustion route. Thiourea was used as a fuel and reducing agent while soaking was carried at 1000ºC with different soaking periods. After slow drying of mixed solutions at 80ºC for 4-5 hours a gel was formed and got characterized by DTA/TGA (Differential Thermal Analysis and Thermal Gravimetric Analysis) to observe the effect of temperature variation and identify the range of temperature where crystalline nature of the powder was noted. Powder sample was prepared from the gel after annealing at 1000ºC followed by soaking for 4 hours, 5 hours, 6 hours to compare the variation of particle size with respect to time. The calcined powders were characterized by XRD (X-ray powder diffraction) to determine the phases and crystal planes present in the sample, FT-IR (Fourier-transform infrared spectroscopy) to study the types of metal oxide or metal-metal bond present in the sample along with M-O coordination studies, FESEM (Field emission scanning electron microscopy) to observe the morphological structure of the sample, EDAX (Energy Dispersive X-Ray Analysis) to observe the percentage of each element present in the sample. Bulk densities were estimated from 2.4156 g/cm3 to 2.8571 g/cm3 and the rapid increase in apparent porosity of samples 7.4289%, 10.3630% and 32.51% for 4 hours 5 hours and 6 hours respectively were also noted. It had been observed that the average crystal size of spinel particles was about 48 nm, 36 nm, and 47 nm respectively. Finally, hardness of spinel was evaluated by Vicker Hardness test and evaluated to be10.52GPa (1073 HV), 4.087GPa (416.7HV) and 5.079 GPa (517.9HV). more...

Summary Metal penetration into a solid electrolyte (SE) is one of the critical problems impeding the practical application of solid-state batteries. In this study, we investigate the conditions under which electronic conductivity of the SE can lead to metal deposition and fracture within the SE. Three different stages for void filling (metal plating initiation, metal growth, and metal compression) in the SE are identified. We show that a micron-size isolated void in the SE near the anode can be quickly filled in by metal and fractured when the developed pressure in the void grows larger than the maximum pressure the SE material can sustain. We find that the anode voltage and applied current density play a significant role in determining the vulnerability to metal deposition. We discuss several strategies to prevent electronic conductivity-driven metal propagation in electrolytes that are not fully dense, including the densified layers between the anode and SE. more...

The effects of applying an alumina (Al2O3) coating by atomic layer deposition, with a thickness of about similar to 1 nm, on two PtGa catalysts (PtGa/MgAl2O4 and Pt/MgGaAlO) were explored for the propane dehydrogenation reaction (PDH). The combined application of small angle X-ray scattering (SAXS) and X-ray absorption spectroscopy (XAS) was employed on the samples to gain insight into the effect of this coating on catalyst stability. The coating restricted the mobility of surface metal nanoparticles, thereby preventing sintering of the catalyst. On the PtGa/MgAl2O4 catalyst, the presence of the coating hindered the alloy formation between Pt and Ga, while it did not negatively affect the formation of an alloy for the Pt/MgGaAlO catalyst as the Ga is delivered from the support. The SAXS and XAS findings were reflected in the PDH activity tests. The alumina-coated PtGa/MgAl2O4 performed worse than its uncoated counterpart due to the limited alloy formation in the presence of the coating. The coated and uncoated Pt/MgGaAlO catalysts were tested for PDH after 1, 5, and 10 H-2/O-2 redox cycles to see the effect of the coating on activity and stability. In general, the coating reduces the total amount of carbon formation, and the rate of deactivation for the coated sample is slower than for the uncoated counterpart. A higher thickness of coating led to reduced activity due to increased blockage of active sites but at the same time drastically reduced total carbon formation at similar conversions. The coated and uncoated Pt/MgGaAlO samples were then subjected to another 30 redox cycles (40 in total) and subsequently examined with HAADF STEM. Through particle size distribution of STEM images, it is determined that the coating reduced the extent of sintering of the sample. The direct correlation between increased coating thickness and lower extent of sintering of the surface metal nanoparticles was confirmed. more...

Contact resistivity quantifies the charge transport barrier, which is one of the key parameters for choosing the carrier selective contact for silicon solar cells. Optically transparent and electrically selective contacts such as transition metal oxide (TMO)-based contacts are employed in solar cell applications. Therefore, the extraction of contact resistivity for such Schottky contacts requires apposite validation. In this article, we have extracted the contact resistivity of TiOx/LiFx/Al stack over n-type c-Si wafer using two conventional techniques: 1) Shockley's transfer length method (TLM) and 2) Cox and Strack method (CSM). The extracted contact resistivity is validated by comparing with the solar cell's contact resistivity ( true contact resistivity) and fill factor (FF). We found that TLM overestimates the contact resistivity for highly resistive TiOx films, due to the asymmetrical nature of the TMO barrier and correlated with the reported experimental data. In contrast, CSM extracts more accurate contact resistivity for TiOx contacts when total resistance is extracted closer to the J mpp (38 mA cm−2). Besides, we recommend including the passivating layer along with the contacts (in the case of passivating contacts) to extract the actual contact resistivity felt by the solar cell. more...

A rechargeable lithium ion battery has captured prime importance in the modern era due to its cycle life and energy density. In the present study hexagonal shaped 18650 lithium ion cylindrical cell battery pack was designed and fabricated with paraffin wax as a Phase Change Material (PCM). But low thermal conductivity of the PCM causes impediment to the development of Electrical Vehicles (EV’s) which remains as a significant challenge. In the cylindrical cell battery module the maximum temperature is obtained in the mid region which causes uneven temperature distribution among cell. In order to overcome the limitation and to achieve efficient performance of battery module, the nano enhanced Phase Change Material (Ne-PCM) was incorporated in middle four cells by using graphene platelet nano powder (GPN), Multi Walled Carbon Nano Tube (MWCNT) and Graphite Synthetic Powder (GSP). Experiments on the battery module were conducted without any cooling, with PCM cooling and with Ne-PCM cooling. The results revealed that Battery pack with Ne-PCM has shown successful performance by minimizing the temperature below 50 °C in all considered discharge rates i.e., (1C, 2C and 3C) and maintained even temperature distribution among cells. more...

Benzotriazole loaded Cellulose reinforced 2 k polyamide coating system was developed to check the Corrosion inhibition performance of mild steel in 3.5 wt% nacl solution. Self-healing coatings were prepared utilizing cellulose nano fiber as a carrier for the Benzotriazole (BTA) with different loadings of 2, 4 and 6 wt%. Cellulose consists of hydroxyl groups and has sulphate and half ester groups on its surface that are acquired during Sulphuric acid hydrolysis of delignified sawdust. These hydroxyl and sulphate groups are negatively charged and provides anions to develop patina on the site of damaged coatings of mild steel for providing corrosion protection. TEM images confirmed the extracted cellulose nano fibres having cylindrical hallow shape with an average length of 176 nm and a lumen of 23 nm in size. The Electrochemical Impedance Spectroscopy (EIS) following 120 h of immersion proved that corrosion rate was decreased for BTA stacked cellulose reinforced coatings when compared to coatings without reinforcement. While Potentio dynamic examinations shows decrease in current density with increase in corrosion potential (Ecorr) for bare, standard, and for different compositions of CNB. It was also observed that the decrease in corrosion rate with respect to weight loss by reinforcement of encapsulated BTA in cellulose nano fibers implies better corrosion inhibition when compared to Bare and standard coatings of mild steel. more...

In this present experimental work, magnesium matrix composites (MMCs) were manufactured by stir casting method. Magnesium is a metal which is more abundant and has very less density but the problems is it has better wear resistance and low hardness. To improve the properties of magnesium, ZrSiO4 ceramic powder are reinforced. The tribological and mechanical properties of composite materials were investigated. The effects of reinforcement on the mechanical properties of the composites were investigated by 0, 4 and 8 wt% of ZrSiO4 ceramic powder with a size of 40–60 µm. The primary aim is to investigate the mechanical and tribological behaviour of AZ91/ZrSiO4 composites. ZrSiO4 powders are added at required proportions to produce magnesium alloy (AZ91) matrix composites. AZ91 along with ZrSiO4 confirms fine mechanical properties. The demand of magnesium matrix composites has increased mainly due to its high specific strength, better damping properties, excellent cast ability and superior machining ability. more...

In the present work, the effect of process parameters, substrate heating and cooling on bead geometry during the wire arc additive manufacturing of Inconel 625 on EN 8 steel is investigated. Further, the molten pool thermal history during the deposition was monitored using an IR pyrometer and the effect of these parameters on cooling rate was investigated and correlated with bead geometry. The cooling rate was found to increase with increase in travel speed from 500 mm/min to 700 mm/min while decreased with increase in energy input by varying the applied current between 190 A and 250 A. Though the bead geometry was found to vary with substrate heating, it was found to saturate with increase in current from 190 A to 250 A. Similarly, with increase in current to 250 A, the cooling was found to be ineffective due to increased amount of heat input. Cooling rates were found to effectively indicate these saturation limits which would help in process monitoring and control. more...

Levyne type SAPO-35 synthesized in aqueous medium, subsequently Pd metal loaded on the surface of SAPO-35 using borohydride reduction method. The resulting products were analyzed in detail. PXRD studies shows that the synthesized samples are highly crystalline without any amorphous phase. FE-SEM analysis shows synthesized samples are in rhombohedral shaped well crystalline without impurity phases. From BET analysis it shows that, SAPO-35 is higher surface area compared to metal loaded SAPO-35, this is due to Pd particles are placed over the rhombohedral SAPO-35 crystals. The efficiency of the prepared catalyst tested on Suzuki-Miyaura Cross Coupling reaction of Benzeneboronic acid conversion about 99% with 10% Pd/SAPO-35. more...

In today’s world slurry handling equipments are facing lot of engineering problems which is namely erosion. Slurry erosion plays a very important role in the design and operation of slurry transportation systems. In the work an attempt is made to reduce slurry erosion by cobalt based clad developed through microwave energy. The microwave clads are developed on AISI 420 substrate with a microwave exposure of 07 min. The developed clad shown great improvement in the erosion resistance than substrate. Slurry erosive wear studies were carried out with focus of three important parameters such as speed, impact angle and time of slurry exposure. ANOVA and control factors analysis studies were carried out with 95% of confidence level. Impact angle shown most dominating parameter on wear rate. Mixed mode of erosion was noticed on the target surface. more...

This experimental study presents the effect of partial replacement of Ordinary Portland Cement (OPC) by crushed rock dust (CRD) as filler material on the flexural strength of concrete when subjected to elevated temperatures of 200 °C, 400 °C, 600 °C and 800 °C for duration of 2 h using an electrically controlled furnace. The OPC replacement percentages are: 0% (T20), 10% (T21), 20% (T22), 30% (T23) and 40% (T24) by weight. Ultrasonic pulse velocity (UPV), Mass loss, flexural strength, and scanning electron microscope (SEM) are evaluated at the targeted elevated temperatures. At ambient temperature, up to 40% CRD, a dense microstructure with less pores is observed using SEM micrographs. Both T20 and CRD concrete beams begin to crack when temperature reached to 600 °C and pronounced surface cracks are observed at 800 °C. UPV values obtained with T20 and CRD concrete beams at elevated temperatures are in good agreement with flexural strength and mass loss values. SEM micrographs signify the use of CRD in concrete at elevated temperatures. The results of T20 and CRD concrete beams at elevated temperatures are found to be acceptable when exposed up to 400 °C. more...

Self-healing coatings were prepared for corrosion inhibition of mild steel by amino Silanization of lignin nano capsules. In-situ polymerization techniques through sonochemical approach was used for preparation of lignin nano capsules. Coatings have been developed using natural healing materials such as combination of lignin and safflower oil and coupling agents i.e APTES in water borne epoxy curing agent. Successful encapsulation of lignin and safflower oil was carried out via in-situ polymerization with the aid of urea–formaldehyde pre-polymer solution in presence of surfactant polyvinyl alcohol (PVA). Further Functionalization of lignin nanocapsules was done by amino Silanization. TEM and FE-SEM images confirm the encapsulation of nano particles and its histogram gives the average particle size distribution of the lignin nano particle and Capsuleas 106 and 146 nm. Total phenolic content of lignin extract were found to be 936 mg GAE/g. Potentio dynamic polarization studies revealed that the current density decreases to minimum of 3.703E-8A/cm2 with increase in weight percentage of lignin in nanocapsules (1.5 wt%) . Electrochemical Impedance spectroscopy showed a maximum impedance value as 6.44E6 for 1.5 wt% LNC coatings. Immersion studies give better corrosion rate for 1.5 wt% LNC coatings when compared to bare and standard coatings. more...

Achieving a high electrical conductivity while maintaining a good thermal insulation is often contradictory in the material design for the goal of simultaneous thermal protection and electromagnetic interference shielding. The reason is that materials with a high electrical conductivity often pertain a high thermal conductivity. To address this challenge, this study reports a multifunctional ceramic composite system for carbon fiber-reinforced polymer composites. The fabricated multifunctional ceramic composite system has a multilayer structure. The polymer-derived SiCN ceramic reinforced with yttria-stabilized zirconia fibers serves as the thermal protection and impedance-matching layer, while the yttria-stabilized zirconia fiber-reinforced SiCN ceramic with carbon nanotubes provides the electromagnetic interference shielding. The thermal conductance of the multilayered ceramic composite is about 22.5% lower compared to that of the carbon fiber-reinforced polymer composites. The thermal insulation test during the steady-state condition shows that the hybrid composite can be used up to 300 °C while keeping the temperature reaching the surface of carbon fiber-reinforced polymer composites at around 167.8 °C. The flame test was used to characterize the thermal protection capability under transient conditions. The hybrid composite showed temperature differences of 72.9 and 280.7 °C during the low- and high-temperature settings, respectively. The average total shielding efficiency per thickness of the fabricated four-layered ceramic composite system was 21.45 dB/mm, which showed a high reflection-dominant electromagnetic interference shielding. The average total shielding efficiency per thickness of the eight-layered composite system was 16.57 dB/mm, revealing a high absorption-dominant electromagnetic interference shielding. Typical carbon fiber-reinforced polymer composites reveal a reflection-dominant electromagnetic interference shielding. The electrons can freely move in the percolated carbon nanotubes within the inner layers of the composite material, which provide the improved electromagnetic interference shielding ability. The movement of electrons was impeded by the top and bottom layers whose thermal conduction relies on the lattice vibrations, resulting in a satisfactory thermal insulation of the composite materials and impedance matching with the free space. Results of this study showed that materials with a good thermal insulation and electromagnetic interference shielding can be obtained simultaneously by confining the electron movement inside the materials and refraining their movement at the skin surface. more...

The Hall-effect magnetic sensors suffer from large offset that is described by the resistance mismatch in the Wheatstone bridge-like equivalent electrical circuit model of the Hall plate. After a first order cancellation of the raw offset using spinning current technique, a residual offset still exists, significantly limiting the accuracy of the Hall sensor in the detection of low magnetic field. In this paper we analyzed the residual offset in silicon Hall sensor using a nonlinear lumped resistor network model to derive a closed form expression. We further analyzed the residual offset in silicon Hall sensor under the influence of stress. Using these results, we show that eight-terminal, octagonal-shaped silicon Hall sensors employing eight-phase spinning current technique provide greater immunity to stress effects on residual offset due to a second order cancellation compared to the conventional four-phase spinning. The measurement results suggest superior offset performance of eight-terminal silicon Hall sensor. more...

In this article, electroluminescence (EL) imaging is applied to characterize monocrystalline silicon photovoltaic (PV) modules under indoor and outdoor conditions. EL images of PV modules are analyzed to extract dark saturation current density and series resistance for individual cells within the module. These individual solar cells’ parameters together with the terminal voltages of the modules, are used to model the current–voltage ( I–V ) characteristics of individual cells and the module using the one-diode model of solar cells and LTspice. We have explored the method for both indoor and outdoor EL images and compared the results with indoor I–V measurements under standard test conditions (STC). The electrical parameters of the PV module estimated using this approach for both, indoor and outdoor EL measurements are in good agreement with a relatively small deviation of less than 3% from the reference measurements performed under STC. This method is particularly useful to extract the electrical parameter and information on module degradation in the field using the EL only, without performing an I–V measurement. more...

Purpose The purpose of this paper is to find out the optimal level as well as the influence of end mill cutter geometrical and machining parameters while machining metal matrix composite. End milling is carried out on Al 356/SiC metal matrix composites (MMC) using high-speed steel (HSS) end mill cutter. The optimum level of input parameters such as helix angle, nose radius, rake angle, cutting speed, feed rate and depth of cut are calculated for minimum temperature rise. Design/methodology/approach L27 Taguchi orthogonal design, signal-to-noise (S/N) ratio, are applied for conducting experiments, and to find the optimal level of input parameters for minimum temperature rise, respectively. Analysis of variance (ANOVA) is used to analyze the significance of input parameters on temperature rise. Findings It is found that the optimal combination of helix angle 400, nose radius 0.8 mm, rake angle 80, cutting speed 30 m/min, feed rate 0.04 mm/rev and depth of cut 0.5 mm have generated minimum temperature rise. From ANOVA analysis, it is found that rake angle influence is more on output performance followed by cutting speed and nose radius compared with other machining and geometrical parameters. Originality/value The influence of geometrical parameters such as helix angle, nose radius and rake angle of end mill cutter on temperature rise while machining MMC has not been explored previously. more...

Fe-modified MgAl2O4 makes a surprisingly active catalyst support, likely linked to a structural effect of the Fe incorporation. Two catalyst supports, MgAl2O4 and MgFeAlO4, have been studied in fre... more...

In the present work, investigation of slurry erosion wear performance of nickel-based clads on austenitic steel SS-304 substrate has been reported. Clads were developed through microwave hybrid heating technique using a low-cost microwave oven. The microwave-induced clads were characterized through scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. The tribological properties of clads were determined using a slurry erosion wear testing setup. Experimental trials were conducted as per Taguchi L27 orthogonal array considering three factors: spindle speed, specimen angle and time of exposure of clad surface to spinning slurry. The developed clads exhibited considerable resistance to slurry erosion; however, higher wear resistance characteristics were observed at lower spindle speed and higher specimen angle. ANOVA results indicated the specimen angle as the most significant factor followed by speed and time. A multiple linear regression equation was obtained to determine the correlation between the parameters. The clad specimens tested at a lower specimen angle were completely damaged due to microcutting, grooves and crater formation. more...

Detailed heat transfer measurements using transient liquid crystal thermography were performed on a novel cooling design covering the mid-chord and trailing edge region of a typical gas turbine blade under stationary and rotating conditions. The test section comprised of two channels with aspect ratio (AR) of 2:1 (mid-chord) and 4:1 (trailing edge), where the coolant was fed into the AR = 2:1 channel from the root. Rib turbulators with a pitch-to-rib height ratio (p/e) of 10 and rib height-to-channel hydraulic diameter ratio (e/Dh) of 0.075 were placed in the AR = 2:1 channel at an angle of 60° relative to the direction of flow. The coolant after entering this section was routed to the AR = 4:1 section through a set of crossover jets. The purpose of the crossover jets was to induce sideways impingement onto the pin fins that were placed in the 4:1 section to enhance heat transfer. The 4:1 section had a realistic trapezoidal shape that mimics the trailing edge of an actual gas turbine blade. The pin fins were arranged in a staggered array with a center-to-center spacing of 2.5 times the pin diameter in both spanwise and streamwise directions. The trailing edge section consisted of both radial and cutback exit holes for flow exit. Experiments were performed for a Reynolds number (ReDh(AR = 2:1)) of 20,000 at Rotation numbers (RoDh(AR = 2:1)) of 0, 0.1 and 0.14. The channel averaged heat transfer coefficient on trailing side was ∼28% (AR = 2:1) and ∼7.6% (AR = 4:1) higher than the leading side for Rotation number (Ro) of 0.1. It is shown that the combination of crossover jets and pin-fins can be an effective method for cooling wedge shaped trailing edge channels over axial cooling flow designs. more...

Concrete is a commonly used construction material all over the globe. Environmentally conscious construction is essential in today's society. By using the proper materials, we may achieve long-term construction. RHA is often used as a cementitious product replacement, and in such cases, we may mix RHA with hydrated lime. Many research has been conducted on RHA, and they all indicate that it outperforms other kinds of concrete. The importance of rice husk ash in construction and its applications are the subject of this essay. Many studies have been undertaken to identify appropriate replacements for cement in concrete mixes to reduce our over-reliance on cement as a component in concrete production owing to its contribution to CO2 emissions. This article examined the research on the usage of fly ash and rice husk ash as partial concrete replacements and the chemical composition of these materials, and their impact on concrete compressive strength. The mix was created using a logical approach in which solid components were set, and water and superplasticizer content were modified to get the best viscosity and flowability. Rice husk ash (RHA) is a rice milling byproduct. Its usage as a soil stabilizer provides an environmentally friendly alternative to ultimate disposal. Because RHA is not self-cementitious, a hydraulic binder, such as lime, must be added to create cement types to strengthen the soil. In sandy soils, studies on stabilization using RHA and lime mixtures were carried out. RHA of rice husk incineration in ordinary ovens with no temperature control and laboratory burning at regulated temperatures were utilized. In soil mixes with varying RHA and lime concentrations, cementitious compounds were found to develop. Soils treated with RHA and lime underwent unconfined compression strength testing. All RHA and lime concentrations and periods tested showed strength gains, and all materials created were changed rather than stabilized. The use of RHA to improve sandy soils offers environmental, social, and economic advantages as an alternative to ultimate disposal more...

Tungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to ~4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from ~133 nm for W to ~20 nm for the film containing ~4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is ~13 GPa hard, while the W:C films achieve a peak hardness of ~24 GPa. The W:C films are ~11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from ~3.8 to ~8.3 GPa and no brittle fracture was observed., Materials & Design, 208, ISSN:0264-1275, ISSN:1873-4197 more...

CoMoCrSi-WC + CrC + Ni and CoMoCrSi-WC + 12Co composite coatings are coated on titanium substrate by high velocity oxygen fuel method (HVOF). Prior to spraying, CoMoCrSi feedstock are processed through high energy ball milling (HEBM) in order improve the intermetallic laves phases and to reduce its particle size. The processed feedstock exhibits amorphous nature by improving laves phases and particle size of 60.12 μm. Microwave heating energy is utilized as post heat treatment technique to improve the mechanical and metallurgical properties of as-sprayed coatings. Fused coatings reveals better properties in terms of surface roughness, porosity, microhardness and adhesion strength compared to as-sprayed coatings. Metallurgical bonding is observed in case of fused coatings due to diffusion of substrate elements. Frictional and wear behaviors have been investigated by a pin on disc apparatus at temperatures of 200 °C, 400 °C, and 600 °C under normal loads of 10 N and 20 N. Both wear trace and friction coefficients of the fused coatings are smaller than as-sprayed coatings and substrate at all test temperatures. The wear traces of fused coatings decreased with increasing the surface temperature due to the lubricant effect of cobalt oxides formed on the sliding surface. As a result, cobalt based cermet coatings are highly recommended as a durability improvement coating for the protection of sliding surface, such as high speed spindle. more...

Coatings are implemented on engineering metals and alloys to augment the surface properties such as hardness as well as resistance to wear and corrosion. Heat treatments of coated metals/alloys are performed to aid in the progress of the bonding of the coatings to the substrate. During the air cooling process, the difference in the compositions of the coating and the substrate materials causes them to cool at different rates, which leads to straining in them. The paper presents the research on the mathematical investigation to evaluate the residual stresses in coatings caused due to heat treatments and subsequent air cooling. The mathematical modelling is executed to formulate the equations to represent the residual stresses retained in the coatings due to the heat treatments and subsequent air cooling. Air cooling undergoes two stages namely the initial quenching phase and the final cooling phase. During the quenching phase, the strain was expressed by considering the elastic, plastic and thermal strain components. Poisson’s ratio, deviatoric stress differential of the modulus of plasticity, coefficient of thermal expansion and change in temperature are used to express the elastic, plastic and thermal strain components. During the final cooling phase, the strain was expressed by considering only the elastic and thermal stain components, as the plastic staining the coating material generally does not occur during the final cooling phase and occurs only during the initial quenching phase. From the strain components, the residual stresses for the coatings in the x, y and z axis were formulated. Thus, the total residual stress is the sum total of stresses caused during the initial quenching phase and the final cooling phase. more...

In recent times, LuFeO3 is found to be an interesting material exhibiting room temperature multiferroic properties both in its stable orthorhombic and meta-stable hexagonal phase [1, 2]. To stabilize the single phase and also to enhance the magnetic and ferroelectric properties rare earth doping is a possibility [3, 4]. In this work, magnetic rare earth atom, Holmium is doped in place of Lu, the structural, magnetic and ferroelectric properties are investigated. Bulk nanocrystallineLu0.9Ho0.1FeO3 compound is synthesized by hydrothermal method. Doping with ionic radius larger than Lu, helps to stabilize the structure in a stable orthorhombic- Pnma phase. Rietveld refinement of structural data is carried out on the synthesized sample and the lattice parameters are found to be increasing as expected. Also, Ho being an element with a large magnetic moment, the effect of doping on magnetic properties is investigated. M-H isotherms didn’t saturate even at magnetic field, H= 9T reflecting a strong antiferromagnetic interaction that arises from the super exchange Fe3+-O-Fe3+ interactions. Finite remnant and coercivity values obtained from the M-H loop measured at 300 K confirms that the TN lies above room temperature (RT). Observation of P-E loop at 300 K confirms ferroelectric ordering at RT. more...

Orthorhombic SrFeO3-δ is synthesized through solid-state reaction in nanocrystalline form with controlled oxygen flow. Neutron diffraction measurement with Rietveld refinement and selected area electron diffraction (SAED) confirms the crystal structure. Magnetization against temperature shows that orthorhombic SrFeO3-δ is an antiferromagnet with Neel temperature (TN) of 230 K. Field-cooled hysteresis (M-H) measurements show exchange bias present in this system. It undergoes charge ordering near the Neel temperature and large change in resistivity around TN is found. Behavior of transport and magnetotransport properties are understood using the three-dimensional variable range hopping (3DVRH) mechanism and hysteresis is observed around TN in transport data. Ferromagnetic resonance (FMR) study shows that the linewidth is minimum around TN. Charge order and magnetic phase transition are coupled to each other around TN in the orthorhombic SrFeO3-δ system. more...

Conventional materials are general purpose and indispensible but their supply is limited. In particularly, the supply of material is limited for specific applications. Light weight low strength applications are very wide. This investigation focuses the natural fiber hybrid with artificial fiber based hybrid composite preparation. The sisal fiber is used to prepare the composite with Textile-Grade Glass fiber. The sisal fiber is here treated with specific concentration of sodium hydrate and Potassium Permanganate in the distilled water. The composites synthesized with treated and untreated sisal fibers. The alternate fashion of horizontal and vertical is followed for fibers’ orientation. The bio epoxy is employed as matrix material with mix of hardener. The prepared composite are characterized by water absorbability, tensile properties, flexural properties and shock absorption capacities. more...

Stability of 20 mol% Zr doped BaTiO3 (BZT20) and 20 mol% Sr doped LaMnO3 (LSM20) phases in their ceramic composite under the conventional heat treatment is discussed. (1−x)BZT20-xLSM20 x = 0, 0.25, 0.5, 0.75 and 1.0 composites are prepared from mechanical mixing of sol–gel synthesized BZT20 and LSM20 powders. The composite powders were pelletized under 610 MPa hydraulic pressure, sintered at the temperatures of 900 and 1000 °C for 12 h and characterized for the phase structure by X-ray diffractometer. Crystal structure of the pure phases is established from the Rietveld refinement method. Weight fraction of the phases is estimated from the internal standard method. The stoichiometric observation is correlated with the data available in the literature. It is observed that the A-site cations of the two phases start, though weakly, inter-diffusing at the lower temperature of 900 °C. The two phases at the temperature of 1000 °C partially dissolves into each other with the segregation of Zr-Ti-O based oxide as an intermediate phase. The shift in the LSM20 peak by Ba2+ substitution for La3+ and segregation of Zr-Ti-O is stronger in 75:25 and 25:75 compositions respectively due to percolation effect. more...

EN 24 (817M40) is used for creating punches and dies due to its hardenability, it's very tough to machine, so we investigate the parameters affecting the surface roughness produced within the turning process for the carbon steel EN24. Design of experiments was conducted for the analysis of the influence of the turning parameters like cutting speed, feed rate, tool wear and depth of cut on the surface roughness. The results of the machining experiments were accustomed characterize the most factors affecting surface roughness by the Analysis of Variance (ANOVA) method Taguchi’s parametric design is that the effective tool for robust design it offers an easy and systematic qualitative optimal design to a comparatively low cost. The Taguchi method of quality control encompasses all stages of product and process development. However, the key element for achieving prime quality at low cost is Design of Experiments (DOE). during this Analysis Taguchi’s (DOE) approach used to analyze the effect of process parameters like cutting speed, feed rate, tool wear and depth of cut on Surface Roughness and to get an optimal set of those parameters which will lead to good surface finish. more...

MgAl2O4 and its Fe-modified analogue (MgFexAl2−xO4) were synthesized as supports with a nanostructure by a hydrothermal process, and employed as supports for Ni catalysts in methane dry reforming (DRM). All prepared supports had a hierarchical architecture displaying clusters of nanosheets. Fe-modified MgAl2O4 was characterized by X-ray diffraction (XRD), N2 adsorption–desorption, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and temperature-programmed desorption (TPD). The activity and stability of the catalysts with a hierarchical support were tested in DRM at 750 °C, 111.3 kPa, and a CH4 : CO2 ratio of 1. The Ni/MgAl2O4 sample with a 0.5 Mg : Al molar ratio showed higher activity than Ni on common MgAl2O4 due to the larger surface area and stronger metal interaction with the hierarchical support. Besides, a series of Ni/MgFexAl2−xO4 catalysts with an Fe/Ni ratio between 0 and 0.5 was synthesized and reduced, yielding a supported Ni–Fe alloy. The structure evolution of the Ni/MgFexAl2−xO4 catalyst during H2 temperature-programmed reduction (H2-TPR), CO2 temperature-programmed oxidation (CO2-TPO), and dry reforming was investigated by in situ XRD. For Fe/Ni ≤ 0.05, a Ni–Fe surface alloy is obtained with high catalyst activity, efficient control of carbon deposition and superior regeneration ability. Ni supported on hierarchical Fe-modified MgAl2O4 proves to be a promising and effective catalyst for methane dry reforming. more...

Despite its excellent bulk mechanical properties, titanium performs poorly in tribological applications. Efforts to overcome this shortcoming have focused mainly surface modification using laser cladding with ceramic additives or intermetallic compounds (IMCs) formed during cladding. We present an alternative method using weld deposition for the production of IMC-based hard surface layer on titanium using gas metal arc welding (GMAW) with nickel as the filler wire. We observe formation of different Ti-Ni based IMCs (Ti2Ni, NiTi and Ni3Ti) in the fusion zone which results in considerable hardening of the surface. Microstructural characterization of the deposited samples give insight into the formation of IMCs. more...

A fast and non-destructive method based on electroluminescence (EL) imaging is presented to extract the front side resistive loss for individual cells within a crystalline silicon photovoltaic module. As the local luminescence intensity of a solar cell is an exponential function of local voltage, the voltage distribution along individual ribbons within the solar cell can be extracted. The front side resistance can then be computed using the distributive nature of current flow along the ribbon. As the soldering ribbons are much more conductive than the cell busbars, and due to the contact resistance between the cell busbars and soldering ribbons, the extracted front-side resistance describes mainly the front ribbon resistance. The method requires only two EL measurements on finished modules, which makes cell-to-module resistive loss analysis simple and fast. The proposed method is then compared with the measured and predicted voltage difference along the ribbon for individual solar cells. Simulation results are also presented and compared with our proposed method. more...

The present study deals with a detailed investigation of bioactivity, degradation and antibacterial activity of silver doped wollastonite (CaSiO3) synthesized using natural waste. Natural waste such as rice husk ash (RHA) and eggshells have been used as precursors for extracting silica (SiO2) and calcium oxide (CaO) respectively. Silver oxide (AgO) (0, 2, 4 and 6 mol%) doped wollastonite at the expense of CaO were synthesized through sol-gel process, and were characterised with thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). Thermal analysis revealed that the crystallization temperature of all samples was below 800 °C, and so all samples were sintered at this temperature. The bioactivity was explored in vitro, employing simulated body fluid (SBF) and the hydroxyapatite phase formation was confirmed by XRD. FTIR spectra showed the presence of characteristic functional groups, while, surface morphology was observed using SEM images, revealing the spherical shape of hydroxyapatite. The chemical constituents of apatite were confirmed by EDS spectra. The degradation study results have shown that degradation rate of silver doped wollastonite decreased with increase in silver content. Antibacterial activity was tested using disk diffusion method against different bacteria. Silver doped wollastonite showed good antibacterial activity and enhanced bioactivity. more...

Aluminium Metal Matrix composites (AMC) are known to be very promising light weight materials with enhanced mechanical properties which are used in various industries [1]. Aluminium metal–matrix composites reinforced with SiC and Al2O3 are used in automotive and aerospace applications due to reduction in weight and increase the engine efficiency and thereby reducing fuel consumption [2]. Replacing cast iron engine components with light-weight Al alloys requires overcoming of the poor adhesion and seizure resistance of Aluminium achieved by dispersing SiC, Al2O3 or graphite particles in aluminium, Considerable reduction in wear and friction can be achieved by the use of these reinforcement particulate [3]. more...

CNT based material are of vital importance in modern technology for their superior physical and chemical properties. In recent times, material developments for energy applications are focused for improvement of battery, capacitors, and electrodes for enhanced efficiency. High performance Supercapacitors with high energy densities are at the leading edge for renewable energy engineering device sector. CNT based Ni-Co-O material is of keen interest due to its possible applications as supercapacitors, electrocatalyst for metal/air battery and others. The hybrid material synthesis, morphology features and electrochemical features are vital to evaluate the material performances for energy applications. Electrical studies are also vital to evaluate the properties for device applications. In the present article, some stresses have been laid forward for the development of CNT-Ni-Co-O based hybrid material for supercapacitor high energy density applications. more...

In the present work a detailed microstructural investigation of Cobalt based microwave cladding on S-355 stainless steel was carried out. The experimentations were carried out in a home based domestic microwave oven. This article clears the circumstances of clad formation during microwave hybrid heating. The solidification texture and grain structure of the developed clad scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy, and measurement of Vicker’s microhardness. Cobalt based clads developed with an approximate thickness of 1 mm without interfacial cracking. The microstructure of clad clearly illustrated excellent metallurgical bond with S-355 substrate and found dominantly fine cellular grains. Iron and cobalt were recognized inside the cells while chromium was ascertained segregated around the cell boundaries. The average microhardness of the cobalt based clad was observed in the range of 402±60 HV. more...

Simulation plays a vital role in present-day product development. Simulation of manufacturing process in product design and development helps to save valuable resources in terms of materials, energy and also in the optimisation of process parameters. Metal rolling accounts to majority of the materials used in the bulk-forming. It is difficult to predict metal flow in the lateral direction in the conventional metal rolling. Manufacturing the rollers of different shapes and conducting experiments physically consumes valuable resources. These valuable resource are saved using the simulation of rolling operations using FEM-based metal forming simulation software. Simulation experiments are carried out to determine the effect of different shapes of rollers on the spread of material. In this work, spread of the material is analysed when the material is passed through different shaped rollers. Three types of rollers have been designed to study the effect of adding grooves on the spread of materials. It is seen that smaller groove size decreases the spread whereas larger size groove on the rollers increases the spread. more...

Level sensors find use in various applications for liquid-level monitoring in tanks, containers, and vessels. In this paper, an impedance spectroscopy-based sensing platform has been reported, employing a co-axial sensing probe. The supporting electronics was developed using the MSP 432 microcontroller unit (MCU) from Texas Instruments (TI) and a newly designed Impedance Analyzer-Analog Front End (IA-AFE), also developed at TI. Different signal processing and data processing methods were employed for coaxial probe impedance modeling and their results discussed. The sensor can be used for conductive as well as non-conductive liquids, including liquids with low dielectric constant. Successful measurements of liquid levels were shown for water ( ${\epsilon \sim 80}$ ) as well as vegetable oil ( ${\epsilon \sim 3}$ ). The developed sensing platform can measure water level with the accuracy of about 1.2 mm across a 400-mm-long sensing probe while exhibiting a maximum error under 0.6 mm for oil over 150-mm range. The proposed level sensing system provides an accurate and economical solution for level sensing, which is cheaper than the commercially available level sensors while outperforming the accuracy compared with the present state of the art, to the best of our knowledge. more...

This research reports the improvement of high-temperature sliding wear resistance of a grade 15 titanium alloy protected by an HVOF sprayed CoMoCrSi-Cr3C2 coating. The coatings have been tested in as-sprayed condition and after a post-deposition microwave heating step. The powder feedstock has been manufactured by high energy ball milling. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with the Energy Dispersive Spectroscopy (EDS) methods were used for coatings characterization. Surface roughness, microhardness, adhesion strength, and porosity of coatings were also measured. The wear test was conducted at an applied load of l0 N and 20 N with varying temperatures of 200 °C, 400 °C, and 600 °C under dry sliding conditions. Co3Mo2Si, Co7Mo6, Mo3Si, Co3Mo, and Co2Mo3 were the intermetallic laves phases generated in the CoMoCrSi feedstock during HEBM process. The microwave-fused coating exhibited metallurgical bonding, homogeneous structure, less porosity, and greater hardness as compared to as-sprayed coating. Microwave-treated coating revealed better wear property than an as-sprayed coating. This was mainly due to the intermetallic formation and metallurgical bonding in coatings. The fused coatings exhibit tribo-oxide layers during sliding action which was the main phenomenon of improving the wear resistance of the fused composite coatings. more...

Different amounts of graphene-wrapped magnesium oxide (G@MgO) powders are uniformly dispersed in poly(vinyl alcohol) (PVA) solution in different experiments to obtain solutions which are coagulated to obtain solid materials, which are then hot pressed at 413 K and 3 t of pressure to finally obtain 1 mm thick freestanding G@MgO/PVA composite sheets in which the constituents, namely, graphene and MgO (in the form of G@MgO), are the nanofillers in PVA matrix. During synthesis of G@MgO powder, MgO nanoparticles are in situ wrapped by the graphene nanosheets as revealed by electron microscopy. Uniformity of G@MgO dispersion in PVA was confirmed by secondary electron micrographs and the consistency in X-ray diffraction and Raman scattering data collected from different locations of the samples. Temperature (303-393 K) dependent complex permittivity of G@MgO/PVA composite sheets (including those prepared by casting) in low frequency (20 Hz to 2 MHz) and high frequency (i.e., X-band, 8.2-12.4 GHz) ranges are measured. In both frequency ranges, G@MgO/PVA composite sheets prepared by coagulation exhibited dielectric properties superior to those of PVA and G@MgO/PVA composite sheets prepared by casting. A strong interfacial polarization is observed in coagulated and as-cast G@MgO/PVA composite sheets. It is noticed from the calculated activation energies that conduction is the dominating mechanism for energy transfer in both composite sheets' cases, while it is predominating in coagulated composite sheets due to the better network formation of the fillers in the coagulated samples than in the cast composite samples. The electromagnetic interference shielding effectiveness (EMI SE) values in the X-band frequency range (i.e., 8.2-12.4 GHz) of the G@MgO/PVA composite sheets prepared by coagulation are more than those prepared by casting for a particular weight fraction of G@MgO. At 393 K, for a particular G@MgO/PVA composite sheet prepared by coagulation, an excellent EMI SE of ∼27.5 dB is measured. It is also experimentally elucidated that the absorption is the dominating mechanism for EMI SE in the prepared composite sheets. more...

Synthesis of a novel three-dimensional mesoporous Pd-KIT-6 is carried out by a room temperature sol–gel method. The synthesised material is well crystalline observed from the Small angle powder X-ray diffraction. Calcination at 550 °C for 8 h retains the structure. The particle sizes are in the micron range. Si/Pd ratio of the as-synthesized material is found to be 45 against the input ratio 100. Transmission electron micrograph reveals the presence of the porous hexagonal structure. Thermogravimetric studies reveal that the KIT-6 (Korea Advanced Institute of Science and Technology number 6) undergo less weight-loss compared to Pd-KIT-6, which indicates the material is more crystalline than its metal-free counterpart due to the enhanced crystallisation rate. These results also supported by BET-surface area and Transmission electron microscopic picture. The 960 cm−1 band at Fourier transform Infrared spectroscopic analysis shows that the incorporation of Pd in the framework. These FT-IR results also supported by Raman Spectroscopic analysis. Electron spin resonance spectroscopic analysis shows that the Palladium is present in the +2 oxidation state in as-synthesized samples. Diffused reflectance Ultraviolet–Visible spectroscopic results show that Palladium is in tetrahedral coordination. Microwave irradiated Suzuki–Miyaura (SM) cross-coupling reactions studied by using the Pd-KIT-6 catalyst in detail without any organic solvent at 100 °C for 10 min. The reaction carried out in the presence of phenyl iodide, phenylboronic (PhB(OH)2), and K2CO3 produce biphenyl, with 98% yield. Change of halide to Phenyl bromide gave similar results, but Phenyl chloride gave lesser conversion (20%). It is due to the electronegativity difference between the halides. A plausible reaction mechanism is also proposed. more...