Showing papers in "Transactions of The Indian Ceramic Society in 1975"
TL;DR: The thermal expansion of hard porcelain samples is a function of the asymmetry of size distribution of mullite crystals and internal stresses originating in the samples from the thermal expansion mismatch between the phases also influence the thermal-shock resistance as mentioned in this paper.
Abstract: Thermal-shock resistance of hard porcelain samples are dependent on the concentrations of the crystalline phases (mullite and quartz) and the glassy phase and also on the size of mullite crystals. Internal stresses originating in the samples from the thermal expansion mismatch between the phases also influence the thermal-shock resistance. The thermal expansion of the samples is a function of the asymmetry of size-distribution of mullite crystals.
11 citations
TL;DR: In this paper, the formation of crystallites and subgrain boundary formation was demonstrated on alumina with X-ray diffraction and electron microscopy studies, and the contribution made by particle fracture during ball milling was discussed.
Abstract: Ball milling is a process of comminution where strains in the nature of dislocations, formation of crystallites and subgrain boundary formation were shown to occur in addition to normal particle fragmentation with increase in surface area. The phenomena was demonstrated on alumina with X-ray diffraction and electron microscopy studies. In the context of the above studies the nature of brittleness of alumina was outlined and the contribution made by particle fracture during ball milling was discussed.
4 citations
TL;DR: In this paper, the effects of forming pressure, particle size, sintering temperature and sinter time on tricalcium aluminate were investigated using the empirical equation D = K log t+C.
Abstract: Sintering studies were carried out on tricalcium aluminate prepared by solid-solid reaction between calcium carbonate and aluminium oxide. Effects of forming pressure, particle size, sintering temperature and sintering time were investigated. The data were analysed using the empirical equation D = K log t+C.It was observed that the activation energy for the later stage of sintering increases with particle size from-53+45μto-75+63μ. Increase in compaction pressure, sintering temperature and use of multisized particles gave nearly theoretical density.
4 citations
TL;DR: In this paper, the suitability of various compositions in MgO-ZrSiO4 and CaCO3-MgOZrNiO4 systems for industrial applications was studied.
Abstract: Various compositions in MgO-ZrSiO4 and CaCO3-MgO-ZrSiO4 systems heated up to 1450° for different periods were studied. While in both the systems, there was complete decomposition of zircon under suitable conditions, it was found that either the magnesite-zircon composition in the molar ratio of 2:1 or the dolomite-zircon composition in the molar ratio of slightly greater than 1:1 may be used for industrial applications. The suitability, in the decreasing order, of the three systems studied was CaCO3-ZrSiO4, CaCO3-MgO-ZrSiO4 and MgO-ZrSiO4. The various products of decomposition were also identified with the help of chemical and X-ray analysis.
3 citations
TL;DR: In this paper, the faujasite family of molecular sieve zeolites were synthesized at 80°-150°C from gels of different alkali and silica concentrations.
Abstract: Sodium zeolites X and Y (SiO2/Al2O3 ratio varying between 2.15 and 4.40), belonging to the faujasite family of molecular sieve zeolites, were synthesized at 80°-150°C from gels of different alkali and silica concentrations. Free gel, zeolite A and zeolite NaP* were found to be the most common impurities likely to be obtained while crystallizing zeolites X and Y from sodium aluminosilicate gels. Formation and/or persistence of these impurities were found to be dependent on the water content of the starting gel, or the time of crystallization. Synthesis of “ultrastable” Y zeolite was achieved by stepwise (though incomplete) removal of Na+ ions from a NaY sample. The compositional breaks and the associated problems of an uniform nomenclature for the entire range of the faujasite family of zeolites are discussed.
3 citations
TL;DR: In this article, 18 batch compositions containing varying proportions of blast furnace slag, bagasse ash and glass cullet were fired in an oil fired furnace at 1425±25°C for 2 hours, in order to investigate the possibility of using these waste materials for melting glasses.
Abstract: Eighteen batch compositions containing varying proportions of blast furnace slag, bagasse ash and glass cullet were fired in oil fired furnace at 1425±25°C for 2 hours, in order to investigate the possibility of using these waste materials for melting glasses. Of the eight compositions which gave glasses upon firing, two compositions containing 50: 50 blast furnace slag and bagasse ash together with 5% TiO2 and 5% B2O3 respectively, were having superior properties. All the glasses showed better chemical resistivity than normal container glass, particularly those containing minor addition of TiO2. The thermal expansion of the latter was also comparatively lower. Glasses for making containers, fibres, foams etc can be made out of the above waste raw materials economically.
3 citations
3 citations
TL;DR: In this paper, the effect of iron oxide on direct bonding in chrome magnesite refractories was studied in two series of experiments, and it was observed that additions of iron promote direct bond in purified chromite and magnesia compositions.
Abstract: The effect of iron oxide on direct bonding in chrome magnesite refractories was studied in two series of experiments. In one series purified chromite and pure magnesium carbonate sintered with different iron oxide additions were used; and in the other a high grade chrome ore and natural magnesite sintered with different iron oxide additions. It was observed that additions of iron promote direct bond in purified chromite and magnesia compositions. But with natural chrome ore and magnesite, even with high iron oxide concentration some amount of silicate phase is necessary to develop direct chromite-periclase bond.
2 citations
TL;DR: In this article, the authors examined Chrome-Magnesite bricks used in the burning zone of an oil fired kiln during a shutdown period to study the mechanism of wear where slagging action is ruled out.
Abstract: Chrome-magnesite bricks used in the burning zone of an oil fired kiln were examined during a shutdown period to study the mechanism of wear where slagging action is ruled out. The hot end of the bricks were decomposed resulting in formation of a powdery zone in kiln. Detailed study indicated vaporization of magnesio-chromite from the hot face of the brick and deposition of the same in comparatively cooler portions of the kiln. The left over bricks did not undergo any appreciable chemical alteration.
2 citations
TL;DR: In this paper, a high density (95% theoretical) single-phase uranium monocarbide has been fabricated by warm pressing a mixture of suitably sized dicarbide and uranium metal powders at 800°C at 675 kg/cm2 for 5 minutes and by subsequent sintering at 600°-1000°C.
Abstract: High density (95% theoretical) single-phase uranium monocarbide has been fabricated by warm pressing a mixture of suitably sized dicarbide and uranium metal powders at 800°C at 675 kg/cm2 for 5 minutes and by subsequent sintering at 600°-1000°C. The high density and the single phase structure could be retained upto 1800°C, though some grain growth occurs during this treatment (from 15 to 50 microns). The relatively low temperature reaction sintering technique enables production of high density pellets with controlled microstructure, free from other phases.
1 citations
TL;DR: In this article, a study of aluminous clays from Sarodabas area of Jammu Province has been reported and the mineralogical composition of the clays has been established.
Abstract: X-ray, I-R and D.T.A. study of aluminous clays from Sarodabas area of Jammu Province has been reported and the mineralogical composition of the clays has been established.
TL;DR: In this paper, a review of the crystallography and crystal chemistry of the faujasite family of zeolites has been presented, up to 1974, with the help of schematic diagrams and the way they would lead to activity of the dehydrated forms.
Abstract: Research work, up to 1974, on crystallography and crystal chemistry of the faujasite family of zeolites has been reviewed. The nature of the aluminosilicate framework, the intracrystalline zeolitic fluid, compositional range of the different members of this family, and crystallographic siting of non-framework cations and water molecules in the different cavities of the framework wherever it has been possible to do so, have been analysed. Migration of non-framework cations consequent upon dehydration has also been reviewed with the help of schematic diagrams and the way they would lead to activity of the dehydrated forms, so characteristic of this family of zeolites, has been emphasized.
TL;DR: In this paper, changes in the values of interplanar spacings and relative intensities of X-ray diffraction lines of some kaolinites have been studied and it has been interpreted to be due to disorder in kaolinite layers.
Abstract: Changes in the values of interplanar spacings and relative intensities of X-ray diffraction lines of some kaolinites have been studied. It has been found that there is a large variation in values of inter-planar spacings of some of the basal lines and it has been interpreted to be due to disorder in kaolinite layers.
TL;DR: In this paper, an aliquot is taken out for the determination of SiO2 and Al2O3 based on the titration of liberated HF on hyrolysis of K2SiF6 in hot water.
Abstract: After fusion of the sample with KOH in nickel crucible, extracting the same with water and acidifying the homogeneous solution, an aliquot is taken out for the determination of SiO2 based on the titration of liberated HF on hyrolysis of K2SiF6 in hot water and the other aliquot for the determination of Al2O3 based on the titration of released EDTA from Al-EDTA complex on boiling with NaF. This simultaneous determination of SiO2 and Al2O3 in aluminosilicate samples, particularly high alumina refractories, mullite, kyanite, etc is very rapid and simple. The time required for the determination of SiO2 and Al2O3 of such samples is only two hours and a half.
TL;DR: In this paper, various high and low-quartz solid solutions (stuffed derivatives of quartz) are enumerated; their crystal chemistry is discussed in terms of parameters like co-ordination, effective ionic radius and site preference of the candidate cations for such structures.
Abstract: The various high- and low-quartz solid solutions (stuffed derivatives of quartz) synthesized so far are enumerated; their crystal chemistry is discussed in terms of parameters like co-ordination, effective ionic radius and site preference of the candidate cations for such structures. Conditions of synthesis and stability/metastable persistence of these solid solutions are surveyed and their characteristic properties are summarized.
TL;DR: In this article, the quality of refractories that would be required in future are reviewed with a view to focusing on the possibilities of manufacturing them indigenously in the future.
Abstract: The process technology of iron and steel making is undergoing rapid changes throughout the world. Larger capacity blast furnaces and taller coke ovens are the order of the day. Basic oxygen steelmaking processes are replacing the conventional method of steel making in open hearth furnace. Vacuum degassing, continuous casting, slide gate valves etc are also gaining popularity.The service conditions required to be met by refractories in the modern iron and steel making units are very much severe demanding improved quality of materials.In India, some of the existing steel plants are on the threshold of expansion and a few mini steel plants are also being put up. All these units are expected to adopt some of the latest techniques in iron and steel making requiring improved quality of refractories which are not available in our country at present. The quality of refractories that would be required in future are reviewed in this paper with a view to focusing on the possibilities of manufacturing them indigenously.
TL;DR: In this article, the distribution ratio of the cations and the anions for the alumino-silicate hydrogel under various exchanging conditions and related to the extent of exchange has been determined.
Abstract: The distribution ratio of the cations and the anions has been determined for the alumino-silicate hydrogel under various exchanging conditions and related to the extent of exchange. This has been compared with that of the organic exchanger and also non-exchanging material. From the unequal distribution of the counterions as compared to the non-exchanging materials under varying conditions of exchange and with different cations, an explanation of the materials of the variations in the extent of exchange has been obtained.
TL;DR: In Tisco, coal-bonded ramming material was used for trough and sand was used to line the runner of the blast furnace as mentioned in this paper, which required constant attention and involved heavy maintenance job.
Abstract: Smooth operation of blast furnace largely depends on a good cast house practice, i.e. on the maintenance of trough and runner. In Tisco, clay bonded ramming material was used for trough and sand was used for lining the runner. Both these materials required constant attention and involved heavy maintenance job. Carbonaceous lining material has been developed to overcome these difficulties and successfully used in the Plant. Details of the laboratory work on various compositions and their service performance have been discussed.
TL;DR: In this article, it is shown that on annealing such particles, the deformation is relieved by a process of recovery phenomenological to the anneal of a ductile metal.
Abstract: Alumina is known to be a brittle substance; however, recently it has been shown that deformation in the nature of dislocations could be introduced by scratching, milling, diamond indentation etc. The effective deformation produced in alumina particles particularly by ball milling is discussed. It is shown that on annealing such particles, the deformation is relieved by a process of recovery phenomenological to the annealing of a ductile metal. A two stage recovery process (primary and secondary) was identified and activation energies of the order of 15.64 and 27.4 Kcal/mole respectively were measured. The behaviour was analysed considering the hexagonal structure of an alumina crystal.
TL;DR: In this paper, the authors present a survey of refractory corrosion, a potential cause of their destruction, is dependent on certain physico-chemical characteristics of both the refractories and of the environment i.e. the fusible molten materials that they contain.
Abstract: Corrosion of refractories, a potential cause of their destruction, is dependent on certain physico-chemical characteristics of both the refractories and of the environment i.e. the fusible molten materials that they contain. The present literature survey aims at indicating these characteristics together with the studies of reactions between these materials. It has been indicated, for example, that the refractory corrosion is primarily dependent upon factors such as the porosity and pore size distribution of the refractory, the viscosity and surface tension of the molten material, in addition to the time and temperature of the corrosive reaction. The studies on mechanism of the refractory corrosion have been touched upon. The various test procedures, some being more simulative of the actual service conditions than others, have been presented. The most satisfactory test procedure to be selected depends on the conditions existing during use of the refractories. The suggestions to minimise the refractory corr...