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

TM ile üretilmiş Alumix-231 SiCp ve B4Cp kompozitlerin farklı üretim yöntemlerinin mekanik özelliklere etkisi

Bu çalışmada, Alumix–231 ötektiküstü Al-Si alaşımlı (Al15Si2,5Cu0,5Mg) alüminyum matrisli parçacık takviyeli kompozitler toz metalurjisi yöntemiyle üretilmiştir. Üretilen kompozitlerde %5, %10, %20 oranında silisyum karbür (SiC) ve/veya bor karbür (B4C) parçacık takviye malzemeleri kullanılmıştır. Mekanik alaşımlama (MA) veya klasik yöntemle (turbula tipi karıştırıcı) karıştırılan tozlar soğuk preslenme (SP) yöntemiyle üretilmiştir. Klasik yöntemle üretilen soğuk presleme numunelerine ekstrüzyon (EK) ve yüksek basınçlı burulma (HPT) işlemleride uygulanmıştır. Alüminyum matrisli kompozitlerin mekanik özellikleri (yoğunluk, sertlik, çekme, eğme ve darbe dayanımları), mikroyapı ve kırık yüzeyleri incelenmiştir. Kompozitlerde; TM methodu ile üretilen SP numunelerine uygulanan EK ve HPT ikincil işlemlerinin mekanik özellikler üzerindeki etkisi tesbit edilmiştir. MA, EK ve HPT işlemleri uygulandığında numunelerde gözenekliliğin azaldığı gözlemlenmiştir. Gözenekliliğin azalması, mekanik özellikleri daha da iyileştirmiştir. Alumix–231 matris malzemesin de SP’ye göre EK işlemi çekme mukavemetin %400 artırırken, EK’ya göre HPT işlemi %200 artış sağlamıştır. HPT işleminde Alumix–231 matris malzemesine %5 SiC tozu takviyesi ile çekme mukavemeti azalmış, sertlik değerleri ise bir miktar artış göstermiştir. Ayrıca, MA veya EK işlemleri uygulandığında SiC takviyeli kompozitlerin mekanik özellikleri B4C’ünküne göre daha iyi olduğu belirlenmiştir.In this study, hypereutectic Al-Si alloy namely Alumix–231 (Al15Si2,5Cu0,5Mg) aluminium matrix composites were produced via powder metallurgy route. In these produced composites, 5%,10 %, 20% silicon carbide (SiC) and/or boron carbide (B4C) reinforcing particules were used. The powders mixed with mechanical alloying and classical method-that is spex type mixing- were produced via cold pressing method. Extrusion and high pressure torsion were applied onto the cold pressing specimens that were produced with classical method. The mechanical properties (density, hardness, tensile strenghts at normal and different strain rates, bending and impact strengths), microstructure and fracture surfaces of produced aluminium matrix composites were examined. When the mechanical alloying, extrusion and high pressure torsion processes were applied on the composites, it was observed that the powder grain size got smaller and porosity decreased. It was found out that as the porosity decreased, the mechanical properties improved It was also observed that in the produced specimens when the ratio of reinforcement particles increased, porosity also increased. When the mechanical properties were examined, it was identified that the hardness increased but the tensile strength decreased. It was also determined that among the reinforcement materials the mechanical properties of SiC were better than B4C

Mechanical properties of hot pressed SiCp and B4Cp/Alumix 123 composites alloyed with minor Zr

In the present study, effect of Zr addition on the microstructure and wear behavior of aluminum alloy composites (AMCs) reinforced with B4Cp and SiCp particles fabricated via hot pressing were investigated. The samples for the study composed of unreinforced aluminum alloy (Alumix 123) and the composites reinforced with 10% B4Cp and % SiCp were prepared by hot isostatic pressing (HIP) method. Similarly, all the samples alloyed with 0.2% Zr were also produced in order to make a comparison. The produced samples were evaluated for microstructural properties and mechanical tests for hardness, tensile and bending strength were performed. Wear test was carried out at 5 mm/s sliding speed under 3.0 N load for the all kind of hot pressed produced samples. The hot pressed composite microstructures have a more uniform distribution of the reinforcements. After HIP process, the composites were successfully produced with high density (>99%). The addition of Zr increased the yield and tensile strength of the samples. The highest strength value was found for the sample Al 123 matrix alloy with Zr. Evaluation of microstructures showed that copper and zirconium dispersed equally within the matrix microstructure without agglomeration. For the composite samples, Al3Zr, appeared as white precipitate, were inspected around B4C and SiC particles. The composite containing SiC particles and Zr had wear resistance value superior to those of the other counterparts. © 2013 Elsevier Ltd. All rights reserved

Effects of cold pressing and extrusion on the microstructures and mechanical properties of SiC and B4C reinforced alumix-231 alloys

In this research, mechanical and microstructure properties of cold pressing (CP) and extrusion (EXTR) specimens produced via powder metallurgy were investigated and compared. For this comparison, EXTR specimens were hot extruded at 565°C with an extrusion ratio of 4:1. Likewise, CP specimens were compacted under a pressure of 600 MPa and sintered at 565°C. Then, the effects of volume fraction on SiC and B4C particle reinforced Alumix-231 composites were investigated using optical microscopy, SEM and macro hardness testing. Compared to CP specimens, it was found that the hardness and mechanical strengths of Alumix-231 specimens without reinforcement produced using EXTR increased in the ratio of 140 and 190%, respectively. The test results showed that increase in uniformity of reinforcement dispersion and enhancement of interfacial bonding strength of the composites is the main reasons for the improvement of EXTR specimens. As a result, EXTR improves mechanical properties of the specimens by decreasing the porosity and thus increasing the density and interfacial bonding strength. © 2011 Academic Journals

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

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

TiO 2 -SiO 2 Nanokompozit Üretimi ve Deri Finisajında Kullanımı ile Derinin Bazı Performans Özelliklerinin Geliştirilmesi

Deri, kendine özgü özelliklere sahip olan doğal bir üründür. Doğal bir ürün olmasına rağmen deri farklı kalitelerde ve finisajlarda bulunmaktadır. Finisaj işlemi derinin mekanik dayanımı ve çeşitli haslık değerlerini artırmak için önemli bir rol oynamaktadır. Derinin haslık özellikleri büyük ölçüde finisaj veya finisaj kaplamaların karakterini belirlemektedir. Kaplama ile ışık veya sürtünmeye karşı renk haslıkları, ton, parlaklık ya da tutum gibi yüzey özellikleri kazandırılabilmekte ya da iyileştirilebilmektedir. Aynı zamanda, deri hasar veya kusurları (yüzey-sırça kusurları, çizikler) örtülmektedir. Polimer kimyası ve teknolojinin gelişimi deri yüzeyinin pek çok yolla değiştirilmesini mümkün kılmaktadır. Günümüzde müşteri memnuniyeti olgusunun ön plana çıkmasına paralel olarak üreticiler de taleplerinde daha gelişmiş ve daha nitelikli ürünler aramaktadırlar. Geliştirilmiş ürünler olarak deri ürünlerine artan talep yeni teknolojiye dayalı gelişmiş özelliklere sahip malzemelerin kazandırılmasını gerektirmektedir. Bu çalışmada, sol-jel yöntemi ile TiO2-SiO2 nanokompozitin üretimi ve finisaj işleminde deri kaplaması olarak kullanımı ile derinin sürtünmeye karşı renk haslığı, aşınma dayanımı ve finisaj adhezyonu gibi performans özelliklerinin arttırılması amaçlanmıştır. Çalışmamız üç ana bölümden oluşmuştur. Birinci bölümde, TiO2-SiO2 nanokompoziti asit katalizörlüğünde tetraetoksisilan (TEOS) ve titanyum n-butoksit (TBO) karışımının üzerine oda sıcaklığında 3- glisidoksipropiltrimetoksisilan (GLYMO, [(OCH2CH) CH2 OCH2 CH2 CH2]-Si(OCH3)3) ilavesi yapılarak sol-jel yöntemiyle sentezlenmiştir. Elde edilen kompozitin incelenmesi, tane büyüklüğü ve doku fazının oluşumu, kompozit filmin yüzey topografisi ve morfolojisi gibi geniş çaplı fiziksel, kimyasal ve yapısal karakterizasyonlar, Atomik kuvvet mikroskobu (AFM) ve Taramalı elektron mikroskobu (SEM) gibi yüzey analiz tekniklerine başvurularak gerçekleştirilmiştir. Kompozit filmlerin kimyasal yapısını karakterize etmek için Fourier dönüşümü kızılötesi spektrometresi (FTIR) ve Raman spektrometre kullanılmıştır. İkinci bölümde, hazırlanan kompozit finisaj işleminde el tabancası ile püskürtülerek deri yüzeyine uygulanmış, daha sonra deriler, üzerinde kaplama filminin elde edilmesi için kurutma ve ütü işlemlerinden geçirilmiştir. Finisaj işleminde derilerin üzerine kompozit dört farklı varyasyonda uygulanmıştır. Üçüncü bölümde ise, TiO2-SiO2 nanokompoziti ile işlenmiş ve işlenmemiş derilerin fiziksel ve mekaniksel özellikleri karşılaştırmalı olarak değerlendirilmiş ve söz konusu kompozit işleminin mamul derilerin performans özelliklerine etkisi incelenmiştir. Derilerin yapısı ve yüzey özellikleri analizleri SEM, FTIR ve Raman cihazları vasıtasıyla gerçekleştirilmiştir. Derilerdeki titanyum (Ti) ve silisyum (Si) içeriği İndüktif Eşleşmiş Plazma-Optik Emisyon Spektroskopisi (ICP-OES) ile tespit edilmiştir. Bu çalışma sonucunda, sol-jel yöntemi ile saydam ve homojen özellikte TiO2-SiO2 nanokompoziti üretilmiş; kompozitin deri üzerine uygulanması ile ince, düzgün dağılımlı, yapışkan bir kaplama elde edilmiş; kompozitin içerdiği titanyum ve silisyum dioksit bileşiklerinin özellikleri ve avantajlarından yararlanarak derilerin sürtünme haslığı, aşınma dayanımı, finisaj adhezyonu ve UV ışığı haslığı gibi bazı performans özellikleri arttırılmış ve daha iyi bir görünüme sahip, dış etkilere karşı daha dayanıklı deriler elde edilmiştir. Ayrıca, plazma aktivasyon ve kompozit ile plazma kaplama kombinasyonları yapılarak derilere hidrofobik özellik de kazandırılmıştır

Concurrent Enhancement of Strength and Corrosion Resistance in Ultrafine-grained Al6063 Tubes

This paper deals with the employment of the successive ECAP method on tubular Al6063 samples and its related properties. Application of the four passes process improved yield strength, ultimate tensile strength, and hardness up to 231%, 54%, and 92% so that the increasing rate was high at the initial passes. As compared to the as-received sample, hardness distribution uniformity which was considerably reduced at the first pass was enhanced to some extent in further passes. Microstructural analyses showed the transformation of coarse-grained structure into the elongated ultrafine-grained counterpart by successive new dislocations formation, accumulations, and their final arrangements. The corrosion performance was enhanced by the addition of pass numbers through the reduction of the depth and size of pits so that the four passes sample had a denser and more stable passive layer which in turn decreased the corrosion rate and corrosion current density. © 2021, The Indian Institute of Metals - IIM.University of MaraghehThe authors would like to thank the University of Maragheh for the financial support of this research