Indian Journal of

Engineering & Materials Sciences

VOLUME 8

NUMBER 4

AUGUST 2001

CONTENTS

Engineering

 

Experimental and numerical investigation of an axisymmetric free jet

189

  K B S N Viswanath & V Ganesan

 

 

 

An experimental investigation on the mechanism of wear resistance improvement in cryotreated tool steels

198

  M Satish Kumar, D Mohan Lal, S Renganarayanan & A Kalanidhi

 

 

 

Design of electron cyclotron resonance based reactive ion  etching system

205

  S K Angra, Parshant Kumar & R P Bajpai

 

 

 

Materials Science

 

Thermal behaviour of synthetic metals : Polyanilines

209

  D Kumar & R Chandra

 

 

 

Transport properties of ferroelectric (lead titanate) doped zinc-borate glasses

215

  S K Ubale & C S Adgaonkar

 

 

 

Anharmonic phonon-electron problem in high temperature superconductors

219

A P Singh, A Kr Dimri, B D Indu, R Kumar & R P Vats

 

 

 

Growth of multilayer Bi2Se3-Sb2Se3 thin films by SILAR technique

223

  B R Sankapal, H M Pathan & C D Lokhande

 

 

 

Effect of silica fume on the chloride and sulphate attack of sulphate resisting  and high alumina cement composite

228

  I M Helmy, H El-Didamony, A H Ali  & T M El-Sokkary

 

 

 

Hydration of rice husk ash blended portland cement

235

  N B Singh, Neelam Singh, Sarita Rai & Namwar Singh

 

 

 

Effect of temperature and air feed rate on adiabatic gasification of Okaba sub-bituminous coal in Nigeria

239

  J Soji Adeyinka & F O Akinbode

 

 


 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 189-197

 

Experimental and numerical investigation of an axisymmetric free jet

K B S N Viswanath & V Ganesan

Department of Mechanical Engineering,

Indian Institute of Technology Madras, Chennai 600 036, India

Received 9 May 2000; accepted 17 May 2001

The experimental and numerical investigations of an axisymmetric jet issuing from a nozzle are reported here. Experiments have been carried out using hot-wire anemometer and theoretical predictions made using the finite volume technique. The k–e models, with modified constants to take care of free shear flows, have been used for the physical modelling. The present investigations are aimed at comparing the predicted results with reported experimental measurements. The present numerical method along with k–e model has been found to predict the flow quite well. Therefore, the k–e model can be used with confidence for the evaluation of flow characteristics of similar turbulent flows.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 198-204

 

An experimental investigation on the mechanism of wear resistance improvement in cryotreated tool steels

M Satish Kumar, D Mohan Lal*, S Renganarayanan & A Kalanidhi

Department of Mechanical Engineering, Anna University, Chennai 600 025, India

Received 17 July 2000; accepted 21 May 2001

Cryogenic treatment is an inexpensive one time permanent treatment that influences the entire section of the component. It is a supplementary process to conventional heat treatment process in steels. Though the benefits have been reported widely the degree of improvement experienced and the underlying mechanism are still debated upon. An attempt has been made to understand the basic mechanism of improvement in the wear resistance of cryogenically treated tool steels. The studies indicate that there is a minor increase in the hardness value of the cryogenically treated specimens. The optical microscopy study and X-ray diffraction pattern are discussed. A variation in the carbon content of the martensitic matrix, indicate that though there is no large scale formation of new carbides, there can be subtle clustering of carbides in the supersaturated martensite. This clustering taking place at sub-micron level and being very finely dispersed all over the matrix, is very hard to get characterised in the X-ray diffraction or optical microscopy studies. However, this could influence the wear resistance and hardness value resulting in the life improvement.

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 205-208

 

Design of electron cyclotron resonance based reactive ion etching system

S K Angra, Parshant Kumar & R P Bajpai

Central Scientific Instruments Organisation, Sector-30, Chandigarh160 020, India

Received 5 January 2000; accepted 11 January 2001

Designs of the subsystems of the Electron Cyclotron Resonance (ECR) plasma stream source at frequency 2.45 GHz are explored. The assembled machine on this design has been evaluated using Langmuir probe and etching of Si based compound. The plasma densities have been found to be above the critical value at this frequency and etching rates are compatible to the reported values.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 209-214

 

Thermal behaviour of synthetic metals: Polyanilines#

D Kumar* & R Chandra

Department of Applied Chemistry, Delhi College of Engineering, University of Delhi, Delhi, India

Received 24 November 2000; accepted 28 May 2001

Polyanilines have been synthesized by chemical polymerization technique using ammonium persulphate as an oxidant. These polymers have been doped using an inorganic dopant, i.e., HCl and an organic dopant like p-toluene sulphonic acid (PTSA). Thermal behaviour of polyanilines has been studied by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. The thermogravimetric analysis shows a three-step decomposition of the polymer corresponding to loss of water molecules, dopant, and degradation of the polymer backbone respectively. The morphological behaviour has also been studied using scanning electron microscopy (SEM) technique.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 215-218

 

 

Transport properties of ferroelectric (lead titanate) doped zinc - borate glasses

S K Ubalea & C S Adgaonkarb

aDharampeth, M. P. Deo Memorial Science College, Nagpur 440 010, India

bInstitute of Science, Nagpur 440 001, India

Received 7 December 2000; accepted 9 April 2001

Ferroelectric doped zinc-borate glasses of the composition (1-x) [40 ZnO – 60 B2O3] + x PbTiO3 with = 0,0.05,0.1,0.15,0.2 were prepared. Physical properties such as density (d), molar volume (V), hopping distance (R), number of zinc ions per cc (N), and polaron radius (rp) were reported. DC–conductivity was measured between 443 K to 573 K. From this, two graphs (a) –log s versus 1/T and (b) – log m versus 1/T were plotted. Activation energy W was determined from the plots. Effect of ferroelectric doping on the hopping conduction was studied. Polaron bandwidth (J) was found to satisfy the inequality for all samples thus suggesting adiabatic hopping conduction mainly governed by the activation energy.

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 219-222

Anharmonic phonon-electron problem in high temperature superconductors

A P Singha, A Kr Dimrib, B D Induc*, R Kumara & R P Vatsb

aPhysics Department, Gurukul Kangri University, Hardwar 249 404, India

bPhysics Department, M.S. (P.G.) College, Saharanpur 247 001, India

cPhysics Department, Roorkee University, Roorkee 247 667, India

Received 24 February 2000; accepted 3 October 2000

Owing to the fact that effects of anharmonicities on the electron-phonon problem in high temperature superconductors are relatively unknown, the problem is solved with the help of double time thermodynamic electron-Green’s function theory. The ab initio development of the theory includes a very general and newly formulated Hamiltonian which involves the contributions due to harmonic-, anharmonic-, localized phonons and electron-phonon and electrons. This almost approximation-free technique is capable of automatically predicting the formation and decay of Cooper pairs in the superconducting crystals. Expressions for the life times and density of states of electrons are obtained in the new framework which are responsible to describe a large number of dynamical properties of high temperature superconductors.

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp.223-227

Growth of multilayer Bi2Se3-Sb2Se3 thin films by SILAR technique

B R Sankapala , H M Pathanb & C D Lokhandeb

aDepartment of Physics, Devchand College, Arjunnagar 591269, India

bThin Film Physics Laboratory, Department of Physics, Shivaji University,

Kolhapur 416 004, India

Received 6 October 2000; accepted 14 May 2001

The successive ionic layer adsorption and reaction (SILAR) technique is well suited for producing large area thin films, as they are required in solar energy related applications. It is applied for the growth of multilayer Bi2Se3-Sb2Se3 thin films onto glass substrates. The preparative parameters are optimized to get multimonolayers of Bi2Se3-Sb2Se3 of terminal thickness ~ 0.185 mm. Structure, surface morphology, optical band gaps and electrical resistivity of the Bi2Se3-Sb2Se3 thin films are studied. Structural study by X-ray diffraction shows that multilayer Bi2Se3-Sb2Se3 thin film formation is possible by SILAR technique. Scanning electron microscopy and atomic force microscopy studies show that films formed are nanocrystalline. The optical band gap was estimated to be 1.57 eV using optical absorption studies, which lies between the individual band gaps of Bi2Se3 and Sb2Se3 . The dark electrical resistivity is found to be of the order of 105 W-cm.

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 228-234

 

Effect of silica fume on the chloride and sulphate attack of sulphate resisting and high alumina cement composite

I M Helmya, H El-Didamonya, A H Alib & T M El-Sokkaryb

aFaculty of Science, Zagazig University, Zagazig, Egypt

bBuilding Research, Centre, Dokki, Cairo, Egypt.

Received 27 November 2000; accepted 1 June 2001

The present investigation aims to study the chloride as well as sulphate attack on the composite of 85% SRC and 15% HAC. The effect of substitution of HAC with silica fume on the aggressive attack was also studied. The results indicate that the free lime contents decrease with silica fume and curing time in sulphate as well as chloride solution. The XRD results are in a good agreement with the compressive strength and chemical analysis. The substitution of HAC with SF improves the attack of chloride and sulphate ions on cement pastes. It can be concluded that superplastecizer must be added to the silica fume blended cements.

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp. 235-238

Hydration of rice husk ash blended portland cement

N B Singh, Neelam Singh, Sarita Rai & Namwar Singha

Department of Chemistry, DDU Gorakhpur University, Gorakhpur 273 009, India

aTGPG College, Jaunpur, India

Received 30 July 1999; accepted 31 March 2001

Effect of different concentrations of lactic acid on the hydration of rice husk ash blended portland cement has been studied by employing different experimental techniques. Lactic acid has been found to accelerate the hydration of blended cement.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, August 2001, pp 239-242

 

 

Effect of temperature and air feed rate on adiabatic gasification of Okaba sub-bituminous coal in Nigeria

J Soji Adeyinkaa* & F O Akinbodeb

Chemical Engineering Department, University of Port Harcourt, Nigeria

bMechanical Engineering Department, Federal University of Technology Minna, Nigeria

Received 7 September 2000, accepted 21 May 20001

The present investigations deal with, gasification of Okaba sub-bituminous coal (OSB) of Nigeria at varying temperatures and air feed rates. Analysis of gaseous product showed that the best yield of CO (80%) was recorded at 90% stoichiometric air feed, while the least CO yield (55%) was recorded at 110% stoichiometric air demand. It was observed that CO yield followed a pattern above 850 K thereby stabilising CO and increasing CO2 yield at air variation. This study will help in evaluating both thermal efficiency and product distribution of OSB coal gasification.

 

 

 

 

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