Table of Content

26 December 2013, Volume 1 Issue 4

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Determination of accurate theoretical values for thermodynamic properties in bulk metallic glasses

Pei-You Li Gang Wang Ding Ding Jun Shen

2013, 1(4):  293-304.  doi:10.1007/s40436-013-0040-3

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Deviation values of specific heat difference DCp; the Gibbs free energy difference DG; enthalpy difference DH; and entropy difference DS between the
supercooled liquid and corresponding crystalline phase produced by the linear, hyperbolic, and Dubey’s expressions of DCp and the corresponding experimental values  are determined for sixteen bulk metallic glasses (BMGs) from the glass transition temperature Tg to the melting temperature Tm: The calculated values produced by the hyperbolic expression for DCp most closely approximate experimental values, indicating that the hyperbolic DCp
expression can be considered universally applicable,compared to linear and Dubey’s expressions for DCp;which are accurate only within a limited range of conditions.For instance, Dubey’s DCp expression provides a good approximation of actual experimental values within certain conditions.

Tandem rapid manufacturing of Inconel-625 using laser assisted and plasma transferred arc depositions

P. Bhargava C. P. Paul C. H. Premsingh S. K. Mishra Atul Kumar

2013, 1(4):  305-313.  doi:10.1007/s40436-013-0044-z

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This paper presents an investigation on deposition of Inconel-625 using laser rapid manufacturing (LRM) and plasma transferred arc (PTA) deposition in
individual and tandem mode. LRM has advantages in terms of dimensional accuracy, improved mechanical properties,finer process control, reduced heat input and lower thermal distortion, while PTA scores more in terms of lower initial investment, lower running cost and higher deposition rate.To quantify the clubbed advantages and limitations of both processes, these were studied individually and in tandem. A number of samples were deposited at different process parameters like power, scan speed, powder feed rate. They were subjected to tensile test, adhesion-cohesion test,impact test and micro hardness measurement. The results of individual tests showed the comparable mechanical properties with ±20% variation. The mixed dendritic-cellular and dendritic-columnar microstructures were respectively observed for LRM and PTA deposits with a distinct interface for the case of tandem deposition. The interface
strength of tandem deposits was evaluated employing adhesion-cohesion test, and it was found to be (325 ±35) MPa. The study confirmed the viability of LRM and PTA deposition in tandem for hybrid manufacturing.

Machining of circular micro holes by electrochemical micro-machining process

Alok Kumar Das Partha Saha

2013, 1(4):  314-319.  doi:10.1007/s40436-013-0042-1

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Machining of micro holes with micro electrochemical machining (micro ECM) process has been carried out with an indigenously developed set up. This paper describes relevant problems and solutions for the circular micro holes machining process on 304 stainless steel sheets with 60 lm thickness using high speed steel cylindrical tool of diameter 500 lm and using dilute H2SO4 as electrolyte.The taper angle variation of the machined hole is analyzed and reported for different experimental setting parameters. The minimum value of the taper angle of machined holes is achieved at the parameter setting of
0.4 mol/L H2SO4, 700 kHz, 600 ns and 21 V, for stainless steel sheets and HSS tool.

Study of structural, electrical and optical properties of vanadium oxide condensed films deposited by spray pyrolysis technique

M. Mousavi A. Kompany N. Shahtahmasebi M. M. Bagheri-Mohagheghi

2013, 1(4):  320-328.  doi:10.1007/s40436-013-0045-y

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Vanadium oxides condensed films are prepared on glass substrates, using spray pyrolysis (SP) technique.The effects of substrate temperature, vanadium concentration in initial solution and the solution spray rate on the nano-structural, electrical, and optical properties of deposited films were investigated. Characterizations of the samples were performed using X-ray diffraction (XRD),scanning electron microscopy (SEM), and UV-Vis spectroscopy methods. The type and concentration of the charge carriers were determined and measured by Hall effect experiment. XRD patterns showed that the prepared films had polycrystalline structure, mostly tetragonal β-V₂O₅ and V₄O₉ phases with the preferred orientation along (200) direction. The Hall effect experiment revealed that all samples were n-type, except the ones deposited at substrate temperatures Tsub = 300 ℃ and Tsub = 450 ℃, vanadium concentration 0.1 mol/L and solution spray rate 10 mL/min.The charge carrier concentrations obtained were in the range 10¹⁶–10¹⁸ cm^-3. The lowest sheet resistance (R_s) was obtained for the samples prepared at T_sub = 450 ℃, vanadium concentration 0.05 mol/L and solution spray rate 10 mL/min. It was also found that the optical transparency of the samples changed from 20% to 75% and the optical band gap of the samples was from 2.22 eV to 2.58 eV, depending on the deposition conditions.

Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

Satyanarayana Kosaraju Venu Gopal Anne

2013, 1(4):  329-339.  doi:10.1007/s40436-013-0047-9

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Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work
hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force (F_z) and surface roughness (R_a). In the present work, the performance of PVD/TiAlN coated carbide inserts was investigated using response surface methodology (RSM) for turning Ti-6Al-4V. The effects of process parameters such as speed (v), feed (f), depth of cut (d) and back rake angle (γ_y) on F_z and R_a were investigated.
The experimental plan used for four factors and three levels was designed based on face centered, central composite design (CCD). The experimental results indicated that F_z increased with the increase in d, f and decreased with the increase in v and γ_y, whereas Ra decreased with the increase in v and γ_y, and increased with d and v. The goodness of fit of the regression equations and model fits (R ²) for F_z and R_a were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.

Influence of defect density on the ZnO nanostructures of dye-sensitized solar cells

Yan-Yan Lou Shuai Yuan Yin Zhao Zhu-Yi Wang Li-Yi Shi

2013, 1(4):  340-345.  doi:10.1007/s40436-013-0046-x

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The relationship between bilayer nanostructure,defect density and dye-sensitized solar cell (DSCC) performances was investigated. By adjusting bilayer nanostructures,defect density of ZnO nanodendrite-nanorods structure was decreased comparing to that of nanoflowernanorods structure. The performances of DSCC based on ZnO nanodendrites-nanorods structure and nanoflowernanorods structure were studied by Raman spectrum, room
temperature photoluminescence, dye loading, photocurrent density-voltage characteristic and open-circuit voltage decay (OCVD) technique. The device with nanodendritenanorods structure has lower charge recombination rate and prolonged electron lifetime due to its microstructure feature.

Current status, enablers and  barriers of implementing cellular manufacturing system in Indian industries

Amit R. Dixit Manish Gupta

2013, 1(4):  346-356.  doi:10.1007/s40436-013-0048-8

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The cellular manufacturing (CM) has been proved as a well-known manufacturing strategy that helps to improve manufacturing efficiency and productivity by
utilizing the philosophy of group technology. Large number of papers has been published in the area of design issues of CM system. Unfortunately, the issues related to acceptability of CM in Indian industries are typically not examined rigorously as technical issues. This paper presents the results of a survey carried out to find the status, enabler and barrier of implementing CM system in Indian industries.

Microwave-assisted rapid synthesis of alumina nanoparticles using tea, coffee and triphala extracts

Prasant Sutradhar Narayan Debnath Mitali Saha

2013, 1(4):  357-361.  doi:10.1007/s40436-013-0043-0

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Alumina nanoparticles (AlNP) were synthesized from aluminium nitrate using extracts of tea, coffee and triphala—a well known herbal plant as well as a nontoxic and eco—friendly green material. The synthesis was carried out taking 1:4 ratio of metal salt and these extracts under microwave irradiations at 540 W, which gave better yield of nanoparticles. Water was taken as solvent medium. The formations of AlNP were initially monitored by the colour changes occurring in the reaction mixture during the incubation period. As synthesized nanoparticles were characterized by scanning electron microscope (SEM),
UV–Visible (UV–Vis) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The AlNP were found to be spherical in shape in case of tea and coffee extracts with a size of 50–200 nm and to be oval shaped in case of triphala extract with an average size of 200–400 nm. The formation of AlNP with the microwave-assistance using these plant extracts has proved to be very faster than any other methods. In addition, excellent reproducibility of these nanoparticles, without the use of any additional capping agent or stabilizer will have great advantages in comparison with microbial synthesis, avoiding all the tedious and hygienic complications.

Experimental investigation on the effects of process parameters of GMAW and transient thermal analysis of AISI321 steel

A. G. Kamble R. Venkata Rao

2013, 1(4):  362-377.  doi:10.1007/s40436-013-0041-2

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Gas metal arc welding (GMAW) develops an arc by controlling the metal from the wire rod and the input process parameters. The deposited metal forms a weld bead and themechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height (HB), bead width (WB) and bead penetration (PB) and investigating the effects of four process parameters
viz: welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions.