Indian Journal of
Engineering & Materials Sciences

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VOLUME 15	NUMBER 3		JUNE 2008
CODEN: IEMSEW		ISSN: 0971-4588

CONTENTS

A graphical approach for kinematic design and development of an automatic stamping machine using four bar chain	229
Rakesh Sehgal & Ashim Sharma
Comparison of properties of silver-tin oxide electrical contact materials through different processing routes	236
Asmita Pandey, P Verma & O P Pandey
Nucleation kinetics studies on embedded nanosized indium (In) particles	241
Sanjay Chaubey
Microstructural features and mechanical properties of carbon nanotubes reinforced aluminum-based metal matrix composites	247
A K Srivastava, C L Xu, B Q Wei, R Kishore & K N Sood
An investigation of ion transport properties in silver phosphate glassy systems doped with Fe, Mn and Zn chlorides	256
S S Das, N P Singh , Vibha Srivastava & P KSrivastava
Optical thin films of silica and titania deposited by plasma polymerisation process: System design and fabrication	265
K M K Srivatsa, Mrinmoyee Bera, A Basu & T K Bhattacharya
n-HgxCd1-xSe thin film electrodes for photoelectrochemical applications	275
V B Pujari, D J Dhage & L P Deshmukh
Relationship between the electric spark sensitivity and detonation pressure	281
M H Keshavarz

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 229-235

A graphical approach for kinematic design and development of an automatic stamping machine using four bar chain

Rakesh Sehgal & Ashim Sharma

In this paper, an attempt has been made to develop a stamping machine for making the labelling operation in any production line automatic. An inversion of the four bar chain with one link suitably shaped in the form of a stamp has been designed such that it labels each of the boxes present on the conveyor one by one. Though the stamping machine is not a new device and such devices have been made and are currently being used the world over, it is, the methodology of design used in this paper, which is rather unconventional. The mechanism has been designed graphically using the three position synthesis of four bar chain mechanism in which three positions of the coupler link of the mechanism have been fixed to carry out the synthesis. A prototype of the stamping machine has been fabricated and checked for smooth working.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 236-240

Comparison of properties of silver-tin oxide electrical contact materials through different processing routes

Asmita Pandey, P Verma & O P Pandey

In the present work silver-tin oxide (Ag-SnO₂) electrical contact materials have been prepared by different processing techniques, viz., powder metallurgy (P/M), internal oxidation (I/O) and internal oxidation of alloyed powders (IOAP). The influence of processing routes on the physical properties such as electrical conductivity, density and microstructure of these Ag-SnO₂ composite materials are compared. The microstructural study reveals that internal oxidation (I/O) technique provides most uniform structure.

Indian Journal of Engineering & Materials Sciences

Vol 15, June 2008, pp. 241-246

Nucleation kinetics studies on embedded nanosized indium (In) particles

Sanjay Chaubey

Indium exhibits a monotectic reaction with Al at an invariant temperature (910 K) and composition (4.7 at.% In). Ultra rapid cooling, using gun technique, of monotectic compositioned alloy led to a microstructure in which In was distributed uniformly with a bimodal size distribution. Quantitative metallographic analysis revealed size of small sized In particles to be in the range of 10-20 nm whereas bigger particles were found to be even greater than 200 nm in size. These particles of In undercooled by 19 K in the rapidly solidified product of Al-In system. In the as-cast condition the degree of undercooling was only 9 K. Analyses of the nucleation rate measurements showed that the activation energy barrier to nucleation is
2.666 kcal/mol at undercoolings approaching 19 K. The nucleus-substrate contact angle was found to be 20°, which signifies that Al provides a potent catalytic surface for the nucleation of In.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 247-255

Microstructural features and mechanical properties of carbon nanotubes reinforced aluminum–based metal matrix composites

A K Srivastava, C L Xu, B Q Wei, R Kishore & K N Sood

The composites of aluminum-carbon nanotubes, produced using catalytic chemical vapour deposition method, are prepared with initial composition of aluminum homogeneously mixed with 1, 2, 4 and 10wt% nanotubes and subsequently hot-pressed. TEMs and a STEM have been used to study the as prepared carbon nanotubes and their distribution in aluminum matrix after reinforcement. A set of preliminary observations delineated that the yield of as produced nanotubes in carbonaceous is very high with an average diameter of about 45 nm and with straight and spiral shapes. In composites, these tubes have been seen uniformly distributed in aluminum matrix without any significant dimensional alteration. An enormous increase in microhardness of aluminum – 10wt% carbon nanotubes composites in contrast to pure aluminum has been a remarkable study. Some of the important microscopic details, electrical measurements and mechanical properties in the nanotubes and their composites have been elucidated and discussed.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 256-264

An investigation of ion transport properties in silver phosphate glassy systems doped with Fe, Mn and Zn chlorides

S S Das, N P Singh , Vibha Srivastava & P K Srivastava

The ion transport properties of silver phosphate glasses doped with different weight percent of chlorides of iron, manganese and zinc have been studied .The synthesized glasses have been characterized by X-ray, FTIR, differential scanning calorimetry, transference number measurements and electrical conductivity studies. Their amorphous nature, structure, glass transition temperature, transference number and ionic conductivity have been investigated. The variation of room temperature conductivity with dopant composition has been found to be controlled by the variation in the amount of dopant ions (Fe³⁺, Mn²⁺ and Zn²⁺) present in the glass samples and the trend is

s ( – ZnCl₂ ) > s ( – MnCl₂ ) > s (– FeCl₃ )

The Ag₂O–P₂O₅–(10%) ZnCl₂ glass system yielded maximum while the system Ag₂O–P₂O₅–(10%) FeCl₃ exhibited the lowest conductivity values respectively .The temperature variation of conductivity has been found to follow an Arrhenius relation.

The results of ion transport studies are in accordance with the variation of glass transition temperature and changes in the structure of Ag₂O–P₂O₅ glass by the addition of Fe, Mn and Zn ions as studied by infrared spectroscopy.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 265-274

Optical thin films of silica and titania deposited by plasma polymerisation process: System design and fabrication

K M K Srivatsa, Mrinmoyee Bera, A Basu & T K Bhattacharya

Plasma polymerization provides a very versatile and cost-effective technique for the deposition of a wide variety of dielectric films, in particular optical thin films of silica (silicon dioxide) and titania (titanium dioxide) that are widely used as low and high index films in optical multilayer coatings for a variety of applications. The deposition of these films is often carried out using toxic and corrosive precursors–silane gas for silica and titanium tetrachloride liquid for titania – that are expensive and difficult to handle. The use of non-toxic organic liquid precursors, that are cheaper and safer and easier to handle, has been reported for the deposition of these films. In order to develop indigenous expertise in such deposition processes, a plasma polymerization deposition system that uses non-toxic and safe organic liquid precursors for the deposition of optical quality silica and titania films has been designed and fabricated in-house and successfully made operational. The problems that arise in this deposition process, the methods adopted to overcome them, the precautions that must be taken, have been studied in detail. Optical quality silica and titania films with satisfactory refractive indices and extinction coefficients have been deposited using this home-made deposition system.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 275-280

n-Hg_xCd_1-xSe thin film electrodes for photoelectrochemical applications

V B Pujari, D J Dhage & L P Deshmukh

Mercury cadmium selenide (Hg_xCd_1-xSe) thin film semiconductor photoelectrodes of various compositions (0 £ x £ 0.2) are fabricated on glass and stainless steel substrates by a simple chemical bath technique. The different preparation parameters and deposition conditions are optimized to yield quality samples. By increasing the Hg-content in host CdSe- lattice, an optical gap (E_g) of the alloyed semiconductor is reduced from 1.72 to 1.06 eV, which corresponds to maximum absorption in the visible and near infra-red regions of solar spectrum. The photoelectrochemical (PEC) cells are then fabricated and studied for their performance through the various parameters. It has been observed that the flat band potential (V_fb) increased with electrode composition, x and reached a maximum at x = 0.01. The variations in the photopotential (V_ph) and photocurrent (I_ph) are studied as a function of the electrode composition. Both V_ph and I_ph are found to be boosted significantly and are explained on the basis of the electrode materials properties.

Indian Journal of Engineering & Materials Sciences

Vol. 15, June 2008, pp. 281-286

Relationship between the electric spark sensitivity and detonation pressure

M H Keshavarz

A new method for the prediction of electric spark sensitivity of polynitro arenes through maximum obtainable detonation pressure has been proposed. This work uses two additional factors, which depend on the contribution of some structural parameters. Twelve polynitro arenes as training set were applied to optimize new correlation and twenty two polynitro arenes as test set were also used to check the validity of the method. The calculated electric spark sensitivities have a root mean square (rms) deviation of 2.27 J and a maximum deviation of 4.48 J from experimental data for training set. The rms and maximum deviations of predicted electric spark sensitivities from experimental values for test set are 2.28 and 4.77 J, respectively.