Indian Journal ofEngineering & Materials Sciences

 

VOLUME 8

NUMBER 1

FEBRUARY 2001

 

CONTENTS

Engineering

Effect of in-cylinder catalytic coating on the performance of a two-stroke spark

           ignition engine

1

           N Nedunchezhian & S Dhandapani

 

 

 

Influence of strain rate and cyclic compression on physico-mechanical behaviour of rock

8

           T N Singh & A Suresh Naidu

 

Materials Science

 

Fracture toughness in bi-axial loading—Critical crack and validity condition

13

           V M Radhakrishnan

 

 

 

Effect of grain size on the transmission of zinc sulphide windows in the 8-12 mm range of infrared

18

           S S Singh, Surendra Pratap, Jagdish Prasad, Rajeev Kumar & Krishna Murari

 

 

 

Additive and inhibitor effect study on corrosion behaviour of nickel-zinc alloys

22

           Kehar Singh & Chandra Shekhar Dwivedi

 

 

 

A comprehensive study on some bonders for piezo-electric ceramics

26

           S R Sangawar, J P Agarwal & D B Sarwade

 

 

 

Silicon nitride/SiAlON ceramics—A review

36

           C B Raju, S Verma, M N Sahu, P K Jain & Shompa Choudary

 

 

 

X-ray diffraction studies of Ga2Te3

46

           D P Singh & M Y Khan

 

Notes

 

Study of knoop hardness of tin chalcogenides

50

           G R Pandya, S M Vyas, R C Shah & N R Shah

 

 

 

Charge decay and relaxation times in electrets

53

           Amarjit S Dhaliwal & K S Mann

 

 

 

Microwave absorption study in some iodine doped polyblends

55

           Priya Meghal, Seema Ubale & C S Adgaonkar

 

 

 

Electrical characterization of superionic materials in the system (Cu1-xAgxI)-(Ag2O)-(P2O5), (0.05 £x£0.25) for solid state batteries

57

           S Austin Suthanthiraraj & P Maruthamuthu

 

 

 

 


 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 1-7

 

Effects of in-cylinder catalytic coating on the performance of a two-strokespark ignition engine

 

N Nedunchezhian*a & S Dhandapanib

aDepartment of Automobile Engineering, Institute of Road & Transport Technology, Erode 638 316, India

bDepartment of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore-644 014, India

Received 28 October 1999; accepted 21 November 2000

Two-stroke spark ignited engines offer superior power to weight ratio, which is best suited for two-wheeler applications. But, low thermal efficiency and higher emission levels are the main drawbacks of these engines. In-cylinder catalytic coating was applied in a two-stroke single cylinder spark ignited engine for improving thermal efficiency and reducing emission levels. The selected catalyst (copper), which is an oxidation catalyst, was coated over the inside surface of cylinder head and piston crown by plasma coating method. Detailed studies were carried out to evaluate the performance of catalyst under varied operating conditions. The copper coated engine showed improved fuel economy at all operating conditions. The brake thermal efficiency was improved by 10% and the unburned hydrocarbon emission was reduced by 25% at full load condition of the engine. The plasma coating of catalyst showed no deterioration after 50 h of operation and the catalytic action was not affected. Detailed combustion analysis was carried out to find out the effect of catalyst action on combustion parameters. It was found that the rate of burning, Pmax, and heat release rate were increased. Combustion duration was reduced by 8° of crank angle at full load condition.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 8-12

 

Influence of strain rate and cyclic compression on physico-mechanical behaviour of rock

 

T N Singh & A Suresh Naidu

Department of Mining Engineering

 

Received 25 October 1999; revised received 21 March 2000

 

Effect of cyclic loading and strain rate are considered to be most important parameters which govern the rock mass in various loading environments. They are directly related to the long-term stability of any structure. The present investigation mainly deals with the response of cyclic loading and varying strain rate on physico-mechanical properties of Chunar sandstone which is considered to be nearly isotropic, fine grained and homogeneous in nature. It is found that compressive strength decreases as the number of cycles increases, but in this case after 400 cycles, decrease percentage in strength is not significant. The failure strength increased with increase in strain rate between 10-5/s to 10-1/s. Young’s modulus also shows the same trend.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 13-17

 

Fracture toughness in bi-axial loading —Critical crack and validity condition

 

V M Radhakrishnan

Metallurgy Department, Indian Institute of Technology Madras, Chennai 600 086, India

Received 6 July 2000; revised received 25 September 2000

Fracture toughness relation of high strength materials in bi-axial loading is analysed in conjunction with the stress intensity factors, their corresponding Mohr's type of circle and the crack angles. The critical crack angle with respect to the principal directions to cause fracture and the condition for valid fracture toughness relation in bi-axial loading condition are discussed.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 18-21

 

Effect of grain size on the transmission of zinc sulphide windows in
the 8-12
mm range of infrared

 

S S Singh, Surendra Pratap, Jagdish Prasad, Rajeev Kumar & Krishna Murari

Materials Science Group, Laser Science & Technology Centre, Metcalfe House, Delhi1100 54, India

Received 27 December 1999; revised received 23 October 2000

Zinc Sulphide is widely used in the fabrication of windows/domes transmitting in the far IR range (8-12 mm). Fabrication of zinc sulphide windows from ZnS powder prepared by a modified acid process has been described. IR transmission of these windows in 8-12 mm region has been found to be strongly dependent upon grain size of the windows.

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 22-25

Additive and inhibitor effect study on corrosion behaviour of nickel-zinc alloys

Kehar Singh & Chandra Shekhar Dwivedi

Chemistry Department, D.D.U. Gorakhpur University, Gorakhpur 273 009, India

Received 6 December 1999; accepted 25 August 2000

Electrosynthesis of nickel-zinc alloy films from the electroplating bath consisting of nickel sulphate, zinc sulphate and various concentrations of surface active cetyl-pyridinium chloride (CPC) has been carried out under galvanostatic control to study their corrosion behaviour in sodium chloride solutions. Polarization method has been used for the estimation of the resistance of these films. Effect of inhibitors di-propyl ether and di-propyl sulphide on corrosion characteristics of nickel-zinc alloys has also been studied. Substantial improvement in resistance towards corrosion has been observed in both the cases.

 


Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 26-35

A comprehensive study on some binders
forpiezo-electric ceramics

 

S R Sangawara, J P Agarwalb* & D B Sarwadeb

 

aArmament Research and Development, Establishment. Pashan, Pune, India

bHigh Energy Materials Research Laboratory, Sutarwadi, Pune, India

 

 

Received 6 March 2000; accepted 4 January 2001

 

Binders play a vital role in formulating piezoelectric materials. A number of binders such as poly (vinyl alcohol) [PVA], methocel, starch, hydroxy propyl methyl cellulose [HPMC], hydroxy ethyl cellulose [HEC], poly vinyl pyrrolidone [PVP], gum-arabic, and poly ethylene glycol [PEG] have been studied for solubility, viscosity, pH, thermal behaviour and ash content incorporating them in a standard PZT formulation. Further, the resulting PZTs have been studied for green density, sintered density, shrinkage characteristics, microstructure, compressive strength and electrical properties. The generated data indicate that PVA is a potential candidate as a binder for this purpose.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 36-45

Silicon nitride/SiAlON ceramics — A review

 

C B Rajua, S Vermab, M N Sahua, P K Jaina & Shompa Choudarya

 

aRegional Research Laboratory (CSIR), Bhopal 462 026, India

 

bGrasim Industries Ltd, Engineering and Development Division, Birlagram, Nagda 453 433, India

 

Received 4 May 1999; accepted 20 January 2000

 

 

Advanced ceramic materials such as Si3N4 and SiAlON are reviewed here with particular reference to their synthesis, properties, and applications in various sectors such as transport and defense. It is noticed that synthesis by the simultaneous carbothermic reduction and nitridation (CTR) is relatively easy and economical. The products thus obtained by CTR, have unusual combination of unique properties, viz., high strength at higher temperature, chemical inertness, wear resistance, etc., and therefore they are very much useful in high-tech areas. In addition, some of the leading manufacturers of Si3N4/SiAlON are listed in this paper. Ceramic whisker growth mechanism and its importance in improving the mechanical properties of ceramic matrix composites (CMCs) are also discussed. This paper is mainly intended to cover important properties like structural, mechanical, oxidation/corrosion and wear resistance of Si3N4 and SiAlON.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 46-49

 

X-ray diffraction studies of Ga2Te3

D P Singh a & M Y Khanb

aX-ray Analysis, National Physical Laboratory,  Dr.K.S.Krishnan Road, New Delhi 110 012, India

bDepartment of Physics, Jamia Millia Islamia,  New Delhi 110 025, India

Received 20 November 1998; revised received 23 September 1999; rerevised received 30 August 2000

Compound Ga2Te3 was prepared from the melt of initial elements of purity > 99.999% and characterized by powder and single crystal techniques of X-ray diffraction analysis.Powder X-ray pattern was obtained up to sin q/l =0.634Å–1 and indexed. The powder data were corrected and explained on the findings of single crystal, obtained from the polycrystalline ingot. The studies revealed that it crystallized in the cubic form of zinc blende structure with ao=5.8984A, Z=1.333, space group F43m and Dx=5.668 g/cc. Single crystals exhibited the property of cleavage along <111> and twinning along <> directions.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 50-52

 

Study of knoop hardness of tin chalcogenides

 

G R Pandya, S M Vyas, R C Shah, & N R Shah

Physics Department, Faculty of Science, The M S University of Baroda,Baroda 390 002, India

Received 13 April 1999; accepted 28 November 2000

SnSe, SnS and SnSe2 single crystals have been grown by the Bridgeman Stockbarger method and cleaved along the cleavage plane. The load dependence of Knoop hardness has been studied for these crystals. Variation of hardness in the low applied load range has been as to be due to coherent region.  The results for bulk hardness of all these crystals are also reported.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 53-54

 

Charge decay and relaxation times in electrets

 

Amarjit S Dhaliwal & K S Mann

Physics Department, Sant Longowal Institute of Engineering & Technology, Longowal, Sangrur, India

Received 24 February 2000; accepted 17 November 2000

In the present communication, the decay of surface charge density of bees wax and the role of a variety of relaxation times in describing the nature of charge carriers have been studied in detail. Thermo-electrets of bees wax were prepared under different conditions of polarizing field, temperature and time. The results of present investigations show that a single line does not fit the complete exponential decay of the surface charge. The values of decay constants range from 2.0´102 sec to 1.3´107 sec. Due to the presence of a large number of dipoles and ions of different kinds in bees wax, a number of dipole relaxation frequencies are expected.

 

Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 55-56

 

 

Microwave absorption study in some iodine doped polyblends

Priya Meghal,a Seema Ubale,b & C S Adgaonkara

aDepartment of Physics, Institute of Science,

Nagpur 440 001, India

bDepartment of Physics, Dharampeth,

M.P. Deo Memorial Science College,

Nagpur 440 010, India

Dielectric constant ( e¢ ) and dielectric loss (e¢¢) were determined at a microwave frequency of 9.586 GHz (X-band wavelength of 3cm.) for iodine doped polyblends of polystyrene (PS) and polymethylmetha-acrylate(PMMA). These values increased with iodine percentage. This can be attributed to the complex formation in polymer due to iodine doping.

 


Indian Journal of Engineering & Materials Sciences

Vol. 8, February 2001, pp. 57-58

Electrical characterization of superionic materials in the system
(Cu1-xAgxI)-(Ag2O)-(P2O5), (0.05
£ x £ 0.25) for solid state batteries

 

S Austin Suthanthiraraj*, S Murugesan & P Maruthamuthu

Department of Energy, University of Madras, Guindy Campus, Chennai 600 025, India

 

Received 24 February 2000; accepted 24 November 2000

 

 

Superionic materials in the system 30(Cu1-xAgxI)-46.66(Ag2O)-23.33(P2O5), where x = 0.05, 0.1, 0.15, 0.2 and 0.25 respectively, were prepared using the melt quenching process. The electrical conductivity measurements were made in the temperature range 295–445 K by the complex impedance method. The room temperature electrical conductivity observed for five different samples of the system are found to be of the order of 10–6 to 10–4 Scm-1. The best conducting composition was found to exhibit an electrical conductivity as high as 1.15 x 10–4 Scm–1 at 295 K. From the temperature-dependent conductivity studies, the values of activation energy of these materials are found to be less than 0.5 eV. The ionic transport number (ti) values for these materials are found to be greater than 0.96. These measurements confirm the formation of superionic materials in this system and their suitability for battery applications as solid electrolytes.

 

 

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