Journal of Modern Materials
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Performance and Prospects of Severe Plastic Deformation for Effective Biomedical Titanium Alloys
No full textApplication of severe plastic deformation (SPD) technology to process effective biomedical titanium alloys has shown promising results at laboratory scale. However, more research is still required before adopting this technology from laboratory scale to industrial scale production. This review presents performance and prospects of SPD for effective ultra-fine/nanograin structure-biomedical titanium alloys. Effective biomedical titanium alloys should have desired properties for the medical application. The properties include; high static and fatigue strengths, surface hardness for wear resistance, good ductility, corrosion resistance and biocompatibility. Based on current works reported in the literature, the review focused on; high-pressure torsion (HPT), equal channel angular pressing (ECAP), asymmetric rolling (AR), accumulative roll bonding (ARB) and repetitive corrugation and straightening (RCS). Overview of biomedical application of titanium alloys and desired material properties is presented. A detail discussion on the working principle, performance (e.g. induced strength, hardness, grain size and texture etc.) and material deformation homogeneity of each SPD method are presented. Also, prospects and challenges of each SPD method to be implemented at industrial scale for continuous and mass production are highlighted. The review concludes with the effectiveness of SPD processes, characteristics of processed samples and suggestion of future work for SPD to process effective biomedical titanium alloys at industrial scale
Effect of Electron Beam Irradiation on Polymers
No full textElectron energy loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM) is widely used for chemical state analysis of variety of chemical compounds. High beam sensitivity of substances like polymers hinders the possibility of exploring in-depth analysis provided through the high spatially resolved EELS spectroscopy. In this study, the electron beam irradiation damage on polymers were analyzed with varying dose of electron beams. The stability of the polymers under electron beam exposure depends on the chemical structure on the polymers. In this study the polymers with and without phenyl groups namely Polycarbonate, Polyethylene terephthalate, Polystyrene, Styrene Maleic Anhydride and Polymethylmethacrylate are selected for the comparative degradation study. Effect of varying the electron dose on the stability of polymers were monitored by recording the low-loss EELS spectrum in π to π* transition and (π+σ) to (π+σ)* transition region
Calculation of Normalized Pinning Force and Nature of Pinning Mechanism for Nano-Al Doped MgB2 Superconductor
No full textThe Jc(H) of nano-Al doped MgB2 samples has been calculated from M(H) loop measurements at different temperatures. Normalized volume pinning forces as a function of the reduced field have been analyzed at different temperatures and doping level which was taken from the Jc(H) data. The modified scaling law was used as discussed by the Eisterer to analyze the pinning forces. This law was compared with the scaling law used by the Fietz and co-worker. The grain boundary pinning is found the dominant pinning mechanism in all the doped samples and exhibit the scaling behavior. The XRD and temperature dependence of resistivity confirms the successful substitution of nano-Al at Mg sites. The results endorse that the magnetic anisotropy decreased from pure to the dirty limit with the doping of the nano-Al. The enhancement in the Jc(H) of the sample with the nano-Al doping is due to decrease in the anisotropy and increase in the volume pinning forces. The 2 % nano-Al doped sample between 15–30 K shows the highest Jc(H) among all the samples
Effect of Embedded Strain Gage on the Mechanical Behavior of Composite Structures
No full textFiber reinforced composites are increasingly used in several fields such as aeronautics and civil engineering due to their increased strength, durability, corrosion resistance, resistance to fatigue and damage tolerance characteristics. The embedding of sensor networks into such composite structures can be achieved. In the present study, glass fiber reinforced Epoxy composite with integrated strain gage was analysed. Firstly, the mechanical behaviour of this material with embedded strain gage is investigated. The as-prepared samples have been tested under tensile and flexural loading in order to study the effects of the strain gage embedding on the structural stiffness and strength of the composite. It was found that the tensile stiffness decreases by 5.8% and the tensile strength decrease by 1.5% when the strain gage embedded in the material. On the other hand, the flexural strength and stiffness is increased, respectively, by 1.5% and 5.5% with an embedded strain gage. The experiments showed that embedded strain gage is functional and demonstrated the successful integration of sensor networks into composite parts. The obtained results confirm that integrated strain gage can be used for the Structural Health Monitoring (SHM) of glass fiber reinforced Epoxy composite
Progress and Prospect on Stability of Perovskite Photovoltaics
No full textSolar energy has the potential to solve world energy problem as it is pollution- free. It could be enhanced using perovskite material as an absorber in perovskite solar cells. The history and what this material is made up of are emphasized. Different methods of fabrication, improving the power conversion efficiency (PCE) and factors influencing degradation of perovskite-based solar are stated. Because of the fact that this material based solar cells are not yet developed, its stability was reviewed to bring different technology employed in tackling the stability aiming for a better understanding of the material and the devices and facilitates the commercialization of perovskite solar cell
Upgrading of the Crude Yellow Cake to a Highly Purified Form using Tris (2-ethylhexyl) Phosphate in Presence of EDTA or CDTA
No full textUpgrading crude yellow cake was done by 0.05 M Tris 2-ethylhexyl Phosphate / kerosene from 5 M nitrate solution. More than 98 % of uranium extracted after 5 stages of contact, shaking time 5 minutes and volume phase ratio 1/1. Uranium stripping efficiency reached 99 % using distilled H2O, 10 minutes shaking time, (O/A) ratio 4/1 and three stripping stages. The purity of the produced cakes was enhanced by the addition of EDTA or CDTA. The produced cake using TEHP followed by EDTA addition to the stripping solution before uranium precipitation step was the most preferable cake with lower gangues
Synthesis, Characterization and Properties of MgB2 Doped Polyaniline
No full textPresent paper reports novel synthesis of MgB2 doped Polyaniline (PAni). PAni is synthesized through oxidative polymerization method using Ammonium Peroxodisulphate and doped by different compositions of MgB2. The DC conductivity of undoped and doped polymers is measured in the temperature range of 300 – 400 K and is found to increase with temperature. An increase in conductivity by five orders of magnitude has been observed after doping. Conduction mechanism was also studied in all of the samples. FT-IR (Fourier Transform Infrared spectroscopy) and Ultraviolet (UV)-Visible studies confirm the occurrence of PAni in conducting emeraldine salt form in the composites. The optical studies signify that absorption mechanism is due to direct allowed transition and the band gap decrease after doping. Thermal stability of all the composites has been explained on the basis of variation in Tc–Tg and ∆Hc by using DSC (Differential Scanning Calorimetery) measurements
Scanning Transmission Electron Microscopy for Polymer Blends
No full textPhysical properties of the polymer can be altered by mixing one or more polymers together also known as polymer blending. The miscibility of polymers is a key parameter in determining the properties of polymer blend. Conventional transmission electron microscopy (CTEM) plays a critical role in determining the miscibility and morphology of the polymers in blend system. One of the most difficult part in polymer microscopy is the staining by heavy metals to generate contrast in CTEM. RuO4 and OsO4 are commonly used to stain the polymer materials for CTEM imaging. CTEM imaging is difficult to interpret for blends due to lack of clear distinction in contrast. Apart from having difficulty in contrast generation, staining procedures are extremely dangerous as improper handling could severely damage skin, eyes, lungs etc. We have used scanning transmission electron microscopy (STEM) to image polymer blends without any staining processes. In current work, Acrylonitrile Butadiene Styrene (ABS)/Methacrylate Butadiene Styrene (MBS) and Styrene Acrylonitrile (SAN) along with filler additive were dispersed on Polycarbonate (PC) matrix and studied by STEM/HAADF (high angle annular dark field). By using HAADF, contrast was generated through molecular density difference to differentiate components in the blend
Three Body Abrasive Wear Behaviour of Polyamide 66/ Polypropylene (PA66/PP) Thermoplastic Blends
No full textThree body abrasive wear behaviour of Polyamide 66 and Polypropylene (PA66/PP) blends in different weight percentages of 95/5, 90/10, 85/15, 80/20, 75/25 and 70/30 are investigated. The experiments were carried out as per ASTM G65 by using rubber wheel abrasion tester (RWAT). The tests were conducted for a load of 50 and 75 N at a sliding velocity of 2.5 m/s with an abrading distance of 500, 1000 and 1500 m using fine abrasive dry sand particles as third body. The experimental results revealed that the wear volume and specific wear rate are the functions of load, abrading distance and composition of blend. It was observed from the experimentation that the lower loading of PP into blend decreases the wear resistance. The effective wear resistance starts from higher loading of PP (30 wt.%) in the blend. The abrasive sand particles and their size played a major role in determining the wear characteristics of PA66/PP blends. Substantiate amount of rubber wheel wear contributes to the development of wear resistance. The worn surfaces are studied by using Scanning Electron Microscope (SEM) photographs
The Development of Ternary Nitride Chemistry During the Last Few Decades
No full textThe developments of charged and neutral ternary nitrides during the last few decades have been fast and progressively varied in terms of its preparation, properties, and structures. Ternary metal nitrides of the type MxM’yN draw significant attention as of their overall superior properties such as mechanical, electrical, magnetic, and catalytic. The progresses in ternary nitrides study have become important in the last few decades up to the degree where the scientist is beginning to associate these compounds in level of certain desired kinds of structures. The current relevance of these nitrides overall depends on the fact that they are very narrowly connected to the pure one-dimensional systems that are immensely examined for their remarkable properties and strongly connected to their short dimensionality. Whether its vital investigations to make presently unidentified ternary nitrides or to evolve innovative and prevailing applications, it is evident by going through the numerous articles in this area that regardless of the striking growth in the preceding few decades, substantial is left to be completed