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Advanced polycrystalline ceramics such as Y2O3, YAG are gaining importance on development of light-emitting diodes, infrared detectors, solid-state lasers, etc. The physical properties of these materials are dependent on variety of dopant concentrations. These materials such as Y2O3 could be synthesised along with Rare Earth Elements such Nd, Er, Yb etc using co-precipitation method. These synthesised samples could be tested by X-ray diffraction patterns confirm the presence of cubic phase for pure Y2O3 nanoparticles and mixed phase (cubic + monoclinic) when doped REE-Y2O3 nanoparticles. One of our recent studies of Yb doped-Y2O3 shows average crystallite size is found in the range 71 to 31 nm and lattice strain 1 × 10−4 to-5 × 10−4 calculated using Debye-Scherrer formula and Willimission-Hall plot. The crystallite size decrease with dopant concentration upto x = 0.10 and material is found to exhibit compressive lattice strain. Field-emission scanning electron microscopy shows agglomerated nanoparticles. The Fourier-transform infrared spectroscopy confirms the presence of metal oxide functional groups (Y-O and Yb-O) and vibrational bands corresponding to O-H vibration, C-O bending, and stretching modes in the samples. The band gap energy (Eg) is found to decrease from 5.14 eV for x = 0.0 to 3.60 eV for x = 0.14 composition. The photolumincence spectra show characteristic blue and green emission at 486 nm for x = 0.10 and 525 nm for x = 0.0, respectively. The frequency-dependent dielectric studies confirm the enhancement in dielectric constant with increase in Yb doping. These structural, morphological, optical, and electrical properties of Yb:Y2O3 nanoparticles are helpful for selecting this material as an appropriate candidate for laser host material for medical imaging and display devices applications.

https://doi.org/10.1111/ijac.13603

High entropy alloys are part of a novel area of metallurgy concerning alloys containing at least five elements with an atomic percentage ranging from 5 at% to 35 at%. The interest arises as for plenty of compositions, the formation of simple solid solutions gives rise to promising properties, pertaining their use in different fields such as structural, nuclear, automotive and aerospace industries. The main objective of this study was to synthesize CoCrFeNi1.75-xTi0.25+x(x = 0, 0.05, 0.15, 0.25) nonequiatomic, single-phase, high entropy alloys (HEAs) based on the multi-component Co-Cr-Fe-Ni-Ti system were produced by melting route in vacuum arc furnace. The characterization of newly developed HEAs was carried out using X-Ray Diffraction (XRD) and Optical Microscopy. XRD and optical microscopy confirmed the formation of single phase Ni(CoCrFeTi) FCC alloys system and dendritic structure respectively. Electrochemical workstation was used to test the corrosion behaviour of newly developed High entropy alloys in 3.5 wt% NaCl and 0.5M H2SO4 aqueous solution at room temperature. The corrosion current density (Icorr) of the alloys decreased with the increase of Ti content. When the Ti content increased from 5 at% to 10 at% the value of (Icorr) decreased from 0.423 μA to 0.270 μA in 3.5 wt% NaCl and from 21.42 μA to 16.84 μA in 0.5M H2SO4 aqueous solution, respectively.

https://doi.org/10.1016/j.matpr.2022.04.344

Corrosion behavior of FeAl-based alloys containing carbon produced through arc melting in argon atmosphere has been studied at 500 oC to 700 oC. The samples were tested in the aggressive environment of molten salts (80% V2O5/20% Na2SO4). The corrosion behavior was observed by weight change method and the layer products formed were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The different phase components were observed in the surface layer after the test in Fe-22Al alloy. A protective Al2O3 layer was confirmed for Fe-22Al alloy containing carbon only. However, an additional TiO layer was also observed in Fe-22Al alloy containing carbon with Ti addition. The microstructural and XRD examinations revealed that this additional TiO layer protects better against penetration of corrosive media. The corrosion resistance behavior of FeAl-based alloys was addressed on the basis of microstructural evidence.

https://doi.org/10.3390/met11122040

Owing to superior properties, i.e. high hardness, high wear resistance, and weight reduction of transparent ceramics (TCs) over glasses. TCs have shown promising tribological potential for applications such as face shields, explosive ordnance visors, windows for aircraft, spacecraft and, re-entry vehicles, electromagnetic windows, laser igniter windows, screens for smartphones and more. Researchers globally have been attracted to explore more about TCs, considering the tremendously increasing demand over different other transparent materials. The optical quality of TCs is mostly characterized by the in-line transmittance, and the effect of various processing parameters on transmittance has already been studied by various researchers. In this review, the current research progress regarding tribological performance of TCs is compiled. TCs with potential in tribological applications include MgAl2O4, Al2O3, AlON, Lu2O3, c-BN, Y2O3, Si3N4, and SiAlON. The relevant strategies to improve the tribological properties, including microstructures and mechanical properties are comprehensively discussed.

https://doi.org/10.1016/j.jeurceramsoc.2022.06.080

Today's machine components have more power, so researchers have to engineer materials that can withstand high-speed dry sliding stress. Consequently, this study examined dry sliding wear in an Austempered ductile iron (ADI) with fine ausferrite microstructure and low retained austenite. In addition, a chrome steel counterbody ball with a hardness of 60 HRC was evaluated. The wear rate, coefficient of friction and wear mechanisms were investigated. Two friction and wear regimes were identified. In the first regime of wear, wear rate increases from 21.68 to 36.29 x 10-6 mm3/Nm at low pressure; however, with high pressure, it decreases from 36.29 to 17.06 x 10-6 mm3/Nm. In second regime, at higher speed range, wear rate decreased from 17.68 to 3.11 x 10-6 mm3/Nm with applied pressure range. This behaviour well explained by the strain hardening of filmy austenite, causing compressive stress development in the neighbourhood, resulting in ADI becoming tougher at higher pressures and speeds in response.

10.1007/s12633-021-01407-7

Transparent glass nanocomposites comprising piezoelectric ZnO and β-Zn2SiO4 nanocrystallites in 44SiO2-11Al2O3-35ZnO-10K2O (mol%) glass matrix were explored for piezocatalytic dye degradation application. X-ray diffraction and Raman spectroscopy confirmed the crystalline phases of ZnO and β-Zn2SiO4 in glass-nanocomposites samples. Scanning electron microscopy images evidenced the presence of nanocrystals on the surface of glass-nanocomposites samples. UV-visible spectroscopy revealed the adequate transparency of glass-nanocomposites samples. Piezocatalytic dye degradation experiments were performed with the use of glass-nanocomposites piezocatalysts using sonication energy. Glass-nanocomposites samples were optimized for piezocatalytic dye degradation performance as well as transparency through tuning of heat treatments. It was found that the glass-nanocomposite heat-treated at 750℃-2 hr has shown the best piezocatalytic dye degradation performance and higher transparency among other samples heat treated at 750℃-4 hr and 750℃-6 hr.

https://doi.org/10.1039/D2EW00745B 

In this article Flat FSSW of three sheets of AA6082 was carried out having thickness of 1mm for each plate. The tool with probe and tool without probe were used for welding process. The use of these tools helps in obtaining the sound quality weld free from keyholes and cracks. The process parameters considered are tool rotational speed of 400, 975 and 1550 rpm, dwell time of 4, 6 and 8 s and plunge depth of 2.6, 2.8 and 3.0 mm. Taguchi analysis was used to optimize the parameters of this investigation for obtaining high tensile strength. An orthogonal array, L9 was applied and analysis of variance (ANOVA) was done to explore the importance of process parameters on various response.

DOI: https://jusst.org/influence-of-flat-friction-stir-spot-welding-process-parameters-on-quality-characteristics-of-aa-6082-weld/

Urinary tract infection (UTI) is a public health concern, estimated to cost billions of dollars in diagnosis and treatment every year. Consumption of cranberry has been correlated with the prevention of UTI, due to the presence of key plant metabolites called polyphenols. We fabricated functionalized screen-printed electrodes (SPEs) and tested the effectiveness of the biosensor for detecting the presence of Escherichia coli (ExPEC) in aqueous suspensions. Results indicated that thewas highly sensitive (limit of quantification of 1 CFU/mL of ExPEC), and its response was linear over the concentration range of 1–70,000 CFU/mL.

https://doi.org/10.3390/bios11060199

Aluminum alloys find application in aerospace, automobile, and structural sectors. However, these alloys are susceptible to corrosion attack in chloride environments. Introducing a second species on the surface by surface composite fabrication can be a way to increase the corrosion resistance of the aluminum alloys. Here, we present corrosion studies on aluminum matrix surface composites fabricated using friction stir processing. The reinforcement of Mo particles is considered with varying percentage and distribution in the surface composite. The particle content and distribution are analyzed using SEM–EDS and optical image analysis. Based on the potentiodynamic polarization analysis, the surface composites exhibit improved corrosion resistance with higher corrosion potential and lower corrosion rate. Increase in corrosion resistance is observed for higher Mo content with homogenous distribution. While the base alloy exhibit mixed corrosion behavior, the surface composites show charge-transfer controlled corrosion behavior in the Electrochemical Impedance Spectroscopy. Reduced pitting in the Mo-rich areas is confirmed by microscopic analysis of the corroded material.

https://doi.org/10.1007/s11665-021-06050-2

The applications of aluminum foams in the automobile and aerospace sector are growing day by day because of their unique properties such as high specific strength, greater stiffness, and higher energy absorption capacity. In the current work, the Al2024-B4Cp composite foams were developed by the direct foaming method. The effect of different sized B4C particles (fine particles: Average Particle size (APS) 5lm and coarse particles: APS 45lm) and its wt % (2, 4, 6, and 8) on foam characteristics, hardness, quasi-static compressive response, and energy absorption capacity was investigated. Varying B4C particle size and wt % had a significant impact on foam parameters such as foam expansion, relative density, cell size, and cell wall thickness. Hardness increases with increasing wt % of particles and fine particles added foam showed higher hardness than that of coarse particles added foam. An increase in wt % of particles improves the peak stress, plateau stress, and energy absorption capacity. Coarse particles added foam showed superior compressive properties and energy absorption capacity than that of fine particles added foam.

DOI: https://doi.org/10.1007/s40962-022-00837-2