Papers by Keyword: FESEM

Abstract: Polyurethane coating has been widely used as a protective coating due to its wide range of mechanical strength, excellent abrasion resistance, toughness, low-temperature flexibility, and chemical resistance, simplicity in production and application, and superior protection on corrosion to mild steel. No studies have been reported utilizing coconut-based/PPG blend polyols to produce polyurethane-based protective coatings on mild steel. Therefore, in this work, we fabricated polyurethane-based protective coating using coconut-based/PPG blend polyols for anti-corrosion application. Due to low adhesion strength of Polyurethane-based protective coating, the incorporation of nano-fillers into the polymer matrix improved the adhesion strength of the coating due to its functional benefits and its effects gave rise to increased intermolecular bonding, hydrogen bonding, van der waals, magnetism, and surface energy. Therefore, we fabricated PANI/PU composite coatings with varied amounts of polyaniline nanoparticles on mild steel using coconut-based/PPG blend polyols exposed in 3.5 wt% NaCl aqueous solution for anti-corrosion application. Characterizations like Fourier Transform Infrared Spectroscopy (FTIR), Potentiodynamic Polarization (Tafel plot), contact angle, adhesion test, FESEM, XRD, and UV-VIS were used in this study. Tafel plot revealed that PU-based and PANI/PU composite coatings exhibited a significant reduction in corrosion current density (I_corr), perhaps due to the adsorption of inhibitor in the surface of the mild steel which reduced corrosion rate of the metal by retarding the anodic process and impeding the corrosive species from the surroundings. Among all fabricated coatings, 0.5-PANI/PU composite coating was the best, having a less corrosion rate of 5.66x10^-5 mmpy compared to others. In addition, its surface was more compact, smooth, rigid, and no voids present at the interface according to the result of FESEM, suggesting better corrosion protection to mild steel. Hence, PU-based protective coating and PANI/PU composite coatings using coconut-based/PPG blend polyols inhibited the penetration of the corrosive species and served as an adequate barrier protection against corrosion for mild steel.

Abstract: Nickel Oxide nanofibers were successfully prepared by electrospinning with a precursor mixture of Ni acetate/polyvinylpyrrolidone (PVP), followed by calcination treatment of the electrospun composite nanofibers. The parameter of solution and effect of applied voltage to the morphology of nanofibers were studied. Both Ni acetate/PVP and NiO NFs, nanofibers were characterized by FESEM and XRD. The results found that the nanofibers form with smooth surface without beads and the calcination temperature was at 500°C to produce NiO nanofibers.

Abstract: This paper highlights a study on the effects of medium dose gamma (γ) irradiation towards physical properties of TiO₂ nanoparticles. Doses applied for gamma irradiation are 60, 100 and 150 kGy. Structural and morphological results show that gamma radiation did not change the crystallinity and shapes of TiO₂ nanostructures. Ratio percentages of anatase:rutile for irradiated samples is around 89:11. Agglomerated samples shown in morphology images is support with the existence of binodial shapes peak from particles size distribution analysis.

Abstract: A set of n-type porous silicon (PS) layers were fabricated by photoelectrochemical etching using direct current (DC) and pulse current (PC) techniques. The study aims to compare the effect of different resistivity (5 Ω and 10 Ω) on the formation of the PS structure. The samples were etched in a solution of HF:C₂H₆O with a composition ratio of 1:4. The etching process were done for 30 minutes with the current density of J = 10 mA/cm². In the time of PC etching process, the current was supplied through a pulse generator with 14 ms cycle time (T) which the on time (T_on) set to 10 ms and pause time (T_off) set to 4 ms respectively. The samples were then being characterized in terms of surface morphology by using FESEM, AFM and XRD. Through the FESEM results, it can be seen that sample with 10 Ω resistivity which using PC form a more homogeneous structure of pores as compared to other samples.

Abstract: Graphene, the most unique member of carbon family has fuelled a huge interest across the globe with its superior mechanical, chemical, optical and electronic properties. It has opened enormous avenues for humankind in terms of different applications. Since its discovery in 2004, people have tried various techniques to extract graphene, such as mechanical exfoliation, chemical exfoliation, epitaxial growth, CVD (chemical vapour deposition) etc. However, the above methods are not optimal for mass production, neither are they simple and cost effective. The present work highlights synthesis of graphene through electrochemical approach and its subsequent characterization. Pyrolytic graphite is subjected to intercalation of two different concentrations of HNO₃ electrolyte. XRD, FESEM and TEM were utilised to understand the structure and morphology of the obtained few-layer graphene nanosheets (FLGNs). Scanning probe spectroscopy is a useful technique for understanding the morphological structure of a sample at atomic level. Authors have utilised AFM which shows the thickness of the FLGNs to be in the range of 5-6 nm. STM studies of graphene nanosheets revealed atomic scaled periodicity and atomic flatness.

Abstract: Zinc Oxide (ZnO) thin films were produced by the sol gel dip coating process on the p-type silicon substrate with various withdrawal speeds changing from 1 to 4 cm/min, respectively. The films were annealed at a temperature of 500 ^°C for an hour in air ambient. The thin film thickness was found to be raised with the rise in withdrawal speed. The uniform distribution of the grains was appeared for all the films. The evolution of c-axis oriented (002) peak was revealed from X-ray diffraction (XRD) studies. The microstructural and optical properties of ZnO films were investigated by Raman, FTIR and photoluminescence spectroscopy (PL). The resistive switching properties of ZnO based memristors were studied by performing the current-voltage (I-V) measurements, where the thin films coated with lower withdrawal speed, have shown better switching property with rapid rise and fall of current during SET and RESET process, respectively.

Abstract: Multifunctional fibrous systems were developed within this research work, giving special importance to the electrical conductivity and antibacterial activity. The functionalization of several natural fibres (jute, sisal, coir, flax and cotton) with silver nanoparticles (Ag NPs) was successfully achieved using a sustainable and eco-friendly method, namely polyethylene glycol (PEG) reduction. FESEM images, GSDR and ATR-FTIR analysis show that the Ag NPs were incorporated onto the fibres surface. The resistivity values obtained by analysing the fabrics without functionalization was about 1.5x10⁷ Ω.m while with the Ag NPs functionalization the resistivity values decreased almost 15000 times, to 1.0x 10³ Ω.m. Jute fibres’ antibacterial efficiency was also studied using the fibres with incorporated nanoparticles. Jute/Ag NPs showed some activity against E. Coli and S. Aureus. Polylactic acid (PLA) was used to develop flexible biodegradable composites with the functionalized jute. The compatibilization of the jute with PLA was successful and the characterization of the final composites was performed by GSDR, ATR-FTIR and TGA.

Abstract: This work reported the influence of seaweed (Sargassum crassifolium) extract on the absorption of magnetic iron oxide nanoparticles (MIONPs) via green synthesis route. The seaweed extract acted as reducing and capping agent. Ultraviolet-visible (UV-Vis) spectra revealed the presence of sharp peaks at around 366 nm to 371 nm which corresponds to the absorption spectra of MIONPs. The absorption peaks corresponding to MIONPs was significantly affected by the varying amount of seaweed extract. On the other hand, Fourier Transform-Infrared (FTIR) spectra revealed the presence of the vibration mode around 532 cm^-1 to 551 cm^-1 which corresponds to Fe-O bands suggesting the successful formation of MIONPs. Thermogravimetric (TGA) spectra showed that the produced MIONPs stabilizes at 400 °C. The synthesized MIONPs are spherical in shape with an estimated average diameter of 20 nm as revealed by the Field Emission Scanning Electron Microscopy (FESEM). Finally, the produced MIONPs exhibit magnetic property via attraction with an external magnet. This straight forward green synthesis of MIONPs can be a good route for possible industrial and environmental application.

Abstract: Limited connectivity and poor infrastructure of roads acts as a roadblocks hampering the socio-economic development of one region. In order to overall development of these regions an effort should be given to cultivate well established road network. But due to scarcity of good quality soil PWD engineers are often forced to build roads over the weak soil which directly affects the strength and durability of the road. It is therefore essential to improve the engineering properties of such problematic soil with suitable stabilization technique as and when encountered. Lime stabilization is one such well known chemical stabilization technique extensively used to improve the poor subgrade condition and it is recommended by several codes in INDIA. This paper attempts to study the effect of lime on strength and bearing capacity improvement of soft clayey soil. A series of UCS and CBR tests are conducted with different percentages of lime (i.e. 3, 5, 7 and 9%) and at different curing period to assess the potential of lime in strength improvement. Test results indicate that strength, stiffness and bearing capacity of the soil is considerably improved after lime amendment. Both unconfined compressive strength (UCS) and California bearing ration (CBR) improved up to 7% of lime beyond that it decreases. The improvement of UCS and CBR is found approx three and five fold as compared to original soil. Underlying mechanisms of this improvement is further scrutinized by microstructural analysis such as X-ray diffraction (XRD), Field Emission scanning electron microscope (FESEM) with Energy dispersive X-Ray Analysis (EDAX). Apparent formation of some new peaks in XRD analysis and change of textural and structural morphology of clayey soils obtained from FESEM confirms the formation of cementitious compounds in the lime stabilized soil.

Abstract: Polycrystalline samples with the nominal composition YBa₂Cu₃O_7-δ (Y-123) were prepared using the co-precipitation method. The effect of the calcination process (single and multiple calcinations) on the samples was investigated by using the four-point temperature-resistance measurement, x-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM). This study is divided into two parts. For the first part, the obtained oxalate powder underwent two calcination processes at 900 °C for 12 h and 900 °C for 24 h, respectively. Then, the powders were pressed into pellets and sintered at 920 °C for 15 h with oxygen flow during the entire heat treatment. In the second part, only one calcination process was undertaken at 900 °C for 24 h before the sintering process in oxygen flow at 920 °C for 15 h. From the XRD patterns, all of the peaks were indexed to the Y-123 phase showing that this superconducting phase was already formed after the first calcination. The volume fraction of Y-123 of the samples with single calcination process was higher compared to multiple calcination processes. From the temperature-resistance measurement, all the samples showed metallic behavior in the normal state and a superconducting transition to zero resistance. The superconducting transition temperature, T_c, for the samples prepared in a single calcination process is higher than that of the multiple calcination processes.