Synergetic Effects of Graphene Nanoplatelets/Tapioca Starch on Water-Based Drilling Muds: Enhancements in Rheological and Filtration Characteristics

Several borehole problems are encountered during drilling a well due to improper mud design. These problems are directly associated with the rheological and filtration properties of the fluid used during drilling. Thus, it is important to investigate the mud rheological and filtration characteristics of water-based drilling muds (WBMs). Several materials have been examined but due to the higher temperature conditions of wells, such materials have degraded and lost their primary functions. In this research, an attempt was made to prepare a water-based mud by utilizing graphene nano platelets (GNP) in addition to the native tapioca starch at different ratios. The combined effect of starch and graphene nano platelets has been investigated in terms of mud’s rheological and filtration parameters, including its plastic viscosity (PV), yield point (YP), fluid loss volume (FLV) and filtercake thickness (FCT). The morphological changes in the filtercake have also been observed using Field Emission Scanning Electron Microscope (FESEM) micrographs. Plastic viscosity was increased from 18–35 cP, 22–31 cP and 21–28 cP for 68 °F, 250 °F and 300 °F, respectively. The yield point was also enhanced from 22–37 lb/100ft2, 26–41 lb/100ft2 and 24–31 lb/100ft2 at the studied range. The fluid loss was dramatically reduced from 14.5–6.5 mL, 17.3–7.5 mL and 36–9.5 mL at 68 °F, 250 °F and 300 °F respectively. Similarly, filtercake thickness was also reduced which was further illustrated by filtercake morphology.

Exothermic behaviour of aluminium and graphene as a fuel in Fe2O3 based nanothermite

The main frontier of this research is to study the influence of multi-layer graphene (MLG) and aluminium as a fuel in Al/Fe2O3 and MLG/Fe2O3 nanothermites, fabricated by physical mixing and ultrasonication techniques. To study the structural and energy release properties, prepared samples were characterized by XRD, FESEM, EDS, FTIR, Raman spectroscopy and DSC. The X-ray diffraction (XRD) technique showed that all the phases remain intact during the synthesis. Field emission electron microscopy (FESEM) micrographs displayed the surface morphology of the samples, and besides this, energy dispersive spectroscopy (EDS) was used to check the elemental composition of samples. Raman spectroscopy revealed that the ultrasonication waves did not deteriorate the aromatic structure of graphene sheets. Fourier transform infrared spectroscopy (FTIR) spectra were used to observe the information about various functional groups present in the thermite samples. The exothermic energy released by the thermite reaction in both the samples was investigated by differential scanning calorimetry (DSC) and the observed values of energy release for Al/Fe2O3 and MLG/Fe2O3 are 215 J/g and 1640 J/g.

A-Site Substituted BaTiO3: Analysis of Structural, Optical, Ferroelectric and Dielectric Nature

The well-known ferroelectric and dielectric materials based on barium titanate (BaTiO3) with the compositional formula Ba[Formula: see text]AEMxTiO3 [[Formula: see text] and AEM (alkaline earth metal) [Formula: see text] Ca and Sr] denoted as BTO, BCTO and BSTO are reported in this work. The solid-state reaction method was used to synthesize these titanates. The as-synthesized samples were characterized for structural elucidation via X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Raman inelastic scattering, energy dispersive analysis of X-rays (EDAX) and field emission scanning electron microscopy (FESEM). In addition to this, the samples were studied for optical bandgap, dielectric constant, dielectric loss, ac conductivity and polarization ([Formula: see text]–[Formula: see text]) studies. The XRD data analysis revealed that all the samples have acquired a tetragonal structure (P4mm) and are single phased. The Rietveld refinement of Ba[Formula: see text]Ca[Formula: see text]TiO3 confirms XRD results. In FTIR spectra, the absorption modes appearing at about 400[Formula: see text]cm[Formula: see text] and 500[Formula: see text]cm[Formula: see text] are attributes of the vibration of Ti–O bonds and Ba–O bonds, confirming the formation of desired samples. The appearance of the Raman mode of vibration at about 310[Formula: see text]cm[Formula: see text] is an indication of the tetragonal phase. FESEM micrographs of Ba[Formula: see text]Ca[Formula: see text]TiO3 reveal grain growth in the range of about 1[Formula: see text][Formula: see text]m and its EDAX spectrum confirms the composition of the sample. The optical bandgap was found to be 3.35[Formula: see text]eV, 3.1[Formula: see text]eV and 2.65[Formula: see text]eV for pristine, Ca[Formula: see text]- and Sr[Formula: see text]-doped BaTiO3, respectively. Frequency-dependent dielectric studies infer the samples to be extremely good dielectrics in nature with very low loss values. Polarization against a field at 1000[Formula: see text]V witnesses the samples to exhibit low polarization effects with lossy character. The dielectric and [Formula: see text]–[Formula: see text] behavior of Ba[Formula: see text]Sr[Formula: see text]TiO3 was found exceptional among all the reported titanates.

Mechanical, microstructural properties and cell adhesion of Sr/Se-hydroxyapatite/graphene/polycaprolactone nanofibers

Electrospun nanofibrous scaffolds containing co-dopant of Sr/Se into carbonated hydroxyapatite has been synthesized in situ with graphene (G) nanosheets and carried on polycaprolactone at different contributions of G. The powder and the nanofibrous samples were investigated using X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy (FESEM). The FESEM micrographs show that the highest content of G (0.2 G) was formed in non-oriented/rough/cracked fibers with diameters around 0.3–0.4 µm at the maximum. The tensile strength of nanofibrous scaffolds was improved with the addition of G nanosheets and the maximum tensile strength of 0.2 G was around 6.39 ± 0.24 MPa, while the minimum cell viability ratio was about 94.4 ± 3.2% for the free G nanofibers. The in vitro attachment of HFB4 cell lines was investigated and it showed that nanofibrous scaffolds have induced cells to be proliferated and spread on the nanofibrous scaffolds’ surface. This behavior of cells growth encourages more investigations for these nanofibrous scaffolds to be promoted for clinical applications.

EFFECT OF ELECTRODE MATERIAL ON CUT QUALITIES OF SHAPE MEMORY ALLOY DURING WEDM: A COMPARATIVE STUDY

This paper compares some of the vigorous machinability characteristics of SMA-Nitinol during WEDM process using uncoated and zinc coated brass wire electrodes. A series of experiments were regulated based on Taguchi’s L[Formula: see text] orthogonal array with an objective of unveiling the benefits of using coated brass wire electrodes in comparison to uncoated counterparts. Five factors, namely pulse-on time ([Formula: see text]), discharge current ([Formula: see text]), wire tension (WT), wire speed (WS) and flushing pressure (FP), were considered, each at three different levels to scrutinize four responses, viz. surface roughness (Ra), kerf width (KW), machining time (MT) and micro-hardness ([Formula: see text]h). It was perceived that zinc-coated brass wire was more preferable to get favorable responses like Ra, KW and [Formula: see text]h when compared with brass wire counterparts. FESEM micrographs also revealed that micro and large cracks, wide craters, recast layer were more prominent on the WEDMed surface of brass wire compared to zinc-coated brass wire. Use of zinc-coated brass wire electrode significantly improves the machinability of the selected work material within the specified range of process variables.

Calcium Carbonate Reinforced Polypropylene Nanocomposites: Effect of Nano-Filler Loadings on the Melt Rheological Properties

In recent years, polymer-based nanocomposites have been investigated by many researchers due to their enhanced properties. Different types of nanomaterials have been used to produce polymer nanocomposites. One of them is nano-CaCO3. In the present work, nano-CaCO3 material reinforced polypropylene (PP) nanocomposites have been fabricated by melt compounding the PP pellets and nano-CaCO3 masterbatch. The effect of four different loadings of nano-CaCO3 (0, 5, 10, 15 wt%) on the melt rheological properties of the nanocomposites has been investigated. The morphology of the nanocomposites was analyzed by a Field Emission Scanning Electron Microscopy (FESEM) to study the dispersion state and distribution of nanoCaCO3 particles in PP matrix. Whereas, the melt rheological behavior of the nanocomposites was analyzed by an oscillatory rheometer. The FESEM micrographs showed that the nano-CaCO3 particles were well dispersed and distributed in the PP matrix. Additionally, the melt rheological analysis results showed that the complex viscosity of all nanocomposites samples were higher than that of neat PP and increased with increasing nano-CaCO3 loadings. Furthermore, the complex viscosity data from the rheological test has been fitted by Carreau-Yasuda equation and it was found to be well fitted.

Effect of Temperature and Magnetic Dopants on Particle size and Electrical Properties of ZnO Ceramic Varistor

We report here structural and electrical properties of Zn0.95 M0.05O ceramic, M = Zn, Co and Mn. It is found that addition of magnetic doping did not influence the hexagonal wurtzite structure of ZnO. Furthermore, the lattice parameters ratio c/a for hexagonal distortion and the length of the bond parallel u to the c axis were nearly unaffected. The average crystalline diameters, deduced from XRD analysis are 83.75, 72.86 and 70.97 nm for Zn, Mn and Co, which are 15 times lower than those obtained from FESEM micrographs (1570, 1380 and 1150 nm). The breakdown field EB was decreased as the temperature increased, in the following order: Mn> Zn > Co. The nonlinear region was observed for all samples as the temperature increased up to 400 K and completely disappeared with further increase of temperature up to 500 K. The values of nonlinear coefficient, α were between 1.65 and 56 for all samples, in the following order: Mn> Zn > Co. Moreover, the electrical conductivity σ was gradually increased as the temperature increased up to 500 K, in the following order: Co > Zn > Mn. On the other hand, the activation energies were 0.194, 0.155 eV and 0.231 eV for all samples, in the following order Mn, Zn and Co. These results have been discussed in terms of valence states, magnetic moment and thermo-ionic emission which were produced by the doping, and controlling the potential barrier of ZnO.

The effect of sintering temperature on Cu-CNTs nano composites properties produced by PM method

In this research work, copper and CNTs have been processed using high energy milling in different milling times (5, 10 and 15 hours). FESEM and XRD have been used to characterize the milled powders. The FESEM micrographs of the milled powders indicated that the morphology of powders changed from spherical shape to flake as milling time increased. The effect of sintering temperature as well as CNTs content on the properties of Cu-CNTs nanocomposite has been investigated. The optimum sintering temperature to produce Cu-CNTs nanocomposites is determined to be 900 oC. The microstructure and phase analysis of Cu-CNTs nanocomposites were studied by field emission scanning electron microscopy and X-ray diffraction. Mechanical properties of nanocomposite samples at various sintering temperatures were investigated. Cu-CNTs nanocomposite with 4 vol.% CNTs fabricated by powder metallurgy method indicated the highest value of the micro-hardness and bending strength as compared to pure copper.

Synthesis, Structural and Optical Properties of Cerium Oxide Nanoparticles Prepared by Thermal Treatment Method

A sample thermal treatment technique was utilised to synthesis cerium dioxide (CeO2) nanoparticles, using cerium (111) nitrate as a precursor, Polyvinylpyrrolidone as a capping agent, and deionized water as a solvent. The product underwent calcination treatment of 500, 550, 600, and 650 1C to crystallize the nanoparticles and to remove organic compounds. It was verified by XRD that by varying the calcination temperature, the cubic fluorite structure of CeO2 nanoparticles with pure products was achieved. Furthermore, the crystal sizes of the CeO2 nanoparticles were assessed to be 4 nm for the lowest calcination temperature and 23 nm for the highest calcination temperature. The FESEM micrographs of the CeO2 nanoparticles revealed a structure of CeO2 nanospherical that exhibited a tendency to amalgamate at higher calcination temperatures. The optical characteristics that were evaluated with the help of a UV-Vis spectrophotometer indicated a decrease in the band gap energy with an increase in calcination temperature as a result of the increase in the crystal sizes.

A new approach to synthesis and growth of nanocrystalline AlOOH with high pore volume

In this study, AlOOH nanostructures were successfully synthesized using the solvothermal method at 180?C. The effects of the pH of the solution (3, 4.5, 6.5, 10 and 12.5) on the synthesized samples were investigated systematically in detail, when ethanol and NaOH were the solvent and pH-adjusting agent, respectively. Fourier transform infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore structure of different AlOOH structures at various pH levels were also discussed in terms of the N2 adsorption/desorption test. According to the experimental results, the FESEM micrographs showed that the products were nanostructures, and the AlOOH nanoparticles larger on increasing the pH from 4.5 to 12.5. The structure characterization revealed that the resulting AlOOH nanostructures were pure and had a well-defined crystalline structure with a crystal size of 9.3?20.5 nm. Furthermore, the boehmite obtained at pH 12.5 exhibited a large surface area of 131 m2 g-1 and a high total pore volume of 1.24 cm3 g-1.