bluuebunny/crossref_metadata_2025 huggingface dataset:
Wetting Kinetics and Cooling Performance of PAG Polymer Quenchants
Authors: Pai Ashwin , Vignesh Nayak U. , Pranesh Rao K.M. , Prabhu K.N.
Published: September 2015

The present research work is aimed at the estimation of quench severity Polyalkylene Glycol (PAG) polymer quenchants having varying concentrations. An Inconel600 probe instrumented with thermocouples was used for this purpose. The thermal history at various locations in the probe was used as an input to the inverse heat conduction model. The inverse analysis yields spatially dependent heat flux transients. The quench severity was assessed using the Grossmann technique. The wetting kinematics of quenching was studied by cooling curve analysis. The severity of quenching as measured by the Grossmann’s technique was found to be higher for polymer quenchants. However, the heat flux transients estimated by the inverse technique and rewetting times measured form the cooling curve analysis suggested comparable and uniform heat transfer with polymer quenchants compared to water quenchants.
Development of Hot Isostatic Pressing Technology for Investment Cast Products
Authors: Dineshraj S. , Acharya Mayukh , Agarwal Alok , Girikumar S. , Govind  , Sharma S.C. , George Koshy M.
Published: September 2015

Hot isostatic pressing (HIPping) technology is used for healing the casting defects for aerospace applications. Castings used for aerospace applications like turbo-pumps need to meet very stringent quality requirements. Complexity of the castings used in these applications, makes it difficult to meet the quality requirements in all the areas. Defects like gas holes, shrinkages, cavities etc. may occur in few locations and need to be repaired by welding or healed by HIPping. In the present study, we attempted to simulate the defect healing capability of HIP in a systematic manner. Artificial defects were created in Austenite-Martensite grade stainless steel cast rod. These rods were then subjected to HIP prcoss cycle at 1150 °C and at a pressure of 1620 bar. Healing of the defects was ensured through X-ray radiography. Detailed microstructural analysis using optical metallography and scanning electron microscopy (SEM) with EDX was carried out before and after HIPping, to understand the defect healing mechanisms. These results are discussed in detail here.
Application of Small Punch Test to Evaluate Tensile Properties of SA213T22 Grade Boiler Steel
Authors: Rao M. Venkateswara
Published: September 2015

Conventional tensile test methods are used for service exposed high temperature boiler tubes to evaluate the deterioration in mechanical properties such as tensile strength, yield strength and percentage elongation. The mechanical properties are required to be evaluated periodically as the boiler components undergo material degradation due to aging phenomena. The aging phenomena occurs due to continuous exposure of tubes to high temperature & pressure steam prevailing inside the tubes and high temperature exposure to corrosive combustible gases from the external surfaces within the boiler.A recent developed new technique called small punch testing has been used to evaluate the tensile properties of SA 213T22 grade steel predominantly exists in super-heater and re-heater sections of boiler. The small punch tests have been carried out on the miniature disk shaped specimens of diameter of 8.0 mm and 0.5 mm thickness extracted from both the new and service exposed tubes. Conventional uniaxial tensile tests on standard specimens from the same tube material have also been performed for comparison. The service exposed tubes showed considerable loss in mechanical properties in both the conventional and small punch test results. Correlations of tensile properties have been obtained based on the comparative analysis of both small punch and uniaxial tensile test results. Further, the study showed that an appropriate empirical relation could be generated for new and service exposed materials between both the techniques. Conventional test methods require large quantity of material removal for test samples from in-service components whereas small punch test method needs only a miniature sample extraction. This small punch test technique could also be extended to evaluate the thicker section boiler components such as pipelines and headers in the boiler as a part of remaining life assessment study. Also this technique could be a useful tool to any metallic component where large quantity of sample removal may be difficult or may not be feasible.
Evaluation of Elastic Properties of CP Ti by Three Different Techniques
Authors: Saravanan K. , Sumit Bhal , Nithilaksh P.L. , Ramesh Narayanan P.
Published: September 2015

Elastic constants are the fundamental key parameters in the mechanical behaviour of engineering materials under stressed condition. This paper explains the determination of elastic constants of commercially pure titanium (Grade-2) at ambient temperature using three independent test methods including quasi-static tensile test with strain gauged specimen, ultrasonic pulse echo method and resonance based impulse excitation technique. The results are statistically analysed and compared.
On the Measurement of Dynamic Elastic and Internal Friction Properties of Nickel Based Super Alloys up to 650°C Temperature
Authors: Saravanan K. , Sharma V.M.J. , Ramesh Narayanan P. , Sharma S.C. , George Koshy M.
Published: September 2015

Elastic constants are the fundamental key parameters to understand the mechanical behaviour of engineering materials under stressed condition. This paper explains the test methodology and provides results of experiments carried out using resonance based high temperature impulse excitation technique test facility for the measurement of technical elastic moduli i.e., Young’s modulus (E), Shear modulus (G), Poisson’s ratio (ν) and internal friction (Q-1) of two nickel-base polycrystalline super alloys IN718 and Haynes 214 from ambient to 650°C temperature in argon environment during heating and cooling.
Effect of Bending Strain in Forming Limit Strain and Stress of IN-718 Sheet Metal
Authors: Prasad Sajun , Panda Sushanta Kumar , Kar Sujoy Kumar , Narayana Murty S.V.S. , Sharma S.C.
Published: September 2015

The forming limit diagram (ε-FLD) was estimated by deforming IN-718 sheet metal in different strain paths using a sub-size limiting dome height test set-up. The bending strains induced due to the use of smaller punch were estimated in all the strain paths, and the corrected ε-FLD was evaluated. The mathematical models such as Hill localized necking, Swift diffuse necking and Storen-Rice bifurcation theories were implemented to predict the limiting strains. In-order to avoid the path dependency of the ε-FLD during multi-stage forming process, stress based forming limit diagram (σ-FLD) was estimated using von-Mises and Hill-48 anisotropy plasticity theory with incorporation of Hollomon power hardening law. It was found that the bending strain influenced the limiting strains and stresses in the forming limit diagram. However, IN-718 material has encouraging formability in stretch forming process. The plot of the equivalent strains versus triaxiality indicated increasing limiting strain of the material in tension-tension mode.
Effect of EBW Parameters on Weldment Quality of Ti6Al4V Alloy
Authors: Gopalakrishna Pillai M. , Sreejith P.S. , Gupta R.K. , Pant Bhanu , Harikumar P.C. , Venugopal N.
Published: September 2015

The penetration characteristics of EBW are primarily dependent on the main beam current (Iw), potential difference between the cathode and anode (voltage, V) and the welding speed (S). There are other influencing parameters like weld focus current (If), welding gun to work distance (GW) and beam oscillation.In the present study, the effect of work distance on focus current and on penetration of Ti6Al4V weld is studied using a 60kV, 30kW EB welding machine. Weld focus current is measured over a range of work distance and variation in its pattern is studied. Similarly, the variation of depth of penetration by varying the work distance and varying the focus current at a particular work distance constant are also analyzed.It is observed that, focus current is inversely proportional to the work distance and the variation in focus current per unit change of work distance is high in the shorter work distance region. The change in focus current and work distance affects the weld penetration and fusion zone geometry. For optimum penetration at a given work distance, the beam focus should be below the surface in keyhole welding. As the work distance increases, the penetration capacity of the beam decreases and maximum penetration is obtained in lesser work distance region.
Characterization of Electron Beam Weld Joints of Alpha-Beta Titanium Alloys for Cryogenic Applications
Authors: Naresh Kumar Kurnala , Muneshwar Pravin , Singh Satish Kumar , Jha Abhay Kumar , Pant Bhanu
Published: September 2015

Titanium alloys play a major role in launch vehicle due to its high specific strength, good weldability, excellent corrosion resistance and retain toughness at cryogenic temperatures. In the present paper we discuss on the electron beam welding studies carried on alpha-beta titanium alloys for cryogenic applications in launch vehicle programme. The Ti6Al4V having extra low interstitial elements and Ti5.4Al3Mo1V alloys were joint individually through electron beam welding on 6.8mm thickness coupon. Carried microstructural observations of the weld by optical microscope and are reported. Further tensile properties evaluated in welded condition at ambient and cryogenic (20K) temperatures are compared with parent metal properties. Micro hardness plot was generated across the weld in the transverse direction for both the alloys. Showing highest hardness in the weld region and drops towards the parent metal, due to formation of very fine martensitic alpha with high dislocation densities within coarse beta grains of the weld and HAZ region. The failure location of all the weld specimens is in parent metal far away from the weld region.Keywords:Ti6Al4V-ELI,Ti5.4Al3Mo1V,electronbeamwelding,cryogenic,microstructure,microhardnessandtensileproperties.
Modelling and Simulation of Temperature and Stress Analysis in TIG Welding Process
Authors: Chandak Nayan , Pradhan Mohan Kumar , Boriwal Lokesh
Published: September 2015

In this study, the welding process is modelled and analysed using ANSYS software. The temperature and residual stress produced during the process is depicted. During heating, the material conditions, parts affected by residual stress and the stress–strain state at different time interval is recorded and a subsequent structural analysis is used for the analysis, the same is used in the analysis where thermal and structural results are investigated. Subsequently, with sensitivity analysis the results are evaluated. Non-uniform meshing is used to entrap the result with fine mesh in the heat affected zone and coarse mesh away from it to save processing time. The results from the thermal structural analysis are presented to understand the process deeply and comparison of the graph plot between temperature and time is explained.
Influence of Filler Wire Material on Dissimilar Welding of 15-5PH to KC20WN (Haynes 25)
Authors: Thomas Joby V. , Thomas Tharian K. , Anoop C.R. , Chakravarthy P.
Published: September 2015

Many of the components/assemblies used in strategic sectors involve dissimilar metal weld joints and dissimilar welding has always imposed challenges in terms of the weld quality because of the physical and chemical mismatches of the base metals. In the present study, dissimilar welding of stainless steel 15-5PH (UNS S15500) to a Cobalt-base super alloy KC20WN (UNS R30605/ Haynes 25) is attempted for specific purpose in space applications. Gas Tungsten Arc Welding is carried out with two types of filler wires, viz., KC20WN and ER 630 (17-4PH). Visual inspection, Dye Penetrant testing and X-ray radiography testing revealed defect free joints and the joints were also characterized for microstructure. Superior properties were observed when welding was carried out with KC20WN filler wire compared to that with ER630 filler wire.
Explosive Welding of SS304 and Al6061 Using Copper as Interlayer – Development of Trial Methodology and its Optimisation
Authors: Srivastava Niraj , Upadhyay Abhishek , Kumar Sandeep , Diva  , Singh Jaspreet , Agarwal Arun
Published: September 2015

This paper explains the technique of explosive welding for joining SS304 and Al 6061 using Copper interlayer. The joining was done in two stages. In the first stage SS304 (thickness: 20 mm) was joined to Copper (thickness: 3mm). Second stage involved joining of SS-Cu plate to Al 6061 (thickness: 8 mm).The paper presents detailed discussion on important parameters required for explosive welded process. The most important parameter is minimum and maximum flyer plate velocity required for creating the impact. Collision angle and angle of impact are also discussed. Another important parameter is the Velocity of detonation (VOD) of explosive to be used. The explosives used have VOD of the order of 2500 m/s and 1600 m/sec. Since the explosive welding process involves formation of jet between two surface, therefore surface conditions of the base and flyer plate like its flatness, roughness and cleanliness which are very critical for proper joining have been discussed in this paper. Chisel test (which is considered to be most rugged test) was conducted on the joint. The test confirmed successful joining.The paper explains how use of trimonite expands the weldability window in comparison to NGU when used for direct SS to Al alloy welding.It also compares the results obtained by use of two different powder explosives to obtain the same tri-layered plate via two different routes. The results are particularly interesting because both the explosives have substantial difference in their properties such as Velocity of Detonation, Gurney Characteristic Velocity, density and homogeneity which can be used as advantages from different angles of views.
Microstructure Mapping: An Approach to Quantitative Interpretation of Microstructural Evolution in Indian Fast Reactor Advanced Clad Material during Hot Forging
Authors: Aashranth B. , Kumar Santosh , Samantaray Dipti , Albert Shaju K. , Borah Utpal , Bhaduri A.K.
Published: September 2015

In this paper, microstructural evolution of Indian Fast Reactor Advanced Clad (IFAC-1) steel during thermo-mechanical processing has been investigated. Hot isothermal forging has been simulated in a Gleeble® thermo-mechanical simulator in the temperature range 1173-1473K and true strain rate range 0.01-100s-1. Instability map has been developed using the stress-strain data obtained. Effect of major forging parameters on various microstructural features has been studied quantitatively. Results from this study have been used to construct various maps (‘μ-maps’) representing different aspects of microstructural evolution. An analogy between the μ-maps and instability maps provides essential insights into possible instability mechanisms operative in the material. The μ-map analysis shows potential as a tool for optimisation of industrial-scale forging parameters.
Understanding Fatigue Damage Progression in Low Velocity Impacted CFRP Laminates through Stiffness Measurements
Authors: Prakash Raghu V. , Sudevan Deepika
Published: September 2015

Carbon fibre composites used in many safety-critical applications experience damage due to operating environment such as bird strike, hailstorm etc., In some cases, the damage is barely visible and its presence in the structure can cause accelerated damage leading to catastrophic failure. In this paper, the results of fatigue damage progression in woven CFRP laminate subjected to constant amplitude loading for un-impacted specimens as well as impacted specimens are presented. The stiffness of the specimens was periodically monitored during fatigue testing to arrive at the rate of damage progression. Special experiments were carried out under a programmed version of an equivalent fighter aircraft loading – FALSTAFF (Fighter Aircraft Loading Standard for Fatigue and Fracture) and it was observed that the damage progression is slower in case of spectrum loading compared to constant amplitude loading. The effect of load sequencing on damage is investigated in this paper.
Development of Machinable Glass-Ceramic without Nucleating Agents
Authors: Venkateswaran C. , Padala Amarnath , Sreemoolanadhan H. , Ajith M.R. , Mathew Mariamma , Sharma S.C.
Published: September 2015

Mica containing glass-ceramic is prepared by crystallizing magnesium alumino silicate glass between 600°C and 1100°C without the use of any additives or nucleating agents. Effects of ceramization heat treatment conditions on phase constitution and microstructures are analyzed using XRD and HRSEM respectively. Developed glass-ceramics have been analyzed for its microhardness and machinability. Optimum heat treatment condition for achieving uniformly distributed fluorophlogopite phase essential for machinability, and at the same time, magnesium aluminum silicate phase for increasing the hardness, is presented.
Synthesis and Characterization of RADAR Absorbing BaFe12O19/ZnFe2O4 Magnetic Nanocomposite
Authors: Tyagi Sachin , Singh Amandeep , Paul Ashok Kumar , Agarwala R.C. , Agarwala Vijaya
Published: September 2015

Magnetic composite comprising zinc ferrite and barium hexaferrite; BaFe12O19/ZnFe2O4 nanoparticles having super paramagnetic nature were synthesized by co-precipitation of iron, zinc and barium chloride salts using 7.5 M sodium hydroxide solution. The resulting precursors were heat treated (HT) at 800 and 1200°C for 4 h in nitrogen atmosphere. The hysteresis loops showed an increase in saturation magnetization from 1.040 to 52.938 emu/g with increasing heat treatment (HT) temperatures. The ‘as synthesized’ particles have size in the range of 20–22 nm with spherical and needle shapes. Further, these spherical and needle shaped nanoparticles tend to change their morphology to hexagonal plate shape with increase in HT temperatures. The effect of such a systematic morphological transformation of nanoparticles on microwave absorption properties were estimated in X band (8.2–12.2 GHz). The maximum reflection loss of the composite reaches-23.12 dB (more than 99% power attenuation) at 10.46 GHz which make it a potential material in the area of stealth technology.
Effect of Nanoreinforcement on Fabrication of Al/Al2O3 Surface Composite by Friction Stir Processing
Authors: Naresh P. , Kumar Adepu
Published: September 2015

In this investigation, the effect of nanoreinforcement particles such as Al2O3, tool rotational speed and traverse speed on microstructure and mechanical properties of Al/Al2O3 surface nanocomposites fabricated by friction stir processing was studied. The surface nanocomposites were produced by varying volume percentage of nanoreinforcement, tool rotational speed and traverse speed to attain the best outcome. The fabricated composites were characterized through microstructural evaluation, microhardness measurements and energy dispersive spectroscopy analysis. Microstructural evaluation of the composites revealed that the composites were produced finer grain structure in this stir zone and it is evident for, a dynamic recrystallization was taken place. Higher hardness values were found at the stir zone of the entire composite because of the equiaxed and well dispersion of reinforced particles. The energy dispersive spectroscopy analysis revealed the presence of various elements at the stir zone. A defect free parameter setting for friction stir processing of Al/Al2O3 was obtained at 1120 rpm and 16 mm/min.
Structure and Properties of Electroless Cu and Ni-B Coated B4C Particle Dispersed Aluminum Composites by Powder Metallurgy Technique
Authors: Deepa J.P. , Abhilash S. , Rajan T.P.D. , Pavithran C , Pai B.C.
Published: September 2015

The widespread demand for light-weight materials in various emerging industrial sectors lead to the fabrication of aluminum- boron carbide composites. In this study, the B4C particles were coated copper and Ni-B through electroless process using formaldehyde and sodium borohydride respectively as reducing agents under optimized condition. The microstructural and hardness behavior were investigated for powder metallurgy processed 20 vol. % of B4C and coated B4C particles in the aluminum matrix. Microscopic observation revealed that coating improved the dispersibility of B4C particles in the matrix. The coated particles showed an increase in hardness and particle compaction with reduced porosity.
Development of Al 319-Micro Silica Metallic Composite by Squeeze Infiltration Technique
Authors: Sree Manu K.M. , Rahul P.S. , Ajay Raag L. , Rajan T.P.D. , Brahmakumar M , Pai Bellampettu Chandrasekhar
Published: September 2015

The objective of present investigation is to synthesize porous micro silica based ceramic preform with varying composition of particles using burn out technique and processing of Al-Micro silica metal-ceramic composites by squeeze infiltration method. Direct squeeze infiltration of 319 aluminum alloy on micro silica preform is successfully carried out with the controlled process parameters of initial preform temperature, liquid metal superheat, squeeze pressure and its rate of application, and die temperature. The preform and composites are characterized using optical microscopy, electron microscopy, hardness and compression strength testing. Porous ceramic preform with more than 70% porosity has been fabricated by PEG as pore former. The infiltrated composite have shown uniform and complete infiltration of aluminum alloy in between micro silica particles.
Effect of Nd Substitution on the Structural and Magnetocaloric Properties of Gd5Si2Ge2
Authors: Uthaman Bhagya , Raama Varma Manoj
Published: September 2015

In the present work, Nd substituted Gd5-xNdxSi2Ge2 with x = 0.05, 0.1 and 0.2 have been synthesized by arc melting and the effect of Nd substitution on the structural and magnetocaloric properties of Gd5Si2Ge2 has been investigated. The composition with x=0.05 undergoes a first order phase transition with a Curie temperature of 275 K. With the increase in Nd content to x=0.1 and x=0.2, the compounds undergo a second order magnetic transition at 300 K and 293 K respectively. Maximum entropy changes (-ΔSM) for Gd5-xNdxSi2Ge2 alloys with x = 0.05, 0.1 and 0.2 are 12.8, 7.6 and 7.2 J/kg K, respectively, for 50 kOe. The critical exponent analysis of the paramagnetic to ferromagnetic transition and the scaling behaviour of field dependence of MCE for x=0.1 and 0.2 compositions is also carried out.
Colossal Magneto-Dielectricity in La2NiMnO6 Probed by Raman Spectroscopy
Authors: Neenu Lekshmi P. , Raama Varma Manoj
Published: September 2015

In this work we demonstrate that La2NiMnO6 exhibits a colossal magneto-dielectric (MD) effect (5%-55%) over a broad range of temperatures (100–270 K), when compared to other Rare Earth (RE = Pr, Sm, and Tb) containing Ni-Mn double perovskites. The noticeable magneto-dielectric effect in RE2NiMnO6 signals the influence of spin orientations in the two magnetic sublattices on the spin-lattice coupling. Finally with the help of Raman spectroscopy we clarify that the presence of spin-phonon coupling alone is not the cause for the observed colossal MD effect in RE2NiMnO6.
A Simple Method of Synthesis of Graphene Oxide-Silicon Nanoparticle Composite as Potential Anode Material for Lithium Ion Batteries
Authors: Aswathi R. , Sandhya K.Y.
Published: September 2015

Herein, we report a simple method towards achieving graphene oxide-silicon nanoparticle (GO-Si NP) composite in aqueous solution. The preparation method is environmental friendly and the product formed was characterized using various techniques such as SEM, EDAX, XRD etc. The results confirm the formation of the nanocomposite and the composites with various percentage of Si NP was prepared and is expected to improve the cycling stability of Si NP as an anode material in lithium battery.
Green Synthesis, Characterization and Antibacterial Activity of CuO Nano Particle
Authors: Amith Yadav H.J. , Eraiah B. , Nagabhushana H. , Basavaraj R.B. , Lingaraju K. , Rajanaika H.
Published: September 2015

A green low temperature combustion route is proposed for the synthesis of CuO nanoparticles, using Copper nitrate powder and Nigella sativa (Kalonji) seed extract as the starting materials. The formation of CuO Nps was characterized by PXRD, SEM, UV-Visible etc. The PXRD Pattern reveals that as-synthesized CuO Nps of monoclinic phase and Crystallite structure. The scanning electron microscopy (SEM) images reveal the morphology of the nanoparticles are spherical in shape. CuO Nps show significant antibacterial activity against both gram +ve and Gram-ve bacterial strains using agar well diffusion method. The present method brings out a promising green, simple, low cost and low temperature way to prepare multifunctional CuO nanomaterials.
Non Aqueous Synthesis of Titania Ink for Printed Electronics
Authors: Varghese Mini , Aiswarya R. , Surendran K.P.
Published: September 2015

A non-aqueous synthesis technique of room temperature curable titania ink, screen printed on flexible BoPET film for printed electronics applications is reported. The phase evolution of rutile titania powder, formulation of a fast curing titania ink, as well as the microstructure and dielectric properties of printed pattern are discussed. In terms of ease of synthesis, cost effectiveness and faster curing time, the developed ink is found to be advantageous over water based dielectric inks.
Polymer Grafted Multi-Walled Carbon Nanotube as a Novel Toughening Agent for Epoxy System
Authors: Konnola Raneesh , Joseph Kuruvilla
Published: September 2015

Hydroxyl terminated poly (ethersulfone) was used to modify the surface of multi-walled carbon nanotube (MWCNT). The grafting reaction was confirmed by different characterization techniques such as Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and Transmission Electron Microscope. Epoxy nanocomposites using the modified fillers were prepared. The fracture toughness of the system was examined and compared with MWCNT-epoxy nanocomposite.
Synthesis and Characterization of Nanostructured Tungsten-30 Atomic % Chromium Produced by Mechanical Attrition and Hydrogen Sintering
Authors: Patra Anshuman , Karak Swapan Kumar , Pabi Shyamal Kumar
Published: September 2015

Nanostructured W70Cr30 powders were produced by mechanical alloying (MA) of elemental tungsten (W), Chromium (Cr) powders in a high energy planetary ball-mill using tungsten carbide as grinding media and toluene as a process control agent. The crystallite size and lattice strain of the nanostructured powders at different milling time (0 h to 10 h) was calculated from X-ray diffraction patterns (XRD). The crystallite size of W in W70Cr30 powder reduced from 100 μm at 0 h to 32.8 nm at 10 h of milling with increase in lattice strain of 0.43% at 10 h of milling. The lattice parameter of tungsten shows initial expansion of lattice upto 0.56% at 5 h of milling and contraction of lattice upto 0.93% at 10 h of milling. The scanning electron microscopy (SEM) micrograph also revealed mixed morphology of elemental W and Cr powders consist of spherical and elongated particles during mechanical alloying (0 h to 10 h). The dark-field transmission electron microscopy (TEM) observations indicated that the crystallite size (~30 nm) of W in W-Cr alloy in the as-milled powder is in good agreement with calculated crystallite size from XRD. Maximum solid solubility of 4.4 at.% Cr in W was found at 10 h of milling. The dislocation density increases from 6.75 (1016/m2) to 17.56 (1016/m2) with increase in the milling time from 0 h to 20 h. No cracks in the sintered pellets were visible under scanning electron microscope (SEM). Hardness and Elastic Modulus of sintered W70Cr30 alloy determined by nanoindentation test are less compared to pure W.
Structural and Superconducting Properties of BaF2 Doped SmFeAsO
Authors: Jayakumari Babu Anooja , Pillai Mohan Aswathy , Varghese Neson , Raama Varma Manoj , Upendran Syamaprasad
Published: September 2015

We have studied the impact of simultaneous Ba2+ doping at Sm3+ site (hole doping) and F- doping at O2- site (electron doping) on the structural and superconducting properties of Sm1111 system using a single source, BaF2. With BaF2 doping the extent of layering of the grains and the grain size have been improved considerably. High transport current of 875 A/cm2 at 12 K has been achieved for the doped sample. The binary doped sample shows higher TC of 51 K than the corresponding F-alone doped sample. In addition, substantially high values of HC2 and better JC-H behavior are observed for the BaF2 doped samples. These results strongly indicate the scope for SmFeAsO based conductors with higher current carrying capacity.
Study of Silicone Rubber Based Composites with Nanosized Fillers
Authors: Chakerwarti H.K. , Agarwal Arun , Kumar Pravendra , Gupta Nandini
Published: September 2015

Polymer based insulating dielectric materials have been replaced ceramic dielectric materials in the recent past due to their better electric, thermal and mechanical properties. They are user friendly and can be poured into any shape and size. In this work, room temperature vulcanized silicone rubber (RTVSR) is used as the base insulating material on account of its hydrophobicity and consequent low leakage losses. Further, addition of nanosized fillers into bulk polymers has often been seen to improve their electrical and non-electrical properties. Here, nanosized alumina fillers have been used in the RTVSR matrix. A concentration level of 3% by weight of nanoAlumina (Al2O3) is used. Mechanical mixing and ultrasonic mixing are used for reducing the agglomeration of nanofillers. In this work, we study the effect of incorporation of nanofillers into RTVSR on its propensity to tracking and associated degradation. Inclined plane test for erosion (IPT) as per the IEC60587 is performed. To estimate the extent of erosion, SEM and weight loss analysis are also done. Silicone rubber filled with nanosized alumina is seen to have a greater resistance to erosion in comparison to pure silicone rubber.
A Comparative Study on Corrosion Behavior of Mg-Zn-Gd Alloys by Varying the Gd Content
Authors: Karuna Ratnakaran Athul , Srinivasan Amirthalingam , Pillai Uma Thanu Subramonia , Pai Bellampettu Chandrasekhar
Published: September 2015

In this study, two Mg-Zn-Gd alloys (Mg-5Zn-5Gd and Mg-5Zn-3Gd) are fabricated using high purity raw materials and by a clean melting process and subjected to immersion testing. The results indicate an increase in corrosion rate for increase in Gd content and the results are correlated using SEM, XRD and EDS analyses. It is seen that RE addition provides a protective oxide coating over the sample surface thereby assisting the corrosion resistance.
Electrodeposition of Sn-Ni Alloy Coatings and their Characterization
Authors: Shetty Sandhya , Hegde Ampar Chitharanjan
Published: September 2015

A new alkaline bath has been proposed for deposition of bright Sn-Ni alloy coatings on mild steel (MS). Depositions were carried out at different current densities (c.d.) and their corrosion behaviors were studied in 5 % NaCl solution by electrochemical AC and DC methods. Sn-Ni coating, deposited at low c.d. i.e. at 1.0 A/dm2 was found to be the most corrosion resistant compared to those at other higher c.d., even up to 4.0 A/dm2. This least corrosion rate (CR) is attributed to high wt. % Sn in the deposit. Increase of CR at high c.d. range is due to decrease of wt. % Sn, explained by the observed anomalous type of codeposition, followed by the bath. Regardless of the deposition c.d., the bath developed bright coatings, inherent of Sn-Ni alloy. Experimental results are discussed taking in account of the phase structure, composition and surface morphology of the coatings, evidenced by X-ray diffraction (XRD), Energy Dispersive X-ray (EDX) and Scanning Electron Microscopy (SEM) analysis.
Microstructural and Mechanical Characterization of Alumina Coating on 07X16H6M Substrate
Authors: Srinath J. , Sudarshan Rao G. , Dinesh Deepak , Ramesh Narayanan P. , Sharma S.C. , George Koshy M.
Published: September 2015

Alumina coating is given to a 07Х16Н6M stainless steel substrate, to withstand high frictional loads at elevated temperatures. Properties like high hardness, good adhesion and low thermal mismatch are essential for the coating. An 80%Ni-20%Cr bond coat is given for better adhesion of the alumina coating to the substrate. Air plasma spray technique was used for bond coat as well as the alumina coating.The substrate, bond coat and the alumina coating were characterized using optical microscopy, scanning electron microscopy (SEM) and nanoindentation. Hardness was evaluated using nanoindentation in all the three regions at loads varying from 2 mN in the bond coat to 50 mN in the alumina coating. Alumina coating showed the highest hardness of 11.5 GPa, followed by the bond coat – substrate interface having a hardness of 7.4 GPa. Substrate exhibited the least hardness of 6.3 GPa.
Plasma Ion Nitriding of Low Carbon Stainless Maraging Steel
Authors: Agilan M. , Venkateswran T. , Sivakumar D. , Pant Bhanu
Published: September 2015

Low carbon stainless maraging steel (0.03%C-12%Cr-10Ni-0.6Mo-0.2Ti) is being used widely for various components of the aerospace engines. To improve the wear resistance of the steel various surface hardening processes are being utilized to improve the surface hardness above 900HV. In this present research, plasma nitriding was carried out at two different temperatures of 450 °C and 475 °C for the holding duration of 10 hrs. Temperature of the nitrding process was ensured below the ageing temperature (500 °C) of the steel to avoid lowering of mechanical properties. Effect of plasma nitriding parameters on the surface hardness, case depth, microstructure and phases present in the nitrided layer were investigated in detail using microhardness analysis across the nitrided layer, X-ray diffraction (XRD), optical microscopy and scanning electron microscopy (SEM). It was observed that increase in nitriding temperature increased the surface hardness and case depth. In addition, the presence of Fe3N and Fe4N phases in the nitrided layer were observed using X-ray diffraction technique.
Studies on Corrosion of Mg-Al-Zn Alloy in 30% Aqueous Ethylene Glycol
Authors: Medhashree Harishbhat , Shetty A.Nityananda
Published: September 2015

The Mg-Al-Zn alloy is used in the coolant systems of automobile engines. Corrosion of Mg-Al-Zn engine components by coolants, which consist of 30% aqueous ethylene glycol as a coolant composition, is an important issue in automobile industries. With this preview, in the present study it is intended to study the effect of environmental contaminant sulphate ions on the corrosion behavior of Mg-Al-Zn alloy in 30% (v/v) aqueous ethylene glycol solution. Electrochemical investigations were carried out by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Scanning electron microscopy (SEM) and energy dispersion X-ray analysis (EDX) were used to study the surface morphology and composition of the alloy. Activation parameters for the corrosion process were calculated by conducting the corrosion studies at different temperatures. It was observed that corrosion rate of the alloy in 30% (v/v) aqueous ethylene glycol increases with the increase in the concentration of sulphate ions and also with the increase in temperature.
Microstructure and Nanomechanical Behaviour of Electron Beam Evaporated Yttria Stabilized Zirconia Films on Ni Base Superalloy
Authors: Ponmudi Selvan T. , Shyju Thankaraj Salammal , Kirubaharan A.M. Kamalan , Devapal Deepa , Kuppusami P.
Published: September 2015

Yttria Stabilized Zirconia (YSZ) coating was developed using electron beam physical vapour deposition as a top coat material for thermal barrier application. In the present study, attempt to develop YSZ films by evaporating ZrO2 stabilized with 8 wt% Y2O3 powder using EBPVD technique. YSZ films were deposited on Inconel-718 (Ni-Cr-Fe) substrate by varying the substrate temperature in the range of 673 K to 1073 K. The deposited films have shown good adherence to the substrate and exhibit uniform dense microstructure. The effect of substrate temperature, phase and surface morphology were investigated by XRD, AFM and SEM. The film deposited at 673 K shows crystalline nature and the crystallinity of the deposited films increase with increasing substrate temperature. The surface roughness of the films increases with increase in the deposition temperature due to the increase in crystallinity of the films. SEM images shows that the films are grown with triangular shaped morphology. Nanomechanical characteristics of the tetragonal phase of the YSZ films were investigated by nanointendation technique and the young’s modulus of the coating was found to be 118 GPa.
Grain Refinement in the Magnesium Alloy ZK60 During Multi-Step Isothermal Forging
Authors: Nugmanov Dayan , Sitdikov Oleg , Markushev Michael
Published: September 2015

Transformations of hot-pressed partially recrystallized structure of the magnesium alloy ZK60 into ultrafine-grained one with the (sub) grain size of ~1 μm under multi-step isothermal forging were analyzed. The mechanisms of recrystallization, as well as the role of the processing temperature and second phases in the development of new grains are discussed.
Abrasive Water Jet Machining of Aluminum-Silicon Carbide Particulate Metal Matrix Composites
Authors: Arul Kumar B. , Kumaresan G.
Published: September 2015

Particle Reinforced Metal Matrix Composites (PRMMC's) have proved to be extremely difficult to machine using conventional manufacturing processes due to heavy tool wear caused by the presence of the hard reinforcement. This paper presents details and results of an investigation into the machinability of SiC particle reinforced aluminium matrix composites using Abrasive Water Jet Machining (AWJM). Al-SiC MMC specimens, prepared with stir casting method. The surface roughness of the composite material for these different compositions are examined and compared. The influence of the ceramic particle reinforcement on the machining process was analyzed.
Evaluation of biogenic amines levels, and biochemical and microbiological characterization of Italian-type salami sold in Rio de Janeiro, Brazil
Authors: Dos Santos Luiz Felipe Lopes , Mársico Eliane Teixeira , Lázaro César Aquiles , Teixeira Rose , Doro Laís , Conte Júnior Carlos Adam
Published: September 2015

The objective of the present study was to evaluate the levels of biogenic amines (cadaverine, putrescine, tyramine, histamine, spermidine and spermine) by high performance liquid chromatography (HPLC) and the physicochemical (moisture, lipids, proteins, pH, water activity and fixed mineral residue) and microbiological (lactic acid bacteria and aerobic heterotrophic mesophilic bacteria count) characteristics of six Italian-type salami brands sold in the city of Niteroi (Rio de Janeiro, Brazil). The salami showed lactic acid bacteria count from 5.7 to 8.6 CFU•mL-1, and heterotrophic mesophilic bacteria count from 5.8 to 8.7 CFU•mL-1. Three brands showed moisture contents above 35% and one brand had protein content below 25%. The mean values obtained for the amines were: 197.43, 143.29, 73.02, 4.52, 90.66 and 36.17 mg•kg-1 for tyramine, putrescine, cadaverine, spermidine, histamine, and spermine respectively. Two brands presented histamine contents above the legal limit established in 100 mg•kg-1. We concluded that the evaluated salami presented a wide variation in the count of the bacterial groups whit a predominance of lactic acid bacteria. The moisture contents indicate insufficient drying before commercialization and protein content had values below the minimum limit determined by the Brazilian legislation. Finally, the levels of biogenic amines found could cause adverse reactions in susceptible consumers, depending of the amount and frequency of intake of these products.
The central principle of Calvinism? Some criteria, proposals and questions
Authors: Coletto Renato
Published: September 2015

Is there a ‘central principle’ of Calvinism? This article explores this question mainly from the viewpoint of reformational philosophy. It does so firstly by introducing criteria that should be used to identify, if possible, such a central ‘organon’ of Calvinism. Then a few proposals are evaluated, and their strong and weak points are discussed. The most credible candidate for the role of central principle is argued to be an ‘idea of law’ rooted in the biblical groundmotif and traditionally defined as ‘sphere-sovereignty’. More recent characterisations of this cosmonomic idea are considered. A few objections and alternative proposals are also discussed. The article is concluded with a few questions, calling for further research on the topic.Wat is die sentrale beginsel van Calvinisme? Enkele kriteria, voorstelle en vrae. Is daar ’n ‘sentrale beginsel’ by Calvinisme te bespeur? Hierdie artikel ondersoek genoemde vraag hoofsaaklik vanuit die perspektief van die reformatoriese filosofie. Dit word eerstens gedoen deur die kriteria bekend te stel wat gebruik moet word om, indien moontlik, sodanige ‘organologie’ van Calvinisme te identifiseer. ’n Paar voorstelle word dan geëvalueer en hulle sterk en swak punte bespreek. Die geloofwaardigste kandidaat vir die rol van ’n sentrale beginsel is moontlik ’n ‘wetsidee’ wat in die bybelse grondmotief gewortel is en tradisioneel as ‘sfeersoewereiniteit’ gedefinieer word. Meer resente karakteriserings van hierdie kosmonomiese idee word ook oorweeg. ’n Aantal besware en alternatiewe voorstelle word daarna bespreek. Die artikel sluit af met enkele vrae waarmee ’n oproep tot verdere navorsing oor die onderwerp gedoen word.
Пример нелинеаризуемой квазициклической подгруппы в группе автоморфизмов алгебры многочленов
Authors: Bardakov Valeriy Georgievich , Neshchadim Mikhail Vladimirovich
Published: September 2015

Известно, что всякая конечная подгруппа группы автоморфизмов алгебры многочленов
ранга 2 над полем нулевой характеристики сопряжена с подгруппой
линейных автоморфизмов. Мы покажем, что для произвольной периодической подгруппы это неверно.
Будет построен пример абелевой $p$-подгруппы группы автоморфизмов алгебры многочленов
ранга 2 над полем комплексных чисел,
которая не сопряжена подгруппе линейных автоморфизмов.
Библиография: 10 названий.
Центральные элементы в универсальной обертывающей алгебре и функции от матричных элементов
Authors: Artamonov Dmitrii Vyacheslavovich , Golubeva Valentina Alekseevna
Published: September 2015

В работе приведено построение центральных элементов
в $U(\mathfrak{o}_N)$ и $U(\mathfrak{g}_2)$ на основе
первой основной теоремы теории инвариантов. Построены новые функции
от матричных элементов, естественно возникающие при описании
центра $U(\mathfrak{g}_2)$, подобно тому, как пфаффианы возникают
при описании центра $U(\mathfrak{o}_N)$.
Библиография: 11 названий.
О среднем значении меры иррациональности вещественных чисел
Authors: Shatskov Denis Olegovich
Published: September 2015

В работе рассматривается асимптотическое поведение интеграла
$$
I_\alpha(t)=\int_1^t \psi_\alpha(\xi) d\xi,\qquadгде\quad \psi_\alpha(t)=\min_{1\leqslant q\leqslant t}\|q\alpha\|
$$
(здесь минимум берется по целым $q$ и $\| \cdot \|$ обозначает
расстояние до ближайшего целого).
Библиография: 9 названий.
Оценки функции Грина и параметров экспоненциальной дихотомии гиперболической полугруппы операторов и линейных отношений
Authors: Baskakov Anatoly Grigorievich
Published: September 2015

На основе применения уравнения Ляпунова, метода подобных операторов и методов гармонического анализа получены оценки параметров экспоненциальной дихотомии и функции Грина, построенной по гиперболической полугруппе операторов и гиперболическому линейному отношению. Оценки получены с использованием величин, которые определяются резольвентой инфинитезимального оператора полугруппы операторов и
линейного отношения
Библиография: 51 название.
Efficient Delivery of Local Public Services in Ethnically Fragmented Municipalities
Authors: Nikolov Marjan , Brosio Giorgio
Published: September 2015

Macedonia started its transition from a command to a market economy after its declaration of independence in 1991 from the former Yugoslavia. In 1991, ethnic Albanians abstained from voting for the first Macedonian constitution. Soon claims of ethnic Albanians in Macedonia started to aim at proportional representation in all political institutions, more education in the Albanian language at the university level and changes to the constitution proclaiming Macedonia to be a multi-ethnic country made up, on an equal basis, of Macedonians and Albanians. In 2001, immediately after the Macedonian parliament ratified a border treaty with Serbia, ethnic Albanians clashed with Macedonian armed forces. The clashes ended with the signing of the Ohrid Framework Agreement (OFA) in 2001. Decentralization was a main preferential policy choice out of the OFA. This paper estimates the efficiency of Macedonian municipalities by using the Stochastic Frontier Analysis (SFA). We hypothesise that ethnic fragmentation may have a negative impact on the efficiency of Macedonian municipalities. We also hypothesise that political variables at municipalities in Macedonia also have impact on the municipal efficiency.
Comparing and Measuring Subnational Autonomy across Three Continents
Authors: Ferreira Do Vale Helder
Published: September 2015

The literature on comparative local government has been primarily focused on measurement of local governments while it has fallen short in theorizing on diverse structures, dynamics, and functioning of local governments throughout the world. This article posits that large data sets measuring local government indicators help to accumulate knowledge but fail to identify and explain the main dynamics behind local governments activities and processes. Attempting to increase comparability of local government across different regions, this article builds on qualitative indicators of decentralization in three sub-regions—South America, South Asia and Southern Africa—and assesses the evolution of subnational autonomy in the most decentralized countries in these sub-regions; namely, Brazil, India and South Africa.
Occupational Therapy: Meeting the Needs of Families of People With Autism Spectrum Disorder
Authors: Kuhaneck Heather Miller , Watling Renee
Published: September 2015

Occupational therapy has much to offer to families of people with autism spectrum disorder (ASD). However, people outside the profession may be unaware of occupational therapy’s breadth and scope. It is our responsibility and our duty to express the full range of occupational therapy services through research, clinical practice, advocacy, and consumer education. This special issue of the American Journal of Occupational Therapy, with its focus on autism, embarks on this endeavor by highlighting research and theoretical articles that address the various aspects of occupational therapy practice that can help to fully meet the needs of people with ASD and their families.