PREPARATION AND CHARACTERIZATION OF TIO2-SILICONE NANOCOMPOSITE OBTAINED BY SOL-GEL METHOD

The sol-gel process is attractive for the nanocomposite preparation due to its unique advantages such as low temperature processing, high homogeneity of final products and its capability to generate materials with controlled surface properties. The preparation of TiO2-Silicone nanocomposite by sol–gel method, which is efficient at producing thin, transparent multi-component oxide layers, was considered due to its possible application as finishing coating on leather. In this study the preparation and characterization of TiO2-Silicone nanocomposite were investigated. TiO2-Silicone nanocomposite was prepared from titanium n-butoxide (TBO) and tetraethoxysilane (TEOS) catalyzed with acid. The chemical structure of the composite was evaluated by means of Raman spectroscopy. Atomic Force Microscopy (AFM) was employed to characterize the surface properties of composite films. In summary, the colloidal TiO2–Silicone nanocomposite solution was successfully synthesized using the sol-gel method. The turbidity value of the TiO2–Silicone nanocomposite solution was 12.7 ntu. The TiO2–Silicone nanocomposite was mildly acidic with a pH value of 5.2. It was determined that the viscosity of the TiO2– Silicone nanocomposite solution was approximately equal to 1-3 mPa.s. The particles sizes were approximately 5.4 nm, with the coatings being approximately 0.06 µm in thickness. From the results obtained it was revealed that the TiO2-Silicone nanocomposite can be used as coating in leather fninshing process

Determination of rutin by CoFe2O4 nanoparticles ionic liquid nanocomposite as a voltammetric sensor

Rutin is a class of flavonoids. Flavonoids have crucial antioxidant and chelating properties and are present in fruits and vegetables. Despite of their elusive metabolism, the enteric absorption reduces plasma oxidant status. Due to these reasons, rutin detection is important based on sensitive method. In the present report, a new electrochemical sensor based on CoFe2O4 nanoparticles ionic liquid nanocomposite was developed for rutin analysis in orange juice samples. Firstly, the structure analysis of prepared nanocomposites was characterized by transmission electron microscopy, cyclic voltammetry, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and energy dispersive X-ray analysis. The linearity range and detection limit of the prepared sensor were obtained as 1.0 × 10− 10–1.0 × 10− 8 and 3.0 × 10− 11 M, respectively. In addition, the voltammetric sensor was applied to orange juice samples with high recovery. © 2017 Elsevier B.V

Molecular imprinting polymer with polyoxometalate/carbon nitride nanotubes for electrochemical recognition of bilirubin

In this work, a new molecular imprinted sensor based on polyoxometalate (H3PW12O40, POM) functionalized carbon nitride nanotubes (C3N4 NTs) nanocomposite was prepared for bilirubin (BR) analysis. The structures of prepared surfaces based on the nanocomposite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray analysis (EDX). After that, BR imprinted electrode on H3PW12O40/C3N4 NTs nanocomposite was developed by cyclic voltammetry (CV) in 100 mM pyrrole containing 25 mM BR. The linearity range and the detection limit of the developed method were calculated as 1.0 × 10−12–1.0 × 10−10 M and 3.0 × 10−13 M, respectively. In addition, the imprinted sensor was applied to human plasma samples with high recovery and selectivity. © 2017 Elsevier Lt

Evaluating influence degree of equal-channel angular pressing parameters based on finite element analysis and response surface methodology

The current paper presents a collection of numerical, mathematical, and statistical techniques to predict strain behavior and required pressing force of 7075 aluminum alloy within the different parameters of equal-channel angular pressing (ECAP). Accordingly, response surface methodology was utilized to estimate the contribution percentage of the processing parameters (i.e., die channel angle, outer corner angle, coefficient of friction, and punch rate) on effective plastic strain, standard deviation of effective strain, and required pressing force of the deformed sample; then, regression modeling relationships were presented for each of the three outputs. Also, a suitable coincidence was found between the predicted regression model, numerical approach, theoretical technique, and experimental work. It is found that the achieved results could be used as a successful guideline for evaluation of the ECAP process. © 2019, The Brazilian Society of Mechanical Sciences and Engineering

Tailoring twist extrusion process; the better strain behavior at the lower required loads

This study dealt with discovering the optimal conditions of the twist extrusion parameters for producing materials possess enhanced strain behavior with the least amount of extrusion load. It was found that the twist angle has a dominant influence on the strain behavior of the deformed sample with the contribution percentage of 56%, while the effect of friction coefficient would be the most noticeable if the required extrusion load is considered. Based on above, pure copper with the square cross-section was subjected to the process with the large twist angle at the best lubricant state. The results showed that the strength and hardness of the deformed copper were considerably enhanced compared to the initial condition due to the substantial grain refinement. The uniform plastic deformation zone of the deformed sample is limited which causes the reduction of strain-hardening exponent and ductility. Moreover, the lateral region of the sample's cross-section endures larger plastic strain compared to the central one, leading to owning higher hardness. A combined microstructure consisting of low angle dislocation walls and high angle grain boundaries was also determined for the deformed copper. © 2020 Elsevier B.V

Microstructural refinement and wear property of Al-Si-Cu composite subjected to extrusion and high-pressure torsion

The effect of high-pressure torsion (HPT) on the microstructure and the mechanical properties, especially the wear properties, of an Al-Si-Cu alloy (represented by Al-15%Si-2.5%Cu-0.5%Mg) and its composite, which was reinforced by SiC particles (SiCp) at a volume fraction of 5%, was investigated systematically in this study. The Al-Si-Cu/SiCp composite is produced in a powder metallurgy process followed by hot extrusion (EXTR) at 565°C. The EXTR specimen is also subjected to HPT processing at an anvil rotation speed of 0.5rpm under a quasi-hydrostatic pressure of 5GPa.HPT processing leads to a nanostructured microstructure comprised of equiaxed α-Al grains (60-70nm) and secondary particles and phases; the SiCp with a damaged facet, the phase exhibiting high Mg content and the intermetallic CuAl2 phase, for the Al-Si-Cu/SiCp composite. The values of the tensile strengths and hardness of the HPT specimens are nearly twice higher than those of the EXTR specimens for the Al-Si-Cu alloy and the Al-Si-Cu/SiCp composite. Ball-on-disc tests were used to examine the wear resistance of the processed materials. The wear test results indicated that HPT processing significantly reduces the wear loss, thereby leading to improvement in the load bearing capacity and the wear resistance of the Al-Si-Cu alloy and the Al-Si-Cu/SiCp composite. This behavior is linked to HPT processing, based on the refined and homogenous microstructure that results in an increase in the hardness. © 2014 Elsevier B.V

An investigation into the effect of alloying elements on corrosion behavior of severely deformed Cu-Sn alloys by equal channel angular pressing

To overcome some possible deficiencies of pure copper, dilute alloying and employment of equal channel angular pressing seem the cost-effective solutions. In this work, dilute copper alloys with the tin amount of 0.18, 0.3, and 0.5 wt.% were obtained with continuous casting and subsequently, they were subjected to ECAP process up to four passes. It was shown that integrated treatment by dilute alloying and ECAP lead to 182% improvement of the corrosion resistance as compared to the as-received condition due to the grain refinement. Meanwhile, the alloying impact on current density is decreased with the ECAP process which may result from the changes at the distribution of Sn atoms in Cu. The difference in measured corrosion current density of unprocessed and ECAPed samples for the alloys Cu-0.3%Sn and Cu-0.5%Sn are 15% and 2%, respectively. The corrosion improvement by means of current density reduction due to the alloying before the ECAP process is about 45% while this value after the ECAP diminishes to 35%. Microstructure analysis showed that four passes of ECAP process cause the average grain size of the pure copper to less than 700 nm and the Cu-0.5%Sn to about 550 nm. Also, the HAGBs fraction of the ECAPed pure Cu is 74%, while the corresponding magnitude for the Cu-0.5%Sn is 78%. © 2019 Politechnika Wrocławsk

Investigation of the penetration behavior of alsi7 foam, produced by powder metallurgy method, under low-velocity impact energies

In this study, the impact behaviors of AlSi7 foams under low-velocity impact energies were investigated. The low-velocity impacts (1,2 -3 ms(-1)) were applied to the samples with 55x55x20 mm dimensions using the weight drop test machine. The impact tests were performed until perforation took place on a sample and so penetration and perforation impact behavior were analyzed. The changes in the internal structures of the samples after the impact were observed in the macro level

Turkish Guideline for Diagnosis and Treatment of Allergic Rhinitis (ART)

Object: To prepare a national guideline for Oto-rhinolaryngologist who treat allergic rhinitis patient