Journal of Metastable and Nanocrystalline Materials Vol. 29

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Authors: Ketul Arvindbhai Patel, Ganesh R. Karthikeyan, S. Vincent
Abstract: Determining mechanical properties of Bulk Metallic Glasses (BMGs) requires synthesizing of the alloys in bulk form. However obtaining metallic glass in bulk form is quite challenging due to its tendency towards crystallization. In such circumstances it is beneficial to determine the mechanical properties of materials using finite elemental analysis of microstructures. Thus, in the present investigation, using Object Oriented Finite Element Analysis (OOF2) software package, Stress-Strain analysis has been carried out on Zr60Cu10Al15Ni15 BMG to determine such mechanical properties. Specimen of Zr60Cu10Al15Ni15 BMG exhibiting three microstructurally distinct regions amorphous, partial crystalline and crystalline regions was used for this analysis. The Stress-Strain relationship have been estimated for each of the three distinct phases and the results are validated by determining the Modulus of Elasticity for all the phases and comparing it with the available experimental results from Nano-indentation test.
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Authors: Mochamad Asrofi, Hairul Abral, Anwar Kasim, Adjar Pratoto
Abstract: The isolation and characterization of nanocrystalline cellulose (NCC) from water hyacinth (WH) fibers were carried out. There are two treatments to obtain NCC from WH fibers by chemical and mechanical treatments. The chemical treatment involved alkalization with NaOH 25% in a highly-pressured tube, acid hydrolysis with 5M HCl, and bleaching with (NaClO2:CH3COOH) in ratio 5:2. The mechanical treatment was performed by using ultrasonic homogenizing at 12000 Rpm for 2 h. The morphological surface was observed by Transmission Electron Microscopy (TEM). TEM reported that the size of NCC was 10–40 nm. Crystallinity index and functional group analysis of the NCC WH fibers were also examined using X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. XRD reported that the crystallinity index increased significantly after chemical and mechanical treatment due to the presents of crystalline area in the WH fibers. The crystallinity index of raw fiber, digester, bleaching, and ultrasonic homogenizing were 7%, 68%, 69%, and 73% respectively. The content cellulose of final product was 68% as measured by the chemical composition test. Meanwhile, FTIR reported that WH fibers after being given chemical treatment lead the functional group change due to removal hemicellulose and lignin. The result of XRD and FTIR were indicated that the sample of NCC WH fibers presents the structure of cellulose crystal type I.
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Authors: Akeel M. Kadim
Abstract: The white light generation mechanism was explained depending on mixing colors from the illuminated CdTe/ZnSe core/shell nanocrystals. The color mixed in CdTe/ZnSe core/shell system were used to generate intense white light when illuminated by InGaN/GaN UV LED (λ=360 nm) the core/shell system tuned the chromaticity coordinates to (0.30, 0.32) and increased the intensity of the emitted white light. This improvement was attributed to the overlap of emission with the photoluminescence (PL) spectrum of CdTe/ZnSe core/shell which leads to a cold white light generation.
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Authors: S. Nallusamy, J. Logeshwaran
Abstract: In recent times, it could be observed that metal matrix composites receive considerable importance on account of improved properties compared to unreinforced alloys which includes high specific strength, specific modulus, damping capacity and good wear resistance. Interest in composites containing low density and low cost reinforcements has been since growing. Among various discontinuous particulate, silica is one of the most inexpensive and low density reinforcement available in large quantities. Hence, composites with aluminium oxide as reinforcement after the in-situ reaction of aluminium and silica are likely to overcome the cost barrier for wide spread applications in automotive and small engine applications. It is therefore expected that the incorporation of aluminium oxide particles in aluminium alloy will improve the mechanical properties of base material that will see increased usage in aircraft application due to reduced weight. In this research an effect on aluminum matrix composite reinforced with nano sized silica particles with different weight percentage was carried out. From the results it was found that the composites with 4 to 6wt% particle volume fraction to be the best with good tensile strength, yield stress and percentage elongation.
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Authors: Nanang Eko Wahyuningtiyas, Heru Suryanto
Abstract: The research is to investigate influence of sonication treatment on the morphologi and mechanical properties of bioplastic filler nanoclay with different nanoclay concentration. The bioplastic was prepared using blending method among bioplastic, glycerol, and nanoclay with assistance of sonication treatment of 30 mins. Structural characterization of bioplastic was examined using scanning electron microscopy (SEM), mechanical properties using durumeter Shore A, tensile strength and the physical properties using density. SEM evidence on a bioplastic basis. Hardness of bioplastic with addition of nanoclay 5.0% (b/b) and sonication treatment produce bioplastic with maximum hardness properties increased to 76.24 Shore A, tensile strength of 13.5 and Young’s modulus of 47, as well as the added density of 1.238 g/cm3. Nanoclay 7.5% (b/b) upwards will experience decreased hardness and experience agglomerate and debonding.
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Authors: Sergei I. Tretiakov, Elena N. Koptelova, Natalia A. Kutakova, Nina V. Bagretsova, Nadezhda L. Voropaeva
Abstract: Birch bark attracts attention of researchers as a source of betulin and other extractive substances (ES) useful for chemical, pharmaceutical and food industries. A challenge is to develop an efficient way of obtaining these bioactive agents. This paper presents a microwave-assisted technique of extracting these substances from the waste birch bark of the plywood industry. The kinetics of the extraction was investigated. With the process going on in the pore-diffusion area, the hydrodynamic conditions of the operation are discussed. An algorithm for calculating the kinetics of the procedure was developed and experimentally confirmed. The estimations for the process were made at constant values of the internal diffusion coefficient. The value of the coefficient was found to be a function of the birch bark fragments dimensions. An equation was established to estimate the duration of the extraction to obtain the given yield of ES and betulin.
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