Showing papers in "Transactions of The Indian Ceramic Society in 1987"
TL;DR: In this paper, the outline of the sol-gel method for producing glasses and related materials has been described, which makes it possible to synthesize glasses at relatively low temperatures and also prepare new glasses which could not be prepared by conventional melting techniques.
Abstract: The outline of the sol-gel method for producing glasses and related materials has been described. This method makes it possible to synthesize glasses at relatively low temperatures and also prepare new glasses which could not be prepared by conventional melting techniques. Thus, this method has a great potential in applications to the synthesis of high technology materials.
20 citations
TL;DR: In this article, the progress made by CG & CRI in developing appropriate technologies for the small and tiny scale pottery industries of the country is described, where special stress has been laid in these technologies on the meaningful use of low grade raw materials in the manufacture of rural sanitaryware, unglazed flooring and facing tiles and low maturing white stonewares with matching glazes.
Abstract: This article presents an account of the progress made by CG & CRI in developing some appropriate technologies for the small and tiny scale pottery industries of the country. Special stress has been laid in these technologies on the meaningful use of low grade raw materials in the manufacture of rural sanitaryware, unglazed flooring and facing tiles and low maturing white stonewares with matching glazes. In addition, an energy efficient low thermal mass down draught kiln was also designed and developed in this programme for reducing firing cost. Transfer of these technologies through training-cum-demonstration programmes has been described.
9 citations
TL;DR: The improvement in usage and development of better refractories has continued over the last decade, so much so, that float and container glass furnaces are now being confidently designed for continuous lives of up to 10 years as discussed by the authors.
Abstract: The improvement in usage and development of better refractories has continued over the last decade, so much so, that float and container glass furnaces are now being confidently designed for continuous lives of up to 10 years. Clearly the refractory manufacturers and furnace builders are helping the glass manufacturers to keep ahead of their problems. This is despite the additional difficulties imposed by energy saving and environmental controls, which are making glass manufacture more demanding.
6 citations
TL;DR: In this article, a simple and rapid method has been worked out for accurate determination of boron in commercial glasses, enamels and other silicate materials by alkalimetric titration of Boron as mannitoboric acid.
Abstract: A simple and rapid method has been worked out for accurate determination of boron in commercial glasses, enamels and other silicate materials by alkalimetric titration of boron as mannitoboric acid. In the method, the error due to the loss of boron during decomposition of a sample at high temperature by fusion with Na2CO3 in existing methods has been eliminated by fusing at low temperature with NaOH. Bromothymol blue has been advantageously used as the indicator at pH 6.5 (pale yellow to bluish green) for neutralization of free acids and titration of mannitoboric acid. The interference of phosphate has been successfully eliminated by precipitating it out as zirconyl monohydrogen phosphate. Fluorine, calcium and magnesium up to 50 mg per 50 ml did not interfere.
3 citations
TL;DR: In this paper, the decomposition characteristics of four magnesium oxychloride phases in the system MgO-MgCl2-H2O were studied by the thermogravimetric method.
Abstract: The decomposition characteristics of four magnesium oxychloride phases in the system MgO—MgCl2–H2O were studied by the thermogravimetric method. The decomposition rate curves obtained at different temperatures in the interval 100°–500°C were found to follow formal first order kinetics. The activation energy values of the decomposition reactions were calculated to compare the thermal stabilities of the phases. The 5-phase was suggested as the desirable one in magnesium oxychloride cement for high temperature application as refractory castables.
3 citations
TL;DR: In this article, a theoretical basis for UO2 sintering has been developed in the first part of the paper and subsequently its relevance to industrial practice has been brought out, the effect of variables such as oxygen to uranium ratio, specific surface area of uO2 powder and additions on the sinterability of UO 2 have been discussed.
Abstract: UO2 is one of the most commonly used nuclear power reactor fuels today. The sintering process of UO2 presented in this article brings out the special features of UO2 including the effect of nonstoichiometry and dependence of its defect structure on the sintering atmosphere. A theoretical basis for UO2 sintering has been developed in the first part of the paper and subsequently its relevance to industrial practice has been brought out. The effect of variables such as oxygen to uranium ratio, specific surface area of UO2 powder, sintering temperature and additions on the sinterability of UO2 have been discussed and the optimum conditions for the production of UO2 fuel have been brought out.
3 citations
TL;DR: In this paper, the elastic properties of mica-reinforced composites have been analyzed in terms of the classical model of Voigt and Reuss and it has been shown that Hill's average based on these two models best represents the data.
Abstract: The elastic properties of mica-reinforced composites have been analysed in terms of the classical model of Voigt and Reuss. It has been shown that Hill's average based on these two models best represents the data. Over the range of volume fractions of mica studied, it is given by the equation
Ec = ½VfEf + Em(1 + ½Vf2)
where Ef is the effective value of reinforcement modulus, Vf is the volume fraction of the reinforcement phase and subscripts c, f and m refer to composite, reinforcement and matrix properties respectively.
2 citations
TL;DR: In this article, a preliminary report on p.z.c. data on TiO2-ZrO2powders calcined at 500° and 1000°C, obtained by the potentiometric method, is presented and the results are briefly discussed.
Abstract: Surface properties like point of zero charge (p.z.c.) of oxide powders greatly influence ceramic processing of such materials. Data on p.z.c. for single oxides obtained by using various techniques abound in the literature; however, relatively few data for mixed/multiple oxides are available. In this preliminary report p.z.c. data on TiO2—ZrO2powders calcined at 500° and 1000°C, obtained by the potentiometric method, are presented and the results are briefly discussed.
2 citations
TL;DR: In this paper, the various aspects of achieving homogeneity of ferrites during the process of manufacture were discussed, and an Electron Probe micro-analyzer was used extensively to ascertain the homogeneity.
Abstract: This paper deals with the various aspects of achieving homogeneity of ferrites during the process of manufacture. Electron probe micro- analyser is used extensively to ascertain the homogeneity of ...
2 citations
TL;DR: In this article, the nucleation and crystallization behavior of basalt glass has been studied dynamically by small angle neutron scattering (SANS) and the interparticle interference effect shows a pronounced maximum in the SANS spectra at the growth temperature of 710°C for different nucleated samples.
Abstract: The nucleation and crystallization behaviour of basalt glass has been studied dynamically by small angle neutron scattering (SANS). The interparticle interference effect shows a pronounced maximum in the SANS spectra at the growth temperature of 710°C for different nucleated samples. The number density of particles decreases with the time of growth and then saturates at longer time. This behaviour is interpreted as due to the redissolution of the smaller particles as the larger ones continue to grow with the stabilized number density in the ripening stage. The process of redissolution of the particles during growth of the stable nuclei of the basalt glass is discussed.
2 citations
TL;DR: In this article, the Mossbauer spectra of a basalt glass containing about 13 wt% Fe2O3, which forms magnetite on heat-treatment, have been studied both at 300 K and at 4 K and without magnetic field.
Abstract: The Mossbauer spectra of a basalt glass containing about 13 wt% Fe2O3, which forms magnetite on heat-treatment, have been studied both at 300 K and at 4 K and without magnetic field. The observed magnetic hyperfine splitting at 300 K is related to the anisotropy of the magnetite particles having a particle size higher than a critical value. The observed hfs pattern at 4 K with H = 0 in the Mossbauer spectra is found to be independent of the particle size. The Mossbauer spectra at 4 K with H ≠ 0 show that the ▵mI = 0 lines do not disappear in the magnetite particles below the critical size, while above the critical size, these lines disappear with the progressive application of the magnetic field applied parallel to the γ-ray direction. The above results are represented in terms of a model of magnetic structure of the small particles of magnetite embedded in a glassy matrix.
TL;DR: In the field of glass science and technology, all the main aspects of chemical thermodynamics are used as mentioned in this paper, and they will be briefly outlined in Section 2.2.1.
Abstract: Chemical thermodynamics is finding increasing application in glass science and technology. It results from the necessity to realize in a deeper way the nature of glass and the phenomenon of glass transition, as well as from the development of modern methods of optimization of technological processes using electronic computers.In the field of glass science and technology all the main aspects of chemical thermodynamics are used. They will be briefly outlined.
TL;DR: Work done on uranium glazes from the beginning of this century to the time of World War II, when the use of uranium compounds was banned for non-strategic use in most countries, is reviewed in this article.
Abstract: Work done on uranium glazes from the beginning of this century to the time of World War II, when the use of uranium compounds was banned for non-strategic use in most countries, is reviewed. Glazes were formulated using sodium diuranate as the colourant. Satisfactory bright vermillion shades were obtained which exhibited uniform results under conditions of commercial artware production. The high lead content of these glazes, however, precluded their use on tableware. Further work to improve the acid resistance of these glazes is suggested.
TL;DR: In this paper, partial and full stabilization of zirconia was attempted by using stabilizers like calcium chloride and bromide (10, 15 and 20 mol%) in powder form in the temperature range of 300° to 1300°C.
Abstract: Partial and full stabilization of zirconia was attempted by using stabilizers like calcium chloride and bromide (10, 15 and 20 mol%). The green mixture was heated in powder form in the temperature range of 300° to 1300°C. The stabilization was studied through thermal analysis and powder X-ray diffraction techniques. The green mixture showed crystallinity only above 300°C. Crystal size increased with increase in calcination temperature. Calcined samples showed the presence of cubic/tetragonal phase along with a certain amount of monoclinic phase at room temperature. The intensity of the compound peak (30.2 2θ), where 10 mol% CaCl2 was used as stabilizer, increased rapidly with temperature up to 550°C, while in case of CaBr2 stabilizer it increased rapidly up to 750°C. Above these temperatures, marginal increase in intensity was observed in both the cases. A comparative study shows that below 800°C firing temperature, CaCl2 was more effective than CaBr2. However, above this temperature the reverse was obser...
TL;DR: In this article, an explanation for the experimental data, obtained earlier, and concerning the glass irradiation at low temperatures and registration of radiation effects with respect to ESR-spectra is suggested.
Abstract: An explanation is suggested for the experimental data, obtained earlier, and concerning the glass irradiation at low temperatures and registration of radiation effects with respect to ESR-spectra. The quasi-metallic line shape of the ESR-spectrum has been accounted for by the occurrence of tunnel-interacting states. The mechanism of the radiation centre formation on irregular units has been described by potential curves plotted in configurative coordinate. Such diagrams allow to penetrate deeper into the nature of processes peculiar to material-radiation interaction.
TL;DR: In this article, the dehydration transformation in a Mg-rich trioctahedral sample of hectorite has been studied by applying DTA and a X-ray line profile technique developed by De et al. The transformation was explained in terms of layer disorder which has been found to increase with dehydration leading finally to the metaphase.
Abstract: Dehydration transformation in a Mg-rich trioctahedral sample of hectorite has been studied by applying DTA and a X-ray line profile technique developed by De et al.4,5 The transformation has been explained in terms of layer disorder which has been found to increase with dehydration leading finally to the metaphase. The results have been compared with those of 1:1 and 2: 1 dioctahedral layer silicates. Several useful conclusions have been drawn on the thermal behaviour of the di- and trioctahedral layer silicates.
TL;DR: In this paper, the sintering behavior of 80 m/o ZrO2 −20m/o CeO2 was investigated in air and vacuum in the temperature range of 1300°-1600° C. Nb2O5 and Ta2Os additions were both found to improve densification.
Abstract: Ceria-stabilized zirconia is a potential MHD electrode material because of its refractoriness, oxidation and corrosion resistance, as also adequate electrical conductivity at operating temperatures. The sintering behaviour of 80 m/o ZrO2–20 m/o CeO2 and 80 m/o CeO2–20 m/o ZrO2 has been investigated in air and vacuum in the temperature range of 1300°–1600° C. Nb2O5 and Ta2Os additions were both found to improve densification. Room temperature electrical conductivity improved considerably when sintering was carried out in vacuum and values of the order of 10 −4 (ohm-cm)−1were obtained.
TL;DR: In this paper, the methodology adopted for structure refinement from powder diffraction data is discussed at length, focussing on the various assumptions that are required to be made to simplify the procedure.
Abstract: BaxTiO3 prepared through coprecipitation method may contain vacancies in either Ba-position or Ti-position. Since by chemical analysis it has been ascertained that the mole content of Ti-ion is in excess of that required to maintain the stoichiometric ratio of Ba: Ti as 1:1 it is assumed that there occur vacancies in Ba-position in the structure of BaTiO3. On this assumption, when exact positional coordinates in the lattice structure, P4mmm, are determined on refinement of X-ray intensity data with respect to the calculated intensities, it is found that more agreeable results are obtained when atomic positions in the lattice structure are such that a certain portion of Ba-positions is lying vacant than when the ratio of Ba: Ti is 1:1.
In this paper, the methodology adopted for structure refinement from powder diffraction data will be discussed at length, focussing on the various assumptions that are required to be made to simplify the procedure.
TL;DR: In this article, the authors have shown that the material exhibits high potentiality as lining material in LD converters in steel industry due to low flux content, high density and improved resistance to hydration.
Abstract: Two hundred thousand tons of relatively pure grade of dolomite fines are likely to be generated per annum in course of beneficiation of the low grade rock phosphate ore of Jhamarkotra Mines, Rajasthan by Rajasthan State Mines and Minerals Ltd. The material contains CaO 33%, MgO 19–20%, SiO2 less than 0.1% and P2O5 1.0% by wt, and is extremely fine (>90%–170 BS sieve).
Chemical analysis, TGA, DTA and X-ray analysis of the above sample have been carried out. The material has been sintered both by single stage and double stage sintering process at 1650°C. The bulk density of the material achieved by single stage process with additive is around 3.19 gm.cm−3 and by double stage sintering process is 3.32 gm.cm−3. A comparative study in terms of hydration resistance by ASTM—C492 method of the present material and those currently being used by Indian Steel Plants has shown much improved shelf-life of the former. The developed material exhibits high potentiality as lining material in LD converters in steel industry due to low flux content, high density and improved resistance to hydration.
TL;DR: In this paper, a method has been developed where alumina has been directly determined via indirect titration with EDTA overcoming the interfering effects of iron and titanium, when present in large amounts, interfere due to intense yellow colour of Fe(III)-EDTA complex and slow hydrolysis of TiO-EDTA complexes.
Abstract: Usually, complexometric determination of aluminium in solution involves a back titration procedure using zinc acetate and EDTA at pH 5.3. Iron and titanium, when present in large amounts, interfere due to intense yellow colour of Fe(III)-EDTA complex and slow hydrolysis of TiO-EDTA complex. A method has been developed where alumina has been directly determined via indirect titration with EDTA overcoming the interfering effects of iron and titanium. An excess of EDTA is added, the solution is brought to pH 5–6 and boiled. NaOH solution is then added to bring the pH of the alkaline solution to 11–11.5, when iron and titanium complexes break down, producing the respective hydroxides. The solution is then made to a definite volume along with the hydroxide precipitates. An aliquot of the filtered solution is analysed for alumina following the usual back titration procedure with EDTA. Synthetic solutions of alumina containing large amounts of iron and titanium, as well as iron and titanium bearing materials were analysed for alumina. The results obtained showed excellent precision and accuracy compared to those by other standard methods.