Showing papers in "Transactions of The Indian Ceramic Society in 1969"
TL;DR: In this article, the role of non-bridging oxygen in glass is compared with that of hydroxyl ion in aqueous solutions and a new hypothesis to define basicity of a borate or a silicate glass has been proposed.
Abstract: The conventional acid-base concepts in glass are discussed and a new hypothesis to define basicity of a borate or a silicate glass has been proposed. The role of non-bridging oxygen in glass is compared with that of hydroxyl ion in aqueous solutions. Chromium (VI), Vanadium (V), Uranium (VI), Cobalt (II), and Nickel (II) are found to exist in glass in acidic and basic forms with very different optical absorption; these ions can successfully be used as “colour indicators” to study the acid-base character of a glass. The influence of acid-base property on oxidation-reduction equilibrium of transition metal ions in glass is discussed.
11 citations
TL;DR: In this article, the influence of origin and calcination treatments on the development of crystallinity, surface area and morphology of Magnesia powders was studied by thermal decomposition/calcination of different parent compounds.
Abstract: An attempt was made to study the influence of origin and calcination treatments on the development of crystallinity, surface area and the morphology of magnesia powders. Magnesia powders were prepared by thermal decomposition/calcination of different parent compounds namely, magnesium hydroxide, oxalate, carbonate, salicylate and succinate. Calcination temperatures upto 900°C in either air or vacuum and soaking time from half to 16 hrs were used. The development of crystallinity in the resultant magnesia powders was studied at room temperatures by X-ray line broadening techniques. The surface areas of the magnesia powders were determined by the BET method. A limited study was made on the morphology of the powders using electron microscope.It was found that at the decomposition temperature of the parent compound, the crystallinity of the resultant magnesium oxide was very poor, and the surface area extremely high. With an increase in calcination temperature, the crystallinity of the oxide powders improved ...
7 citations
TL;DR: In this paper, the influence of alkalies, alkaline earth oxides, Fe2O3 and TiO2 on the mullitization of pure kaolinitic clay was studied by quantitative X-ray diffraction measurements, using γ-alumina as the internal standard.
Abstract: The influence of alkalies, alkaline earth oxides, Fe2O3 and TiO2 on mullitization of a pure kaolinitic clay was studied by quantitative X-ray diffraction measurements, using γ-alumina as the internal standard Earlier investigations indicate that the yield of mullite varies, within wide limits, with the concentration of the mineralizers The results show that the amounts in which these impurities are generally present in clays have profound influence on the process of mullitization
7 citations
TL;DR: In this paper, it is observed that after the initial dissolution of a small percentage of oxygen in the Niobium lattice, oxidation commences with the formation of lower-oxides of niobium.
Abstract: The oxidation of pure niobium powder in air has been investigated It is observed that after the initial dissolution of a small percentage of oxygen in the niobium lattice, oxidation commences with the formation of lower-oxides of niobium The existence of a sub-oxide ascribed as NbOx is detected below 350°C having a structure closely resembling that of the pure metal The other known lower oxides of niobium, it is thought, exist only as relatively thin layers and therefore cannot be detected by X-ray At about 400°C, the sub-oxide is found to decompose and further oxidation above this temperature leads to the formation of the pentoxide, Nb2O5 Two allotropic modifications have been observed in Nb2O5 namely, a low-temperature -form which transforms irreversibly to the high-temperature β-form at about 850°C β-Nb2O5, once formed, becomes stable throughout and hence is the equilibrium phase at all temperatures above room temperature
6 citations
TL;DR: In this article, three glass compositions, one corresponding to β-Eucryptite, another corresponding to Lithium Metasilicate and the third corresponding to 1070°C eutectic, were studied with respect to their crystallization behavior.
Abstract: Three glass compositions, one corresponding to β-Eucryptite, another corresponding to Lithium Metasilicate and the third corresponding to 1070°C eutectic on the lithium metasilicate-β-eucryptite join in the composition triangle lithium metasilicate-β-spodumene-β-eucryptite of the system Li2O-Al2O3-SiO2 were studied with respect to their crystallization behaviour. The phases crystallizing out after different heat treatment schedules and using different nucleating agents were identified by X-ray diffraction patterns. In all cases, the initial crystallization product was Eucryptite silica-O form. However, in the case of 1070°C eutectic composition the development of lithium metasilicate phase was also noticed after heat treating at 800°C for 5 hours.The first DTA peak due to crystallization was used to distinguish the effects of ZrO2, TiO2 and V2O5 as nucleating agents. With 5% zirconia additions the first crystallization peak temperature was maximum while in the case of 5% V2O5 additions it was minimum. The...
5 citations
TL;DR: In this article, the physicochemical properties of some Indian bentonites were systematically studied in view of their wide application in recent years in ceramic industries as plasticizer, in glazes etc.
Abstract: Physico-chemical properties of some Indian bentonites were systematically studied in view of their wide application in recent years in ceramic industries as plasticizer, in glazes etc. The study includes the general properties of bentonites e.g. colour, fracture, sp. gr., hardness, plasticity, pH, sp conductivity, particle size, soapy touch, swelling, thixotropy and settling behaviour. The bentonites studied were Bihar, Jaipur, Akli, Hathi-ki-dhani, Rajula and Karauli. Of the bentonites studied Akli showed maximum fineness, swelling and dry linear shrinkage. Akli and Hati-ki-dhani appeared to be Na-based bentonite, and Bihar appeared to be a Ca-based. Jaipur and Karauli did not exhibit the characteristic properties of bentonite.
4 citations
TL;DR: In this article, a hypothesis explaining the mechanism of annealing has been formulated and confirmed by extensive studies of the phase composition, carried out by means of X-ray analysis and determination of the valence state of chromium ions.
Abstract: On the basis of chemical determinations of the conversion as a function of time and temperature of annealing, kinetics of this process has been analysed and a hypothesis explaining its mechanism has been formulated. The hypothesis has been confirmed by extensive studies of the phase composition, carried out by means of X-ray analysis and determination of the valence state of chromium ions.
3 citations
TL;DR: The influence of high silica content in a brick for a given lime/silica molar ratio has been studied in this paper, where a systematic variation of chemical composition, the mineralogical constitution and physical properties of magnesite refractories were investigated.
Abstract: By a systematic variation of chemical composition, the mineralogical constitution and physical properties of magnesite refractories were investigated. The influence of high silica content in a brick for a given lime/silica molar ratio has been studied. The lime/silica molar ratio varied between 0.38 to 2.24 and the silica contents upto 9.5%. The composition of matrix minerals changed with the lime/silica molar ratio. At 5% silica level, best refractoriness under loads were obtained at lime/silica molar ratios of below 0.38 and above 2.0.
3 citations
TL;DR: In this article, the effect of interfering ions like K+, Ca2+, Mg2+, Al3+, Fe3+ and SO42- was studied and the results of Na2O determinations made with sodium electrode were compared with those determined by flame spectrophotometry and they were analyzed statistically.
Abstract: Five Lithia Alumina Silicate glasses having different proportions of additives were melted and studied for their suitability as sodium electrodes. A particular composition was found to be the best so far as the sodium ion specificity was concerned. The effect of interfering ions like K+, Ca2+, Mg2+, Al3+, Fe3+ and SO42- was studied and it was found that only Al3+ and Fe3+ had interference which also could be completely suppressed by using triethanol-amine. The results of Na2O determinations made with sodium electrode were compared with those determined by flame spectrophotometry and they were analysed statistically.
2 citations
TL;DR: In this paper, the exchangeable ions in Tinpahari bentonite were substituted by Na+, K+, NH4, Mg+2, Ca+2 and Ba+2 separately.
Abstract: The exchangeable ions in Tinpahari bentonite were substituted by Na+, K+, NH4, Mg+2, Ca+2, Ba+2, Al+3 and Th+4 ions separately. The amount of interlayer water in bentonite is fairly large (about 10–15%) and the water content is determined primarily by the principal exchangeable cation present. The dehydration-rehydration flexibility of the bentonite as well as the cation exchange characteristics have been studied and the specific role of the exchangeable cations has been examined.
2 citations
TL;DR: In this paper, the maximum solubilities of NiO, CoO, FeO and Cu2O have been measured, at different temperatures, in a standard silicate solvent containing 18.4 mole per cent Na2O, 31.6 Mole per cent K2O and 50 Mole per percent SiO2.
Abstract: Maximum solubilities of NiO, CoO, FeO and Cu2O have been measured, at different temperatures, in a standard silicate solvent containing 18.4 mole per cent Na2O, 31.6 mole per cent K2O and 50 mole per cent SiO2. Solubilities have been determined by equilibrating the pure oxides with the solvent melt and chemically analyzing the saturated melt. Furthermore, the effect of NiO addition on the viscosity of the melt was studied using a viscometer to substantiate some of the conclusions of the solubility measurements.
TL;DR: In this article, the hydraulic properties of high alumina cements with different amounts of SiO2, Fe2O3, and TiO2 were studied, and it was found that hydraulic properties are not much affected if SiO 2 content is within 15% but the cements had quick setting and slow hardening tendency when Si O2 content is more than 5%.
Abstract: Hydraulic activities and high temperature strength retaining capacities of high alumina cements containing different amounts of SiO2, Fe2O3 and TiO2 were studied. It was found that hydraulic properties are not much affected if SiO2 content is within 15% but the cements had quick setting and slow hardening tendency when SiO2 content is more than 5%; presence of Fe2O3 to the extent of 5% remarkably improves the hydraulic properties but further addition deteriorates the hydraulic properties. TiO2 content to the extent of 5% did not alter the hydraulic properties appreciably. High temperature strength retaining capacities of high alumina cements are lowered by the presence of both SiO2 and Ti02 mid improved by the presence of Fe2O3. More than 5% SiO2 content is undesirable. Fe2O3 may be present upto 15% but for better performance the amount should not exceed 5%.
TL;DR: Two calcium aluminate cements comprising predominantly of CaO.Al2O3 and CaOO.2Al 2O3 respectively were prepared by sintering process and the physical and refractory properties of these cements were determined as mentioned in this paper.
Abstract: Two calcium aluminate cements comprising predominantly of CaO.Al2O3 and CaO.2Al2O3 respectively were prepared by sintering process. These cements were used in different proportions along with Assam sillimanite, calcined kyanite and calcined Kashmir bauxite as refractory castables. The physical and refractory properties such as apparent porosity, bulk density, modulus of rupture, refractoriness underload, PCE, spalling resistance and also modulus of rupture and linear change after firing to different temperatures were determined.Castables with kyanite as aggregate material had the best refractory properties. The refractoriness of the castables was adversely affected due to the presence of titania in the aggregate materials.
TL;DR: In this paper, the effects of shape, size and relative proportions of the crystalline phases usually present in the aluminosilicate refractories on their thermal-shock resistance are compared.
Abstract: Thermal-shock resistance of aluminosilicate refractories is influenced by their chemical composition and mineralogical constitution. Attempts have been made in this paper to compare the effects of shape, size and relative proportions of the crystalline phases usually present in the aluminosilicate refractories on their thermal-shock resistance.
TL;DR: In this paper, a rapid method for direct determination of total iron in chrome-bearing materials is given, where the sample after fusion with sodium peroxide in a nickel crucible is taken into sulphuric acid solution and Chromate is reduced by boiling with ethyl alcohol.
Abstract: A rapid method for direct determination of total iron in chrome-bearing materials is given. The sample after fusion with sodium peroxide in a nickel crucible is taken into sulphuric acid solution and Chromate is reduced by boiling with ethyl alcohol. Iron is then titrated with mercurous nitrate in presence of a large excess of thiocyanate ion. Other ions which are generally present in chrome-bearing materials do not interfere. Oxides of nitrogen interfere but their effect is eliminated by boiling with urea. A determination can be completed within 20 minutes after opening the sample. The standard deviation has been found to be 0.056.
TL;DR: In this article, the absorption spectra of ruthenium in simple soda silica glasses were determined, and the maximum absorption rate was found to be at 680-690 milli micron in all glasses and at 465 and 510 milli-micron in basic and relatively acidic glasses.
Abstract: Absorption spectra of ruthenium in simple soda silica glasses were determined. Absorption maximum occurred at 680–690 milli micron in all glasses and at 465 and 510 milli micron in basic and relatively acidic glasses. Absorption spectra of a tetravalent ruthenium complex in KOH solution was reported. Comparison of absorption spectra of ruthenium in glass with that of the known spectra of ruthenium in solution indicated that ruthenium may be present in glass as tri-, tetra- and hexavalent ruthenium depending on glass composition.
TL;DR: In this article, the health care of the Indian Ceramic worker is discussed and the authors propose a health care system for the workers in the field of ceramics, based on Indian culture.
Abstract: (1969). Health Care of Ceramic Worker. Transactions of the Indian Ceramic Society: Vol. 28, No. 1, pp. 1N-6N.
TL;DR: In this article, two soil samples from Agartala were studied for their suitability for high strength bricks and they showed that bricks from these soils are highly siliceous in nature and contain illitic group of clay minerals.
Abstract: Two soil samples from Agartala were studied for their suitability for high strength bricks. The soils are highly siliceous in nature and contain illitic group of clay minerals. Bricks from these soils crack during firing. Paving bricks of 500–520 kg/sq cm strength, 4 to 5 per cent water absorption and possessing high abrasion resistance can be developed from these soils at a firing temperature of 1050°-1100°C and at a controlled heating and cooling rate of 20°C/hour. Quartz inversion and overall expansion are considered responsible for cracking in bricks.
TL;DR: In this paper, the same experiments were repeated after treating the clays with neutral salt, and results were used to identify the clay minerals present and also to obtain a quantitative estimation of the montmorillonite content in these bentonites.
Abstract: Potentiometric, viscometric and sedimentation volume studies were carried out on hydrogen clays prepared out of six different Indian bentonites. The same experiments were repeated after treating the clays with neutral salt. Results were utilised to identify the clay minerals present and also to obtain a quantitative estimation of the montmorillonite content in these bentonites.
TL;DR: The constitution and mineralogy of Indian open hearth and L. D. slags were investigated using chemical, petrographic and X-ray diffraction methods in this paper, where β-dicalcium silicate, wustite and nagelschmidtite were the predominant mineral phases present.
Abstract: The constitution and mineralogy of Indian open hearth and L. D. slags were investigated. Chemical, petrographic and X-ray diffraction methods were followed. All the slags were high in CaO. β-dicalcium silicate, wustite and nagelschmidtite were the predominant mineral phases present. Other phases identified were dicalcium ferrite, tricalcium silicate, monticellite, and brownmillerite. Metallic iron occurred in varying proportions in all the slags. Free lime was present only in L. D. slags.