014784   Manocha L M;Yasuda E;Tanabe Y;Manocha S; Vashistha D (Department of Materials Science, Sardar Patel University, Vallabh Vidyanagar-388 120) : Sol-gel processing of carbidic glasses. Bull Mater Sci 2000, 23(1), 1-4.

Carbon incorporation into the silicate network results in the formation of rigid carbidic glasses with improved physical, mechanical and thermal properties. This generated great interest in the development of these heteroatom structured materials through different processing routes. Sol-gel processing has been used to prepare silicon based glasses, especially oxycarbides through organic-inorganic hybrid gels by hydrolysis-condensation reactions in silicon alkoxides, 1,4-butanediol and furfuryl alcohol with an aim to introduce Si-C linkages in the precursors at sol level. The incorporation of these linkages has been studied using IR and NMR spectrospcopy. These bonds, so introduced, are maintained throughout the processing, especially during pyrolysis to high temperatures. In FFA-TEOS system, copolymerization with optimized mol ratio of the two results in resinous mass. This precursor on pyrolysis to 1000°C results in Si-O-C type amorphous solid black mass. XRD studies on the materials heated to 1400°C exhibit presence of crystalline Si-C and cristobalites in amorphous Si-O-C mass. In organic-inorganic gel system, the pyrolysed mass exhibits phase stability up to much higher temperatures. The carbidic materials of produced have been found to exhibit good resistance against oxidation at 1000°C.

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014783   Mannan S L;Shankar V (NO, Materials Development Group, IGCAR, Kalpakkam-603 102) : Weldability of austenitic stainless steels. Indian Weld J 1999, 32(4), 7-17.

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014782   Khare P K;Jain S K (Department of Postgraduate Studies and Research in Physics and Electro, Rani Durgavati University, Jabalpur-482 001) : Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethyl cellulose. Bull Mater Sci 2000, 23(1), 17-21.

Dielectric capacities and losses were measured, in the temperature (50-170°C) and frequency (01-100 kHz range), for undoped and acrylic acid (AA) doped ethyl cellulose (EC) films (thickness about 20 μm) with progressive increase in the concentration of dopant in the polymer matrix. The variation of capacity with temperature is attributed to thermal expansion in the lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature (T_g) and random thermal motion of molecules above T_g. The dielectric losses exhibit a broad peak. Doping with AA is found to affect the magnitude and position of the peak. AA is found to have a two-fold action. Firstly, it enhances the chain mobility and secondly, it increases the dielectric loss by forming charge transfer complexes.

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014781   Kashyap K T;Ramachandra C;Sujatha M;Chatterji B (Central Materials and Processes Laboratory, Foundry and Forge Division, Hindustan Aeronautics Ltd., Bangaloe-560 017) : Role of diffusional coherency strain theory in the discontinuous precipitation in Mg-Al alloy. Bull Mater Sci 2000, 23(1), 39-45.

Discontinuous precipitation (DP) occurs in many alloy systems under certain conditions. It is called discontinuous precipitation because precipitation occurs on prior matrix grain boundaries followed by grain boundary movement. The DP nodule consists of alternate lamellae of the precipitate and the matrix respectively. The chemical driving force for DP is one of solute supersaturation. Although solute supersaturation is responsible for precipitation, it has to be coupled with another driving force to explain grain boundary migration. This coupling driving force has been identified to be diffusional coherency strain which has been verified to be active in diffusion iduced grain boundary migration and liquid film migration. To test diffusional coherency strain theory for discontinuous precipitation Mg-7A1 and Mg-7A1-1Pb alloys were studied. While the fraction transformed was high at 6% in Mg-7Al alloy, it was significantly low at 2% in Mg-7Al-1Pb alloy. The velocity of DP nodules decreased by half in alloy with Pb as compared to the alloy without Pb. Theoretical calculations also predict that the misfit parameter δ_th decreases with the addition of Pb. These observations are an evidence to the fact that diffusional coherency strain is the most active driving force for the movement of the grain boundaries of the DP nodules during discontinuous precipitation in Mg-Al alloy.

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014780   Kashyap K T;Ramachandra C;Dutta C;Chatterji B (Central Materials and Process Laboratory, Hindustan Aeronautics Limited, Banalore-560 017) : Role of work hardening characteristics of matrix alloys in the strengthening of metal matrix composites. Bull Mater Sci 2000, 23(1), 47-9.

Strengthening of particulate reinforced metal-matrix composites is associated with a high dislocation density in the matrix due to the difference in coefficient of thermal expansion between the reinforcement and the matrix. While this is valid, the role of work hardening characteristics of the matrix alloys in strengthening of these composites is addressed. It is found that commercial purity aluminium which has the lowest work hardening rate exhibits the highest strength increment. This effect is due to increased prismatic punching of dislocations. This relationship of decreasing work hardening rate associated with increasing prismatic punching of dislocations in the order 7075, 2014, 7010, 2024, 6061 and commercial purity alluminium leading to increased strength increments is noted.

014779   Harish kundar;Krishna;Srinivasan K (Department of Metallurgical and Materials Engineering, KRE College, Surathkal, Srinivasnagar P O-574 157) : Impact toughness of ternary Al-Zn-Mg alloys in as cast and homogenized condition measured in the temperature range 263-673 K. Bull Mater Sci 2000, 23(1), 35-7.

Impact toughness of six Al-Zn-Mg ternary alloys are compared with two Al-Zn binary alloys and one CP aluminium metal at eight different temperatures of 263, 268, 273, 300, 373, 473, 573 and 673 K. The effects of alloying and temperature on toughness have been compared and analysed. The influence of alloying is more pronounced than that of temperature in reducing the toughness.

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014778   Ghelani L M;Parmar N B;Marviya G V;Patel B K (Tobacco Project, Gujarat Agricultural University, Anand Campus, Anand-388 110) : Chemical composition of non-smoking tobacco products. Tob Res 1998, 24(2), 109-11.

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014777   Datta S;Banerjee M K (Department of Metallurgy, B.E. College (Deemed University), Howrah-711 103) : Precipitation behaviour in trace added Al-Cr alloys. Trans Indian Inst Metals 1999, 52(4), 211-18.

Effect of minor additions of zircomium and rare earths on the ageing behaviour of aluminium chromium alloy is studied and compared by microhardness measurements in samples, isothermally aged at different temperatures. A qualitative assessment of the effect of trace additions on the precipitation kinetics of the aforesaid alloys is also made on the basis of a simple correlation between the extent of age hardening and the amount of precipitation. It is observed that zircomium increases the nucletion density and thus helps to improve age hardening in aluminium chromium alloy. The rare earths on the other hand influence the growth behaviour of precipitates without increasing the nuclei density.

014776   Das S K (Computer Applications Division, National Metallurgical Laboratory, Jamshedpur-831 007) : Quantum mechanistic isomorphism of transient nucleation during rapid solidification processes. Trans Indian Inst Metals 1999, 52(4), 205-10.

Mathematical theory has been proposed to study the dynamic nucleation of crystals from melt at very high cooling rates (10⁶ to 10¹² K/s). The mathematical framework is found to be isomorphic with the function space theory, wave and matrix mechanics embodying the mathematical genesis is quantum mechanics. This enables applicability of some approximate methods of the latter disciplines to the present domain. In principle, the mathematical apparatus of function space and matrix mechanics can be utilized to study the time varying nucleation process. The Arrhenius law has been used to extrapolate the self-diffusion coefficient as a function of temperature above the melting point to those below. Since, the applicability of Arrhenius equation at very high degrees of supercooling is not known and has to be substituted with appropriate constitutive relationship based on free volume theory of transport, the conclusion derived from the present analysis will change accordingly with respect to the certainty of crystalization.

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014775   Das S K (Computer Application Division, National Metallurgical Laboratory, CSIR, Jamshedpur-831 007) : Simulation of free boundary problem in electromagnetic levitation melting of metals in cold crucibles. Trans Indian Inst Metals 1999, 52(4), 197-203.

Phenomenological modelling approach has been developed to solve the free boundary problem of electromagnetic levitation melting in cold crucible with continuous casting. The free boundary problem has been solved to determine the equilibrium shape of the molten metal as a function of electrical operating parameters. The concept of domain derivative formalism has been applied to obtain minimization of the total energy functional of the system in a global framework for determining the free surface of the molten metal under levitated condition. An iterative solution algorithm has been formulated and the magnetic energy is determined by using a boundary integral technique. Distribution of magnetic field has been evaluated on the basis of Biot-Savart's law. The domain derivative approach is found to be useful mathematical apparatus to achieve faster convergence of the solution of the governing free boundary problem.

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014774   Das Gupta D K;Kaveri K (Defence Food Research Laboratory, , Mysore-570-011) : Ultrafiltration and reverse osmosis concentration of guava juice. Indian Fd Packer 1999, 53(5), 5-11.

Ultrafiltration (UF) of guava juice using membranes of three different Molecular Weight Cut Off (MWCO) value and the subsequent concentration of UF processed juice by Reverse Osmosis (RO) using a laboratory model plate and frame RO/UPF equipment. Average permeate flux during ultrafiltration were found to be 18.7, 26.6 and 28.7 L/m²h respectively using membranes of 20,000, 50,000 and 100,000 MWCO. Physico chemical parameters of UF permeate juices from different membranes showed marginal variation. Average permeate flux during RO concentration of UF permeated (using membrane of 20,000 MWCO) juice from 6.4° to 25° Brix was found to be 25.9 M/m²h as compared to 17.4 L/m²h for untreated juice while concentrating from 9.3° to 25° Brix at 50 bar pressure. Fouling of membrance and rejection of solutes in case of UF processed juice were found to be slightly less than untreated one.

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014773   Chandrawat M P S;Yadav R N (Department of Chemistry, RR College, Alwar-301 001) : Effect of aluminium phosphate as admixture of oxychloride cement. Bull Mater Sci 2000, 23(1), 69-72.

Effect of admixing of aluminium phosphate on oxychloride cement in the matrix has been investigated. It is shown that aluminium phosphate retards the setting process of the cement and improves water-tightness.

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014772   Bhirud Y B;Shetty S S (NO, Rieco Industries Ltd, Pune) : Role of classification in powder coating paint production. Engng Adv 1999, 11(9), 60-2.

014771   Bera S;Rathinam K;Mohanty M;Mohanan P V;Sudha J D;Damodaran A D (NO, Manali Petrochemicals Ltd., 97, Mound Road, Guindy, Chennai-600 032) : Block/segmented polymer-V studies on the in vivo, biological properties of poly (amide-ester)-ester copolymer. Biomedicine 1999, 19(3), 233-9.

(Amide-ester) copolymers synthesized from lactones, diamines and dicarboxylic acids have been studied to evaluate its biological properties by in vivo subcutaneous implantation in albino rats. Poly (amide-ester) POLEA 4612 and its block/segmented counterpart POLEA 466/26 showed a little variation of tissue response in the early stages, with eventual fragmentation and absorption. A study at 7 days, 30 days and 90 days post implantation is reported, which proves the material to be biodegradable without any toxicity.

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014770   Banerjee M K;Datta S (Dept. of Metallurgy, B.E. College(D.U.), Howrah-711 103) : Effect of trace additions on the mechanical behaviour of aluminium chromium alloys containing zirconium. Trans Indian Inst Metals 1999, 52(4), 219-25.

Stress strain curves of the aluminium chromium alloys containing trace amount of rare earths at various strain rates are used to determine the parameters of work hardening at various stages. The influence of strain rate and ageing temperature on the work hardening parameters is studied. From the results of experiments, the deformation behaviour of the above alloys is analysed. The high values of strain rate sensitivity measured in the above alloys at different ageing temperatures are indicative of dormant superplasticity, and an explanation on the basis of microstructural analysis is attempted.

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014769   Bala P;Samantaray B K;Srivastava S K (Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur-721 302) : Dehydration transformation in Ca-montmorillonite. Bull Mater Sci 2000, 23(1), 61-7.

Deals with the dehydration transformation of Ca-montmorillonite in the temperature range 30°-500°C. Thermal, infrared (IR), and X-ray diffraction (XRD) analysed were used to describe the thermal transformation. The microstructural and layer disorder parameters like crystallite size, r.m.s. strain (<60>e²<62>^1/2), variation of interlayer spacing (g), and proportion of planes which were affected by the defect (γ), have all been calculated from the (001) basal reflection using the method of variance and Fourier line shape analysis. These investigations revealed that sample underwent transformation from hydrated phase to dehydrated phase at 200°C, and as a consequence, it basal spacing collapsed from 16-02 A Angstrom (30°C) to around 10 A Angstrom (200°C). This transformation occured through a wide range of temperature, i.e. within the range 120°-200°C. The crystallite size was maximum at room temperature (30°C), however, the size decreased with increasing temperature in the hydrated phase, whereas the size increased with increasing temperature for the dehydrated phase. The g, γ and <60>e²<62>^1/2 of the hydrated and the dehydrated phase increased and decreased, respectively with increase of heating temperature.

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013727   Yadav V G;Chandalia S B (Chemical Engineering Division, University Department of Chemical Techn, University of Bombay, Mumbai-400 019) : Efficient method for synthesis of 2-ethyl hexyl-4-methoxy cinnamate: a raw material for cosmetic industry. Indian J chem Technol 1999, 6(1), 19-23.

Methyl, ethyl and isopropyl esters of 4-methoxy cinnamic acid could be synthesized by Claisen condensation of anisaldehyde with the respective alkyl acetate at a temperature of 0 - 5°C using stoichiometric amount of sodium and a few drops of methanol, the latter being used as an initiator. The yield of ester of cinnamic acid was about 77%. When the reaction was extended to the synthesis of 2-ethylhexyl ester of cinnamic acid, the reaction rates were rather very poor and it was necessary to carry out the reaction at the temperature of 28°C which resulted in the extensive hydrolysis of the starting acetate and the product ester. In the case of 2-ethyl hexyl ester, therefore, it may be desirable to resort to the synthesis of ethyl/methyl ester of the cinnamic acid by Claisen condensation followed by transesterification of the ethyl/methyl ester. Thus, transesterification of ethyl 4-methoxy cinnamate with excess of 2-ethyl hexanol and p-toluenesulfonic acid as catalyst at 150°C gave a yield of 93% in 6 h.

013726   To Duy Ca (National Metallurgical Laboratory, , Jamshedpur-831 007) : Influence of rare earth metals on macrostructure of continuously cast steel rolling pipe. NML tech J 1998, 40(2), 57-62.

Influence of rare earth metals on macrostructure of continuously cast steel ingot have been studied in the full-scale industrial trials. The results can be described as follows: RE addition macrosegregation, enlargement of equiaxed zone and reduced loose structure. The centerline ingot segregation was expanded. The length of segregation line was distributed. RE sulphides were mainly precipitated in dendrite arms. These were compared with CaSi treatment.

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013725   Sivaprasad P V;Venugopal S;Venkadesan S (Materials Technology Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102) : Relationship between work hardening and the nature of serrations observed in a 15Cr-15Ni-2.3Mo-Ti modified austenitic stainless steel during tensile testing. Trans Indian Inst Metals 1999, 52(5), 227-44.

Variation of work hardening rate (WHR) on the serrations has been analysed with respect to the type of serrations for a 15Cr-15Ni-2.3Mo-Titanium modified austenitic stainless steel in the temperature range 300 to 1023 K. The results showed that the WHR, its rate sensitivity and the nature of serrations are strongly related. A clearly periodic locking type serrations occurred under conditions where the material in general exhibited high WHRs and when the WHR has a small positive rate sensitivity, as at low temperatures and at high strain rates. The serrations changed over a partial or fully unlocking serrations under conditions when WHRs would be lowered due to strain induced or thermally assisted recovery processes, and the rate sensitivity of the WHR becomes very large, as seen at high temperatures, the serrated flow ceases when the WHR becomes negligible. It is concluded that under conditions of high WHR and low rate sensitivity of WHR periodic locking type serrations occur and under conditions of low WHR and high rate sensitivity of WHR unlocking type serrations occur.

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013724   Singh D D N;Gaur B;Singh B K;Ghosh R (National Metallurigical Laboratory, , Jamshedpur-831 007) : Effective inhibition of corrosion of steel in phosphoric acid solution. NML tech J 1998, 40(2), 35-44.

Some common known inhibitors namely hexamine (HAM), gelatin (GEN), ammonium thiocyanate (ATC) and tri-benzyl methyl ammonium chloride (TBA) provide poor inhibition towards corrosion of steel in phosphoric acid solutions. Polymeric reaction product of tetra-hydro pyrimidine and formaldehye (THP), however, provides superior protection toward the system in comparison to the other tested inhibitors. This inhibitor when tested in combination of the other surface active agents furnishing anionic and 4 cationic species in the solution, provides improved inhibition. THP in combination of ATC and TBA in an optimized composition (OC) affords the protection of the order of <62> 98% to steel in 10% H₃PO₄ (phosphoric acid) solution at 25°C. Rise in temperature from 25 to 90°C has negligible deteriorating affect on the performance of the OC and THP. Electrochemical polarization, Zeta potential, EDAX and reflectance studies have been performed to ascertain the mechanism of functioning of the inhibitors. EDAX studies and XRD have confirmed that an insoluble FePO₄ film forms on the steel surface exposed to H₃PO₄ solutions. In the presence of THP and OC, however, no such film is detected. This is further corroborated by the measurement of reflectance and polarization studies of the surface after exposing them in different compositions of the solutions.

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013723   Savekar V N;Jagtap R N;Shendy M A (Plastics and Paints Division, UDCT, Mumbai) : liquid crystal and liquid crystalline polymer in paints. Paintindia 1999, 44(8), 75-83.

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013722   Saha A K;Khan Z H;Premchand (Non-Ferrous Process Division, National Metallurgical Laboratory, Jamshedpur-831 007) : Reclamation of tungsten metal from tungsten alloy scrap. Trans Indian Inst Metals 1999, 52(5), 353-5.

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013721   Roy M (Defence Metallurgical Research Laboratory, , P.O. Kanchanbagh, Hyderabad-500 058) : Dynamics of impact of sphere on flat surfaces of polymer matrix composites. Bull Mater Sci 1999, 22(6), 1990-12.

Primary objective of this work is to evaluate the influence of various reinforcements and matrix materials on the dynamic hardness of polymer matrix materials (PMC). Therefore, the impact of a WC ball, using a gravity drop system, was studied on PMCs. The two parameters, coefficient of restitution and dynamic hardness, of PMCs were determined. The mechanical properties of the PMCs were evaluated, and the correlation of the two parameters with the mechanical properties of PMCs was attempted.

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013720   Rao M V M S;Shivakumar K;Lei X (NO, National Geophysical Research Institute, Hyderabad) : Fractal analysis of acoustic emission and its applications in the investigation of compressive fracture of brittle rock. J Nondestructive Test Evaluation 1999, 19(3), 60-7.

Acoustic Emission (AE) monitoring and waveform recording experiments during the compressional deformation and failure of brittle rocks under simulated field conditions in the laboratory have been carrieed out. The AE data obtained from each test rock has been subjected to fractal analysis using principles of fractal geometry. The fractal analysis provided a quantitative approach to investigate the amplitude distribution (seismic b-value) and spatial clustering of AE, and it is found superior to the traditional methods of acoustic emission analysis for investigating the stress-induced changes of inferred crack types, crack lengths and crack spacings. The results show that the temporal changes in fractal dimension hold the key for a better prognosis of the failure of brittle rock under compression. The various approaches adopted for fractal analysis of AE are briefly outlined, and the laboratory results obtained from recent experiments on the rocks of Kolar gold mines are summarized and discussed.

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013719   Raghavan S (Department of Metallurigical Engineering, Indian Institute of Technology, Chennai-600 036) : Thermodynamics of formation of high calcium antimonites from E.M.F. measurements. Trans Indian Inst Metals 1999, 52(5), 345-7.

Standard molar Gibbs energies of formation of the high calcium antimonites, namely 2CaO.Sb2O3, 3CaO.Sb2O3 and 4CaO.Sb2O3 from the component oxides have been determined in the temperature range, 1193 to 1296 K by operating galvanic cells with calcium fluoride as solid electrolyte. The Gibbs energy of formation of 4CaO.Sb2O3(s) from the free oxides obtained in the present work at 1193 K is in reasonable agreement with that reported in the literature at 1101 K based on a CaO-stablizied zirconia solid electrolyte study.

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013718   Prasad D N;Panda P K (Foundry Technology, NIFT, Hatia, Ranchi-834 003) : Production of quality castings in hadfield Mn steel. Indian Fndry J 2000, 46(1), 30-8.

013717   Patadia A T;Shah P A;Mehta P C (NO, GNFC, P O Narmadanagar-392 015, Dist. Bharuch) : Productivity improvement in Nitrophosphate plants. Fertil News 1999, 44(12), 39-46.

Nitrophosphate complex of Gujarat Narmada Valley Fertiliser Company (GNFC), Bharuch comprises of an integrated ANP-CAN fertiliser plants, alongwith weak nitric acid and concentrated nitric acid plants. Based on the operating experience and insight gained through indepth study of various parameters, major technological modification and innovative measures were carried out to improve productivity. Describes the systematic approach and efforts made by GNFC to remove bottlenecks and improve capacity utilisation of both ANP and CAN plants.

013716   Parida N;Sivaprasad S;Tarafder S;Ranganath V R;Bhattacharya D K (NO, National Metallurgical Laboratory, Jamshedpur-831 007) : Acoustic emission: a novel technique for the study of fracture micro-mechanisms. J Nondestructive Test Evaluation 1999, 19(3), 51-5.

Acoustic emission (AE) was monitored during J-integral tests of SA333Gr.6 and 40Cr 4B steels using single edge notch bend (SENB) specimens in L-T orientation. The J-integral tests were performed by the single specimen unloading compliance technique as per the guidelines of ASTM standards. In order to eliminate noise generated from the rollers of the specimen fixture and other sources, two AE sensors under linear source location set-up were used to pick up the AE signals. The results show that three AE parameters: the peak amplitude, the energy rate and the count rate, could be used in a combination to identify the point of crack initiation and to characterise the fracture process. It has been observed in the present experiment that brittle pop-in cracks are characterised by 100 dB high energy AE signals.

013715   Mohammad A;Mohamed Najar P A;Iraqi E (Department of Applied Chemistry, Z H College of Engineering and Techn, Aligarh Muslim University, Aligarh-202 002) : Chromato-spectrophotometric determination of cobalt with preliminary separation from nickel on tributyl phosphate impregnated layers prepared from silica gel and stannic arsenate gel mixture. Indian J chem Technol 1999, 6(1), 38-42.

Thin layer chromatography in combination with spectrophotometry has been used for the separation and determination of cobalt after its separation from nickel in aqueous samples. A chromatographic system consisting of a mixture containing stannic arsenate gel and silica gel G in 10:1, w/w ratio and impregated with 0.2M tri-n-butyl phosphate (TBP) as stationary phase and 1 M aqueous potassium thiocyanate as mobile phase has been used to separate cobalt from nickel. Effects of acidity and alkalinity to sample solution on the separation of Co²⁺ from Ni²⁺ have been examined. Microgram separation of cobalt from variable amounts of nickel has been achieved after pre-concentration of metal ions from aqueous solutions by, sulphide precipitation. Determination of cobalt after TLC separation provides a recovery of 92%.

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013714   Mehtotra S P;Srinivasa G;Gupta S P (Department of Materials and Metallurgical Engineering, Indian Institute of Technology, Kanpur-208 016) : Evaluation of properties of aluminium strips produced using a laboratory scale single roll continuous strip caster. Trans Indian Inst Metals 1999, 52(5), 313-25.

Investigation is primarily concerned with the evaluation of aluminium strips directly cast on a single roll continuous strip caster under various operating conditions. The effect of various operating parameters, such as speed of rotation of the caster drum, degree of melt superheat, etc., on the cast strip quality and mechanical properties is examined. Microstructural studies, based on scanning electron microscopy and optical microscopy, have been conducted to examine the grain size and internal quality of the strips. The effect of hot rolling, cold rolling and annealing on the strip microstructure, surface quality and mechanical properties, such as strength, ductility and microhardness, has been investigated in order to establish the feasibility of this technology for commercial exploitation.

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013713   Majumdar S;Dhurendra KumarKumar D;Nirvan Y P S (Govt of India, Ministry of Defence, Naval Materials Research Laboratory, Post Bag No.10012, G P O Mumbai-400 001) : Acrylate grafted dehydrated castor oil alkyd. Paintindia 1999, 44(8), 57-65.

Requirement of improved durability of a alkyl resin for use in weatherwork paints for superstructure of ships, an attempt have been made to chemically modify castor oil alkyd by graft copolymerisation with methyl methacrylate and butyl methacrylate, in view of their ability to provide polymers with good exterior durability. Characterisation of the experimental resin in respect of physical properties was carried out using instruments namely vapour pressure osmometer, rotatonal viscometer, universal tenxile testing instrument (Instron 1123) and differential scanning calorimeter. Performance of the resins was evaluated using fluorescent UV accelerated weatherometer and multi-head glossmeter. The results reveal substantial improvement in drying and weather resistance properties of castor oil alkyd on graft copolymerisation with both, methyl methacrylate and butyl methacrylate. The improvement in these properties is marginally superior in case of MMA grafted alkyds. MMA modification also enhances the mechanical properties the grafted castor oil alkyd.

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013712   Kutumbarao V V (Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi-221 005) : Deformation and fracture of light alloys. Trans Indian Inst Metals 1999, 52(5), 279-88.

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013711   Karunamoorthy L;Kandasami G S;Venkataraman N S (NO, Anna University, Chennai-600 025) : Machining of plastics on CNC lathe using acoustic emission technique. J Nondestructive Test Evaluation 1999, 19(3), 56-9.

Modest contribution to the application of Acoustic Emission Technique (AET) to study typical machining process is given. In any machining process, such as lathe work, milling, grinding etc., surface finish and dimensional accuracy of the finished product are two important requirements. They are dependent on structural integrity of machine tools, type of tools employed, work material, cutting parameters, tool wear etc. The cutting parameters play a vital role in the finish of the products. The ever increasing need for increasing productivity swith maximum reliability has led to the wide acceptance of CNC technology. Apart from increasing productivity and reducing labour cost, CNC technology produces parts with very high degree of repetability and accuracy. To achieve the above objective, acoustic emission technique is carried out on CNC lathe. Acoustic emission is the elastic wave generated by the release of energy internally stored in a structure. The waves thus generated are picked up by highly sensitive transducers located on the surfaced of the material. The transducers convert the stress waves into electrical signals. This is called an AE event. In CNC lathe, machining was carried out on nylon and high density polyethylene rods of 25 mm diameter at different cutting parameters like speed, feed and depth of cut with throw-away indexable carbide insert.

013710   Kapoor K;Swamy S V;Saratchandran N (Quality Assurance Group, , Nuclear Fuel Complex, Hyderabad) : Application of acoustic emission to study hydride cracking in Zr - 2.5% Nb pressure tube material. J Nondestructive Test Evaluation 1999, 19(3), 29-33.

One of the important mechanisms of failure of Zr-2.5% Nb Pressure Tubes of Pressurised Heavy Water Reactors is Delayed Hydride Cracking (DHC). Additional hydrogen present in the tubes, in excess of solid solubility, can migrate to the regions of higher stress concentration (like flaw tips) and form brittle hydrides leading to intiation and growth of cracks. In order to develop materials that resist DHC, it is important to characterise their response. This is done in terms of parameters like Threshold Stress Intensity for DHC to occur (K_IH) and DHC Velocity (DHCV). Measurement of these parameters requires detection of DHC initiation and growth. Acoustic Emission (AE) Technique has been successfully used for measurement of these slow crack growth rates of the order of 10^-3 meters/sec. Compact Tensile (CT) Fracture Toughness samples were pre-charged with hydrogen and fatigue pre-cracked. These were loaded both under `constant load' and `decreasing load' or determination of DHCV and K_IH respectively, at test temperature of 250°C. AE data was obtained using a 150kHz resonant sensor fixed on the grips outside the furnace. The data were obtained for the entire test period lasting over 2-3 days. The data were analysed for calculation of incubation time for determination of DHCV, for various applied stress intensities.

013709   Kail F;Atmani H;Chahed L;Larguet N (Groupe de Metallurgie Physique, Magnetisme et Applications, UMR CNRS 6634 Faculte des Sciences - Universite de Rouen 7 6821 Mont-S, ) : Structural and magnetic study of nitrided Co₇₄Fe₈B₁₂Si₆ and CO₇₄Fe₄Mn₄B₁₂Si₆ ribbons. Bull Mater Sci 1999, 22(6), 987-90.

Nitrided thermochemical treatment (NTT) is commonly used for steels. The experimental conditions required for NTT, and the influence of such treatments on the structure and hysteresis loops of Co₇₄Fe₈B₁₂Si₆ and CO₇₄Fe₄Mn₄B₁₂Si₆ ribbons are reported. The results have been compared with those obtained with ribbons treated according to conventional thermal treatment (CTT) as well.

013708   Kagebayashi Y;Mori Y;Sasaki T (Department of Electrical Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka-565-0871, Japan) : Crystal growth of cesium triborate, CsB₃O₅ by kyropoulos technique. Bull Mater Sci 1999, 22(6), 971-3.

Large single crystals of CsB₃O₅ (CBD), free of cracks and inclusions, were successfully grown by the Kyropoulos technique from a slightly Cs₂ O-enriched melt. The growth conditions were experimentally established. Maximum dimensions obtained were 45 x 41 x 44 mm for a x b x c-axes. Optical uniformity of these as-grown crystals was verified by means of striation observation, and the optical transparency characteristic was measured in the region from vacuum ultraviolet (VUV) to infrared (IR) wavelengths.

013707   Haridas M M;Bellare J R (Microstructure Engineering & Ultramicroscopy Laboratory, Department of, Indian Institutee of Technology Bombay, Powai, Mumbai-400 076) : Chemical processing of advanced ceramics. Indian chem Engr 1999, 41(2), 143-8.

Sol-gel process in the manufacture of advanced ceramics offers an unmatched phase purity and an extremely large scope for microstructural tailoring so as to obtain a large range in properties from intricate variations in processing. However, key processing and characterization parameters from a microstructure standpoint remain unaddressed, possibly not well understood, leading to a fragemented development in this area of research. The greatest shortcoming is perhaps the absence of an experimentally evidenced mechanism on alkoxide gelling. This review identifies several lacunae that exist in the present understanding on the subject and highlights some of the authors' research attempts which address these shortcomings with a view to a better understanding of microstructure controls so that these may be exploited in the synthesis of a microsctructurally tailored advanced ceramic. Amongst the advances reviewed is a dissolution-nucleation gelling mechanism, based on changing particulate morphologies during gel formation, valid form the microscopic to the macroscopic scale.

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013706   Hanna A A;Ali A F;Khalil M S (Inorganic Chemistry Department, National Research Center, Dokki, Cairo, Egypt) : Pure diethylamine phosphate from crude phosphoric acid. Indian J chem Technol 1999, 6(1), 43-7.

Pure diethylamine dihydrogen phosphate was prepared from crude wet-process phosphoric acid (WPA). The prepared samples were characterized by chemical analysis, potentiometric titration, thermal analysis and X-ray diffraction to show good purity levels comparable to those of the standard samples. The obtained results indicate that the prepared salt could be a suitable source for the phosphate value to produce orthophosphates of alkali metals and other important monophosphates.

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013705   Goswami M C;Prakash S;Sinha S N;Tiru P (National Metallurgical Laboratory, , Jamshedpur-831 007) : Experimental study on the foaming phenomena in a non-reacting system. NML tech J 1998, 40(2), 51-6.

Phenomena of foaming occuring in smelting reduction processes has been studied using air-soap solution non-reacting system. It is necessary to study its fundamentals as the control of slag foaming to certain extent is very much desirable for the present iron and steel making processes. This study is concerned with a model study of foaming characteristics when air is passed through a non-reacting soap solution system. Although the soap solution-air system does not necessarily simulate with the actual happenings during in-bath smelting operation at elevated temperatures, it provides with the basic understanding of various factors through which the phenomena of foaming could be expressed. The effects of various operating parameters like foam height, foaming index, foam life, superficial gas velocity etc, on the foaming phenomena make the present fundamental study on foaming characteristics a significant one.

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013704   Galgali R K;Battacharjee S;Patnaik N;Gumaste J L (NO, Regional Research Laboratory, Bhubaneswar-751 013) : Thermal decomposition of molybdenite in a plasma reactor and preparation of ferro-molybdenum. Trans Indian Inst Metals 1999, 52(5), 289-98.

Review on thermal decomposition of molybdenite is presented, Studies on experimental investigations on thermal decomposition of molybdenite and preparations on thermal decomposition of molybdenite and preparation of ferro-molybdenum in a plasma reactor have been made. It has been possible to show that the decomposition product is molybdenum before its conversion to carbide because of the presence of carbon in the experimental setup. Influence of various process parameters on recovery of molybdenum is presented in detail. Ferro-alloy containing about 50 wt % molybdenum has been prepared and a flow sheet for preparation of ferro-molybdenum is presented.

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013703   Fuxiao Y;Dwarakadasa E S;Ranganathan S (Department of Metallurgy, Indian Institute of Science, Bangalore-560 012) : Distribution of lead in lead-containing aluminium alloys obtained by liquid phase co-spray forming technique. Bull Mater Sci 1999, 22(6), 959-63.

Liquid phase co-spray forming (LPCSF) technique was employed to produce Al-Pb and Al-Si-Pb alloys to show that it is possible, using this technique, to distribute lead into very fine-sized particles in Al/Al alloy matrix at low melt temperatures. Microstructural studies were carried out to explore the mechanisms governing lead distribution in the matrix of the alloys during processing. Results showed that, regardless of the alloy compositions and experimental conditions, the microstructures of the preforms exhibited great similarity, i.e. less uniform distribution of Pb particles in the base region, and uniform distribution of fine Pb particles in the equiaxed region. During LPCSF process, the behaviour of Pb droplets was similar to that of ceramic particles, except that the shape and size of liquid Pb phase varied corresponding to local solidification condition.

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013702   Dwivedi D K (Mechanical Engineering, REC, Hamipur-177 005) : Machining behaviour of aluminium-silicon alloy. Indian Fndry J 2000, 46(1), 39-42.

Al-Si base alloy, of eutectic composition has been taken for study. Low spindle speed and small depth of cut produces discontinuous chips. Increase in spindle speed and depth of cut promotes long curled chips. Increase in spindle speed increases the Sp power consumption at given depth of cut and feed. Increase in depth of cut decreases the Sp power consumption at given spindle speed and feed. The non-modified Al-Si alloy cast in sand mould needed greater Sp power consumption than the other two alloys used in this work. Cutting force increases linearly with depth of cut and spindle speed. Cutting forces were maximum for non-modified Al-Si alloy cast in metal mould and minimum for non-modified Al-Si alloy cast in sand mould.

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013701   Durgavalse S V (Goodlass Nerolac Paints Ltd, , G K Marg Lower Parel) : Melamine - formaldehyde resins in surface coating. Paintindia 1999, 44(8), 67-72.

Melamine-formaldehyde resin is a thermosetting type of synthetic resin. It is widely used as crosslinking (curing) agent with alkyd, acrylic, polyester, epoxy resins in industrial paints. This resin can be used in solvent based as well as water based surface coatings

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013700   Dhale A D;Mahajani V V (Chemical Engineering Division, University Department of Chemical Techn, University of Mumbai, Mutunga, Mumbai-400 019) : Recovery of sulphur from H2S bearing gas with the help of Thiobacillus ferrooxidans. Indian J chem Technol 1999, 6(1), 5-11.

Biological process is proposed for the recovery of sulphur from hydrogen sulphite bearing gas. The process involves absorption of the gas in an aqueous ferric sulphate solution wherein, it is converted to elemental sulphur and ferric is reduced to ferrous. Oxidation of ferrous sulphate, which is a rate determining step, is carried out using Thiobacillus ferrooxidans as catalyst, immobilized on a carbon support in a fluidized bed reactor. The experiments are carried out in both batch and continuous modes of operation. The effects of various parameters such as light, ammonium sulphate, urea and carbon dioxide as additives, have been studied to get better insight into the process of oxidation of Fe²⁺ to Fe³⁺. The absence of light and the addition of ammonium sulphate improved the oxidation rate of Fe²⁺. The use of urea as an additive showed substantial enhancement of the oxidation rate. As the catalyst loading is increased, the oxidation rate of Fe²⁺ is also increased. The performance of the reactor in continuous mode of operation has been evaluated at different flow rates of Fe²⁺ solution. Sulphur of high purity has been obtained from H2s gas. The reduced solution is then oxidized to ferric sulphate and reused partly in order to simulate commercial operation.

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013699   Devarajulu T;Vanisree G;Kishnaiah A (Department of Chemistry, S.V. University, Tirupati-517 502) : Competitive adsorption of Phenol and p-chlorophenol from aqueous solution on amberlite XAD-7 resin. Indian J envir Hlth 1999, 41(2), 98-106.

Adsorption equilibria of phenol, p-chlorophenol individually and combined over a wide range of concentration at 303.15 K on Amberlite XAD-7 resin are measured. The data are fitted to Freundlich and Langmuir adsorption isotherms. Effect of pH on adsorption of phenol and p-chlorophenol on Amberlite XAD-7 from single and biosolute aqueous solution is investigated. Break-through capacity and total adsorption capacity of phenol, p-chlorophenol individually and combined are obtained through column adsorption studies. The recovery of solutes from the loaded resin is reported by solvent elution method using methanol as an eluent.

013698   Dani C M;Das R K;Patra U C;Prasad M (Research & Control Laboratory, Rourkela Steel Plant, Rourkela-769 011) : Analysis of ferro-alloys by XRF spectrometer in RSP. Trans Indian Inst Metals 1999, 52(5), 349-52.

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013697   Choudhury A;Natarajan S (Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore-560 064) : Synthetic iron phosphate mineral, spheniscidite, [NH₄]<. Proc Indian Acad Sci-Chem Sci 1999, 111(5), 627-37.

Spheniscidite, a synthetic iron phosphate mineral has been synthesized by hydrothermal methods. The material is isotypic with another iron phosphate mineral, leucophosphite. Spheniscidite crystallizes in the monoclinic spacegroup P2₁/n. (a = 9.845(1), b = 9.771(3), c = 9.897(1), β = 102.9°, V = 928.5(1), Z = 4, M = 372.2, d_calc = 2.02 g cm^-3 and R = 0.02). The structure consists of a network of FeO₆ octahedra vertex-linked with PO₄ tetrahedra forming 8-membered one dimensional channels in which the NH₄⁺ ions and H₂O molecules are located. The material exhibits reversible dehydration and good adsorption behaviour. Magnetic susceptibility measurements indicate that the solid orders antiferromagnetically.

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013696   Choudhary V;Sivadinarayana C;Mantri K (Chemical Engineering Division, Nationala Chemical Laboratory, , Pune-411 008) : Influence of catalyst binder on the acidity and activity/selectivity of Ga/H-ZSM-5 zeolite in propane aromatization. Proc Indian Acad Sci-Chem Sci 1999, 111(5), 669-76.

Acidity and initial and time-on-stream activity in propane aromatization (at 550°C, space velocity of 3100 cm³g^-1_{zeolite) h^-1) of Ga-impegnated H-ZSM-5 zeolite without or with binders (50 wt%), such as silica, alumina and kaolin, have been investigated. Both the acidity and catalytic activity of the zeolite are influenced by the presence of binder in the catalyst, depending upon the binder. The influence is found to be lowest for alumina and highest for kaolin. Among the binders, alumina is the most preferred binder for the zeolite catalyst.}

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013695   Choudhary B K;Bhanu Sankara Rao K;Mannan S L (Materials Development Group, Indira Gandhi for Atomic Research, Kalpakkam-603 102) : Steady state creep deformation behaviour of 9Cr-1Mo ferritic steel forging in quenched and tempered condition. Trans Indian Inst Metals 1999, 52(5), 327-36.

Constant load isothermal creep tests have been carried out to assess the influence of stress (60-300 MPa) and temperature (773-873 K) on the steady state creep deformation of 1000 mm diameter and 300 mm thick 9Cr-1Mo ferritic steel forging in quenched and tempered condition. Applied stress dependence of steady state creep rate obeyed Norton's power law and exhibited two slope behaviour with stress exponents of abvout 5-6 at low stresses and 10.2 at high stresses at all temperatures. The two slope behaviour is also reflected in two apparent activation energy values of 266 and 468 kJ mil^-1 in the low and high stress regimes, respectively. Invoking the concept of resisting stress, the two stress exponents and two apparent activation energy values in the two stress regimes have been rationalized using modified Dorn equation. Following Lagneborg and Bergman, the resisting stress has been determined from the creep data. The variation of resisting stress with applied stress and temperature indicated that at low stresses linearly with applied stress with proportionality constant of 0.77. On the other hand, at high stresses the resisting stress remains constant equal to threshold stress and decreases with increasing test temperature. Incorporating resisting stress in both low and high stress regimes into modified Dorn equation, a single slope behaviour with stress exponent of about 4 and a true activation...

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013694   Chitkara N N (NO, NFL, Vijaipur, Distt. Guna 111, M.P.) : Operating experience of new Ammonia-urea plants at NFL Vijaipur. Fertil News 1999, 44(12), 27-31 & 33-4.

Vijaipur unit of NFL has recently commissioned its expansion plants of 1350 TPD Ammonia based on HTAS technology and 2200 TPD Urea based on Snam Progetti technology alongwith other associated facilites. The ammonia production was started within a record time of 10 days from first feed-in. Inspite of many teething problems, pre-commissioning and commissioning phase passed smoothy without any incident. Plants have been performing exceptionally well till date. This has been made possible because of the adoption of latest technologies working to the systems and the well trained, motivated and fully dedicated human resources.