Indian Journal of

Engineering & Materials Sciences

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VOLUME 14

CODEN : IEMSEW

NUMBER 4

AUGUST 2007

ISSN : 0971-4588

 

CONTENTS

 

Engineering

 

Experimental investigation on the influence of reinforcement and precipitation hardening parameters of AA 6061-SiCp composites

 

277

        K Mahadevan, K Raghukandan B C Pai & U T S Pillai

 

        [IPC Code: C22C 47/00]

 

 

Elastic-plastic stress analysis of a thermoplastic composite disc under parabolic temperature distribution

 

282

        Faruk Sen, Yeliz Pekbey, Onur Sayman

 

        [IPC Code: C08B]

 

 

Current differencing transconductance amplifier-based  current-mode four-phase quadrature oscillator

 

289

        Worapong  Tangsrirat 

 

        [IPC Code: H03L]

 

 

Evaluation of creep coefficient on concrete-filled steel tubular columns

295

        Mustafa Hilmi Acar

 

        [IPC Code: E04C 3/30]

 

 

Materials Science

 

 

Corrosion susceptibilities of Al-Cu/TiC MMCs fabricated by conventional hot pressing

303

        Mehmet Gavgali, Burak Dikici & Fevzi Bedir

 

        [IPC Code: C22F, C22C 47/00]

 

 

Synthesis of nanosized AlN powder using novel nitridation route

309

        Anjan Sil & Pankaj Kumar Verma

 

        [IPC Code: C01F 7/00]

 

 

Study of optical constants in CdxZn1-xS vacuum evaporated thin films

313

        Pawan Kumar, Aravind Kumar, P N Dixit & T P Sharma

 

        [IPC Code: H01C 17/075]

 

 

Low-frequency dielectric response and chain dynamics study of poly(vinyl pyrrolidone)-poly(ethylene glycol) coexisting two-phase polymeric blends

 

317

        R J Sengwa & Sonu Sankhla

 

        [IPC Code C08L 39/04]

 

Predicting heats of detonation of explosives via specified detonation products and elemental composition

 

324

        M H Keshavarz

 

        [IPC Code: C06B]

 

 

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IPC: International Patent Classification

 

Int. Cl.8: International Classification 8th edition, 2006

 

 

  

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 277-281

 

 

Experimental investigation on the influence of reinforcement and precipitation hardening parameters of AA 6061-SiCp composites

 

K Mahadevan, K Raghukandan, B C Pai & U T S Pillai

 

 

The presence of discrete reinforcement particles in the matrix of the discontinuously reinforced metal matrix composites considerably alters the matrix microstructure and hence the precipitation hardening kinetics. Therefore, precipitation hardening schedule of aluminium alloys are not applicable to aluminium matrix based discontinuously reinforced composites. In the present work, an attempt has been made to systematically study the effects of reinforcement percentage and precipitation hardening parameters on the behaviour of AA 6061-SiCp composites. The result reveals that AA 6061-SiCp composites demand longer solutionizing time (3 h) compared to unreinforced AA 6061 alloy (1 h). Moreover, successively during artificial aging, the time required to attain peak aging condition is shorter and almost same for AA 6061-SiCp composites irrespective of percentage of reinforcement.

IPC Code: C22C47/00

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 282-288

 

 

Elastic-plastic stress analysis of a thermoplastic composite disc under parabolic temperature distribution

Faruk Sen, Yeliz Pekbey, Onur Sayman

 

In this study, an elastic-plastic thermal stress analysis was carried out on a steel fiber reinforced thermoplastic composite disc under a parabolic temperature distribution. The thermal elastic and elastic-plastic solutions were obtained both analytically and numerically. Therefore, FORTRAN and ANSYS programs were used to calculate of thermal stresses for comparison. Tsai-Hill theory was used as a yield criterion during the solution. Thermal stresses occurred in the disc for the parabolic temperature distribution due to the different thermal expansions in radial and tangential directions. The magnitudes of the radial stress components were obtained to be small in comparison with the tangential stress components. Additionally, the tangential stress component was found to be compressive and the highest around the inner surface. According to obtained results these two solutions to be in good agreement. The intensities of the residual stress component of the tangential stress and plastic flow were the highest at the inner surface.

IPC Code:   C08B, G01L1/00

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 289-294

 

 

Current differencing transconductance amplifier-based
current-mode four-phase quadrature oscillator

 

Worapong Tangsrirat

 

A realization of a current-controlled current-mode four-phase quadrature oscillator based on current differencing transconductance amplifiers (CDTAs) is proposed. The proposed oscillator circuit employs only three CDTAs and two grounded capacitors, which can provide four high output impedance sinusoidal current outputs with four-phase difference. The oscillation condition and oscillation frequency can be controlled electronically and independently by the transconductance gain of the CDTA. PSPICE simulation and experimental results with the commercially available ICs are given to confirm the operation of the proposed oscillator.

IPC Code:   H03L

  

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 295-302

 

 

Evaluation of creep coefficient on concrete-filled steel tubular columns

 

Mustafa Hilmi Acar

 

This paper presents the evaluation of creep coefficient on concrete-filled steel tubular (CFST) sustained loaded columns. A test of the long-term behaviour of CFST columns has been carried out. Shrinkage and creep of CFST columns are measured. A comparison of results calculated using three prediction models proposed by CEB-FIP, BAZANT-PANULA, and ACI have shown a good agreement with test results. The study also showed that the shrinkage effect of the concrete core in CFST columns is negligible. The creep coefficient measured and calculated by those recommanded CEB-FIP, BAZANT-PANULA, and ACI during 200 days were in agreement for CFST columns.The creep coefficient ultimate calculated for CFST columns has been found 2. At the beginning of test, the percentage of load taken by steel section was 38% and at the end of test, it was 56%. This is a stress transfer from the concrete section to the steel section due to the creep. This creep coefficient ultimate evaluated is proposed for long-term behaviour calculation of CFST columns. In order to take the effect of creep into account, applied sustained load must be multiplied by the value of (1+fultimated)

IPC Code: E04C3/30

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 303-308

 

 

Corrosion susceptibilities of Al-Cu/TiC MMCs fabricated by conventional hot pressing

Mehmet Gavgali, Burak Dikici & Fevzi Bedir

 

The effect of TiC particle volume fraction on the electrochemical behaviours of metal matrix composites (MMCs), which is Al-Cu based reinforced with TiCp has been investigated in both aerated and deaerated 1.0 N H2SO4 aqueous solutions. Composites reinforced with TiC particles at volume fractions of 20, 30 and 40% have been produced by conventional hot pressing method and then, artificially aged (T6). The corrosion susceptibilities of the composites have been analyzed by using the cyclic potentiodynamic polarization technique. The surface morphology of the composites has been determined by scanning electron microscopy (SEM). The results show that the corrosion susceptibilities of the composites increase with increased TiC particle content but decreases with T6 heat treatment performed on the composites.

IPC Code: C22F, C22C 47/00

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 309-312

 

 

Synthesis of nanosized AlN powder using novel nitridation route

Anjan Sil & Pankaj Kumar Verma

 

Nanonsized AlN powders were prepared by nitridation of coarse aluminium powder in flowing N2 and NH3 gases, using NH4Cl and KCl as additives. XRD analysis indicated that the pure phase of AlN powder could be obtained by nitridation at 1000˚C for 4 h with NH3 gas. The average particle size of the AlN powder estimated from the XRD pattern is about 29 nm. FE-SEM micrograph revealed the spherical morphology of the powder particles whose sizes are in the range of 26-43 nm.

IPC Code:  C01F 7/00

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 313-116

 

 

Study of optical constants in CdxZn1-xS vacuum evaporated thin films

Pawan Kumar, Aravind Kumar,  P. N. Dixit & T. P. Sharma

 

Thin films of II-VI group semiconductors have been deposited by the vacuum evaporation technique onto highly cleaned glass substrates under the vacuum of the order of 10-5 torr. The optical properties of these thin films have been determined from transmission spectra by using Manifcier’s envelope method. These films posed, in general good transparency (T > 50%), exhibiting an interference pattern. The wavelength dependence of optical constant (refractive index and extinction coefficient) of these films have been reported.

IPC Code: H01C 17/075

 

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 317-323

 

 

Low-frequency dielectric response and chain dynamics study of poly(vinyl pyrrolidone)–poly(ethylene glycol) coexisting two-phase polymeric blends

 

R J Sengwa & Sonu Sankhla

 

The dielectric response of various concentration poly(vinyl pyrrolidone)-poly(ethylene glycol) (PVP–PEG) blends with change in polymer chain-length and their different volume mixtures over the entire concentration range were investigated in the frequency range 20 Hz-1 MHz at 25°C. The complex dielectric constant e*(w), complex electric modulus M*(w), complex impedance Z*(w), and a.c. conductivity data were used for the confirmation of the electrode polarization effect, ionic conduction and the micro-Brownian motion of the PVP chain (m-process) in the PVP–PEG blends. All the blends show the dielectric dispersion corresponding to the PVP segmental motion in the upper experimental frequency range whereas in the lower frequency side of the spectra has dielectric dispersion is due to ionic conduction and electrode polarization. The different volume mixtures of some of the different chain-length PVP–PEG blends also shows the polymer chain-length and concentration dependence m-process. All the blends show the d.c. conductivity behaviour in the lower frequency region, which is little affected by the blends composition. The appearance of two separate arcs in the complex impedance plane plots confirms the contribution of nickel-plated cobal electrodes polarization effect to the values of complex dielectric constant of the PVP–PEG blends in the lower frequency range up to 500 Hz.

IP Code: C08L39/04

Indian Journal of Engineering & Materials Sciences

Vol. 14, August 2007, pp. 324-330

 

 

Predicting heats of detonation of explosives via specified detonation products and elemental composition

M H Keshavarz

 

Heats of detonation of CaHbNcOd explosives are predicted using H2O-CO2 arbitrary1 as detonation products as well as ratios of oxygen to carbon (RO/C) and hydrogen to oxygen (RH/O). The methodology at first assumes that the heat of detonation of explosive compound can be approximated as the difference between heats of formation of the assumed detonation products and that of the explosive, divided by the formula weight of the explosive; then may be corrected by RO/C and RH/O. For the calculations in which only H2O-CO2 arbitrary were used, predicted heats of detonation for 27 non-aromatic and 31 aromatic energetic compounds have a root mean square (rms) deviation from experiment of 1.21 and 2.08 kJ/g, respectively. The corrected heats of detonation using RO/C and RH/O for both non-aromatic and aromatic energetic compounds have a rms deviation of 0.49 kJ/g from experiment, which show good agreement with respect to measured values. The new method is also applied to four new explosives, i.e., CL-20, FOX-7, ONC and NTO, which gives comparable results as compared to measured values.

IPC Code: C06B